Humans Place in Nature - Essay Example

Human’s Place in Nature A. Natural selection This s the process by which organisms is able to survive the torrents of nature through demonstration of traits that favor their survival. Charles Darwin developed the concept of natural selection. The traits allow the organisms to be able to live and reproduce. For example, the skin color of the people in the tropics is darker compared to those in cold areas due to an adaptation to the strong sun in these regions, the amount of melanin in the skin is too high. This has resulted to the darkening of the skin in order to offer protection from the sun’s radiation. B. Darwinian theory of evolution establishes that the poor mother of seven children is more fit for survival because the children are able to reproduce hence the survival of the lineage. Bill Gates fitness of financial muscle does not apply in this theory, it captures only the aspect of living to produce and have the continuation of generations. C. Neither wealth or might can be used as the measure of fitness when it comes to natural selection. The actual measure is the competitive advantage that is given by nature hence one is able to reach the age that they can reproduce. For example, an extremely wealthy young man may die from a disease like cancer; this indicates that they are not fit despite their financial muscle. D. In this question I will discuss the peppered moth of England. This phenomenal study showed that before the industrial revolution the number of pale moths was quite high because they could camouflage over the barks of the trees. On the other hand, the number of the of dark moths was quite low because they succumbed to predation by birds. However, with the industrial revolution, the industrial smoke made the backs of the trees to be dark hence the selective advantage shifted from the pale moths to the dark ones. The dark ones were able to efficiently hide in the backs while the pale ones could be easily traced by the birds, the result was a tremendous increase in the number of dark moths. E. Sexual selection This phenomenon involves the capability of the males finding their female mates. In sexual selection, the organisms that are more aggressive and capable of finding mates out-reproduce the others hence increasing their chances of spreading their traits to the next generation. The sexual selection may be based on attractiveness or the ability to convince the mate. These individuals have higher chances of possessing as many females as possible. This increases their survival in the population. For example, there are men that are able to sweet-talk almost every woman, while there are others that are incapable of convincing any. 2. A. According to Charles Darwin, traits are hereditary when they are passed from the parent to the offspring. This occurs through reproduction. B. Gregor Mendel He is the first person to explore the concept of modern genetics. He did his experiments using garden pea. He made various manipulations to the plant hence established that genes exhibited two forms of traits that had equal chances of being transferred to the offspring. Through his works, it came to be established that traits were never passed to offspring in singles but rather in units. This is an indicator that no single allele is transferred to the offspring. In addition, he established that some alleles were recessive hence, they could manifest in the organisms phenotype. Finally, he also found that genes were free to assort independently themselves resulting to variations across species. C. Meiosis is a process of germ cell division that results into formation of four haploid cells. The following diagram shows how the process takes place. Mitosis Mitosis and Meiosis differences Two divisions occur in meiosis (Meiosis I and II). While in mitosis one does. Mitosis is a cyclic process while meiosis is not Mitosis produces two daughter diploid cells while meiosis produces four haploid cells. Chromosomal cross over is non-existent in mitosis while in meiosis it does occur. Mitosis occurs in normal body cells while meiosis occurs in gametes. D. Traits are not transferred in equal measure by both parents; there is a difference that is provided by nature. There occurs independent assortment of chromosomes, which may result to loss of some genes hence some traits. Therefore, the genes for Spanish were drastically reduced in the daughter but the little that the daughter had were completely rendered useless in the child. 3. A. DNA is the molecule that carries the genetic material of an organism. It is usually located in the nucleus of the cell while little mitochondrial DNA is found in the mitochondria. DNA is a ubiquitous molecule across all cells. It has a double helical structure that is a characteristic of the bonding of its components. DNA is made up of three major components. These are a deoxyribose sugar, a phosphate and various bases. The bases are the ones that forms these interlinks between the two strands. There are basically four bases that are found in DNA; guanine, thymine, cytosine and adenine. Adenine links with thymine while guanine bonds with cytosine. A DNA strand is made up of many genes. Genes are active sections of a DNA molecule that have the capacity of producing an active polypeptide chain that can fold to form an active and functional protein. B. Transcription of mRNA The enzyme RNA polymerase adds base pairs to the growing mRNA chain while reading the DNA sequence in an antiparallel direction resulting to mRNA formation. Gene transcription is the second process in the central dogma of molecular biology. The enzyme builds the bases one by one with positions occupied by thymine being replaced by uracil. The diagram below provides more information; C. Translation After transcription, a molecule of mRNA is shuttled to the ribosomes where it is translated to protein molecules. The ribosomal complex does the process of translation. The base pairs from the DNA that have been decoded in the mRNA are read in three bases making a component called codon. Each codon encodes a specific amino acid that are joined together to form a polypeptide chain that then folds to form an active protein. The process of translation has four phases that begins with the initiation, then followed by elongation, this involves the joining of the amino acids. There then occurs translocation and finally the termination. The diagram below provides a detailed insight; D. Protein types Receptor proteins; Makes up receptors in the body and are mainly found along the cellular membranes. Such as tyrosine kinase receptor. Defensive proteins; Are found in the body especially in its immune system. These proteins have various roles with the ultimate goal of protecting the body against foreign agents. Such include the immunoglobulins. Hormonal proteins; regulates the activities of the body. They include insulin and glucagon, which regulates the sugar level in blood. Transport proteins are used in transportation of special substances in the body such as oxygen by haemoglobin and myoglobin, which are responsible for oxygen transport in the body. Enzymatic proteins play a role in catalysing the speed of reactions. These includes enzymes like hydrolases. E. A mutation is an aberration from the normal state of genetic composition of an individual in a species. Mutations take various forms. They can be either deleterious and can sometimes be beneficial. When the change involves one base pair, then the effects are minimized, this is what is referred to as single nucleotide-polymorphism. For example, the genetic change from a GC to AT on just one position of the entire gene results in this form of a SNP. Insertion involves an addition of a base that was initially not naturally available hence resulting to a frameshift which can have deleterious effects or beneficial effects as well. If the opposite happens, there is a deletion of a gene or a section of the chromosome, which results to chromosomal errors. On the other hand, the microsatellite DNA entails short repetitive sequences of DNA that appears and reappears in the DNA strand. These sections of DNA can influence of the proteins formed, though they are mainly found as part of the junk DNA. 4. Balanced Polymorhism …….(this question remaining). 5. a) Lactase persistence gene –which is a gene that encodes lactase enzyme. The gene is formed through a change in a nucleotide that occurs 14kb upstream from the point of lactase transcription. This occurs in the intron of MCM6, a gene that is located adjacent to that of lactase. b). The allele is recessive c). Yes, everyone who can drink milk has the same allele coding for lactose persistence. d) In Europe lactose intolerance evolved around the 1970s e) It is because of the foods that have been adopted by different communities; in this case, it is due to variations in milk consumption across the regions. f). Some alleles are not expressed in the phenotype despite them being part of our genes. They are recessive. 6. a). Genetic drift refers to the changes in gene frequencies over a period of time as a result of the effects of random sampling n a population. The alleles in the offspring are variant from the parents and they are the ones that allows the offspring to survive. b) Handy-Weinberg formula is p2+2pq+q2=1. Where p is the frequency of one allele while the other allele is represented by q. The equation changes if the gene under consideration has multiple alleles. It becomes p2+q2+r2+2pq+2qr=1. This formula is used for estimation of the expected genotype frequencies in a population. c). Hardy-Weinberg equation is an equation that was developed by Handy and Weinberg in an attempt to describe the probability of genotypes frequencies occurring in a population as well being able to follow up their changes across generations. The equation assumes that there are no evolutionary forces that the gene is exposed to. Secondly, it assumes that the population that is in possession of the gene is quite large. Thirdly, there is random mating of the members of species bearing the gene. d). A deleterious effect that results from genetic drift in humans is harmful mutations, these can lead to conditions such as development of tumours. 7. a). It is difficult to determine precisely whether a trait such as IQ is influenced by environment or heredity. However, there are methods that can predict, such include the heritability of intelligence. This is a mathematical concept that estimates the amount of a trait is attributable to genetic makeup. For example for the intelligence, it has been found to be between 60% and 80%. b). Environmental factors select for high and low BMI Eating habits Economic status Social cultural inclination Activity c). Environmental factors for dark versus light skin colour Geographical location Dietary uptake Sun’s ultraviolet radiation d). Complex traits are influenced by more than one factor. Complex traits are comparable through gene mapping across generations. 8. Environmental and health-related problems confronting our species now and in future Pollution Global warming Depletion of ozone layer that will result to cancerous effects Incurable diseases such as AIDS Population pressure over limited resources Environmental degradation Food contamination through genetic modifications Allergic reactions from manufactured products Exhaustion of oil as the world’s main energy source. Read More