8.1 Mutations

Question 1

What is a point/gene mutation?

Answer 1

change in DNA base sequence
changes the amino acid sequence
changes primary structure
changes tertiary structure
changes the function

Question 2

When does a point mutation occur?

Answer 2

during DNA replication in interphase

Question 3

What increases the chance of mutations?

Answer 3

mutagens

Question 4

Why are mutations a good thing?

Answer 4

important for an organism to live through natural selection
the population can evolve

Question 5

What is a chromosome mutation?

Answer 5

a change in the number of chromosomes - extra/less

Question 6

When does a chromosome mutation occur?

Answer 6

during meiosis in anaphase 1 or 2

Question 7

What are all the different types of point mutations?

Answer 7

substitution
insertion
deletion
duplication
inversion
transloaction

Question 8

What is substitution mutation?

Answer 8

only 1 amino acid is changed in the sequence

Question 9

Why does a substitution reaction have little effect?

Answer 9

degenerate code - can code for the same amino acid so its a silent mutation

Question 10

What is insertion mutation?

Answer 10

adding an extra base to the sequence

Question 11

What is a frameshift?

Answer 11

every codon downstream of the mutation will change so potentially every amino acid downstream of the mutation will change

Question 12

What is deletion mutation?

Answer 12

removal of a base

Question 13

What is duplication mutation?

Answer 13

the base that came before is copied and inserted

Question 14

What is inversion mutation?

Answer 14

a group of bases becomes separated from the DNA and rejoin in reverse order

Question 15

What is translocation mutation?

Answer 15

bases are separated from DNA sequence and one chromosome is inserted in a different chromosome

Question 16

What 3 types of mutation cause a frameshift?

Answer 16

insertion
deletion
duplication

Question 17

What does polysomy mean?

Answer 17

there is an extra chromosome in the gamete

Question 18

What does polyploidy mean?

Answer 18

changes in the whole set of chromosomes as all homo pairs have failed to seperate and end up in the gametes so there is more than 2 sets of chromosomes

Question 19

What does non-disjunction result in?

Answer 19

the gamete has one more or one less chromosome

Question 20

When does a whole change in a set of chromosomes occur?

Answer 20

when an organism has 3 or more sets of chromosomes rather than 2

Question 21

What is hybridisation?

Answer 21

the combining of genes of different varieties or species of organism to produce a hybrid

Question 22

What is triploid?

Answer 22

3 sets of chromosomes

Question 23

What causes down-syndrome?

Answer 23

a tripsomy 21 gamete

Question 24

What is monosomy?

Answer 24

1 set of chromosomes

Question 25

What type of female gamete is most likely to experience non-disjunction?

Answer 25

older gametes

Question 26

What are mutagens?

Answer 26

any outside factor that increases the rate of mutation

Question 27

What are carcinogens?

Answer 27

mutagens that cause cancer

Question 28

What are examples of physical mutagens?

Answer 28

ionisinf radiation x-rays alpha and beta particles

Question 29

How do physical mutagens work?

Answer 29

breaks the polypeptide chain in DNA

Question 30

What are examples of biological mutagens?

Answer 30

viruses benzopyrene in tobacco smoke

Question 31

How does a virus work as a mutagen?

Answer 31

injects viral material and disrupts DNA bases

Question 32

When does non-dysjunction occur in meiosis?

Answer 32

meiosis 1 = chromosomes fail to serparate during anaphase 1 meiosis 2 = chromatids fail to seperate during anaphase 2

Question 33

What happens to a monosomy zygote?

Answer 33

dies

Question 34

Describe the process in how polyploidy occurs by non-disjunction in meosis 1

Answer 34

1. each homo pair is doubled due to DNA replication in interphase 2. non-disjunction in meiosis 1 = all chromosomes fail to serparate 3. all chromosomes are in 1 cell, the other cell is empty and has no chromosomes 4. normal division in meiosis 2 so chromatids separate equally 5. produces 2x 2n gametes (diploid)

Question 35

What would happen if a diploid gamete fused with is normal haploid gamete?

Answer 35

produce a triploid zygote = 3 copies of every chromosome

Question 36

Describe the process of how polyploidy occurs by non-dysjunction in meiosis 2

Answer 36

1. each homo pair is doubled due to DNA replication in interphase 2. normal dividion in meiosis 1 = chromosomes separate equally 3. non-disjunction in meiosis 2 = all chromatids fail to separate equally in 1 of the cells produced from meiosis 1 4. produces a 2n gamete and a gamete with no chromatids

Question 37

What are the 2 types of chromosome mutations?

Answer 37

polyploidy and aneuploidy

Question 38

What is aneuploidy?

Answer 38

changes in the number of individual chromosomes individual homo pairs fail to separate during meiosis

Question 39

What is the result of aneuploidy?

Answer 39

the gamete will have 1 more or 1 less chromosomes

Question 40

What is an example of aneuploidy mutation?

Answer 40

down syndrome

Question 41

Describe the process of aneuploidy in meiosis 1

Answer 41

1. each homo pair is doubled due to DNA replication in interphase 2. Non-disjunction in meiosis 1 = one chromosome does not separate equally 3. both homo pairs are therefore present in 1 cell 4. meosis 2 occurs = chromatids separate equally 5. results in x2 n+1 gametes and x2 n-1 gametes

Question 42

What does aneuploidy result in in terms of gametes made from non-disjunction in meiosis 1?

Answer 42

x2 n+1 gametes = with an extra chromosome x2 n-1 gametes = with one less chromosome they are all still haploid gametes

Question 43

In terms of number of chromosomes, what is formed when you fuse a n+1 gamete with a normal n gamete?

Answer 43

2n + 1 zygote diploid zygote with an extra chromosome

Question 44

In terms of number of chromosomes, what is formed when you fuse a n-1 gamete with a normal n gamete?

Answer 44

2n - 1 zygote a diploid zygote with one less chromosome

Question 45

Describe the process of aneuploidy in meiosis 2

Answer 45

1. each homo pair doubles due to DNA replication in interphase 2. normal division in meiosis 1 = chromosomes separate 3. non-disjunction in meiosis 2 = one chromatid fails to separate equally 4. resulting in x1 n-1 gamete, x1 n+1 gamete, x2 n gametes (normal)

Question 46

What does aneuploidy result in in terms of gametes made from non-disjunction in meiosis 2?

Answer 46

x1 n-1 haploid gamete x1 n+1 haploid gamete x2 n (normal) haploid gametes