Mutation - 4

Question 1

What 4 nucleotides is the sugar phosphate made up of

Answer 1

2 pyrimidines (cytosine and thymine)
2 purines (adenine and guanine)

Question 2

What are the 6 possible changes that can occur in DNA substitution mutations

Answer 2

2 transitions and 4 transversions

Question 3

Define transitions (ts)

Answer 3

substitution mutation with the same shape change, purine to purine or pyrimidine to pyrimidine

Question 4

Define transversions (tv)

Answer 4

mutation with a different shape change, purine to pyrimidine or vise versa

Question 5

Do we see transitions or transversions more and why

Answer 5

more transitions because they go from similar size and structure whereas transversions result in larger changes and cause much more disruption to DNA therefore either won’t happen or will be more noticeable and repaired quicker.

Question 6

Define point mutation

Answer 6

a change in a single nucleotide that results from random error during DNA synthesis or repair

Question 7

What are the two types of point mutation events

Answer 7

insertions and deletions

Question 8

Define wobble codon

Answer 8

an example of a natural mutation where T-G or C-A occasionally bind, but doesn’t affect its function.

Question 9

what are the 3 types of affects that result if a mutation occurs in the coding region

Answer 9

synonymous, nonsynonymous or nonsense mutation

Question 10

Define synonymous mutation

Answer 10

SILENT
the mutated amino acid is not modified

Question 11

Define nonsynonymous mutation

Answer 11

MISSENSE
mutation that changes the amino acid and may alter the function of a protein

Question 12

Define nonsense mutation

Answer 12

mutation that introduces a premature stop codon which often makes the protein nonfunctional.

Question 13

_____ mutations are more common than ____ mutations because of what two reasons

Answer 13

synonymous, nonsynonymous
1. nonsynonymous mutations are subject to higher selective pressures as they cause a disadvantage to organisms
2. transitions are more likely to cause synonymous mutations which is less likely to be repaired in mechanisms making them more common

Question 14

Define transposons/jumping genes

Answer 14

elements of the DNA that can move from one location to another within a genome
Ex. in kernel colour, there is a gene that can cause another gene to “jump” within the genome and can cause colour inhibition

Question 15

What are the two types of duplicated genes

Answer 15

paralogous and orthologous

Question 16

Define paralogous genes

Answer 16

genes that are similar due to duplication

Question 17

Define orthologous genes

Answer 17

similarity due to ancestry
genes in different organisms that are inherited by speciation instead of the same organisms

Question 18

Define exon and intron of globular genes

Answer 18

introns = noncoding stretch of DNA that occurs between coding regions that must be spliced out to produce functional mRNA
exons = nucleotide sequence that occurs between introns and remain in the mRNA.

Question 19

What are the 3 “fates” of duplicated genes

Answer 19

1. rRNA = still retain original function
2. globin genes = obtain a new function
3. pseudogene = become functionless

Question 20

What are the four types of chromosomal alterations

Answer 20

1. insertions/deletions
2. translocations
3. inversions (flipped in reverse order)
4. polyploidy

Question 21

What does chromosomal rearrangements cause an increase of in ecosystems

Answer 21

variation!

Question 22

Define polyploidy

Answer 22

organisms with more than two chromosomes per set

Question 23

how does polyploidy cause instant speciation

Answer 23

mistakenly creates a tetraploid instead of diploid and they can no longer reproduce with the diploids meaning they created a new species. tetraploids must now reproduce with tetraploids

Question 24

What are 3 reasons why mutations are not always bad

Answer 24

1. high mutation rates can be advantageous to form new habitats and in unstable environments
2. not all mutations are harmful
3. when new mutations occur, selection will likely act on them and create a smaller fitness difference within species

Question 25

Explain the balance between selection and mutation

Answer 25

most mutations are slightly deleterious until selection comes along. selection is necessary to select for or against or else mutation would quickly accumulate. but mutations are also still required for evolution!