Mutations

Question 1

What is a mutation

Answer 1

Any change to an organisms DNA

Question 2

Somatic mutation

Answer 2

Occurs in somatic cells

Not heritable - won’t affect offspring

Only the cell where the mutation occurred will be affected

Question 3

Germline mutation

Answer 3

Occurs in gametes/ cells that make gametes

Heritable - will affect offspring

Question 4

Nondisjunction

Answer 4

When homologous chromosomes or sister chromatids do not to separate when they are supposed to

Question 5

What does nondisjunction result in?

Answer 5

Results in somatic cells or gametes with an incorrect number of chromosomes

Aneuploidy !!!

Question 6

What is aneuploidy?

Answer 6

A condition where an individual has an

Incorrect number of chromosomes

(One extra/ missing)

Question 7

What is polyploidy?

Answer 7

A condition where an individual has extra/missing SETS of chromosomes

More than 2 complete sets of chromosomes

Question 8

What is trisomy?

Answer 8

When an individual has

3 copies of chromosomes instead of 2

(1 extra)

Question 9

What is monosomy?

Answer 9

When an individual has 1 copy of chromosomes instead of 2

Missing 1

Question 10

When looking at karyotypes,

Answer 10

Look whether

• male/female ?
• monosomy/ trisomy ?

Question 11

XO ?

Answer 11

Turners Syndrome

Question 12

XXY ?

Answer 12

Klinefelter’s Syndrome

Question 13

Mitotic nondisjunction results in:

Answer 13

Monosomy and trisomy

Question 14

Meiotic nondisjunction could happen in…

Answer 14

Anaphase I

or

Anaphase II

Question 15

If nondisjunction occurs in anaphase I…

Answer 15

Homologous chromosomes do not separate

Will result in

2 trisomy and 2 monosomy 😓

Question 16

If nondisjunction occurs in anaphase II…

Answer 16

Sister chromatids do not separate

Result in

2 normal, 1 trisomy, 1 monosomy ☹️

Question 17

What is karyotyping?

Answer 17

Process of

analyzing the chromosomes of an individual

Can help to detect aneuploidy in humans

Question 18

Karyogram

Answer 18

The final image of chromosomes which have been stained, photographed and sorted into their pairs

Question 19

What are mutagens?

Answer 19

Physical/ chemical factors that increase the rate of mutation

Question 20

The severity of a mutation depends on…

Answer 20

the overall change to the amino acid sequence

Question 21

Severities of mutations

Answer 21

Silent mutation

Missense mutation

Nonsense mutation

Question 22

Silent mutation

Cat -> Kat

Answer 22

No overall effect on amino acid sequence

Mutated codon still codes for same amino acid

Question 23

Missense mutation

Cat -> hat

Answer 23

Affected codon now codes for a different amino acid.

Substitution mutation or frameshift mutation could cause this!

• Severity varies

Question 24

Point missense mutations vs frameshift missense mutations

Answer 24

Point missense mutations
Less serious - only 1 amino acid changed

Frameshift missense mutations
More serious - many amino acids changed

Question 25

Significant changes to primary structure…

Answer 25

Alters the secondary and tertiary structures of the protein

Change its function or make it non-functional

Question 26

Nonsense mutation

‘I have a cat named’

Answer 26

Results in formation of Stop codon before end of gene

Shorten the amino acid chain - Could make it non-functional

Question 27

If mutation occurs in the intron sequences..

Answer 27

Won’t affect the gene because introns are removed before translation