LESSON 3: MUTATIONS

Question 1

Individuals showing phenotypic
differences in one or more particular characters

Answer 1

Genetic Variants

Question 2

Change in the DNA sequence of a gene

Answer 2

Mutation

Question 3

Grouping into new combinations

Answer 3

Recombination

Question 4

WOBBLE HYPOTHESIS - who and when?

Answer 4

Francis Crick, 1996

Question 5

We only have ___ tRNA

Answer 5

20

Question 6

Also called silent mutations

Answer 6

SYNONYMOUS MUTATIONS

Question 7

Also called nonsynonymous mutations

Answer 7

MISSENSE MUTATIONS

Question 8

The codon for one amino acid is changed into a
translation-termination codon (stop codon)

Answer 8

NONSENSE MUTATIONS

Question 9

● There is an introduction or taking out of a new base
in a sequence
● Affects all codons downstream of the mutation,
resulting in a frameshift

Answer 9

INDEL MUTATIONS

Question 10

● Functional consequences in this region depend on
whether it disrupts or creates a binding site
● Many elicit little to no phenotypic change

Answer 10

NONCODING REGION MUTATIONS

Question 11

SPONTANEOUS MUTATIONS

Answer 11

SPOTANEOUS: ERRORS IN DNA REPLICATION

SPONTANEOUS LESIONS

Question 12

INDUCED MUTATIONS

Answer 12

INDUCED: BASE ANALOG INCORPORATION
INDUCED: SPECIFIC MISPAIRING
INDUCED: INTERCALATING AGENTS
INDUCED: BASE DAMAGE

Question 13

● ____ → Takes something that looks
like a base
● ____ → changes the base → not
functional
● ____ → destroy the base

Answer 13

Base replacement
Base alteration
Base damage

Question 14

● Base replacement
● Some chemical compounds are sufficiently similar
to the normal bases of DNA and are called base
analogs

Answer 14

INDUCED: BASE ANALOG INCORPORATION

Question 15

● Base alteration
● Alteration of a base such that it will form a specific
mispair

Answer 15

INDUCED: SPECIFIC MISPAIRING

Question 16

● Planar molecules that mimic base pairs
● Can slip in between stacked nitrogen bases

Answer 16

INDUCED: INTERCALATING AGENTS

Question 17

● Damage to one or more bases
● No specific base pairing is possible, resulting in a
replication block

Answer 17

INDUCED: BASE DAMAGE

Question 18

genetic variants controlling the same trait

Answer 18

Allele

Question 19

multiples of the basic chromosome set

Answer 19

Euploid

Question 20

one or more chromosomes missing or
in surplus

Answer 20

Aneuploid

Question 21

Extra set/s of chromosomes

Answer 21

Polyploid

Question 22

CHANGE IN CHROMOSOME NUMBER

● Changes in whole sets of chromosomes
● Having more or less than normal number of sets
● Monoploid and Polyploids

Answer 22

ABERRANT EUPLOIDY

Question 23

CHANGE IN CHROMOSOME NUMBER

● Chromosome number differs from the wild type by a
part of the chromosome set
● Can have a number greater or smaller than the
wildtype

Answer 23

ANEUPLOIDY

Question 24

Cause of most aneuploidy in the course of meiosis
or mitosis

Answer 24

NONDISJUNCTION

Question 25

● Missing one copy of a chromosome
● Monosomic autosomes = die in utero

Answer 25

MONOSOMY (2n-1)

Question 26

● Has one extra copy of a chromosome
Abnormality/death

Answer 26

TRISOMY (2n+1)

Question 27

Why are aneuploids so much more abnormal than polyploids?

Answer 27

Due to gene balance → the body is
dependent on ratios (how much it
makes/breaks down)
■ The problem with the ratio → you
would get sick

Question 28

INVERSIONS

● ______: does not involve centromeres, the
change is away from it
● ______: Affects the centromere

Answer 28

Paracentric

Pericentric

Question 29

trading of acentric fragments of two nonhomologous chromosomes

Answer 29

RECIPROCAL TRANSLATION

Question 30

CANCER MUTATIONS
_______ when they have a
gain-of-function mutation, become oncogenes

Answer 30

Proto-oncogenes

Question 31

CANCER MUTATIONS
____ become cancerous
when they have loss-of-function mutations

Answer 31

Tumor-suppressor genes

Question 32

Tumor-suppressor gene

Answer 32

“Guardian of the Genome”

Question 33

50% of human tumors lack a functional ____ gene

Answer 33

p53

Question 34

Naturally occurring mutations that
arise in all cells

Answer 34

SPONTANEOUS

Question 35

Arise through the action of
mutagens that increase the rate of
mutations

Answer 35

INDUCED

Question 36

TRANSITIONS
● Purine→ ___
● Pyrimidine → ___

Answer 36

1. Purine
2. pyrimidine

Question 37

TRANSVERSIONS
Purine → ___(vice versa)

Answer 37

pyrimidine

Question 38

Functional Consequences
● The genetic code is degenerate (___)

Answer 38

Wobble hypothesis

Question 39

Functional Consequences
There exists stop codons (___)

Answer 39

Translation termination

Question 40

Two types:
○ conservative
■ Changes into the amino acid of the same type
● ___→ ___ (both are basic amino acids)

Answer 40

Lysine → histidine

Question 41

Two types:
○ conservative
■ Changes into the amino acid of the same type
● ___→ ___(both are non-polar)
○ nonconservative

Answer 41

Proline → Valine

Question 42

Two types:
○ nonconservative
■ From one amino acid into an amino acid of the different type
● ___→ ___ (acidic base to a non-polar)

Answer 42

Glutamate → Valine

Question 43

Results in ________ → shorter protein product
○ Protein will be not functional

Answer 43

premature chain termination

Question 44

Single base pair changes that INACTIVATE proteins are often due to _____

Answer 44

splice site mutations

Question 45

SPOTANEOUS: ERRORS IN DNA REPLICATION

Structual isomers of the bases and can co-exist in a solution, and would just interchange with one
another at any point

Answer 45

TAUTOMERS

Question 46

SPONTANEOUS LESIONS
● Loss of a purine base
● Interruption of the N-glycosidic bond by hydrolysis

Answer 46

DEPURINATION

Question 47

SPONTANEOUS LESIONS
● Loss of an amino group (NH2) from cytosine

Answer 47

DEAMINATION

Question 48

SPONTANEOUS LESIONS
● Reactive oxygen species are produced by normal aerobic metabolism

Answer 48

OXIDATIVE DAMAGE

Question 49

Some chemical compounds are sufficiently similar
to the normal bases of DNA and are called ___

Answer 49

base analogs

Question 50

Smallest type of mutations one can have but
equally have big effects

Answer 50

POINT MUTATIONS