Genetics BISC 403 - notes from the first few weeks of class PDF

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notes from the first few weeks of class ...

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Genetics BISC 403 Textbook: Genetics from genes to genomes by Hartwell (online access) Quiz on chapter two next Wednesday 2/5/2018 DNA - Made of four subunits -Protein is made of 20 different subunits - Chromosomes contain more protein than DNA by weight Griffith’s experiment that provided evidence of transformation - Heat denatured the protein and the transforming factor was DNA - Protease  didn’t work - RNAse  didn’t work - DNase  only one to be changed and not show the strand in the end - Genes are sequences of DNA - Linear or circular/ double or single stranded - Polymer composed of nucleotides 1) deoxyribose 2) phosphate 3) nitrogenous group -DNA chain has polarity  phosphodiester bonds from a covalent link between the 3’ carbon of one nucleotide and the 5’ carbon of the next nucleotide from 5’ 3’ - Base pairs consist of hydrogen bonds between a purine and a pyrimidine G C and AT - Consistent with chargaff’s rule - the strands are antiparallel, sugar-phosphate backbone is on the outside with the base pairs in the middle G-C base pair = 3 hydrogen bonds A-T base pair = 2 hydrogen bonds Why DNA is good - Can remain intact for up to tens of thousands of years - great stability Chemical constituents of RNA - Ribose and contains uracil instead of thymine - mostly single stranded and without the H bonding there is almost no stability in RNA - The structure of the side chain in the amino acids determine the amino acids chemical properties - The two complementary strands of DNA provide a mechanism for copying biological information

2-7-2018 The model of DNA replication by Watson and crick - Unwinding of double helix exposes bases on each strand - Each strand an act as a template for synthesis of new strands - New strand forms by insertion of complementary base pair - Single double helix becomes two identical daughter double helices Meselson-stahl experiment confirmed semiconservative replication DNA synthesis proceeds in a 5’3’ direction - Template and newly synthesized strands are antiparallel - DNA synthesis can only occur by adding nucleotides to the 3’ end Requirements for replication - Four dNTPs - Single stranded template - primer with exposed 3’ hydroxyl group Initiation: - Initiator protein - Primase – synthesis of RNA primers - RNA primers – complementary and antiparallel to the regular strand - DNA POLYMERASE III catalyzes the phosphodiester bond formation between adjacent nucleotides (polymerization) DNA polymerase I replaces RNA primer with DNA sequence -More missing slides cells must ensure accuracy of genetic information - Redundancy = either strand can specify the sequence of the other strand - Precision of DNA polymerases  I and III have proofreading ability and wonderful accuracy Monday 1-2 wolf room 243 Mendel’s law of segregation (one gene) Mendel’s Law of Independent assortment (more than one gene) Artificial selection was the first applied genetic technique, purposeful control of mating by choice of parents for the next generation - domestication of …. Abbot Cyril Napp 3 questions - what is inherited, how its inherited, and what is the role of chance in heredity?

The homunculus: inherited features of offspring are contributed mainly by one parent. *** Units of inheritance are known as genes while alternative forms of a single gene are alleles alleles have two forms - trait that appears in the f1 progeny is the dominant form - trait that is hidden in the f1 progeny is the recessive form Homozygous Heterozygous 1/3 YY --- 1/3 YY x 0= no green offspring 2/3 Yy - 2/3 x ¼ = 2/12 ¼ offspring are yy recessive A testcross can reveal an unknown genotype - a dominant allele with a dash represents an unknown genotype During gamete formation, different pairs of alleles segregate independently of each other - Y is just as likely to assort with R as it is with r - y is just as likely to assort with R as it is with r test cross one parent is always homozygous recessive and we find genotype of other parent by looking at the offspring Predict offspring for complicated crosses - The number of gametes = 2^n (n= number of genes with different alleles Aa Bb Cc Dd  2^4 = 16 different kinds of gametes **** A punnett square would have 256 boxes 16x16 gametes Iclicker question: Use only the heterozygous choices not the dominant or recessive homozygous genes they don’t count AaBbCcDd x AaBbCcDd what proportion will be AAbbCcDD? Break it down into hybrid crosses How many will show the dominant Phenotype 9/256 is the answer

2-12-2018 How to recognize recessive traits in pedigrees 1. Affected individuals can be the children of two unaffected carriers, particularly as a result of consanguineous matins ¼ 2. All the children of two affected parents should be affected 3. Rare recessive traits show a horizontal pattern of inheritance 4. Recessive traits may show a vertical pattern of inheritance Heterozygous individuals produce enough CFTR for normal lung function - Recessive cystic fibrosis disease allele encodes abnormal CFTR protein. - a horizontal pattern of inheritance indicates a rare recessive trait  cystic fibrosis If individuals 4 and 7 have a child, what is the probability that the child will have CF 1/6

If individuals 4 and 7 have a child, what is the probability the child will not be a carrier Horizontal = rare recessive Vertical = rare dominant 2-14-2018 clicker questions A B D ABO blood types are determined by three alleles A  IA B  IB allele i allele  no sugar missed class Friday no notes Epistasis results from the effects of an allele at one gene masking the effects of another gene Two genes determine coat color in lab retrievers Gene B; alleles determine black and chocolate Bb results in chocolate

Gene E  has no effect as E- ee...