Topic 5-1

Question 1

what are the two basic classes of mutations in multicellular organisms?

Answer 1

• somatic mutations
• germ-line mutations

Question 2

any alteration at the cellular level in somatic tissues occuring after fertilization

Answer 2

somatic mutation

Question 3

congenial genetic mutations in gametes, these genetic mutations are heritable and can be passed down to offspring

Answer 3

germ-line mutations

Question 4

true or false: somatic mutations can be passed onto offspring

Answer 4

false

Question 5

what are the two major categories of germ-line mutations?

Answer 5

gene mutations and chromosomal mutations

Question 6

• mutations that usually affect a single gene
• base substitutions
• insertions and deletions
• expanding nucleotide repeats
  these are characteristics of:

Answer 6

gene mutations

Question 7

mutations affection chromosome structure or number

Answer 7

chromosomal mutations

Question 8

what are the two main types of base mutations?

Answer 8

transition and transversion

Question 9

substitiuting a purine with a purine or a pyrimidine with a pyrimidine

Answer 9

transition mutation

Question 10

substituting a puring with a pyrimidine or a pyrimidine with a purine

Answer 10

transversion

Question 11

which is more common, transitions or transversions?

Answer 11

transitions

Question 12

what are the three main causes of base substitutions?

Answer 12

• spontaneous replication errors
• spontaneous chemical changes
• mutagens

Question 13

what are tautomers?

Answer 13

structural isomers of nucleotide bases

Question 14

nonstandard base pairs can occur as a result of:

Answer 14

flexibility in the DNA structure

Question 15

true or false: insertions and deletions are more common than base substitutions

Answer 15

true

Question 16

loss of a purine

Answer 16

depurination

Question 17

loss of an amino acid

Answer 17

deamination

Question 18

the loss of a purine base from a nucleotide may lead to a:

Answer 18

base substitution

Question 19

what are the two main types of deamination?

Answer 19

cytosine –> uracil
5-methylcytosine –> thymine

Question 20

occurs when one of the DNA strands forms a small loop

Answer 20

strand slipping

Question 21

a spontaneous nucleotide insertion occurs due to strand slippage on the:

Answer 21

newly synthesized DNA strand

Question 22

a spontaneous nucleotide deletion occurs due to strand slippage on the:

Answer 22

template DNA strand

Question 23

in addition to strand slippage, DNA insertion or deletion can also be caused by:

Answer 23

unequal crossing over

Question 24

occurs when a set of nucleotides is increased in copy number beyond what they should

Answer 24

expanding set of nucleotide repeats

Question 25

epanding set of nucleotide repeats are associated with how many human diseases?

Answer 25

~30

Question 26

Fragile-X syndrome, Huntington disease, and amyotropic lateral sclerosis (Lou Gehrig disease) are all caused by

Answer 26

expanding nucleotide repeats

Question 27

how do expanding nucleotide repeats occur?

Answer 27

the formation of a secondary structure on the newly synthesized DNA strand

Question 28

true or false: with the exception of thymine being replaced by uracil, the mRNA strand is the same as the DNA coding strand

Answer 28

true

Question 29

each codon codes for one a.a. with the exception of:

Answer 29

stop codons

Question 30

the protein code is:

Answer 30

degenerate

Question 31

when reading the mRNA codes, which position is not read very carefully

Answer 31

wobble position

Question 32

base substitutions can cause what kinds of mutations

Answer 32

• missense
• nonsense
• silent mutations

Question 33

a type of base substitution mutation where the new codon encodes a different amino acid; causing a change in the amino acid sequence

Answer 33

missense mutation

Question 34

a type of base substitution mutation where the new codon is a stop codon; causing a premature termination of translation

Answer 34

nonsense mutation

Question 35

a type of base substitution mutation where the new codon encodes for the same amino acid as the original; therefore there is no change to the amino acid sequence

Answer 35

silent mutation

Question 36

insertions or deletions can cause what type of mutations?

Answer 36

• frameshift mutations
• in-frame mutations (if in multiples of 3)

Question 37

what is a loss of funtction mutation?

Answer 37

partial or complete abscense of gene product function, usually recessive

Question 38

what is a gain of function mutation?

Answer 38

the gene product has a new function, usually dominant

Question 39

what is a conditional mutation?

Answer 39

the phenotype (expression) of this mutation occurs only under certain conditions