Natural Selection Process - Essay Example

a). Natural selection is the process in which nature allows the survival of organisms that are highly adapted because they have traits that give them an advantage, they are able to produce and transmit their traits to the next generation. A trait like skin color lets say for beetles, makes it possible for the green beetles to be eaten by the predators while the brown ones lives to reproduce hence increasing the population of the brown beetles. b). According to Darwin’s theory of evolution by natural selection those members of species that are capable of surviving to reproduce and are able to transmit their characteristics are mote fit. A mother of seven is more fit than Bill gates because they have spread their traits wide. This increases the chances of the existence of their traits. c). Darwinian fitness cannot be translated into a measure of ‘might is right’, payment or wealth. According to the theory of natural selection, members of species are able to survive through getting adapted to the environment and that makes them able to live to productive age, at this age they produce offspring that pass over their traits. Therefore, irrespective of wealth and might nature can act on any member of a species. d).The peppered moth of England case study is a good example of natural selection. Britain in 19th century witnessed an industrial revolution whose pollution resulted to darkening the backs of trees while killing the lichens that were growing on the back. Before the revolution, moths were pale colored hence they could hide on the back. However, with the darkening of the trees, the moths became clearly visible and could be eaten by birds. This resulted to a decline in the population of pale moths. On the other hand, there were rare dark moths, which were more exposed to predation before the industrial revolution. The darkening of the barks gave them an advantage since the birds could not easily spot them. This caused a dramatic change in population with the dark moths dominating the pale ones. This is a classic example of natural selection where the moths survive based on their traits that allow them to escape predation. e). ‘Sexual selection’ involves the capacity of individuals to secure their mates. The individuals that are better is getting mates are capable of out-reproducing the rest. Sexual selection is based on the ability of the males to possess females as well as features such as color, ornament, structure among others. For example, men that are shy and fear approaching women will be overshadowed by the charismatic ones in getting sexual partners. 2. a). Darwin observed that traits are passed from the parent to the offspring through reproduction. b). Gregor Mendel provided an understanding of how traits are transmitted from the parent to the offspring. He is credited as the ‘Father of Genetics’. He conducted his breeding experiments mainly using garden pea. His observations were that organisms exhibited two forms of a trait which he coined the word ‘allele’ to describe them. His findings established a member of a species can have two similar alleles or they can be different, one of each form. Same alleles indicate homozygosity while different alleles indicated heterozygosity. The studies concluded that traits do pass to the offspring in units, each parent contributes a discrete version of the units to their offspring, some recessive alleles do not appear in the phenotype of the offspring and there is independent assortment of genes. c). Meiosis diagram Differences between meiosis and mitosis Mitosis is the duplication of a cell into two daughter cells that are genetically identical while meiosis is the division of the germ cell that includes nuclear fission that results in the production of four gametes. In this case, the sex cells contain half of the chromosomes in from the mother cell. While mitosis occurs in all organisms, meiosis occurs in animals, fungi, fungi and plants. In mitosis, no crossing over occurs while in meiosis crossing over results in mixing of the chromosomes. Meiosis produces four haploid cells that are produced through two phases of division, Meiosis I and II. On the other hand, mitosis produces two diploid cells that are identical and are formed through one division. d). For the case of a 100% Spanish woman that has 100% Irish man, together having a daughter that marries 100% Irish man can result to no Spanish chromosome offspring. During meiosis, there occurs the independent assortment of chromosomes that allows the chromosomes that forms the germ cell to be from either the mother or the father in 50/50 equal chance. This makes it possible to have a no Spanish traits in the above offspring. 3. a). Deoxyribonucleic acid is a double helical nucleic acid molecule that is found in the nucleus of a cell and it encodes genetic information. it is a composite molecule made up of three components, firstly we have the bases namely guanine, cytosine, adenine and thymine. Secondly, we have the phosphate group and finally there are the deoxyribose sugars. On the other hand, a gene is basically a section of the DNA that is capable of coding for a functional polypeptide DNA Gene b). Transcription of DNA: this process the conversion of DNA strands into mRNA strands which are single stranded. This occurs under the activity of enzyme RNA polymerase that is capable of reading the DNA base sequence to produce an antiparallel strand that is complementary except for the base Thymine that is replaced by Uracil in the primary transcript. The process of transcription involves three steps, namely; initiation, elongation and termination. c). Translation is the process in which protein molecules are made from mRNA strands. This process occurs in the ribosomes of the cell. The ribosome complex decodes the mRNA producing specific amino acids that makes up a continuous polypeptide chain. Three bases are decoded to a specific amino acid, the three bases makes up a codon. Once the polypeptide chain is formed it folds hence forming an active protein. translation occurs in four phases, namely; initiation, elongation, translocation and termination d). Hormonal proteins such as insulin that regulates the amount of sugar in the blood Enzymes which acts to speed up the rate of reactions, for example hydrogen peroxidase that catalyzes breakdown of hydrogen peroxide into water and oxygen. Structural proteins which are the building blocks of the muscles, bones, tendons, cartilage and skin they include keratin, collagen. Defensive proteins that protects the body against foreign invasions; they form the core of the immune system and include antibodies. Storage proteins are capable of storing minerals that are essential in the body such proteins include ferritin, casein and ovalbumin. Transport proteins are involved in transportation of important components in the body. These include haemoglobin and myoglobin that transports oxygen in the body. e). Mutations involve a change in the sequence of DNA that usually results in a change of the encoded protein. When the change occurs in one base pair of the DNA strand, it is described as a single-nucleotide polymorphism (SNP). For example, a change in the DNA having from the usual T-A to something like, G-C at only one point throughout the strand equates to a SNP. Deletion occurs where a section of the chromosome or the DNA is not in the sequence when it is supposed to be. They do cause errors in the chromosomal crossover as well as frameshift, which has deleterious effect. On the other hand, an insertion involves incorporation of base pair(s) that were not meant to be there naturally. Insertion can also result to frameshift, which cause a complete change in the encoded protein. Microsatellite DNA is short repetitive sequences of base pairs in a DNA strand. 4. a).Balanced polymorphism refers to a situation where two gene versions are prevalent in a population, we have individual that are heterozygous while others are homozygous. The heterozygous ones are deemed more fit that the purely homozygous. b). For sickle cells to be formed, there occurs a change in the DNA sequence (GAG) and is replaced by GTG sequence. The amino acid that is formed by normal cells is glutamic acid that is coded by GAG, the aberration causes Valine to be encoded instead (GTG). The change in amino acid sequence changes the entire protein resulting in the change of the protein. One spectacular cause of the change is that glutamic acid is hydrophilic while valine is hydrophobic. This greatly affects the folding haemoglobin resulting to sickle cells. c). There are equal chances of having heterozygous alleles in the same way as the homozygous ones. d). AA means that they are normal and have no chances of contracting sickle cell anaemia while SS indicates that the child has the disease, for AS the child is a carrier and may transmit sickle cell traits to the children. e). A change in HbC sequence from glutamine to lysine results in anaemia that causes a decrease in the solubility of the deoxyhemoglobin. Though the disease is not so bad, there occurs splenomegaly. Another common hemoglobinopathy is the change in amino acid 26 in the beta chain of HbE that results in a change from glutamate to lysine. This results to instability of Hb while the red blood cells survival rate declines. 5. a). the lactose persistence gene is said to be found in some groups of people while in others it is not. A nucleotide change at a position that is 13.95 kb upstream of the position where lactase gene is transcribed and is situated in the intron of MCM6 gene which appears adjacent to that to that of lactase. b). Lack of expression in the phenotype indicates the allele is recessive or the gene is non-existent. c). No, not everyone who can drink milk that has the gene, because it emanates from a nucleotide change. d). It is in Europe that lactose persistence was found around 1968, since then it has been evolving, some individuals found with it while others do not. The gene has also been found in Africa but in very small sections of the population. f). The DNA contains so much genetic information that is expressed in the form of proteins. However, not all the alleles are able to remain active producing proteins; some are recessive and hence have no capacity to express in the phenotype. 6. As a result of random sampling in a population, the gene frequencies changes over time, this phenomenon is described as genetic drift. These effects can present advantageous a well as deleterious effects to the organisms. There occurs a change between the offspring and the parent that increases their chances of survival. b). The Hardy-Weinberg formula is given by; p2+2 pq+q2 = 1 p=frequency of one of the allele. q = frequency of second allele. The significance of his equation is to establish the estimate of the genotype frequency in a population. c). The Hardy-Weinberg equation was developed to facilitate following up of traits across generations. It establishes the probability of a given genotype frequency in a population and the changes that are expected throughout the generations. The equation is based on three main assumptions; The members of a given bearing he gene do random mating. The gene is not under any evolutionary forces that might alter it. The equation also assumes that the number of members of a given species in a population bearing the gene is quite vast. d). Genetic drift can result to mutations in humans. 7. a). Heritability of intelligence establishes the percentage of the traits that are directly connected to genetic predisposition. This method utilizes a mathematical calculation. b). There are a number of environmental factors that select for high and low levels of BMI. Such include; the quantity at disposal for consumption, health status, appetite, the amount of work engagement, feeding habits and the level of poverty. c). The environmental factors that results to dark/ light skin color include; dietary uptake, the exposure to sun and the area where an individual lives in (tropics-black, cold areas-light). d) . When comparing traits that are influenced by many factors (Complex) the best option would be to map the genes. 8. A number of environmental as well as heath related risks faces our species both today and in the future. These include; I. An increase in disease conditions that are complicated and incurable such as cancer, AIDS. II. Industrial pollution that has resulted in global warming due to burning of CFCs ad other environmentally degrading substances III. Over increase in population that has strained the available resources resulting to environmental degradation. IV. Unpredictable scientific outcomes such as genetic engineering that may destroy the natural products hence pausing environmental as well as health risks V. Potential allergic reactions emanating from genetically modified products. VI. Energy crisis especially as a result of petroleum exhaustion. VII. Land dereliction as a result of quarrying and mining. VIII. Destruction of soils hence they are incapable of supporting agriculture. IX. Unpredictable weather patterns Read More