Gene Mutation

Question 1

Define Mutation

Answer 1

a sudden change in the quantity and structure of the genetic material in the cell

Question 2

Where does genetic diversity arise from

Answer 2

mutations

recombining of DNA of 2 individuals after meiosis/ binary fission

Question 3

When are gene mutations most likely to occur?

Answer 3

In interphase

Question 4

What are the three types of gene mutation

Answer 4

addition
substitution
deletion

Question 5

Define chromosome mutation

Answer 5

changes in the structure and number of whole chromosomes

Question 6

Name two types of chromosome mutation

Answer 6

polyploidy (more than 2 chromosomes)

non-disjunction (individual chromosomes don’t divide during meiosis)

Question 7

What are all mutations?

Answer 7

chance mutations

Question 8

Why are errors in DNA replication more damaging than an error in transcription?

Answer 8

The error may be inherited so many have a permanent effect unlike transcription

Question 9

Name three mutagenic agent

Answer 9

UV Light
Ionising particle
carcinogenic

Question 10

Describe how deletion mutation alters gene structure

Answer 10

causes frameshift

removal of 1 or more bases

Question 11

How does deletion have a greater effect than substitution?

Answer 11

Deletion causes a frameshift and alters amino acid past deletion
Substitution causes only one changed substitution

Question 12

Meiosis produces how many daughter cells?

Answer 12

4 with the haploid number of chromosomes

Question 13

Describe what occurs in Meiosis 1

Answer 13

Homologous chromosomes pair up
chromatids wrap around each other
crossing over occurs
By the end, the homologous pairs have separated with one chromosome from each pair in each daughter cells

Question 14

Describe what occurs in Meiosis 2

Answer 14

chromatids move apart 4 cells are formed

Question 15

What happens in independent segregation?

Answer 15

homologous pairs line up at random so the combination of maternal and paternal chromosomes is by chance

Question 16

What happens in crossing over ?

Answer 16

chromatids of each pair twist around one around another
parts of the chromatids break off and regions with homologous partner
to produce new gentic combinations

Question 17

What are the equations associated with this topic

Answer 17

2n ( hapliod number) 2n2

Question 18

Describe and explain the appearance of chromosomes in X form

Answer 18

2 sister chromosomes attached to the centromere

DNA replication has occurred

Question 19

What event happens in meiosis 2 not 1

Answer 19

the separating of sister chromatids

Question 20

Describe what happens to chromosomes in meiosis

Answer 20

X condense and associate into homologous pairs
x are attached to the centromere
x line up at the equator and spindle fibre pull them 2 opposite poles

Question 21

How does meiosis cause genetic variation and explain the advantage of variation to the species?

Answer 21

crossing gene
independent segregation of chromosomes is meiosis 1/2
some better adapted
to reproduce and pass on the alleles
allows for changing environment

Question 22

How can a hybrid be fertile?

Answer 22

the diploid number of chromosomes
gametes receive one copy of all generic information
chromosomes can form bivalents

Question 23

What is the role of the centromere in meiosis

Answer 23

joins the 2 sister chromatids

so they can be separated

Question 24

How have different alleles been produced?

Answer 24

crossing over and allele exchange between chromosomes

Question 25

Define genetic diversity

Answer 25

the total number of different alleles in a population

Question 26

A decrease in the population number affects genetic diversity how ?

Answer 26

genetic diversity decreases

reduced gene pool

Question 27

Sugar Beet was chosen by farmers how does this effect genetic diversity

Answer 27

reduce genetic diversity as allele has been chosen

Question 28

What are the two types of selection?

Answer 28

Directional and stabilising

Question 29

Explain how the mutation causes an increase in allele freq. in a population?

Answer 29

mutation produced allele
selection pressure
more likely to survive and reproduce
increase in allele in the population

Question 30

Give two ways doctors could use base sequences to compare different types of
HPV.

Answer 30

Compare (base sequences of) DNA;

Look for mutations/named mutations
(that change the base sequence);

Compare (base sequences of)
(m)RNA

Question 31

Explain how the chromosome number is halved during meiosis.

Answer 31

Homologous chromosomes (pair);
One of each (pair) goes to each (daughter)
cell / to opposite poles;

Question 32

Describe the process of crossing over and explain how it increases genetic
diversity

Answer 32

Homologous pairs of chromosomes associate
/ form a bivalent;
Chiasma(ta) form;
(Equal) lengths of (non-sister) chromatids /
alleles are exchanged;
Producing new combinations of alleles;