Bio Anth Lecture 5/6 Notes
Bio Anth Lecture 5/6 Notes ANTH1013 001
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This 7 page Class Notes was uploaded by pcoliver96 on Tuesday February 9, 2016. The Class Notes belongs to ANTH1013 001 at University of Arkansas taught by Lucas Delezene in Winter 2016. Since its upload, it has received 49 views. For similar materials see Introduction to Biological Anthropology in ANTH at University of Arkansas.
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Date Created: 02/09/16
University of Arkansas ANTH 1013 – Intro to Biological Anthropology Delezene $KQ▯#PVJTQRQNQI[▯▯.GEVWTG▯▯▯0QVGU▯ PQVGU▯IQKPI▯VQYCTFU▯GZCO▯▯▯▯ ▯ Mendel’s work languished -1866: Mendel published his only study of pea genetics -confirmed his pea results with studies in 4 other plant species but never published these results -correspondence with other botanists suggested that his results were not generalizable to other organisms -his pea research was discontinued in 1864 when pea weevils infested his garden -all research abandoned in 1871 when he was elected abbot of the monastery -died in 1884 from nephritis Mendel’s work rediscovered in 1900 -1900: 3 botanists (de Vries, Correns, Tschermak) all published work saying that they had discovered the laws of inheritance -all found out that Mendel had arrived at the same conclusions nearly 40 years earlier -botanists discovered that there are “units” of inheritance – known as genes -what is the physical nature of a gene? Advances in cytology -mid 1880s: cytologists (cell biologists) discovered microscopic structures in the nucleus of the cell Chromosomes behave according to Mendel’s laws -chromosomes are paired in most cells but not in sex cells -chromosomes segregate during the production of sex cells -chromosomes maintain their identity through generations -once these discoveries were made, it was clear that genes were located on chromosomes University of Arkansas ANTH 1013 – Intro to Biological Anthropology Delezene Cell types -prokaryote: -primitive cell type -characteristic of bacteria -no nucleus -DNA exists as a single circular “loop” -eukaryote: -cells with nucleus and organelles -animals, plants, protists -DNA organized into structures called chromosomes -1.6 billion years old Basic cell components -human karyotype -23 pairs -22 autosome pairs -1 sex chromosome pair -somatic cells: all cells except gametes -46 chromosomes, 23 pairs (diploid) -gametes: cells that join during fertilization -23 chromosomes (haploid) University of Arkansas ANTH 1013 – Intro to Biological Anthropology Delezene Review of Mendelian inheritance -genes come in different forms (alleles) -each copy “segregates” into a different sex cell -Mendel’s “law of segregation” -if two genes are considered: -for each gene, the alleles segregate independently -Mendel’s “law of independent assortment” Overview of mitosis -creates two daughter cells -each daughter cell has exactly the same set of chromosomes -start with a diploid “mother” and produce two identical diploid “daughters” 46 chromosomes (single-stranded)èreplicationè46 double- stranded chromosomesècell division (two daughter cells, each containing 46 single-stranded chromosomes -interphase: chromosomes are single stranded -prophase: chromosomes duplicated during interphase -metaphase: chromosomes line up along a single axis -anaphase: sister chromatids split apart -telophase: splits into two identical daughter cells Overview of meiosis -process of creating “gametes” – sex cells (egg + sperm) -each cell will only have one half of each pair of chromosomes (haploid number) -starts with a diploid parent cell then duplicates the DNA -goes through two rounds of cell division producing four daughter cells 46 chromosomes (single-stranded)èreplicationè46 double- stranded chromosomes arranged into 23 pairs èfirst cell division (reduction division)èsecond cell division -prophase I: chromosomes duplicated -metaphase I: chromosomes aligned along axis -anaphase I/telophase I: homologs go into different cells -prophase II-anaphase II: chromosomes duplicated and chromatids split apart -telophase II: produces four haploid daughter cells University of Arkansas ANTH 1013 – Intro to Biological Anthropology Delezene Meiosis: segregation and independent assortment -separation of homologous chromosomes during meiosis I: process b ehind Mendel’s law of segregation -can’t predict which members of different chromosome pairs will move together through meiosis: Mendel’s law of independent assortment Exceptions to independent assortment -genes are sorted into gametes independently of one another -now known to be true for genes on separate chromosomes -genes on the same chromosome are linked – don’t assort independently Crossing over -crossing over: exchange of genetic material between homologous chromosomes – occurs during meiosis I Meiosis: the big picture -meiosis shuffles genetic variation -humans: 23 pairs of chromosomes – 8,388,608 possible haploid cell types without crossing over SAMPLE QUESTIONS + ANSWERS • If a cell undergoes meiosis, the end result will be… -four haploid daughter cells • In humans, somatic cells… -have 23 pairs of chromosomes, have 22 pairs of autosomes, undergo mitosis (all of the above) • During meiosis, which of the following mechanisms separates alleles linked on a single chromosome? – crossing over • Which of the following is true of eukaryotic cells? – they have a membrane bound nucleus • If an individual has 10 pairs of chromosomes in its karyotype, how many types of gametes can it produce if you ignore crossing over? – 2^10 University of Arkansas ANTH 1013 – Intro to Biological Anthropology Delezene • The X and Y chromosomes are which type of chromosome? – sex chromosomes • When a haploid sperm fertilizes a haploid egg, the resulting zygote is… -diploid • Which of the following does not correctly describe a human diploid karyotype? – 23 single stranded chromosomes in total • The separation of homologous chromosomes during meiosis I is the process behind... -Mendel’s law of segregation • Which of the following statements about eukaryotes is false? – all eukaryotic organisms are multicellular $KQ▯#PVJTQRQNQI[▯▯.GEVWTG▯▯▯0QVGU▯ PQVGU▯IQKPI▯VQYCTFU▯GZCO▯▯▯▯ ▯ -organisms are mainly the way they are because of their DNA -DNA carries the instructions for building proteins and influences most of the characteristics of an organism The structure of DNA -a double-helix of complimentary strands -the rungs of the ladder are made of repeating subunits called nucleotides -1953: structure of DNA was discovered -work done by Rosalind Franklin, James Watson, and Francis Crick The complimentary structure of DNA phosphate + sugar + base (4): Adenine, Thymine, Guanine, Cytosine = nucleotide -Adenine only pairs with Thymine -Guanine only pairs with Cytosine -DNA letters form words called codons – every codon is 3 letters long **there are approx. 3 BILLION base pairs in the human genome University of Arkansas ANTH 1013 – Intro to Biological Anthropology Delezene DNA replication -hemoglobin: oxygen transport -collagen: connective tissue -actin & myosin: muscles -DNA controls many things including the structure of proteins, which are composed of amino acids Protein structures -primary structure: the sequence of amino acids that make up protein -tertiary structure: the 3D shape of the protein Oversimplified list of the characters involved in the protein synthesis 1) DNA with a sequence of base pairs making up a gene 2) mRNA – copied from the gene 3) ribosome – site of protein synthesis 4) 20 different types of amino acids from which the protein is constructed – 20 different types of tRNA, which carry he amino acids used in building the protein DNA vs. RNA -DNA: double stranded, deoxyribose sugar, thymine -RNA: single stranded, ribose sugar, uracil Overview of protein synthesis -transcription: genetic information is copied from the nuclear DNA onto messenger RNA (mRNA) -transcribe = write down -translation: the mRNA serves as a template to construct a protein -translate = convert Transcription -nuclear DNA is ‘unzipped’ in the region of a gene and used to create a complimentary RNA strand – mRNA tRNA -20 different tRNA molecules – each carry a specific amino acid University of Arkansas ANTH 1013 – Intro to Biological Anthropology Delezene Translation 1) mRNA moves through ribosome exposing codons in sequence 2) free-floating tRNAs carrying amino acids move into ribosome 3) tRNA anticodon bonds with mRNA codon and its amino acid is bonded with the growing protein 4) tRNA is ejected Mutation: how heritable variation is created -mutation: change in the nucleotide sequence -can be caused by copying errors during DNA replication or exposure to chemical mutagens, radiation, or viruses -can occur in either somatic cells or gametes (sex cells) -mutations are rare: 0.0000000025 – 0.000000034 mutations per nucleotide per generation -there are 3.2 billion nucleotides in the human genome, so on average, each person has point mutations at 58 positions compared to their parents Mutations can occur during both mitosis & meiosis -somatic (mitotic) mutations are not inherited -meiotic mutations are inherited Insertion or deletion mutation -may have a dramatic effect because all of the codons “downstream” of the mutation are shifted, so many amino acids will be altered Some effects of mutations bad non-viable zygote protein non-functional protein has reduced function neutral effect ▯ ▯ protein has improved function protein has new function good
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