lecture 29

Question 1

what happens when DNA damage is not corrected

Answer 1

when DNA damage is not corrected, an inherited change
in genetic information may occur and this is a “mutation”

Question 2

what is the mutation

Answer 2

A heritable change in the sequence of an organism’s
genetic material-the mutation may alter the phenotype of
the organism.
* The process by which genetic change occurs

Question 3

Mutant?

Answer 3

• An organism that carries one or more mutations in its genetic
  material.

Question 4

Mutation occurs in all organisms with
……….., from viruses to
humans.

Answer 4

Mutation occurs in all organisms with
genetic material, from viruses to
humans.

Question 5

Natural selection preserves the
combinations best adapted to the
existing environment = evolution

Answer 5

Natural selection preserves the
combinations best adapted to the
existing environment = evolution

Question 6

how does the genetic variability happens in the chromosomes

Answer 6

During meiosis, recombination
between homologous chromosomes
rearranges genetic variability into new
gene combinations!

Question 7

what are types of the mutation

Answer 7

Somatic mutations occur in somatic cells; it will occur
only in the descendants of that cell and will not be
transmitted to the progeny.
* Germinal mutations occur in germ-line cells and will be
transmitted through the gametes to the progeny

Question 8

types of mutation

Answer 8

Base substitution
Frameshift mutation
Tautomeric shifts
Expanding nucleotide repeats
Gross chromosomal rearrangement

Question 9

where Base substitution
Frameshift mutation
Tautomeric shifts happen

Answer 9

Occur at localized sites
in DNA-often referred to
as “point mutations”

Question 10

exp Expanding nucleotide repeats

Answer 10

Expanding nucleotide repeats- known as a
“dynamic mutation” because the nucleotide repeat copy
number can expand or contract dramatically in each cell.

Question 11

exp Gross chromosomal rearrangement

Answer 11

Gross chromosomal rearrangement. A change in chromosome
number or structure (usually visible microscopically)

Question 12

types of Base Substitution

Answer 12

Base Substitution
* A transition replaces a pyrimidine with another
pyrimidine or a purine for another purine.
* A transversion replaces a pyrimidine with a purine or
a purine with a pyrimidine

Question 13

……………. changes dramatically after the frameshift

Answer 13

Protein sequence changes dramatically after the frameshift

Question 14

exp Tautomeric shift

Answer 14

movement of H atoms from one
position in a purine or pyrimidine base to another

Question 15

what is a frameshift mutation

Answer 15

A frameshift mutation in a gene refers to the insertion or deletion of nucleotide bases in numbers that are not multiples of three

Question 16

Tautomeric shift is common ?

Answer 16

Rare. Can occur spontaneously during DNA replication
where they alter DNA base pairing. Cause some spontaneous
mutations

Question 17

Tautomeric shift generates rare ……..and …….. base pairs

Answer 17

Tautomeric shift generates rare A:C and G:T base pairs

Question 18

When the bases are
in their rare ……… or
…….. states, they
can form A-C and G-T
base pairs
2. Types of gene mutations (cont’d)

Answer 18

When the bases are
in their rare enol or
imino states, they
can form A-C and G-T
base pairs
2. Types of gene mutations (cont’d)