DNA Mutations and Repairs

Question 1

Mutation

Answer 1

process by which the sequence of base pairs in a DNA molecule is altered

Question 2

Somatic Mutation

Answer 2

mutation in somatic cells, only affects individual

Question 3

Germ-line mutation

Answer 3

mutation in germ line, transmitted by gametes to the next generation

Question 4

Base pair substitutions

Answer 4

one bp replaced by another

Question 5

Base pair insertions or deletions

Answer 5

1+ bp are added or deleted

Question 6

Transition

Answer 6

Bp substitution from purine to purine or one pyrimidine to pyrimidine

Question 7

Transversion

Answer 7

Bp substitution from purine to pyrimidine or vice versa

Question 8

Missense mutation

Answer 8

causes a change in codon and a different amino acid is inserted into the polypeptide

Question 9

Nonsense mutation

Answer 9

change from codon that specifies an amino acid to a stop codon

Question 10

Neutral mutation

Answer 10

change in codon so that a different aa is inserted but the aa substitution doesn’t change the protein function

Question 11

Silent mutation

Answer 11

change in codon but same aa inserted

Question 12

Frameshift mutation

Answer 12

Reading frame changes downstream of the mutation
incorrect aa are added
usually non-functional protein

Question 13

Repair Mechanisms

Answer 13

Enzyme-based repair systems
1.Direct correction: reverses the damage
2. Excision of damaged area and new synthesis of DNA
can read intact info from undamaged strand of DNA

Question 14

What are the 4 chromosomal mutations?

Answer 14

1. Deletion
2. Duplication
3. Inversion
4. Translocation

Question 15

Deletion

Answer 15

part of the chromosome is missing

Question 16

Duplication

Answer 16

doubling of a segment of the chromosome

Question 17

Tandem Duplication

Answer 17

doubling of a segment of a chromosome that is close together

Question 18

Displaced Duplication

Answer 18

doubling of a segment on a chromosome that is in different locations on the same or different chromosome

Question 19

Inversion

Answer 19

a segment of a chromosome is cut and rotated 180 degrees and reinserted

Question 20

PERIcentric inversion

Answer 20

includes centromere

Question 21

PARAcentric

Answer 21

centromere not included

Question 22

What is the difference between inversion on a homozygote vs inversion heterozygote?

Answer 22

Homozygote wont cause any meiotic problems
heterozygote crossing over can serious genetic effect

Question 23

Translocation

Answer 23

change in position of chromosome segments and the genes they contain (involves nonhomologous chromosomes.

Question 24

What are the consequences that can happen because of translocation?

Answer 24

Homozygotes- no effect
Heterozygotes- affects meiosis
gametes unbalanced (duplications and deletions)
some gametes inviable
some viable but produce deficient phenotype (down syndrome)

Question 25

Aneuploidy

Answer 25

Changes in the # of individual chromosomes (2n-1

Question 26

Aneuploidy

Answer 26

Changes in the # of individual chromosomes (2n-1,2n+1,2n+2)

Question 27

Polyploidy

Answer 27

Changes the # of chromosome sets (2n,3n,4n)

Question 28

How are Aneuploids formed?

Answer 28

1. deletion including centromere 2. nondisjunction of 1+ chromosomes during meiosis

Question 29

Nondisjunction

Answer 29

failure of sister chromatids to move to opposite poles at anaphase. one gamete ends up with an extra chromosome and the other missing one

Question 30

Nullisomy

Answer 30

loss of one homologous chromosome (2n-2)

Question 31

Monosomy

Answer 31

Loss of a single chromosome (2n-1)

Question 32

Trisomy

Answer 32

addition of a single chromosome (2n+1)

Question 33

tetrasomy

Answer 33

addition of an extra pair of chromosomes (2n+2)

Question 34

Nullisomic

Answer 34

2n-2, a pair of chromosomes missing in a single slot

Question 35

Monosomic

Answer 35

2n-1, a single chromosome missing from one slot

Question 36

Doubly monosomic

Answer 36

2n-1-1, two single chromosomes missing from 2 slots

Question 37

Trisomic

Answer 37

2n+1, and extra single chromosome in 1 slot

Question 38

Tetrasomic

Answer 38

2n+2, two chromosome pairs added to 1 slot

Question 39

Doubly tertasomic

Answer 39

2n+2+2, two chromosome pairs added to 2 slots

Question 40

Monoploids

Answer 40

individuals with 1 complete set of chromosomes (n)

Question 41

Diploids

Answer 41

Individuals with 2 complete sets of chromosomes (2n)

Question 42

Polyploids

Answer 42

Individuals have 3+ complete sets of chromosomes (3n,4n,5n....)

Question 43

Polypoid plants that are even means? odd?

Answer 43

Plants with even numbers are fertile odd means plant will be sterile

Question 44

Difference between sexual and asexual polyploidization?

Answer 44

Sexual: Produces gametes that are unreduced (parents 2n = gametes 2n = 4n polyploid zygote = 4n polyploid adult) Asexual: doubles chromosomes through abortive mitotic division (parents 2n = gametes n = normal zygote 2n = 4n Polyploid adult)

Question 45

Autopolyploid

Answer 45

chromosome sets from same species

Question 46

Allopolyploid

Answer 46

multiple chromosome sets from different but related species (2n = 4x =48, 2n = 6x = 42.....)