BS 161 FINAL EXAM 2024 NEWEST EXAM 2 VERSIONS
(VERSION A AND B) COMPLETE 450 QUESTIONS AND
CORRECT DETAILED ANSWERS (VERIFIED ANSWERS) |
ALREADY GRADED A+
What is a mutation? - ANSWER: 1. an heritable change to the genome
a. heritability- could be passed on (must be a change to the genetic material)
2. spontaneous and random
3. all mutations create new alleles (combo. of alleles= genotype)
Point mutations - ANSWER: 1. alter in a single nucleotide
a. Ex. adenine changed to guanine
b. if not fixed, when the cell with the mutation divides, one of its daughter cells is
different than the other
i. cell produced may have a different protein than the original parent cell --> could
cause the cell to gain or lose a function
2. to determine the effect of a point mutation, look at. the protein
What are mutations caused by? - ANSWER: 1. errors in replication (mistake by DNA
polymerase)
a. cells have many tools to prevent/ fix the errors
b. DNA polymerase can make a mistake during the S phase
2. environmental damage (toxins)
3. spontaneous chemical reactions
What are the ways DNA can be damaged/ modified? - ANSWER: 1. Chemical
modifications
a. can change nitrogenous bases within nucleotides
b. deamination and depurization
2. Single strands and double strands can break
3. cross-linked base (nitrogenous bases linked in abnormal ways)
4. missing or modified base
Mutation found during Transcription - ANSWER: 1. transcription is performed by RNA
polymerase, which binds to the promoter of a specific DNA sequence
a. if the promoter is changed, transcription could be decreased or increased
b. if the terminator is changed, a new RNA molecule could be made
Mutation of Primary RNA - ANSWER: 1. primary RNA is produced from transcription
2. has exons and introns
a. exons= regions of DNA that encode part of the protein
i. exons are translated to produce the sequence of amino acids between the start
and stop codons
ii. if the exon changes, the amino acid could change
, b. introns= regions of DNA removed during RNA processing and produce messenger
RNA
i. mutation to intron doesn't matter because its removed during RNA processing
Mutation of Messenger RNA - ANSWER: 1. messenger RNA is what the ribosome
translates to produce the final protein
a. begins with the start codon (AUG)
i. if this changed, translation could not happen or the location could be changed
which could produce a longer or shorter protein
b. stop codons cause ribosomes to stop translation (UGA)
i. if the stop codon is removed, additional amino acids could be produced
ii. if the stop codon is inserted in the middle of an exon, than a different short
protein could be produced
c. mutation on 5' or 3' ends of messenger RNA (outside of coding sequence) will
likely have no effect on final protein
Why is double-stranded DNA a more stable genetic material than single-stranded
DNA or RNA? - ANSWER: 1. complementary base-pairing between the two strands
limits the amount of mutations that don't get fixed and then get passed along to
daughter cells
a. if there's a change in one nucleotide, there's another strand with the
complementary sequence
i. so enzymes can use this other strand of nucleotides to determine how to fix a
strand that's been changed
Silent/ Synonymous Mutations - ANSWER: mutations that do not change the amino
acid sequence even though there was a change in the DNA
Missense Mutations - ANSWER: mutations that change one amino acid in the
sequence
Nonsense Mutations - ANSWER: 1. mutations that result in a new stop codon
a. could result in a really small protein being made if the stop codon is at the
beginning of the amino acid sequence
b. make a big difference in the final protein produced
2. do not affect transcription because RNA polymerases read 1 base at a time
a. since each gene has their own start and stop codons, a nonsense mutation on 1
gene would only affect that gene causing only a portion of that gene to be translated
Frameshift Mutations - ANSWER: 1. mutations (insertions) caused by the reading
frame of the ribosome being changed
a. the insertion or deletion of one or two ribosomes cause the reading frame for the
ribosome to completely change which causes many amino acids within the final
protein to be different
What are mutations that involve large changes to chromosomes? - ANSWER: 1.
common in tumor cells
(VERSION A AND B) COMPLETE 450 QUESTIONS AND
CORRECT DETAILED ANSWERS (VERIFIED ANSWERS) |
ALREADY GRADED A+
What is a mutation? - ANSWER: 1. an heritable change to the genome
a. heritability- could be passed on (must be a change to the genetic material)
2. spontaneous and random
3. all mutations create new alleles (combo. of alleles= genotype)
Point mutations - ANSWER: 1. alter in a single nucleotide
a. Ex. adenine changed to guanine
b. if not fixed, when the cell with the mutation divides, one of its daughter cells is
different than the other
i. cell produced may have a different protein than the original parent cell --> could
cause the cell to gain or lose a function
2. to determine the effect of a point mutation, look at. the protein
What are mutations caused by? - ANSWER: 1. errors in replication (mistake by DNA
polymerase)
a. cells have many tools to prevent/ fix the errors
b. DNA polymerase can make a mistake during the S phase
2. environmental damage (toxins)
3. spontaneous chemical reactions
What are the ways DNA can be damaged/ modified? - ANSWER: 1. Chemical
modifications
a. can change nitrogenous bases within nucleotides
b. deamination and depurization
2. Single strands and double strands can break
3. cross-linked base (nitrogenous bases linked in abnormal ways)
4. missing or modified base
Mutation found during Transcription - ANSWER: 1. transcription is performed by RNA
polymerase, which binds to the promoter of a specific DNA sequence
a. if the promoter is changed, transcription could be decreased or increased
b. if the terminator is changed, a new RNA molecule could be made
Mutation of Primary RNA - ANSWER: 1. primary RNA is produced from transcription
2. has exons and introns
a. exons= regions of DNA that encode part of the protein
i. exons are translated to produce the sequence of amino acids between the start
and stop codons
ii. if the exon changes, the amino acid could change
, b. introns= regions of DNA removed during RNA processing and produce messenger
RNA
i. mutation to intron doesn't matter because its removed during RNA processing
Mutation of Messenger RNA - ANSWER: 1. messenger RNA is what the ribosome
translates to produce the final protein
a. begins with the start codon (AUG)
i. if this changed, translation could not happen or the location could be changed
which could produce a longer or shorter protein
b. stop codons cause ribosomes to stop translation (UGA)
i. if the stop codon is removed, additional amino acids could be produced
ii. if the stop codon is inserted in the middle of an exon, than a different short
protein could be produced
c. mutation on 5' or 3' ends of messenger RNA (outside of coding sequence) will
likely have no effect on final protein
Why is double-stranded DNA a more stable genetic material than single-stranded
DNA or RNA? - ANSWER: 1. complementary base-pairing between the two strands
limits the amount of mutations that don't get fixed and then get passed along to
daughter cells
a. if there's a change in one nucleotide, there's another strand with the
complementary sequence
i. so enzymes can use this other strand of nucleotides to determine how to fix a
strand that's been changed
Silent/ Synonymous Mutations - ANSWER: mutations that do not change the amino
acid sequence even though there was a change in the DNA
Missense Mutations - ANSWER: mutations that change one amino acid in the
sequence
Nonsense Mutations - ANSWER: 1. mutations that result in a new stop codon
a. could result in a really small protein being made if the stop codon is at the
beginning of the amino acid sequence
b. make a big difference in the final protein produced
2. do not affect transcription because RNA polymerases read 1 base at a time
a. since each gene has their own start and stop codons, a nonsense mutation on 1
gene would only affect that gene causing only a portion of that gene to be translated
Frameshift Mutations - ANSWER: 1. mutations (insertions) caused by the reading
frame of the ribosome being changed
a. the insertion or deletion of one or two ribosomes cause the reading frame for the
ribosome to completely change which causes many amino acids within the final
protein to be different
What are mutations that involve large changes to chromosomes? - ANSWER: 1.
common in tumor cells
