Week 3 ANTH 1001
Popular in Introduction To Biological Anthropology
Laura Castro Lindarte
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Popular in Biology/Anthropology
This 10 page Class Notes was uploaded by Laura Castro Lindarte on Saturday September 17, 2016. The Class Notes belongs to ANTH 1001 at George Washington University taught by W. Andrew Barr in Fall 2016. Since its upload, it has received 17 views. For similar materials see Introduction To Biological Anthropology in Biology/Anthropology at George Washington University.
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Date Created: 09/17/16
September 12, 2016 Mendelian Inheritance and Genetics I: Molecules ● PreDNA concept of heredity: ○ Blending theory of inheritance hen you have a mother with one characteristic and a dad with another the characterist lend in offspring ■ Parental contribution is averaged out in offspring ■ Variations get blended out so they don’t survive over time ■ Problem for Darwin because natural selection would NOT WORK because traits would disappear ● Gregor Mendel: 18221884 ○ Same time as Darwin but Darwin never saw his work ○ Undertook a systematic investigation of inheritance in pea plants ○ Demonstrate particulate inheritance (inheritance occurs because specific particulates passed down from parents to offspring) ○ Easier to control reproduction in pea plants than others becau asy to control pollination of plants ○ Pea plants have a ariation in a number of different traits: ■ Round or wrinkled seeds ■ Yellow or green seed interiors ■ Purple or white petals ■ Inflate or ripe pods ■ Green or yellow unripe pods ■ Axial or terminal flowers ■ Long or short stems ○ Easy to develop urebreeding lines for pea pla ecause have simple inherited traits ● Mendel’s Experiments: ■ Monohybrid cross: crossing TWO PUREBRED and F generation all had 1 yellow seeds despite parent variation ● Yellow and green produced yellow NOT BLEND ■ F2 eneration: elffertilization1 f F ● The green variant APPEARED UNCHANGED ( about 25%) ● Called variant in F dominant trait and reappeared variant 1 recessive trait ■ Dihybrid cross: 2 traits seen in combo ● Still 3 to 1 ratio ○ Mendel's Conclusions: 1. Particulate inheritance: a. Each heredity characteristic by particles “ unit factor” that exist in pairs (one from each parent) b. There factors remain discrete (unchanged) regardless of external appearance ( no matter if variant not in F , info was still there 1 i. There factors remain discrete (unchanged) regardless of external appearance ( no matter if variant not in F1, info was still there 2. Dominance: a. When and different unit are together, o nly one is shown physically (DOMINANT) while other is not (RECESSIVE) b. There must be two copies of the recessive factor for it to be expressed c. Phenotype: PHYSICAL characteristics (can be seen) d. Genotypes: GENETICS basis of phenotype (influences what is seen) i. Homozygous: 2 copy of SAME TRAIT ( purebreeding) ● Only one trait that it can give to offspring ii. Heterogeneous: h as 2 IFFERENT TRAIT but only SHOW ONE (hybrid) e. Seed color: yellow (dominant), green (recessive) f. Can use P unnett Square: g. Overall in F you would see 3 to 1 ratio ( 25% recessive) 2 3. Law of Segregation: during formation of sex cell, the pair unit in parent is separated RANDOMLY (equal likelihood that it will recessive dominant or recessive) 4. Law of independent assortment: d istribution of one pair of factors doesn’t influence other a. Traits are passed down INDEPENDENTLY AND SEPARATELY→ one trait doesn’t influence other traits i. Mendel’s law are fundamentals though there are lots of exceptions and complications ● Chromosomes and cell division: ○ Mendel knew nothing about genes or DNA ○ Eukaryotic cells are those with nucleus that can be multicell or single cell organism ■ Different organs ○ Inside the nucleus you can see hromosomes are seen → made out of DNA (deoxyribonucleic acid) ■ Until staining appeared in 1800s to see them ■ Usually not seen, only when cell will divide, before there is a soup of DNA ■ Consist of two identical sides called chromatids ○ Gene: g enetic material that encodes to particular traits ○ Locus: where gene is on chromosome ○ Alleles: ALTERNATE version of gene ○ Different size, shape, and pattern on chromosome an arrange chromosomes into KARYOTYPE → list of homologous pair (one from father and one from mother) ■ Have same gene but can have different alleles ○ Human have 23 pairs of chromosomes ■ 22 pairs are autosomes and 1 pair is sex chromosome female=XX, male=XY) a. Y has testees determination factor to change development of fetus to make it a male b. Lots of genes in X not seen in Y leading to sexlinked traits ○ EACH SPECIES HAS OWN NUMBER OF CHROMOSOMES ■ Even close relatives (chimps have 24 pairs while humans have 23 pairs) ○ Somatic cells: component of body tissues ■ Are diploid so have both chromosomes of each pair ■ 23 pair (46 in total) ○ Sex cells (gametes): ■ Haploid: one member of each chromosome a. Haploid + haploid = diploid b. Zygote: union between sperm and ovum c. 23 chromosomes in total ■ Ova = egg cell in female ovaries, sperm = sex cells in male testes ○ Mitosis: cell division resulting to 2 DAUGHTER CELLS THAT ARE IDENTICAL TO EACH OTHER AND PARENTS ■ Make somatic cells 1. Interphase: normal life then DNA is replicated 2. Prophase: c hromosome appear (X) with identical chromide 3. Metaphase: c hromosomes line up 4. Anaphase: c hromosomes separated where chromatids meets ( more to opposite side of cell) 5. Telophase: c ell split resulting in 2 cells ame amount of DNA than in beginning ○ Meiosis: roduce sex cell 2 round of division) 1. Reduction Division: a. Interphase: DNA replicate b. Phosphate 1: creation of chromosome and crossover: one chromatid cross with other and exchange gene i. Result in chromatid that are different from what was present before ii. Increases variation because not only pass on parent chromosome but new ones iii. Provide raw material for natural selection c. Metaphase 1: chromosomes align in h omologous pair and get torn apart random what side each pair is on) d. Anaphase 1: e ach get one chromosome of pair e. Telophase 1: c ell splits f. Interkinesis 1: 2 haploid daughter cells hich are identical 2. Second division: S IMILAR to mitosis except no replication of DNA in interphase a. Results with 4 haploid gametes cells that are GENETICALLY DISSIMILAR b. Can go wrong in various ways t hat result in different things c. Meiosis provides way of how Mendel’s laws occur: i. Law of segregation because meiosis line up randomly ii. Law of independent assortment APPLIES TO TRAITS ON SAME CHROMOSOME NOT IN DIFFERENT ONES September 14, 2016 Genetics 2: From Genotype to Phenotype ● 4 characteristics of heredity particle: 1. Accurate replication 2. Stable structure a. Capable of coding for diverse information b. Capable of transmitting this information ● DNA is a ucleic acid: ○ Found in ucleus ○ STORES AND TRANSMITS INFORMATION ○ Made of smaller molecules called ucleotide ■ 4 different bases (purine = Adenine, Guanine; Pyrimidines = Thymine, Cytosine) → will interlock based on structure a. Phosphate + sugar (deoxyribose) + Nitrogenous base b. Purines have two rings, pyrimidines have one ring ● Chargaff’s Rules: ○ Saw that similar proportion of Adenine and Thymine throughout and similar proportion of Guanine and Cytosine A=T, G=C) ● Rosalind Franklin’s observation provided clues ○ James Watson and Francis Crick created DOUBLE HELIX STRUCTURE ○ Complementary bases important for replication ○ If you have one half you can figure out other half ● SEQUENCE OF BASES ENCODE INFORMATION IS NEEDED ( genetic code) ● DNA functions: ○ Replication ○ Protein synthesis ● Replication occurs during cell divi originals strand separate the original acts as TEMPLATE and attracts other loose bases around it t ave two identical copies) ○ Overlooked by enzymes ● Protein synthesis (genotype → phenotype) ○ Proteins play an tructural or active component in body ● Protein made out of amino acids that link together into polypeptide 20 different amino acids) ○ Sometimes are really long and need to fold, shape determines behaviour of protein ● DNA is r ecipe for sequence of amino acid ○ Every 3 bases will result in one amino ac CODON) → SPECIFIC (a codon will always stand for a specific amino acid) ○ Different chains can be associated to create complex (multimeric) proteins ● 4 bases can combine to make 64 codons but only 20 amino acids exist so there is some amino acids that are coded from more than one codon ○ Because of this some errors do not cause problem because will get same amino acid ● Gene: sequence of DNA that arries information for synthesizing specific protein and occupy specific space in chromosome (chromosomal locus) ● Protein synthesis occurs i ibosomes (outside of nucleus) but DNA cannot leave nucleus so transcription occurs to transfer message from nucleus to ribosome ● Transcription: first phase of synthesis ○ Creation of messenger called NA → single stranded, ribose sugar and uracil base (instead of T it has U) ○ INSIDE OF NUCLEUS ○ DNA unzip along section of DNA needed ■ Just like replication, base pairs come in and fill in what is left and create complementary RNA strand called mRNA ■ U goes in for T ● Translation: econd phase ○ mRNA binds to ribosome ○ Codons are read by ribosome and tRNA comes in and brings amino acid to right place ○ tRNA binds to mRNA bring amino acid which bind together ○ Continues until you get to stop codon ● DNA mutation: alteration of genetic code ○ Source of new variation ○ Happen all the time but only make matter if they occur because in the gametes because only those will be passed on ● Type of mutation: ○ Chromosomal mutation: extra chromosome or deletion of a chromosome (problem with separation or merging) ○ Point mutation ingle letter is changed in DNA ○ Duplication: codons are duplicated resulting in an extra codon ■ New amino acid will be inserted ○ Inversion: codons are in wrong order ○ Deletions: letter is taken out so all shift over so all codon frameshift) ■ Frameshift mutation: AG TC TA T… → AC CC AT Ser Arg Asp STOP ● When mutation occurs to single letter it mig ot lead to change because error builds same amino acid (synonymous mutation) ● Mutation are occurring constantly at random ○ They may be induced by other things ● Mutations may be functionally irrelevant (produce no change) but others are functionally significant ○ Many are lethal or negative, others neutral ○ Small proportions may be beneficial and confer SELECTIVE ADVANTAGES ○ Only mutations in meiosis are passed on ● Mendelian Inheritance looked at ingle gene with autosomal dominant/recessive model ○ Useful when looking at ualitative varia discrete categories) ○ Ex: seed color in peas, albinism ● Codominance: b oth alleles eterozygous are fully expressed → NEITHER DOMINANT OVER OTHER ○ Ex: ABO system: 3 alleles (ABO) with A and B being dominant so can have AB blood type, O is recessive to both (can only be expressed if homozygous oo) ■ Important in donation of blood because will respond to different characteristics ● Sex Linkage (xlinked traits): controlled by gene chromosome so more common in male ○ Males only have one x chromosome so all alleles in X chromosome in male will be expressed no matter if dominant or recessive) ○ Ex: hemophilia, redgreen color blindness ● Polygenic traits: don’t follow Mendel’s rules because h uantitative (continuous) variation that are influenced by many genes and environmental factors ○ Ex: stature, skin color, eye color ● Pleiotropy: single gene influences multiple traits at same time ○ One gene affects all ○ Ex: Marfan syndrome, don’t follow Mendel’s rules ● Environmental effects: genes are not only fact any things in environment can affect phenotype ○ Genotype sets limit or chance for something to develop but might not ● Type of genes: ○ Structural genes: will code for amino acid chain ○ Regulatory genes: may control effect of other genes ■ Homeotic genes: ontrol tissue growth ■ HUGE IMPACT→ h uman and chimps share 99% of DNA but very different, difference might be because of regulatory genes ● Huge part of DNA have no function: ○ Introns and exons: only exons pulled out to make mRNA while information are not ○ Splice variance: ifferent on how genetic code is transcribed ○ Nonprotein coding regions: ■ Introns ■ Pseudogenes ■ Variable number tandem repeats and short tandem repeats September 15, 2016 Lab 3 Notes ● Cladistic: field of study in bio t ladogram to look at inheritance ● Claude: group of species on cladogram that a elated ○ Can divide cladogram based on it ● Taxon: group of organisms wit et of characteristics ○ Interchangeable with species ● Characteristics divided in primitive or derived: ○ Based on glandogram ○ Primitive: shared betwee escendants and ancestors ■ Aka: symplesiomorphic ○ Derived: NOT SHARED with ancestors ■ Aka: synapomorphic ■ As you go back more will be derived and less primitive ● Homologous feature: characteristic that are similar because b oth ancestors and descendants have it ○ More useful ● Homoplasy: characteristics that are similar between species because of ENVIRONMENTAL DRIVERS ○ Confusing especially for extinct animals ● Catarrhini: subunit of primate ● Dental formula: organize organisms based on t eeth count ● Obligate bipedality: b etter mode of movement is upright ● Canine dimorphic: different between canines of male and female ● ● Parsimony: simplest way is right way
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