Exam 2: Mutations I

Question 1

define a somatic mutation

Answer 1

arise in tissues other than those that produce gametes and impact is restricted to the individual
arise post fertilization an ex is cancer

Question 2

define a germ-line mutation

Answer 2

arise in tissue that produce gametes and can be passed to offspring
from mom and dad; incorporated in gametes

Question 3

are mutations always harmful?

Answer 3

no; mutations are building blocks for evolution as mutations can be functionally better than original gene for the environment the organism is in

Question 4

somatic mutations occur in _ cells and are passed to new cells through _

Answer 4

nonreproductive cells and are passed to new cells through mitosis creating a clone of cells having the mutant gene population of mutant cells

Question 5

germ-line mutations occur in cells that give rise to _ through _

Answer 5

cells that give rise to gametes, meiosis and sexual reproduction allow germ line-line mutations to be passed to approx half the members of the next generation who will cary the mutation in ALL THEIR CELLS

Question 6

de novo mutations

Answer 6

an alteration in a gene that is present for the first time in one family member as a result of a mutation in a germ cell (sperm/egg) of one of the parents or in the fertilized egg itself.

Question 7

de novo can be either germ line or somatic?

Answer 7

yes

Question 8

de novo mutations get greater attention when determining pathological causation why?

Answer 8

a de novo mutation happens for the first time in a family (usu during meiosis during replication an aa change happens) neither mom or dad has it so its brand new and gets a marker for being important as it is not inherited

Question 9

a base substitution alters a _

Answer 9

single codon

Question 10

insertions and deletions, 2 types

Answer 10

frameshift mutations

in-frame insertions and deletions

Question 11

an insertion or a deletion alters _

Answer 11

the reading frame and may change many codons

Question 12

expanding nucleotide repeats

Answer 12

increase in the number of copies of a set of nucleotides

Question 13

a transition is the substitution of

Answer 13

a purine for a purine or a pyrimidine for a pyrimidine

Question 14

a transversion is the substitution of

Answer 14

a pyrimidine for a purine or a purine for a pyrimidine

Question 15

trinucleotide repeat mutations increase

Answer 15

generationally

Question 16

trinucleotide repeat mutations (expansion) leads to

Answer 16

inactivation of product of a gene ex fragile x and huntington’s disease

Question 17

trinucleotide repeat mutations (expansion) leads to

Answer 17

increases generationally, results in inactivation of product of a gene ex fragile x (fragile site where repeat is expanded as tendency for mistakes to happen)

Question 18

neutral mutation

Answer 18

missense mutation that ALTERS THE AA seq but does not change the function of the protein

Question 19

neutral mutation

Answer 19

missense mutation that ALTERS THE AA seq but does not change the function of the protein
tolerant bc aa seq change may come from the same family of aas and/or stretch of protein is not critical to protein fcn

Question 20

silent mutation

Answer 20

mutation changes the codon seq but not the aa

new codon encodes the same aa; no change in aa seq

Question 21

missense mutation

Answer 21

missense mutation is when the change of a single base pair causes the substitution of a different amino acid in the resulting protein. This amino acid substitution may have no effect, or it may render the protein nonfunctional.
new codon encodes a diff aa; there is a change in aa seq

Question 22

nonsense mutation

Answer 22

mutation that changes a sense codon into a termination codon
new codon is a stop codon thus premature termination of translation; truncation

Question 23

reverse mutation

Answer 23

mutation that changes the mutant phenotype back into the wild-type

Question 24

what it important of conserved aa seqs

Answer 24

if an aa seq does not change over time it means that the seq is efficient and needs to be conserved bc it is already optimal

Question 25

what is expansion

Answer 25

expansion of trinucleotides

Question 26

if a nucleotide does not change a codon (change in aa), does it have no effect?

Answer 26

not all detrimental mutations are in the coding part of the protein, can be in noncoding. ex is tsar royal family where nucleotide change resulted in loss of splice site; changed aas but not coding part of genome but in splice site. lose exon or gain intron = a lot of aa shuffling

Question 27

we generally think of mutations affecting the coding seq, but they often impact:

Answer 27

the promoter, 5’ or 3’ noncoding seqs, splice jxns, enhancers

Question 28

silent or synonymous mutations change the _ but not the _

Answer 28

changes the codon seq but not the aa

redundancy of genetic code

Question 29

CHARGE syndrome: dna seq analysis of the coding region of the CHD7 gene identified a heterozygous predicted disease-associated nonsense seq variant

is the mutation dominant or recessive?

Answer 29

has to be dominant bc child has one bad and one good copy, but is displaying phenotype so must be dominant

Question 30

gain of function mutation

Answer 30

produces an entirely new trait of causes it to appear in an inappropriate tissue or at an inappropriate time (ex constitutive activation)

Question 31

suppressor mutation

Answer 31

genetic change that hides or suppresses the effect of another mutation turned off inappropriately

Question 32

intragenic suppressor mutation

Answer 32

occurs in same gene as that containing the mutation being suppressed
may alter mutated codon, or re-establish the frame (reverse) if there was a previous frame shift

Question 33

intergenic suppressor mutation

Answer 33

occurs in gene other than the one bearing the original mutation

Question 34

intergenic suppressor mutation

Answer 34

occurs in gene other than the one bearing the original mutation
in other genes, perhaps a pathway, and changes the consequences of a mutation in another gene

Question 35

characteristics of insertion mutation

Answer 35

addition of one or more nucleotides

Question 36

characteristics of deletion mutation

Answer 36

deletion of one or more nucleotides

Question 37

characteristics of frameshift mutation

Answer 37

insertion or deletion that alters the reading frame of a gene

Question 38

characteristics of in-frame deletion or insertion

Answer 38

deletion or insertion of a multiple of 3 nucleotides that does not alter the reading frame

Question 39

characteristics of expanding nucleotide repeats

Answer 39

increases the number of copies of a set of nucleotides

Question 40

characteristics of missense mutation

Answer 40

changes a sense codon into a different sense codon, resulting in the incorporation of a different aa in the protein

Question 41

characteristics of nonsense mutation

Answer 41

changes a sense codon into a nonsense (stop) codon, causing premature termination of translation

Question 42

characteristics of silent mutation

Answer 42

changes a sense codon into a synonymous codon, leaving the aa seq of the protein unchanged

Question 43

characteristics of a neutral mutation

Answer 43

changes the aa seq of a protein w/o altering its ability to function

Question 44

characteristics of loss of function mutation

Answer 44

causes a complete or partial loss of function

Question 45

characteristics of gain of function mutation

Answer 45

causes the appearance on a new trait or function or cause the appearance of a trait in inappropriate tissue or at an inappropriate time

Question 46

characteristics of lethal mutation

Answer 46

causes premature death

Question 47

factors affecting mutation rates (4)

Answer 47

1. frequency w/ which a change takes place in DNA
2. probability that when a change takes place, that change will be repaired
3. environmental factors can increase mutation rates
4. genetics background influences mutation rate

Question 48

what causes adaptive mutation (2)

Answer 48

1. genetic variation critical for evolutionary change that brings about adaptation to new environments
2. stressful conditions, where adaptation might be necessary to survive, induce increased mutation in bacteria

Question 49

mutations that were inherited from a parent describes what time of mutation

Answer 49

germ-line

Question 50

t/f: mutations provide the raw material for evolution

Answer 50

true