WSU MBIOS 301 Unit 2 EXAM 2025

Trihybrid cross - -A cross involving three traits Interference - -1 (observed # double crossovers/expected # double crossovers) Aneuploidy - -Abnormal number of chromosomes 2n +- x Monosomy - -2n-1 chromosomes Disomy - -2n Trisomy - -2n + 1 Down syndrome - -Trisomy 21 Patau syndrome - -Trisomy 13 Edward syndrome - -Trisomy 18, very short life span Monosomy in humans is usually ________ - -Lethal Klinefelter syndrome - -XXY, male, usually infertile Triple X syndrome - -XXX , female Jacob syndrome - -XYY , male, viable Turner syndrome - -XO, female, viable Due to non-disjunction in meiotic cell cycle Polyploidy - -Condition in which an organism has extra sets of chromosomes Triploidy, Tetraploidy - -3n, 4n Not viable in humans, only in fish/plants Abnormal chromosome structure - -Deletion, duplication, non-homologous translocation, inversion Cri-du chat - -Chromosome 5 missing the tip Griffith's experiment - -Virulent 111S bacteria (causes death) Avirulent 11R bacteria WSU WSU WSU 1. Took 111S and injected into mouse, died Took 11R and injected into mouse, lived 2. Took 111S, heated up, inject into mouse, lived 3. Took live 11R and heat killed 111S and injected into mouse, died (when tissue was analyzed, live 111S recovered) Conclusion: some transforming principle - dead 111S bacteria transformed live 11R bacteria into live 111S bacteria Avery, MacLeoud, and McCarty experiment - --Wanted to know what caused live 11R bacteria into live 111S bacteria 1. 111S cells in liquid culture medium centrifuge, 111S spun to bottom of tube heat killed 111S, recover 111S filtrate 2. treat with protease to remove protein, take 111s + protease and inject, see if mouse dies 3. repeat this step with ribonuclease to remove RNA, and deoxyribonuclease to remove DNA 4. Transformation did not occur with the deoxyribonuclease + 111S (mouse lived) therefore the active transforming principle is DNA. Hershey-Chase Experiment - -Used radioactive material to label DNA and protein; infected bacteria passed on DNA; helped prove that DNA is genetic material not proteins Who was awarded this years nobel prize in Physiology/Medicine ? - -James Allison and Tasuku Honjo Ribonucleotides are covalently linked together by _________ - -A phosphodiester linkage Structure of RNA - --single stranded -5' to 3' end -phosphodiester bonds -can fold into many different shapes Proposed helical structure of proteins, pioneered the use of physical models - -Linus Pauling Provided data for DNA structure through x-ray diffraction studies Suggested: helical structure, too wide for single stranded helix, 10 base pairs per turn of the helix - -Rosalind Franklin and Maurice Wilkins He found that the amount of adenine was always similar to the amount of thymine, and the amount of guanine was always similar to the amount of cytosine. Suggested an interaction between A and T and between G and C. - -Erwin Chargaff WSU WSU A is paired to T with ____ hydrogen bonds - -2 G is paired to C with ____ hydrogen bonds - -3 James Watson and Francis Crick - -DNA double helix structure -the two strands are antiparallel, one runs 5' to 3', other runs 3' to 5' -the two strands are twisted together around a common axis -helix is right handed -10 bp and 3.4 nm per complete turn -width of DNA is always 20 ang Has a left handed double helix with 12 bp/turn - -Z DNA Predominant form of DNA found in living cell - -B DNA Both RNA and DNA are synthesized in the ___ to ___ direction - -5' to 3' direction DNA is replicated in a _______ mode - -Semiconservative, semidiscontinous, bidirectional _____ puts down RNA primer - -Primase Messelson-Stahl Experiment - -Found that DNA is replicated in a semi-conservative mode DNA replication can be summarized as ..... - --The 2 DNA strands come apart -Each serves as a template for synthesis of new strands -The 2 newly made strands = daughter strands -The 2 original ones = parental strands -DNA is replicated in a semi "discontinuous" mode, leading - continuous, lagging - discontinuous (okazaki segments) What do primases do? - -Synthesize RNA primers Polymerases in replication - -Many different functions What do helicases do in replication? - -Breaks hydrogen bonds What do topoisomerases do in replication? - -Cuts DNA to reduce torsional stress What do ligases do in replication? - -Seals, makes phosphodiester bonds What do single stranded binding proteins do? - -Keeps single strands apart Steps of replication - -Initiation, elongation, termination WSU WSU Bacterial replication: initiation features - --One origin of replication, rich in AT - oriC -Specific binding proteins (DnaA, DnaB, DnaC ... helicase activity) DNA topoisomerase, DNA gyrase Bacterial replication: elongation features - --Primase - make RNA primer -DNA polymerase -Leading & Lagging strands -Helicase, SSBPs, topoisomerase -Polymerase 1 to remove primer and fill in with DNA -DNA ligase to make phosphodiester bond Bacterial replication: termination features - --Ter DNA sequence -DNA binding protein Tus (termination utilization substance) Eukaryotic replication: termination features - --At the end of linear chromosomes = telomeres -DNA polymerase can only synthesize is 5' to 3' , also cannot initiate DNA synthesis (need an RNA primer) -This makes it so the end of the strand can't be replicated -Can't fill in, makes a 3' SS overhang, DNA does not like it so exonuclease will degrade it -Every replication, length of chromosome is reduced Apoptosis - -Programmed cell death What does telomerase do? - -Add telomeric repeats (deoxynucleotides) to the 3' SS DNA overhang so that more cell cycles can happen Binds to the 3' G-rich tail What is telomerase composed of - -Protein component + RNA component What is recombination? - --Happens in Prophase 1 of Meiosis 1 -DNA strands are cut and rejoined with different strands Transcription - -Process of making a copy of a DNA sequence into an RNA sequence Stages of transcription - --Initiation: RNA polymerase binds to DNA -Elongation: RNA polymerase synthesizes RNA -Termination: RNA polymerase stops synthesizing RNA Transcription: initiation - --Enzyme, RNA polymerase -Proteins called transcription factors (determine rate of transcription) -Specific DNA sequences of the gene Transcription factors - --General TFs - basal, low level transcription -Specific TFs - change the rate of transcription WSU WSU Specific transcription factors - -Activators: increase rate of transcription Inhibitors/repressors: lower rate of transcription Promoter sequence (core promoter) - -Binds general transcription factors and RNA pol Regulatory sequences - -Enhancer sequence: binds activator TFs Repressor/operator sequence: binds repressor TFs Where does transcription occur in prokaryotes - -Cytoplasm Where does transcription occur in eukaryotes - -Nucleus RNA pol - rRNA in prokaryotes - -16s, 23s, 5s RNA pol 1 - rRNA in eukaryotes - -28s, 18s, 5.8s RNA pol enzyme + general TFs = - -Sigma factor Termination in transcription : prokaryotes - -Rho-dependent: rho protein (P) Rho-independent: NusA, other proteins Rho-dependent termination - -Rho protein binds to the RUT sequence on the RNA. When it reaches stem loop where RNA pol has paused, RNA pol falls off and the RNA dissociates from the DNA. Polymerases involved in eukaryotic transcription - --RNA pol 1: transcribes rRNAs -RNA pol 11: transcribes mRNA, miRNA and snRNA (most complicated/controlled) -RNA pol 111: transcribes tRNA and small rRNA (5s) TATA box - -A promoter DNA sequence crucial in forming the