Category: Biology

The genetic composition of an organism is what is referred to as the genotype. The genotype is composed of a pair of alleles and it is what is manifested as the phenotype or observable characteristics of an organism. The pairs of alleles are confined in a locus having different phenotypic dominance thereby causing dominant and recessive alleles. A population can be sad to be a breeding group where the genetic makeup of individuals is transmitted from a generation to the next. Therefore the genotype frequencies may change from a generation to the next due to factors such as mutation, selection, and genetic drift. The genotype frequency would only remain constant if the population is in the Hardy-Weinberg equilibrium. However, this is a very rare situation in life since it requires special conditions to be able to hold the genotype frequency constant. As the genotype frequency changes, it is possible to have the allele frequency remaining constant. Take for example two parents with blood groups AA and BB who end up producing offspring with blood group AB. The genotype frequency has changed from being homozygous to heterozygous; however, the allele frequency remains to be 1:1. It can therefore be concluded that it is possible for a genotype frequency to change s the allele frequency is constant.

The bright red coloring of male stickleback fish is the phenotypic expression of their genes. On mating with the female stickleback fish, they produce offspring that either has the bright red coloring or a blend of the two colors. Since the bright red coloration makes them conspicuous, the predators become prone to being preyed on by the predators. In a situation where all the predators are removed from the environment, the population of the bright red coloring male stickleback fish increases. Once their population increases and the fact that they are preferred mates of the female stickleback fish there will be an increased number of offspring with bright red coloring. The reason behind this is that the bright red coloring is a result of a dominant gene that expresses itself in the offspring. However, this situation will not be arrived at immediately. It will be progressive with the first set of offspring having a partly bright red colored population then after subsequent generations of mating the whole population is highly composed of the bright red colored stickleback fish.

According to the context of natural selection which essentially entails a trait being prevalent or less in a population the above situation is based on the same. Natural selection could either be a result of survival or reproduction in the population. In the case of the stickleback fish, both mechanisms are applied to make the bright red-colored stickleback fish dominate the population. Survival mechanism is applied when the predators are all removed from the environment to make the bright red colored male stickleback fish safe hence increasing their numbers. At the same time, reproduction comes in since the bright red colored stickleback male fish is preferred by the female stickleback fish as their mates. Therefore an increase in their numbers would enhance reproduction hence increasing the population of the bright red colored stickleback fish in the environment.

Molecular biology, along with GenBank plays an important role in genetic disorders. More than 200 single-gene disorders have been detected. It determines the molecular genetic defects in various diseases. These include amongst others cystic fibrosis, sickle cell anemia, and thalassaemia. Modes of inheritance are essential knowledge in genetic counseling and antenatal diagnosis.

Interest is fast increasing to determine nucleotide sequences. Articles are appearing to determine the sequences. Gen Bank and various journals are trying hard to publish nucleotide sequence data. Briefly, the nucleus synthesizes messenger RNA (mRNA). It conveys genetic information in code through the pores in the nucleus. mRNA is formed in DNA strands. In addition, DNA directs the synthesis of specific mRNA. The mRNA coming out of the nucleus conveys the DNA message to the protein-synthesizing center (ribosome) of the cytoplasm. It is attached to the surface of the ribosome to direct the ein synthesis. GenBank is the fundamental element of Molecular biology. It is the sequence formed and stored in the database of the entire genome of life.

Molecular basis of genetics

Deoxyribonucleic acid (DNA) is the storehouse of genetic information. It is a polymer consisting of two strands. Theses two wounds other. Thus a helix is formed. Every single strand consists of a basic unit called nucleotides. On the other hand, nucleotides are composed of three very important parts namely, a pentose sugar molecule known as 2-deoxyribose, a phosphate group, and a nitrogenous base. There are four different nitrogenous bases. These can be further classified into the pyrimidines cytosine (C) and thymine (T) and the other are purines (adenine (A) and guanine (G).

Phosphodiester bonds join the nucleotides into polynucleotide strands. When two of the strands wound up, they form the double helix of DNA. The phosphatee group of one nucleotide and the 5 carbon of the deoxyribose form phosphodiester. Thus, phosphonucleotide has a sugar-phosphate backbone. This sugar-phosphate backbone has a 5 end and a 3 end. The two strands of DNA are held up by the hydrogen bonds between the bases. The length of the DNA is measured by number of base pairs (bp). DNA 1000 bp long is one kilobase pair (km) in length. (Tanaka, 101-113)

Genes

A gene is a portion of a DNA molecule. Genes instruct formation of specific proteins. Number of genes in human beings varies from 30.000 to 100,000 in number. Size of genes varies greatly. The enzymatic function of the cell can decipher one of the many polynucleotide chains of DNA. It can verify particular sequence of a base pair, which constitute a gene. Gene for the muscle protein known as dystrophin may contain millions of base pairs.

Transcription

There is a particular order in a polynucleotide strand in recognizing short DNA sequences of As, Cs, Gs and T3. This particular order differ them from the other. This is the upstream sequence of the gene and is demarcated as the promoter sequence. There are different promoters in different genes. RNA polymerase, an enzyme, pinpoints the DNA sequences in the promoter site. When the sequence TATAAAT is recognized, it binds into the DNA. This is described as the TATA box. This is situated about 35 bp upstream, the site where transcription begins. The RNA polymerase transcribes the DNA sequence. Thus, it becomes single stranded molecule known as ribonucleic acid (RNA). The RNA polymerase follows the route along the strand. It stops transcribing when it reaches the end of the gene.

RNA splicing

Splicing follows transcription in the nucleus of the cell. Enzymes cut the coding sequences and subsequently spliced together. Messenger RNA is thus formed. Then it finally passes into the cytoplasm.

Translation

Organelles ribosomes in the cytoplasm can distinguish RNA sequence. They prepare amino acids in the polypeptide chain. This is encoded by the spliced mRNA. The sequence in the nucleotides is later translated into a polypeptide.

A ribosome is linked to the mRNA. The first nucleotides are possibly regulatory sequences. The middle region of the mRNA is the coding region. These extend over thousands of base pairs. The nucleosides at the end of mRNA are mostly of regulatory sequences.

The nucleotides in the coding region remain as sets of three. Three attached nucleotides, as a group is known as codon. Each codon acts as a specific instructor for an amino acid. It has two instructions for the amino acids. An amino acid may be added to a peptide chain or it may stop the chain. For these instructions, this is known as genetic code. Small RNA molecules in the cytoplasm carry amino acids in the polypeptide chain. These are known as transfer RNA (tRNA). Each tRNA has specific function for one amino acid. It has also three unpaired nucleotide bases. This is anticodon. It has its complimentary codon in the mRNA. The tRNAs carry specific amino acid to the codons of the mRNA. However, there are some other codones, which do not have coding functions for amino acids such as UAA, UAG and UGA. These are stop codones. Translation stops with these codones if ribosome finds one such codone. No amino acids are added to the polypeptide chain. Finally, ribosome and mRNA drift apart.

Mutation

DNA replication is a very intricate and accurate process. Still aberration occurs. These produce changes or mutations. Various factors are responsible for it. These can be enumerated as ultra violet light, radiation or chemicals. Transcription and translation affects the gene by changes in the amino acid sequence in the protein, which remains confined within the gene. However, in some cases protein functions are maintained yet some may cease or absolutely change. These lead to clinical disorder. Mutations are of different types.

Point mutation

When one nucleotide is substituted for another codone, it changes in a coding sequence. This is the simplest type of change. Lysine changes to arginine when AAA is mutated to AGA. When a critical part of the produced protein is changed, a grave clical disorder follows. Generally, substitution do not always seriously affect the function or stability of the protein produced. However, several codones act for the same amino acid. Nevertheless, mutation in beta-globine gene produces sickle cell disease. Valine is incorporated instead of glutamic acid within the poypeptide chain.

Insertion or deletion

Serious changes are found when there is insertion or deletion in one or more bases. With insertion of one nucleotide or deletion of one nucleotide, the sequence is changed. Different amino acids enter the polypeptide chain. Such changes are responsible for thalassaemia of some forms. Many hundred pairs of base pairs of DNA can be involved by insertions or deletions.

Splicing mutations

Abnormal splicing mutations may change intron sequences. It alters the amino acids incorporated within the poypeptide chain.

Termination mutations

When the ribosomes, which process the mRNA, stop codones, normal polypeptide chain terminates. Premature termination or late termination will result in mutations involving these codons.

Techniques for DNA analysis and isolation of genes

Use of recombinant DNA has led to in-depth study of functioning of genes and the pathology of diseases arising out of genetic disorders. Preparation of genomic DNA is the first step in studying the DNA of an individual. 20 ml of blood is drawn. Lymphocytes are made to break open the nuclear membrane and cell membrane too. Chromosomal DNA is extracted chemically. As DNA is very stable it can be stored frozen for many years.

Restriction enzymes cut genomic DNA into many fragments. These enzymes are obtained from bacteria. Recognition of specific DNA sequences is done by these enzymes. They also cut double-stranded DNA at these sites. Human genomic DNA is cut into huge number of fragments. Size and charge of DNA can be determined by electrophoresing the DNA by a gel matrix. Molecular size could be distinguished and it helps in long-range mapping of the genome to diagnose major deletions and rearrangements. (Kameyama & Nakagoshi, 205-216)

Conclusion

Southern blotting and DNA probes visualize individual DNA fragments..Presence or position of a particular gene can be settled using a gene probe. Blotting RNA fragments is known as Northern blotting and blotting proteins is called Western blotting.

With in a few hours the polymerase chain reaction can amplify over a million times minute amounts of DNA. The exact DNA sequence, which has to be amplified, has to be known before hand. Polymerase chain reaction allows millions of amplifications. Genetic research has thus bean revolutionized by this technique. Buccal cell scrapings, blood spots or single embryonic cells can be amplified. DNA cloning can be done by isolating and inserting a DNA fragment into a vector.

References

1. Kameyama, Yoshiaki, & Nakagoshi, N. Patterns and levels of gene flow Molecular Ecology 10.1 (2008): 205-216.
2. Tanaka, Seiji, Systematic mapping of autonomously replicating sequences Yeast 12.2 (2007): 101-113.

Introduction

Cancer is one of the main causes of death in most parts of the world, especially in the Western World. It is the second killer in the USA and in a number of European counties after cardiovascular diseases. Cancer is an abnormal growth of cells that results from changes in gene expression. This causes uncontrollable cell multiplication and proliferation in the body of human beings. It is a condition that can easily cause death when the growth of these cells is not taken care of or not detected and treated early enough. Cancer is basically a group of diseases of higher multi-cellular organisms (Melmed & Conn 39).

Cancer is a family of diseases that is complex and involves carcinogenesis which causes the normal cells in the body of humans to turn into cancer cells. It is a complex process which involves a large group of diseases going up to a hundred or more. These diseases have varying ages of onset, rate of growth, state of cellular differentiation and response to treatment among others. From a molecular and cell biological point of view, cancer is taken a small number of diseases that result from alterations to cell genes.

It is basically a disease of abnormal gene expression. The process of the cancer formation is a complex mechanism characterized by a direct insult to DNA such as a gene mutation, translocation, deletion and amplification among others. All these mechanisms prevent cell death and escalated cell multiplication to an unmanageable level causing the tissues to expand. under normal circumstances, cell proliferation and death are in a state of equilibrium enabling an organism to function normally. Cancer formation is, therefore, a complex process. This paper seeks to interpret the role oncogenes and tumor suppressors play in transformation during cancer formation.

The role oncogenes and tumor suppressors play in transformation

Tumor formation is a process that involves multiple steps. The process involves the uncoupling of interdependent mechanisms of cell proliferation and differentiation. Mostly, the growth of mutant cells is catalyzed by the mutations of either protooncogenes or tumor suppressor genes.

This enables the mutant cells to proliferate at a higher speed than normal cells. This alters the interactions of these cells with their surroundings leading to local invasion and distant metastases. The recent studies in cellular photoocogenes and tumor suppressor genes have improved our understanding of molecular basis of tumorigenesis.

Role of oncogenes

According to Melmed & Conn (23), an oncogene is a gene in the body of an organism with the potential to cause cancer. These genes are usually mutated in tumor cells. In normal cases, the normal cells die after some time and their death is programmed which is called apoptosis. The oncogenes have the ability to make cells that ought to die survive and continue proliferating. However, for oncogenes to cause cancer, they must be accompanied by other processes, such as mutations in another gene.

The oncogenes result from normal gene called proto-oncogene after they are mutated or become highly expressed. Cancer therefore results from the alterations that take place in oncogenes. The alterations of tumor suppressor genes and micro RNA genes may also cause cancer. According to Croce, These alterations are usually somatic events, although germ-line mutations can predispose a person to heritable or familial cancer (1).

A malignant tumor is not caused by a single genetic change but a multistep process of sequential alterations of oncogenes and other genes. It is worth mentioning that, Oncogenes are found in normal cells and encode proteins involved in the control of replication, apoptosis (cell death) or both and they are involved in the normal function of the cell, but if activated can turn that cell into a cancer cell (Fischer 1). The activation of these genes takes place in a number of ways like gene amplification, chromosomes rearrangements and mutations as well. The process may occur due to a number of reasons.

The simple case is where there are single point mutations involved. This affects a single base in DNA which has harmful effects for the ells. There are also complex cases involving larger mutations whereby part of the gene is deleted or a new genetic material is inserted in a cell. This may take place during normal cell replication or results from alteration of the structure of a nucleotide in a cell. This is normally caused by external factors like carcinogens.

There are also viruses that can cause mutations. They do so by inserting genome into the cell thus changing the structure of the gene. Other expression which also causes cancer may happen when there is introduction of promoter.

Tumor Suppressor Genes

According to American Cancer Society, Tumor suppressor genes are normal genes that slow down cell division, repair DNA mistakes, or tell cells when to die (a process known as apoptosis or programmed cell death (2). When these genes are not properly working they tend to grow in an uncontrollable rate. The uncontrollable growth of cells leads to cancer.

The Tumor Suppressor genes may include TP 53 and BRCA1 among others. Their role is to prevent the cells from dividing too quickly. When the genes are interfered with, especially die to mutations, the cell division may occur uncontrollably. Centrally to oncogenes, tumor suppressors cause cancer when they are activated (Ruddon 15).

The RB gene was the first tumor suppressor gene to be discovered and their changes are likely to cause cancer. Mostly, the kind of cancer caused by these changes is referred to as retinoblastoma which is very common in children. The problem is mostly found in children and normally affects the eyes. The mutations of RB genes may be spontaneous or even passed to the children from the mother. The genes therefore play a key role in the growth of cancer.

Conclusion

Cancer is a leading killer disease in the world. There are many people who have succumbed cancer in the world. The alterations in the normal process of the cellular replication are the sole reason for emergence of cancer. The process of cancer formation is a complex one and involves a number of mechanisms that take place in the cell. There are usually multiple genes that are involved in the progression of cancer when they suffer defects due to mutations.

The effects of these defects are that the cell loses control over its replication and proliferation. This also results to overgrowth of the tissues which causes cancerous tumor. The oncogenes, and tumor suppressor genes are the main group of genes that cause cancer when they are damaged. Cancer is therefore a very serious disease and there is a need to know the best measures to curb it.

Works Cited

American Cancer Society 2008, Oncogenes, Tumor Suppressor Genes, and Cancer. 2012. Web.

Croce, Carlo. Oncogenes and Cancer. N Engl J Med, 358 (2008): 502-511. Print.

Fischer, Alexis. The role of oncogenes in cancer, USA: Helium, Inc. 2010. Print.

Melmed, Shlomo and P. Michael Conn. Endocrinology: Basic and Clinical Principles. New Jersey: Humana Press, 2005. Print.

Ruddon, Raymond. Cancer Biology. Oxford: Oxford University Press, 2007. Print.

Fridell (2005, p.8) defines Polymerase Chain Reaction (PCR) as a scientific technique that is applied in molecular biology to amplify a single or specified number of DeoxyRiboNucleic acids. In addition, Park (2004, p.587) claims the PCR technique is used to produce a large number of copies of a particular specific DeoxyRiboNucleic Acid sequence. The DNA sequences are utilized in studies that involve DNA cloning, to conduct DeoxyRiboNucleic Acid-based Phylogeny or when there is a need to carry out functional analysis of genes as documented by Pierce and Wangh (2007, p.75). PCR technique finds application in studies concerned with diagnostic of hereditary disease and conducting genetic fingerprint identification which results in gene matching to identify paternity.

This essay provides different reasons that have made the PCR technique a significant invention in molecular biology to date.

Rainbow (1996, p.2) claims Polymerase Chain Reaction (PCR) technique to be the single most important methodological invention in molecular biology citing PCR as an applied routine procedure in molecular biology (p.4). Fridell (2005, p.88) argues that the PCR technique is applied in the identification and classification of genetic material. Some of the processes whose success depends on PCR technique include cloning, gene sequencing, mutagenesis studies, molecular diagnostic research and genetic analysis (Lawyer et al, 1993, p.23). Khan et al (2008) document that every emerging application of PCR technique has continued to demonstrate competencies in transforming molecular biology.

Ochman et al (1990, pp.623-5) argument claims that the PCR technique has gained wide application in the cloning of genes. The capability to adopt the PCR technique in gene cloning has contributed to the capability to attain a diverse range of genes through mutagenesis and gene recombination which has continued to find application in genetic engineering and the development of drugs through the use of microbes like bacteria. PCR technique has provided foundation for conducting analytical and descriptive studies on functionality of genome. PCR technique has been adapted in mutagenesis studies with aim of identifying gene expression and functional relationships of different protein structure (Rychlik et al, 1990, pp.6410-11). PCR technique has been documented by Pierce and Wangh (2007, pp.66-70) to provide basis for understanding protein-protein interaction, protein engineering and mechanism through which molecular evolution has occured

Khan et al (2008) studies reported that PCR technique is dependent on three cyclical steps namely denaturation phase, annealing phase and extension phase. Denaturation results into conversion of Double helix into a single helix, immediately DNA primers are annealed into complementary single helix DNA. The extension phase of DNA is dependent on support synthetic processes that are dependent on DNA polymerase. The three phases are temperature sensitive and ought to be carried out at specific phase temperature. PCR techniques utilize heat stable DNA polymerase for instance Taq polymerase¹ hence themocycling property of the PCR technique. Pierce and Wangh (2007, pp.72-77) claims DNA polymerase has capability to assemble new copies of DNA from its building units. This process involves use of nucleotides for instance a single stranded DNA as template and a DNA primer for instance DNA oligonucleotides. The elements form basis for initiation process for DNA biosynthesis in vivo or in vitro.

Mueller and Wold (1988, pp.780-86) proposed that PCR technique could be used to carry out early diagnosis of malignant tumors for instance leukemia and Lymphomas. This makes it possible to start early cancer management care hence capability to enhance patient quality of life. This reduces hospital length of stay and forms foundation for early home care for cancer patient. In addition, Sharkey et al (1994, pp.506-9) claims PCR technique could be adopted in PCR assay in order to identify translocation specific malignant cell. When conducting PCR assays, PCR technique provides basis for determination of genomic DNA samples. Zietkiewicz et al (1994, pp.176-83) noted that PCR technique could be adopted towards identification of DNA samples that cannot be cultivated hence saving time and costs. PCR can be applied in DNA samples that demonstrate characteristic feature of slow growths. Examples of slow growing micro-organisms include mycobacterium and anaerobic bacteria. This makes PCR an important tool towards diagnostic applications. As a result, it is PCR has made it possible to detect, isolate, identify and classify nature of infectious microbes (Naber, 1994, pp.1508-10). Similarly, Arnheim et al (1990, pp.177-9) claims PCR technique provides backbone for classification of organisms.

According to Mueller and Wold (1988), PCR technique provides basis for early determination of viral DNA post infection. In addition, Naber (1994a, pp.1508-10) studies determined that Viral DNA detection could occur before observation of clinical signs of the disease which provides physician an early strategic management of the disease. This is carried out through determination of viral load through use of PCR-based DNA quantification processes. Other documented application of PCR technique includes capabilities to determine or estimate population size of specified species (Khan et al, 2008; Ochman et al, 1988). PCR has been applied in determination of dispersal of seeds. This forms basis for determination of reproductive efficiencies of plants hence capability to determine natural factors that affect fertility (Arnheim et al, 1990).

Pierce and Wangh (2007, pp.78-81) studies proposed that PCR technique could be used in selective isolation of DNA molecules. The isolation of DNA occurs through selective amplification of specified portions of DNA. This process results into generation of hybridization probes for example Southern hybridization or Northern Hybridization as documented by Fridell (2005, pp.102-109). Lawyer et al (1993, pp.46-9) claims PCR technique finds application in DNA cloning that relies on DNA isolation technology. Isolation of DNA for instance genomic DNA requires larger quantities of DNA. Thus, PCR amplifies DNA which makes it possible to conduct DNA isolation hence providing required support for Northern hybridization, Southern Hybridization and cloning of DNA. PCR technique is therefore important towards amplification and provision of pure forms of DNA that can later be separated by Thin Layer Chromatography. Enhanced solid phase PCR could also be applied in separation of DNA as documented by Korf (1995, p.1502).

Khan et al (2008, pp.392-3) proposed PCR has been applied in determination of DNA sequence of unknown DNA through use of unknown PCR-amplified sequencing. This forms basis for genetic engineering and capabilities to expendite recombinant DNA. This involves insertion of DNA into DNA plasmids hence PCR application in screening of DNA vector. PCR technique based on Korf (1995, pp.1499-50) doesnt depend on invasive techniques to get samples for DNA typing and amplification. This implies the studies on an organism DNA doesnt need to disrupt lifestyle of the organism or to seek ethical issues with regard to use of human as subjects of research because PCR technique is independent of behavioral perspectives. Samples for PCR technique could be derived from variant sources for instance urine or faecal matter (Khan et al, 2008, p.391-3).

PCR technique finds application in tiny samples of DNA. This is achieved due to capacity of PCR to contribute into DNA amplification. Fridell (2005) advanced argument that PCR technique works with minute samples for instance feces, scents, hair follicles; skin rubbed on trees or urine samples. This has been applied in forensic analysis and fingerprinting or DNA typing (Sharkey et al, 1993). This has resulted into capacity to utilize trace amounts of samples in order to determine DNA sequence through amplification of the DNA. This means PCR technique is instrumental in forensic analysis via DNA typing and fingerprinting. Other authors for instance Mueller and Wold (1988, pp.780-786) claim that in DNA typing (Cohen, 1995), only small sample of the victim is required from sources like the sweat of the victim extracted from cloths, sputum or saliva. PCR has revolutionized DNA fingerprinting. This has made DNA typing to be employed as strong evidence against a criminal.

Housman (1995, pp.318-20) advanced the argument that PCR technique could be used to determine the number of species that inhabited a given region. This knowledge is vital towards determination of evolutionary process of the organism. Through analysis of DNA sequences of the organisms that inhabited a given area and those that currently occupy the region, it could be possible to determine Genetic revolution that has occurred subject to phenotypic demand for survival.

The capability of PCR technique to be applied in determination of DNA sequence is independent of age of the DNA sample. PCR has been applied successfully in Ancient DNA genetic sequence analysis and determination of DNA sequence of damaged ancient DNA material. This implies PCR has profound application in archeology and evolutionary biology. Korf (1995, pp.1499-1502) claims that PCR has potential to be utilized in correcting errors that have previously been made when carrying out DNA analysis. This makes it possible to correctly classify animals and plants that have become extinct into their own species and families (Markham, 1993). As a result, PCR helps to distinguish species that demonstrate similar physiological relationships yet fall in different families for instance the extinct moas bird of New Zealand that resembled extant New Zealand Kiwi that are different though cannot fly (Arnheim et al, 1990, pp.174-182).

Service (1995, pp.26-7) claims PCR is envisioned to contribute into future capability of decreasing costs of biotechnology research and increasing accessibility to biotechnology and genetic engineering technology into other fields of study. PCR is envisioned to contribute into capabilities to reproduce genetic content and facilitate in genetic analysis of any genetic based material regardless of age hence PCR is envisioned to add value to the archeology through determination of genetic composition, DNA sequence of ancient organisms hence forming an important research tool for genetic evolution studies.

In conclusion, it is clear from evidence from different molecular biology studies and application that that PCR technique represents the most important invention in the history of molecular biology to-date.

References

Arnheim, Norman; Tom White, and William E. Rainey (1990) Application of PCR: Organismal and Population Biology, BioScience 4:174-182.

Cohen, Jon (1995) Genes and Behavior Make an Appearance in the O.J. Trial, Science 268.

Fridell R (2005). Decoding life: unraveling the mysteries of the genome. Minneapolis: Lerner Publications. pp. 88

Housman, David (1995) Human DNA Polymorphism, 332:318-320.

Khan Z, Poetter K, Park DJ (2008). Enhanced solid phase PCR: mechanisms to increase priming by solid support primers. Analytical Biochemistry 375(2): 391393

Korf, Bruce Molecular Diagnosis, 332:1499-1502, 1995

Lawyer FC, Stoffel S, Saiki RK, Chang SY, Landre PA, Abramson RD, Gelfand DH (1993). High-level expression, purification, and enzymatic characterization of full length Thermus aquaticus DNA polymerase and a truncated form deficient in 52 to 32 exonuclease activity. PCR Methods Appl. 2(4): 275287

Markham A.F. (1993) The Polymerase Chain Reaction: A Tool for Molecular Medicine, British Medical Journal 306:441-447.

Mueller PR, Wold B (1988). In vivo footprinting of a muscle specific enhancer by ligation mediated PCR. Science 246(4931): 780786

Mullis Kary (1990) The Unusual Origin of the Polymerase Chain Reaction, Scientific American.

Naber, Stephen P. (1994) Molecular Pathology: Diagnosis of Infectious Disease, 331:1212-1215.

Ochman H, Gerber AS, Hartl DL (1988). Genetic applications of an inverse polymerase chain reaction. Genetics 120(3): 621623

Park DJ (2004). 3RACE LaNe: a simple and rapid fully nested PCR method to determine 32-terminal cDNA sequence. Biotechniques 36(4): 586588, 590

Park DJ (2005). A new 52 terminal murine GAPDH exon identified using 5RACE LaNe. Molecular Biotechnology 29(1): 3946

Pierce KE and Wangh LJ (2007). Linear-after-the-exponential polymerase chain reaction and allied technologies Real-time detection strategies for rapid, reliable diagnosis from single cells. Methods Mol Med. 132: 6585

Rabinow, Paul (1996) Making PCR: a story of biotechnology (University of Chicago Press)

Rychlik W, Spencer WJ, Rhoads RE (1990). Optimization of the annealing temperature for DNA amplification in vitro. Nucl Acids Res 18(21): 64096412

Service, Robert F. (1995) The Incredible Shrinking Laboratory, Science 268.

Sharkey D.J., E.R. Scalice, K.G. Christy Jr., S.M. Atwood, and J.L. Daiss (1994). Antibodies as Thermolabile Switches: High Temperature Triggering for the Polymerase Chain Reaction. Bio/Technology 12: 506509.

Zietkiewicz, E., A. Rafalski, and D. Labuda (1994). Genome fingerprinting by simple sequence repeat (SSR)-anchored polymerase chain reaction amplification. Genomics 20(2): 17683

Footnotes

1. Taq Polymerase is extracted from bacterium Thermus aquaticus

The collection of like cells that have an identical origin which carries out a definite function together is what I am. I can only exist if there is a cellular level organization that is intermediate between cells and an organism (Starr, Beverly 67). These cells have similar functioning even though they might not be identical. When several different us are brought together, an organ is formed. I am a tissue.

We have cells with the capacity to contract causing movement of a part of a body. We are formed by contractile muscle cells. It is a soft tissue found in animals. There are three common types of us. The skeletal type that is held to the bone by tendons and its functions are in movement and posture. Smooth type is found within the epithelia. Some examples of the smooth type include arrector pili in the skin, stomach, uterus, intestines, esophagus, bronchi, and urethra among many others. The smooth type does not exhibit conscious control. The cardiac type is another involuntary one of us. It is more analogous in the constitution to skeletal type. It is found in the heart. The Cardiac type undergoes contractions and relaxations allowing the heart to pump blood around the body. Skeletal and cardiac types have sarcomeres crammed into highly even measures of packages. The cardiac type has bundles that join at uneven branching angles. These are called intercalated discs. Such types have short intervals of contractions and relaxations. The smooth type has the ability to sustain longer contractions that can sometimes be permanent. Proteins that make us a contract and relax are actin and myosin (Starr, Beverly 72). We are the tissue muscles.

The epidermis is the peripheral layer of the varies. Its thickness varies, the thinnest epidermis on human skin being about 0. 05mm. and the thickest 1. 5mm. There are five layers in the epidermis, namely stratum corneum, stratum licidum, stratum granulosum, stratum spinosum, and stratum basale from the top to the bottom (Starr, Beverly 68). The stratum basale cells are column-shaped and are actively dividing. The cells in the higher levels are flattened and dead (Starr, Beverly 68). The stratum corneum has of the dead, flat skin cells shed after every fourteen days. The epidermis has keratinized stratified squamous epithelium (Starr, Beverly 68). The cells present are of four different types: the keratinocytes produce keratin, a protein that is waterproof and toughens the skin. Melanocytes produce a pigment that offers the protection of the cells from UV radiations known as melanin. Langerhans cells have phagocytic macrophages. They interact with the white blood cells for immune response. The Merkel cells are found deep in the epidermis they serve a sensory function.

The hair is an extension of filamentous cells. It contains keratin and grows in the dermis from the follicles. There are three layers in the hair shaft, namely cortex, medulla, and cuticle (Starr, Beverly 68). The outermost sheet is the cuticle; it is a see-through tissue and makes hair shiny. The innermost layer is the medulla; it is set up by large cells. The middle layer is the cortex; it has coloring agents and keratin. The extent and the form of hair are cortex controlled. Hair contains some amount of water that helps in the maintenance of moisture and the balancing of physiological and biochemical properties. The hair follicle is a part of hair sunk below the scalp. This is where the hair shaft originates (Starr, Beverly 68).

References

Starr, Cecie, and Beverly McMillan. Human Biology. 9th ed. Stamford, Connecticut, U.S.: Cengage Learning. 2012. Print.

In reality, the human body is an extraordinarily complex and multistage system characterized by genetic malfunctions. Mutations in certain regions of DNA can cause pathological metabolic abnormalities or hereditary features realized through dysfunctional disorders. One such condition is sickle cell anemia, which has a genetic basis. Typically, the human blood contains the active protein Hemoglobin, which is several branched chains.

When the HBB gene located in chromosome 11 is damaged, the synthesis of normal hemoglobin A is disrupted, and instead, the body produces hemoglobin S, which changes the shape of red blood cells (HBB Hemoglobin). This, as is known, sickle cell anemia is inherited by autosomal recessive type: this type of inheritance means that for guaranteed disease, the patients genotype must be represented by two recessive alleles mutation itself localized not in the sex chromosome.

In the case of incomplete dominance, two forms of red blood cells in approximately equal numbers (Sickle Cell Anemia) are observed in the patients blood at once. However, the presence of elongated blood cells in the body does not mean that the individual is sick. In fact, such a patient is a carrier of a recessive gene, or in other words, a sickle cell trait, whereas sick people show a full symptomatic spectrum.

According to the proposed scenario, the man is a sick patient, while the woman is absolutely healthy and is not a carrier of the latent gene. Given the nature of the inheritance of sickle cell anemia, the scheme below can be considered. For instance, Johns genotype is homozygous and recessive for this trait, while the Anns genotype, on the other hand, is dominant. Then, their gametes fusion produces zygotes in which both the dominant and recessive alleles are present. This means that these parents children will not have the pathology, but they will be carriers of the gene. Therefore, their offspring may be susceptible to the disease, depending on the genotype of the future partner.

Work Cited

Sickle Cell Anemia. Cleveland Clinic, 2019. Web.

HBB Hemoglobin Subunit Beta. NCBI. 2021. Web.

A scientific method is a form that which scientific questions are asked and answered through observations and experimenting (Starr 1). The first step in a scientific method is the inquiry of a question about an observation made. The second step involves doing background research on the question. This gives more information on what has been done about the issue. The third step involves the construction of a hypothesis, which is a well-informed guess about what resulted in the question. The fourth step is to test the hypothesis experimentally to ascertain whether the hypothesis is true or faulty. It is important for the experiments to be in replicates because this improves the accuracy. The fifth stage involves data analysis and conclusion. This confirms whether the hypothesis is true or false. A new hypothesis has to be constructed if the previous one is false. The final stage is the explanation of the results. This can be done through a report. (Starr 1).

A carbohydrate is an organic compound. It is made up of oxygen, carbon and hydrogen. Polysaccharides, monosaccharides, oligosaccharides, and disaccharides are the types of carbohydrates. (Starr 28). Polysaccharides function is to store energy, like cellulose in plants. Monosaccharides serve as coenzymes and the structure of RNA. The knowledge of carbohydrates will boost my understanding as to why we require carbohydrates in our bodies and what kind of problems are associated with excessive consumption of carbohydrates (Starr 28).

Proteins are compounds with one or more polypeptides. The order of amino acids in a polypeptide is controlled by the gene sequence. Proteins are essential in living things as they participate in all processes within a cell. In the study of biology, the knowledge of proteins is very important as it enables a person to make informed decisions while choosing a balanced diet. A person is also able to tell which kind of food will provide the body with amino acids that the body cannot synthesize (Starr 33).

The Golgi apparatus is a cell organelle found in the cytoplasm of a cell. It is composed of several cisternae, which are membrane-bound. The Golgi apparatus sorts modifies and packs macromolecules before secretion. It is also involved in the creation of Lysosomes and the transportation of lipids (Starr 50).

The Mitochondrion is a membrane-enclosed to the cell organelle. It has two membranes, the outer and the inner membrane folded forming the cristae. The inside of a mitochondrion there is a matrix, which is a mixture of enzymes. The functions of the mitochondrion are energy production through respiration and regulation of cell metabolism (Starr 52).

Diffusion is the movement of particles from a region of higher concentration to a region of lower concentration, along a concentration gradient. This process does not require energy. Diffusion results due to thermal energy found in particles as the temperature is above absolute zero. The rate at which diffusion takes place is affected by the permeability of the cell membrane. A process when substances are assisted across the membrane by transport proteins is called facilitated diffusion (Starr 54).

Cellular respiration is a process in which cells break down food substances to yield energy (ATP) inside the cell. There are two types of respirations: aerobic where oxygen is used and anaerobic where oxygen is not used. The energy released during respiration is used in the synthesis of ATP, a form in which this energy is stored (Starr 59)

References

Starr, Cecie, and Beverly McMillan. Human Biology. 9th ed. Brooks: Cole Publishing Co., 2012. Print.

The article chosen explores such an aspect of evolutionary biology as phylogenetic analysis. More specifically, it is known that phylogenetic analysis with the construction of a tree is a tool in the hands of biologists to study the relationship between species or strains. Such a tree makes it possible to trace not only the genetic (phylo-) proximity between taxa but also to determine approximately the dates of their evolutionary divergence, as well as to understand who could be their common ancestor. However, it is clear that since phylogenetic analysis works with vast amounts of DNA or RNA data, the statistical significance of such results requires high reliability. In this paper, Shepherd and Klaere (2019) propose several useful tests to assess the fit of a phylogenetic model to the data. Specifically, the authors go through several popular statistical tests of fit and offer a critical evaluation of them. In doing so, Bayesian statistics based on PP distributions carry a high academic weight for phylogenetic analysis, according to the authors.

As such, no new technology was cited in this study, but metaphorically, Shepherd and Klaere brought theoretical novelty to the foundations of phylogenetic analysis. More specifically, they consistently and critically delineated the limits of model fit tests to the data and determined not only the type of test that was best but also why such a test should be conducted at all. It could be said that the authors used the technology of meta-analysis of current research and critical appraisal to determine the ultimate answer: it is Bayesian statistics.

It should also be said that this article was away from all practical research discovering new species. Indeed, Shepherd and Klaere (2019) did not introduce a new taxon to the community or discover excellent metabolic properties of one of the viruses, but they seem to have done much more. The significance of their work is assessed at the level of interspecies relationships and fundamental biology, as it is clear that the number of new species will continue to grow, and the genomics will continue to become more complex. Consequently, critical analysis of fit tests is an essential part of future phylogeny, necessary to ensure the reliability, fidelity, and accuracy of sensitive results.

Reference

Shepherd, D., & Klaere, S. (2019). How well does your phylogenetic model fit your data? Systematic Biology, 68(1), 157-167.

Herbert Spencer is one of the outstanding scientists belonging to the sphere of biology, sociology, and anthropology. He is also known as the author of social Darwinism, presupposing that superior physical force shapes history, and the fittest will survive, while other species will become extinct (Ritzer and Stepnisky 152). At the same time, he tried to apply the ideas of Darwinism to society and create his own ontological system. Thus, Spencer offered his own concept assuming that individuals evolve and, at the same time, precondition the development of society (Ritzer and Stepnisky 152). The thinker started to believe that although evolution begins slowly, its speed increases in time because of different factors impacting communities (Ritzer and Stepnisky 152). Under these conditions, it is possible to observe various effects and how the environment changes over time.

Moreover, Spencer states that social change is unidirectional and depends on factors that can hardly be predicted. Moreover, both evolutionary and progressive changes occur in several sets of stages, vital for the improved understanding of outcomes and the ability to analyze them (Ritzer and Stepnisky 152). In such a way, speaking about social ontology, Spencer was firstly sure that the given phenomenon could be viewed in terms of Darwinism, and its laws can be applied to this process. However, working on the given problem, he introduced his own conceptions, and shifted to a new idea, stating that exact contours of future social life cannot be viewed and lie beyond the intellectual grasp (Ritzer and Stepnisky 157). It means that the analysis of society, its evolution, and possible future becomes an even more complex and sophisticated task that can be performed only considering a various set of factors.

The change in Spencers vision of society and ontology is also followed by the creation of a completely new attitude to the culture, how it emerges, evolves, and impacts human beings. In his early works, Spencer tried to apply the idea of evolutionary thinking to human culture and state that it is an integral part of individuals (Ritzer and Stepnisky 158). However, with the development of the paradigm and the change in his attitudes, Spencer moved to an entirely new view of culture, stating that every class evolves and starts to perform new functions, which also impact the dominant culture (Ritzer and Stepnisky 158). For instance, cogitating about the aristocracy, he admits the shift from mainly military to political functions and the possibility of the further transformation and the creation of a new cultural field shaped by the social evolution.

Altogether, it is possible to conclude that Spencer is an outstanding thinker and scientist who worked in different fields and areas. His contribution to evolutionary theory and sociology cannot be overestimated. Being a representative of Darwinism and the author of multiple conceptions, he managed to form his own theory stating that the changes in the society are unpredictable by specialists and depend on multiple factors. At the same time, he also altered his vision of culture. Spencer was sure that it was an integral part of communities and evolves with them depending on various factors; however, he reconsidered the given idea and assumed that individuals and every class had their own culture different from others and changing over time. In general, his works are vital for the understanding of the ideas of social evolution.

Reference

Ritzer, George and Jeffrey Stepnisky. Classical Sociological Theory. 7th ed., SAGE Publications, 2017.

The Central Dogma

The central dogma is a principle describing the transfer of molecular information in the Nucleus of the DNA. It gives detailed instructions on the processes involved in the conversion of DNA information into a final functional product, the protein. The central dogma was proposed by Francis Crick in 1958 after discovering the DNA structure (Liu et al., 2018). Crick uses the principle of central dogma in suggesting that the DNA has all genetic information required to make all proteins in the body, involving the transfer of specific information from DNA to RNA that finally creates the functional proteins which carry the genetic code in a process known as gene expression (Liu et al., 2018). The flow of this genetic information is irreversible once the genetic information passes from DNA to RNA. Genetic information from DNA controls the type of proteins formed in an organism since it determines the specific traits in different species. The formation of functional proteins through gene expression involves the replication transcription and translation of DNA, where transcription and translation are the key steps.

Transcription

This is a process involved in the formation of messenger RNA (mRNA) through the re-writing and copying of DNA molecules. While DNA stores genetic material in a cells nucleus for long-term referencing, RNA copies the same material but distributes it to other cells since it can easily exit from the nucleus. Although the information copied from DNA is the same, it differs because its only a representation of the actual DNA sequence. For transcription to take place, three stages are involved namely, initiation, elongation, and termination (Liu et al., 2018). The first stage is the initiation process which involves the binding of an enzyme known as RNA polymerase and other assisting transcription factors to a specific DNA promoter and enhancer sequences that guide the RNA polymerase to the right site. When the RNA polymerase binds to the promoter sequence, it unwinds a part of the double helix in the DNA sequence to expose the bases of each strand.

The process then moves on to elongation where RNA polymerase starts the synthesis of mRNA by reading and matching complementary bases. Elongation occurs when nucleotides are added to the mRNA strand and are attached to the unwound DNA strand where the Adenine (A) base of DNA pairs with Uracil (U) base in RNA (Liu et al., 2018). The process of transcription ends with the termination stage in which the mRNA synthesis completes to form an independent strand that unbinds from the DNA sequence. These independent copies are used as blueprints in synthesizing proteins during the translation process.

Translation

In the translation process, the genetic code carried by the mRNA molecule is synthesized and read to produce a particular sequence of amino acids. The process occurs in the ribosomes, which is the site for protein synthesis of both prokaryotic and eukaryotic cells of organisms. Translation requires the mRNA, transfer RNA (tRNA), and ribosomes which enhance the stages of initiation, elongation, and termination. During the translation process, mRNA nucleotides are referred to as codons which are set in combinations of three letters, each representing a specific amino acid. The codons have complementary anticodons contained in tRNA which guide the amino acids to the appropriate site for translation.

Initiation involves the binding of small ribosomal units to the beginning of the mRNA sequence where tRNA binds methionine to the start codon of the sequence (Liu et al., 2018). The initiation process is completed when large ribosomal subunits attach forming a complete complex. In the elongation process, ribosomes continue the translation of all codons and corresponding amino acids are added to the chain which is connected by a peptide bond. When all codons are read, the termination process occurs where ribosomes reach the stop codon which is not recognizable tRNA molecules marking the end of translation. New proteins are released and the translation complex breaks apart.

Reference

Liu, C. C., Jewett, M. C., Chin, J. W., & Voigt, C. A. (2018). Toward an orthogonal central dogma. Nature Chemical Biology, 14(2), 103-106. Web.