Lecture 8 cards

Question 1

<p class=”large” style=”text-align:center”;>Mutation</p>

Answer 1

<p class=”large” style=”text-align:center”;>refers to a heritable change in genetic material</p>

Question 2

<p class=”large” style=”text-align:center”;>What are the 3 main categories of mutations?</p>

Answer 2

<p class=”large” style=”text-align:center”;>1. gene mutations, 2. chromosome mutations,3. genome mutations</p>

Question 3

<p class=”large” style=”text-align:center”;>gene mutations</p>

Answer 3

<p class=”large” style=”text-align:center”;>small change in DNA .. Affects a single or a few genes.</p>

Question 4

<p class=”large” style=”text-align:center”;>chromosome structure</p>

Answer 4

<p class=”large” style=”text-align:center”;>changes in chromosome structure</p>

Question 5

<p class=”large” style=”text-align:center”;>genome mutations</p>

Answer 5

<p class=”large” style=”text-align:center”;>changes in chromosome number</p>

Question 6

<p class=”large” style=”text-align:center”;>Mutations provide for _________ ____________, a component that necessary for evolution to occur?</p>

Answer 6

<p class=”large” style=”text-align:center”;>allelic variation</p>

Question 7

<p class=”large” style=”text-align:center”;>Mutation Rate</p>

Answer 7

<p class=”large” style=”text-align:center”;>likelihood that a gene will be altered by a new mutation; (# new mutations in a gene)/(cell generation)</p>

Question 8

<p class=”large” style=”text-align:center”;>What factors can influence mutation rate?</p>

Answer 8

<p class=”large” style=”text-align:center”;>-mutagens</p>

Question 9

<p class=”large” style=”text-align:center”;>mutS</p>

Answer 9

<p class=”large” style=”text-align:center”;>lack of this gene = no repair made</p>

Question 10

<p class=”large” style=”text-align:center”;>What 2 gene characteristic factors can affect the rate of mutation?</p>

Answer 10

<p class=”large” style=”text-align:center”;>1. size of gene (…larger genes have a greater chance for mutation);2. hot spots ( locations on chromosome that are more susceptible to mutation)</p>

Question 11

<p class=”large” style=”text-align:center”;>Somatic hypermutation (SHM)</p>

Answer 11

<p class=”large” style=”text-align:center”;>mechanism that involves a programmed process of mutation affecting the variable regions of immunoglobulin genes which diversifies B cell receptors to expand their recognition range</p>

Question 12

<p class=”large” style=”text-align:center”;>Mutation Frequency</p>

Answer 12

<p class=”large” style=”text-align:center”;>the number of mutant alleles divided by the total number of that allele in a population</p>

Question 13

<p class=”large” style=”text-align:center”;>What is the mutation frequency if: 1 million bacteria were plated and 10 of them were mutant?`</p>

Answer 13

<p class=”large” style=”text-align:center”;>1 in 100,000 or 10^-5</p>

Question 14

<p class=”large” style=”text-align:center”;>What 3 things does mutation frequency depend on?</p>

Answer 14

<p class=”large” style=”text-align:center”;>1- mutation rate; 2- timing of the mutation; 3- likelihood that the mutation will be passed on to future generations</p>

Question 15

<p class=”large” style=”text-align:center”;>Different types of DNA mutations:</p>

Answer 15

<p class=”large” style=”text-align:center”;>-point mutation,-INDEL; -silent mutations; -missense mutations; -nonsense mutations; -frameshift mutations</p>

Question 16

<p class=”large” style=”text-align:center”;>point mutation</p>

Answer 16

<p class=”large” style=”text-align:center”;>change in a single base pair</p>

Question 17

<p class=”large” style=”text-align:center”;>What are the 2 types of point mutations?</p>

Answer 17

<p class=”large” style=”text-align:center”;>1. transition; 2. transversions</p>

Question 18

<p class=”large” style=”text-align:center”;>What is a Transition point mutation?</p>

Answer 18

<p class=”large” style=”text-align:center”;>a change of a pyrimidine (C,T) to another pyrimidine (C,T) OR a purine (A,G) to another purine (A,G)</p>

Question 19

<p class=”large” style=”text-align:center”;>What is a Transversion point mutation?</p>

Answer 19

<p class=”large” style=”text-align:center”;>a change of a pyrimidine to a purine or vice versa</p>

Question 20

<p class=”large” style=”text-align:center”;>Which is the more common type of point mutation?</p>

Answer 20

<p class=”large” style=”text-align:center”;>Transition</p>

Question 21

<p class=”large” style=”text-align:center”;>INDEL</p>

Answer 21

<p class=”large” style=”text-align:center”;>insertion or deletion of base pairs</p>

Question 22

<p class=”large” style=”text-align:center”;>silent mutations</p>

Answer 22

<p class=”large” style=”text-align:center”;>do not alter the amino acid sequence of the polypeptide ( due to degeneracy and wobble)</p>

Question 23

<p class=”large” style=”text-align:center”;>missense mutation</p>

Answer 23

<p class=”large” style=”text-align:center”;>base substitutions in which an amino acid change occurs</p>

Question 24

<p class=”large” style=”text-align:center”;>nonsense mutations</p>

Answer 24

<p class=”large” style=”text-align:center”;>base substitutions that change a normal codon to a stop codon</p>

Question 25

<p class=”large” style=”text-align:center”;>frameshift mutations</p>

Answer 25

<p class=”large” style=”text-align:center”;>the addition or deletion of bases not divisible by three</p>

Question 26

<p class=”large” style=”text-align:center”;>Explain the effect of a nonsense mutation on translation</p>

Answer 26

<p class=”large” style=”text-align:center”;>(figure slide #12) altered codon= a nonsense codon and therefore premature termination of translation</p>

Question 27

<p class=”large” style=”text-align:center”;>Different types of gene mutations:</p>

Answer 27

<p class=”large” style=”text-align:center”;>-forward mutation; -reverse mutation; -suppressor mutation</p>

Question 28

<p class=”large” style=”text-align:center”;>forward mutation</p>

Answer 28

<p class=”large” style=”text-align:center”;>changes the wild-type genotype into a new variation</p>

Question 29

<p class=”large” style=”text-align:center”;>reverse mutation</p>

Answer 29

<p class=”large” style=”text-align:center”;>changes a mutant allele back to the wild-type allele</p>

Question 30

<p class=”large” style=”text-align:center”;>Mutations described based on their effects on the wild-type phenotype:</p>

Answer 30

<p class=”large” style=”text-align:center”;>–deleterious mutations;–beneficial mutations;– conditional mutations;–neutral mutations</p>

Question 31

<p class=”large” style=”text-align:center”;>deleterious mutations</p>

Answer 31

<p class=”large” style=”text-align:center”;>decrease the chances of survival</p>

Question 32

<p class=”large” style=”text-align:center”;>beneficial mutations</p>

Answer 32

<p class=”large” style=”text-align:center”;>enhance the survival or reproductive success of an organism</p>

Question 33

<p class=”large” style=”text-align:center”;>conditional mutations</p>

Answer 33

<p class=”large” style=”text-align:center”;>affect the phenotype only under a defined set of conditions.;-temperature-sensitive mutation</p>

Question 34

<p class=”large” style=”text-align:center”;>supressor mutations</p>

Answer 34

<p class=”large” style=”text-align:center”;>describes how mutations can be altered: a second mutation that counteracts the effects of a first mutation</p>

Question 35

<p class=”large” style=”text-align:center”;>2 types of suppressor mutations:</p>

Answer 35

<p class=”large” style=”text-align:center”;>1- intragenic suppressors; 2-intergenic suppressors</p>

Question 36

<p class=”large” style=”text-align:center”;>intragenic suppressors</p>

Answer 36

<p class=”large” style=”text-align:center”;>second site is within the same gene as the first mutation</p>

Question 37

<p class=”large” style=”text-align:center”;>intergenic suppressors</p>

Answer 37

<p class=”large” style=”text-align:center”;>second site is in a different gene from the first mutation; (figure on slide #15); -tRNA suppressor gene mechanism for nonsense mutation:</p>

Question 38

<p class=”large” style=”text-align:center”;>The tRNA suppressor is an example of which type of suppressor mutation?</p>

Answer 38

<p class=”large” style=”text-align:center”;>intergenic suppression</p>

Question 39

<p class=”large” style=”text-align:center”;>What is the result of the tRNA suppressor gene mechanism for nonsense mutation?</p>

Answer 39

<p class=”large” style=”text-align:center”;>transcription and translation of mRNA with nonsense codon. The altered codon = nonsense codon. The altered anticodon in mutant tRNA gene. There is no premature termination of translation so a complete polypeptide is formed with one incorrect amino acid !</p>

Question 40

<p class=”large” style=”text-align:center”;>chromosomal breakpoint</p>

Answer 40

<p class=”large” style=”text-align:center”;>occurrence of this within a gene is affected by chromosomal rearrangement</p>

Question 41

<p class=”large” style=”text-align:center”;>position effect</p>

Answer 41

<p class=”large” style=”text-align:center”;>a gene is left intact but the expression is altered bc of its new location</p>

Question 42

<p class=”large” style=”text-align:center”;>What are 2 common reasons for position effects?</p>

Answer 42

<p class=”large” style=”text-align:center”;>(figure on slide # 16);1-movement to a position next to regulatory sequences;2-movement to a heterochromatic region</p>

Question 43

<p class=”large” style=”text-align:center”;>Germ-line mutations VS somatic cell mutations</p>

Answer 43

<p class=”large” style=”text-align:center”;>can be passed to future generations…. cannot be passed to future generations</p>

Question 44

<p class=”large” style=”text-align:center”;>Where can somatic cell mutations occur?</p>

Answer 44

<p class=”large” style=”text-align:center”;>-all body cells (no gametes); -autosome or sex chromosome</p>

Question 45

<p class=”large” style=”text-align:center”;>spontaneous mutations</p>

Answer 45

<p class=”large” style=”text-align:center”;>-result from abnormalties in cellular/biological processes ; -underlying cause originates within the cell</p>

Question 46

<p class=”large” style=”text-align:center”;>induced mutation</p>

Answer 46

<p class=”large” style=”text-align:center”;>-caused by environmental agents</p>

Question 47

<p class=”large” style=”text-align:center”;>mutagens</p>

Answer 47

<p class=”large” style=”text-align:center”;>agents that can alter DNA structure (can be chemical or physical)</p>

Question 48

<p class=”large” style=”text-align:center”;>Salvadore Luria and Max Delbruck: what did they study & what was their question?</p>

Answer 48

<p class=”large” style=”text-align:center”;>-studied resistance of E. coli to infection by bacteriophage T1. ; -Is ton^r due to spontaneous mutations or to a physiological adaptation that occurs at a low rate?; -fluctuation test</p>

Question 49

<p class=”large” style=”text-align:center”;>ton^r</p>

Answer 49

<p class=”large” style=”text-align:center”;>T1 resistance</p>

Question 50

<p class=”large” style=”text-align:center”;>Luria-Delbruck: What does the physiological adaptation theory predict?</p>

Answer 50

<p class=”large” style=”text-align:center”;>the number of ton^r bacteria is an essentially constant proportion of the total population. (in different bacterial populations this proportion should be very similar)</p>

Question 51

<p class=”large” style=”text-align:center”;>Luria-Delbruck: What does the random mutation theory predict?</p>

Answer 51

<p class=”large” style=”text-align:center”;>the number of ton^r bacteria will fluctuate in different bacterial populations based upon the timing of the mutation</p>

Question 52

<p class=”large” style=”text-align:center”;>fluctuation test</p>

Answer 52

<p class=”large” style=”text-align:center”;>figure on slide #22</p>

Question 53

<p class=”large” style=”text-align:center”;>Joshua and Ester Lederberg</p>

Answer 53

<p class=”large” style=”text-align:center”;>looked at relationship bw mutations and environmental conditions that select for mutation.</p>

Question 54

<p class=”large” style=”text-align:center”;>What were the two theories of the J&E Lederberg experiment?</p>

Answer 54

<p class=”large” style=”text-align:center”;>1- physiological adaptation theory (Lamarck’s viewpoint); 2- random mutation theory (Darwin’s viewpoint)</p>

Question 55

<p class=”large” style=”text-align:center”;>Describe the Joshua and Ester Lederberg experiment:</p>

Answer 55

<p class=”large” style=”text-align:center”;>figure on slide #25</p>

Question 56

<p class=”large” style=”text-align:center”;>CRISPR system</p>

Answer 56

<p class=”large” style=”text-align:center”;>Lamarck wasn’t entirely wrong …. well, at least for the bacteria that carry this system: adaptive immune defense</p>

Question 57

<p class=”large” style=”text-align:center”;>3 chemical changes that lead to spontaneous mutations:</p>

Answer 57

<p class=”large” style=”text-align:center”;>1- depurination; 2- deamination; 3- tautomeric shift</p>

Question 58

<p class=”large” style=”text-align:center”;>spontaneous mutations can occur by mispairings or “_________” during DNA replication : all of these fall under this category</p>

Answer 58

<p class=”large” style=”text-align:center”;>-wobble pairing; -INDELs; -“slipping”-slippage</p>

Question 59

<p class=”large” style=”text-align:center”;>depurination</p>

Answer 59

<p class=”large” style=”text-align:center”;>removal of a purine: Adenine or Guanine</p>

Question 60

<p class=”large” style=”text-align:center”;>How does depurination occur?</p>

Answer 60

<p class=”large” style=”text-align:center”;>covalent bond bw deoxyribose and purine base is somewhat unstable and it undergoes hydrolysis (beta-N-glycocidic link) that releases the base from the sugar.</p>

Question 61

<p class=”large” style=”text-align:center”;>apurinic site</p>

Answer 61

<p class=”large” style=”text-align:center”;>lack of a purine caused by depurination</p>

Question 62

<p class=”large” style=”text-align:center”;>deamination</p>

Answer 62

<p class=”large” style=”text-align:center”;>removal of an amino group from cytocine resulting in uracil!</p>

Question 63

<p class=”large” style=”text-align:center”;>What happens if DNA repair enzymes do not recognize the faulty Uracil (from deamination)?</p>

Answer 63

<p class=”large” style=”text-align:center”;>a C-G to A-T mutation will result during later rounds of DNA replication</p>

Question 64

<p class=”large” style=”text-align:center”;>deamination of 5-methyl cytosine results in…</p>

Answer 64

<p class=”large” style=”text-align:center”;>Thymine (T)</p>

Question 65

<p class=”large” style=”text-align:center”;>What happens when the deamination of 5-methyl cytosine occurs?</p>

Answer 65

<p class=”large” style=”text-align:center”;>DNA repairenzymes cannot determine which of the two bases on the DNA strands is the incorrect base</p>

Question 66

<p class=”large” style=”text-align:center”;>methylated cytosine bases tend to create _____ _____ for mutation</p>

Answer 66

<p class=”large” style=”text-align:center”;>hot spots (CpG islands)</p>

Question 67

<p class=”large” style=”text-align:center”;>Tautomeric shift</p>

Answer 67

<p class=”large” style=”text-align:center”;>a temporary change in base structure</p>

Question 68

<p class=”large” style=”text-align:center”;>2 forms of bases:</p>

Answer 68

<p class=”large” style=”text-align:center”;>1-the common (Keto or Amino); 2-the uncommon (Enol or Imino)</p>

Question 69

<p class=”large” style=”text-align:center”;>How do the uncommon forms of bases created by taotomeric shifts differ from the common forms?</p>

Answer 69

<p class=”large” style=”text-align:center”;>Alternate forms differ by a single proton shift in the molecule</p>

Question 70

<p class=”large” style=”text-align:center”;>Stable form of Thymine and Guanine</p>

Answer 70

<p class=”large” style=”text-align:center”;>Keto</p>

Question 71

<p class=”large” style=”text-align:center”;>Stable form of Adenine and Cytosine</p>

Answer 71

<p class=”large” style=”text-align:center”;>Amino</p>

Question 72

<p class=”large” style=”text-align:center”;>T and G can interconvert to an ______ form</p>

Answer 72

<p class=”large” style=”text-align:center”;>enol</p>

Question 73

<p class=”large” style=”text-align:center”;>A and C can interconvert to an ______ form</p>

Answer 73

<p class=”large” style=”text-align:center”;>Imino</p>

Question 74

<p class=”large” style=”text-align:center”;>Rare forms of bases can promote….</p>

Answer 74

<p class=”large” style=”text-align:center”;>incorrect AC and GT base pairs</p>

Question 75

<p class=”large” style=”text-align:center”;>When must a tautomeric shift occur in order for it to cause a mutation?</p>

Answer 75

<p class=”large” style=”text-align:center”;>just prior to DNA replication, when the DNA is not in double helix</p>

Question 76

<p class=”large” style=”text-align:center”;>Example of slippage</p>

Answer 76

<p class=”large” style=”text-align:center”;>figure on slide # 36</p>

Question 77

<p class=”large” style=”text-align:center”;>DNA loops out on template strand</p>

Answer 77

<p class=”large” style=”text-align:center”;>PolIII skips bases</p>

Question 78

<p class=”large” style=”text-align:center”;>DNA loops out on daughter strand</p>

Answer 78

<p class=”large” style=”text-align:center”;>PolIII adds random bases</p>

Question 79

<p class=”large” style=”text-align:center”;>Why might slippage occur?</p>

Answer 79

<p class=”large” style=”text-align:center”;>long run of same nucleotide</p>

Question 80

<p class=”large” style=”text-align:center”;>Slipped Strand Mispairing:</p>

Answer 80

<p class=”large” style=”text-align:center”;>if a DNA strand loops out and becomes displaced or if a DNA polymerase slips small insertions and deletions can occur</p>

Question 81

<p class=”large” style=”text-align:center”;>Where is replication slippage common?</p>

Answer 81

<p class=”large” style=”text-align:center”;>particularly poly-G tracts</p>

Question 82

<p class=”large” style=”text-align:center”;>trinucleotide repeat expansion (TNRE)</p>

Answer 82

<p class=”large” style=”text-align:center”;>causes several genetic diseases… in people with these disorders the length of a trinucleotide repeat has increased above a certain critical size and then disease symptoms occur</p>

Question 83

<p class=”large” style=”text-align:center”;>If expansion due to TNRE occurs within the coding sequence of the gene….</p>

Answer 83

<p class=”large” style=”text-align:center”;>proteins aggregate with each other. typically the expansion is a CAG codon for glutamine)</p>

Question 84

<p class=”large” style=”text-align:center”;>If the expansion due to TNRE is located in noncoding regions of genes expansions may:</p>

Answer 84

<p class=”large” style=”text-align:center”;>-cause abnormal changes in RNA structure</p>

Question 85

<p class=”large” style=”text-align:center”;>2 unusual features in common within TNRE disorders:</p>

Answer 85

<p class=”large” style=”text-align:center”;>1-Anticipation ; 2-anticipation usually depends on who the disease is inherited from</p>

Question 86

<p class=”large” style=”text-align:center”;>anticipation</p>

Answer 86

<p class=”large” style=”text-align:center”;>the severity of the disease (a TNRE disorder) tends to worsen in future generations</p>

Question 87

<p class=”large” style=”text-align:center”;>chemical mutagens are categorized as:</p>

Answer 87

<p class=”large” style=”text-align:center”;>-base analogs; -base modifiers; -intercalating agents</p>

Question 88

<p class=”large” style=”text-align:center”;>base analogs</p>

Answer 88

<p class=”large” style=”text-align:center”;>(may change pairing) become incorporated into daughter strands during DNA replication</p>

Question 89

<p class=”large” style=”text-align:center”;>base modifiers</p>

Answer 89

<p class=”large” style=”text-align:center”;>(change one base into another) covalently modify the structure of a nucleotide</p>

Question 90

<p class=”large” style=”text-align:center”;>base modifier examples:</p>

Answer 90

<p class=”large” style=”text-align:center”;>nitrous acid : replaces amino groups with keto groups ; nirogen mustards and ethyl methanesulfonate (EMS)</p>

Question 91

<p class=”large” style=”text-align:center”;>intercalating agents</p>

Answer 91

<p class=”large” style=”text-align:center”;>(alter the shape of DNA and cause INDEL) contain flat planar structures that intercalate themselves into DNA… when inserted, this distorts the helical structure)</p>

Question 92

<p class=”large” style=”text-align:center”;>what happens when DNA containing intercalating agents are replicated?</p>

Answer 92

<p class=”large” style=”text-align:center”;>the daughter strand may contain single-nucleotide additions and/or deletions resulting in frameshifts</p>

Question 93

<p class=”large” style=”text-align:center”;>intercalating agents examples</p>

Answer 93

<p class=”large” style=”text-align:center”;>acridine dyes; proflavin;Ethidium Bromide</p>

Question 94

<p class=”large” style=”text-align:center”;>2 types of physical mutagens:</p>

Answer 94

<p class=”large” style=”text-align:center”;>1- ionizing radiation; 2- nonionizing radiation</p>

Question 95

<p class=”large” style=”text-align:center”;>ionizing radiation</p>

Answer 95

<p class=”large” style=”text-align:center”;>short wavelength and high frequency </p>

Question 96

<p class=”large” style=”text-align:center”;>free radicals can be created by</p>

Answer 96

<p class=”large” style=”text-align:center”;>ionizing radiation</p>

Question 97

<p class=”large” style=”text-align:center”;>ionizing radiation can cause:</p>

Answer 97

<p class=”large” style=”text-align:center”;>-base deletions; -oxidized bases; -single nicks in DNA strands;-cross-linking; -chromosomal breaks</p>

Question 98

<p class=”large” style=”text-align:center”;>nonionizing radiation</p>

Answer 98

<p class=”large” style=”text-align:center”;>lower energy than ionizing (includes UV light)</p>

Question 99

<p class=”large” style=”text-align:center”;>nonionizing radiation causes:</p>

Answer 99

<p class=”large” style=”text-align:center”;>the formation of cross-linked pyrimidine dimers (C or T) called cyclobutane pyrimidine dimer or less common 6,4-photoproducts</p>

Question 100

<p class=”large” style=”text-align:center”;>when might pyrimidin dimers cause mutations?</p>

Answer 100

<p class=”large” style=”text-align:center”;>when DNA is replicated</p>

Question 101

<p class=”large” style=”text-align:center”;>What is the purpose of an Ames test?</p>

Answer 101

<p class=”large” style=”text-align:center”;>to determine if something is a mutagen</p>

Question 102

<p class=”large” style=”text-align:center”;>Ames test</p>

Answer 102

<p class=”large” style=”text-align:center”;>uses a strain of Salmonella typhimurium that cannot synthesize histidine (amino acid) [it has a point mutation (or a deletion) in a gene involved in histidine biosynthesis]. A second mutation (reversion) may occur restoring ability to synthesize histidine. Ames test monitors the rate at which the second mutation occurs</p>

Question 103

<p class=”large” style=”text-align:center”;>The restoration of the ability to synthesize histidine in the S. typhimurium strain used in an Ames test is…..</p>

Answer 103

<p class=”large” style=”text-align:center”;>a Reversion (reverse mutation) –> second mutation</p>

Question 104

<p class=”large” style=”text-align:center”;>Describe an Ames test</p>

Answer 104

<p class=”large” style=”text-align:center”;>figure on slide #52</p>