Lecture Exam 4 Study Sheet Intro To Biological Anthropology

4302019 Lecture Exam 4 Study Sheet Intro Biological Anthropology E0

Analyze key concepts of biological anthropology, including cellular structures, genetics, inheritance, evolution, human variation, adaptations, and primate biology. Understand mitochondrial and ribosomal functions, DNA and RNA structure and synthesis, genetic mutations, chromosomal behavior, patterns of inheritance, evolution mechanisms, and the biological basis of human diversity and adaptation. Explore processes such as meiosis, mitosis, natural selection, genetic drift, gene flow, and mutation. Examine human evolutionary adaptations like skin color, high-altitude survival, and biocultural evolution including lactose tolerance. Recognize the significance of blood types, genetic variation, and the impact of evolutionary forces on human populations. Differentiate between genetic concepts such as genotype, phenotype, dominance, recessiveness, and inheritance modes, using pedigree analysis and Punnett squares. Study specific genetic conditions like trisomy 21, sickle cell anemia, and their evolutionary implications. Discuss human biological variation through the lenses of homeostasis, adaptation, acclimatization, and evolutionary theory, emphasizing the importance of genetic and environmental interactions in shaping modern humans. Review the stages of human growth, brain development, and life history traits, and understand their relevance to current biological anthropology theories and research.

Paper For Above instruction

Biological anthropology, also known as physical anthropology, examines the biological and evolutionary aspects of humans, their ancestors, and related species. Central to this field is an understanding of cellular structures like mitochondria and ribosomes. Mitochondria are the powerhouses of the cell, responsible for energy production through cellular respiration, vital for sustaining life and cellular functions. Ribosomes are involved in protein synthesis, translating messenger RNA (mRNA) into polypeptide chains, foundational for cellular structure and function (Carlson, 2010).

Genetics forms a core component of biological anthropology. Genes are segments of DNA located at specific loci on chromosomes, and alleles are different forms of a gene. The pairing of DNA nucleotides—adenine (A), thymine (T), cytosine (C), and guanine (G)—is crucial for DNA's function. Adenine pairs with thymine via two hydrogen bonds, while cytosine pairs with guanine via three, a specificity essential for accurate DNA replication and transcription (Alberts et al., 2014). Nucleotides comprise a sugar, phosphate group, and nitrogenous base, forming the building blocks of DNA and RNA.

DNA's double helix structure facilitates its role in storing genetic information. During protein synthesis, transcription occurs in the nucleus where DNA is transcribed into mRNA. Translation happens in the cytoplasm, where ribosomes read mRNA codons—triplet sequences that specify amino acids—and tRNA molecules bring the corresponding amino acids to assemble proteins (Watson & Crick, 1953). Each three-nucleotide codon encodes one amino acid, making the genetic code universal and vital for cellular function.

Proteins are constructed from amino acids, of which there are 20 different types. The sequence of DNA determines the order of amino acids, thus dictating the protein's structure and function. Mutations, such as point mutations—altering a single base—and frameshift mutations—insertions or deletions shifting the reading frame—can significantly influence the resulting proteins, potentially causing genetic disorders or evolutionarily advantageous traits (Miller, 2011). DNA and RNA differ structurally; DNA has deoxyribose sugar and thymine, while RNA contains ribose sugar and uracil instead of thymine. Functionally, DNA stores genetic information, whereas RNA plays roles in gene expression, acting as a messenger and participant in protein synthesis.

Humans typically have 46 chromosomes in somatic cells, comprising 23 pairs, including one pair of sex chromosomes—XX in females and XY in males. Human gametes are haploid, containing 23 chromosomes, ensuring genetic diversity through sexual reproduction (Hartl & Clark, 2007). Homologous chromosomes are pairs, one from each parent, carrying similar genes in the same order. Determining sex involves the presence of sex chromosomes, with males having XY and females XX. The sex of the offspring is determined by the male parent’s sperm, contributing an X or Y chromosome.

Genetic information is transcribed from DNA to mRNA, which then guides protein synthesis. An example is transcribing the DNA segment T A A G A T T G C A T C into mRNA as A U U C U A A C G U A G. During meiosis, homologous chromosomes pair and exchange genetic material in crossing over, increasing genetic variability. Meiosis involves two cell divisions, resulting in four haploid gametes—each with 23 chromosomes—ensuring genetic variation and proper chromosome number in offspring. Mitosis, in contrast, results in two diploid daughter cells identical to the parent, facilitating growth and tissue repair (Pierce, 2017).

Reduction division during meiosis reduces chromosome number, while crossing over mixes genetic material between homologous chromosomes, both critical for genetic diversity. Nondisjunction, when chromosomes fail to segregate properly, can cause trisomy 21—Down syndrome—a condition characterized by an extra copy of chromosome 21. A karyotype visualizes chromosome sets, helping identify anomalies. Comparing somatic and gamete cells, prokaryotic and eukaryotic cells reveals differences such as the presence of a nucleus and membrane-bound organelles in eukaryotes.

Genetic variation is further explained with concepts like homozygous (identical alleles) and heterozygous (different alleles), dominant and recessive traits, genotype (genetic makeup), and phenotype (observable traits). Mendel’s principles of segregation and independent assortment describe how alleles are inherited—segregation ensures alleles separate during gamete formation; independent assortment states they are inherited independently. Evolutionary mechanisms include natural selection, genetic drift, gene flow, and mutation, which shape human variation (Templeton, 2002).

Polygenic traits, influenced by multiple genes, contribute to phenotypes like skin color and intelligence. Blood types A, B, O, and AB exemplify codominance, where both alleles are expressed. Blood group inheritance follows Mendelian patterns, affecting transfusion compatibility. Phenotypic traits can reappear after disappearing, illustrating complex inheritance, including autosomal dominant, recessive, and sex-linked patterns. Pedigree analysis aids in tracking inheritance modes and identifying carriers (Gershenson & Johnson, 2018).

Evolutionary forces—natural selection, genetic drift, gene flow, and mutation—drive genetic change over time. Sickle cell anemia exemplifies balancing polymorphism, where heterozygous individuals have higher fitness in malaria-endemic regions. The sickle cell mutation provides resistance to malaria but causes health problems in homozygous individuals, illustrating natural selection’s role in maintaining genetic diversity (Allison, 1954). Human populations evolve, but not through the concept of biological race; instead, clines—gradual changes in traits across geography—better describe variation (Rosenberg et al., 2002).

Adaptations like skin color emergence through selective pressures related to sunlight and vitamin D synthesis. Melanin protects against UV damage but can limit vitamin D production, influencing skin color evolution, especially at different latitudes. Physiological adaptations to temperature involve vasodilation, vasoconstriction, and sweat production, while acclimatization involves reversible responses to environmental changes. Bergman’s and Allen’s rules explain variations in body shape with climate—shorter extremities in cold environments for heat conservation, and longer limbs in hot environments for heat dissipation (Bergman, 1853; Allen, 1877).

Lactose tolerance exemplifies biocultural evolution—cultural practices influence genetic evolution—where populations with dairy farming cultures retain the ability to digest lactose into adulthood. Human adaptation to high altitude involves increased lung capacity, more hemoglobin, and physiological changes to cope with hypoxia. Throughout development, humans exhibit unique life history traits—extended childhood, long lifespan, and brain growth during early years. The rapid brain development during infancy enhances cognitive abilities, while diet influences growth, development, and reproductive timing, such as age of menarche. Menopause, unique to humans and some primates, may have evolved as a reproductive strategy (Gage et al., 2017).

References

• Alberts, B., Johnson, A., Lewis, J., Morgan, D., & Raff, M. (2014). Molecular Biology of the Cell. Garland Science.
• Gage, T. B., Mortlock, D. P., & Challenger, D. (2017). Human Growth and Development. Elsevier.
• Gershenson, B., & Johnson, J. (2018). Genetics in Medical Practice. Academic Press.
• Hartl, D. L., & Clark, A. G. (2007). Principles of Population Genetics. Sinauer Associates.
• Miller, J. H. (2011). Experiments in Genetics. Brooks Cole.
• Pierce, B. A. (2017). Genetics: A Conceptual Approach. W. H. Freeman.
• Rosenberg, N. A., et al. (2002). Clines, Clusters, and the Effect of Study Design on Inferences about Human Genetic Structure. Science, 298(5602), 1612-1618.
• Templeton, A. R. (2002). The Reality of Human Races. American Anthropologist, 104(3), 661-680.
• Watson, J. D., & Crick, F. H. (1953). Molecular Structure of Nucleic Acids. Nature, 171(4356), 737-738.
• Alberts, B. et al. (2014). Molecular Biology of the Cell. Garland Science.