Chapter 9 - Genetic Diversity, Mutation And Meiosis

Question 1

What are gametes

Answer 1

Haploid sex cells (sperm and eggs)

Question 2

What is meant by haploid

Answer 2

A cell with a single set of unpaired chromosomes (one of each homologous pair)

Question 3

What is meant by a diploid

Answer 3

A cell with 2 complete sets of chromosomes (homologous pairs, one from each parent)

Question 4

What is meant by fertilisation

Answer 4

Fusion of 2 haploid gametes to form a zygote

Question 5

What is the definition of meiosis

Answer 5

Cell division to form gametes

Question 6

What is the definition of mitosis

Answer 6

Cell division for growth and repair

Question 7

How many divisions are there for meiosis

Answer 7

2 divisions

Meiosis I and II

Question 8

How many daughter cells are produced in Mitosis

Answer 8

2

Question 9

How can daughter cells in mitosis be described

Answer 9

Genetically identical to each other and their parent cell

Question 10

Why are daughter cells in meiosis genetically different from each other and their parent cell

Answer 10

• Crossing over

- Independent segregation

Question 11

What is meant by gene mutation

Answer 11

Change to base sequence of DNA during DNA replication

Question 12

What is meant by crossing over

Answer 12

The exchange of alleles between homologous chromosomes, resulting in a different combination of alleles

Question 13

When does crossing over occur

Answer 13

In metaphase I

Question 14

Draw a representation of crossing over

Answer 14

In folder

Question 14

What is meant by independent segregation

Answer 14

Formation of random combinations of chromosomes in metaphase I, instead of homologous pairs

Question 15

What is a substitution mutation

Answer 15

Swapping one base for another

Question 16

What is meant by a nonsense substitution mutation

Answer 16

When swapping one base for another codes for a stop codon instead of an amino acids

Question 17

What is meant by a silent substitution mutation

Answer 17

Mutation that has no effect on amino acids and therefore phenotype

Question 18

What is meant by a deletion mutation

Answer 18

One base is removed causing a frameshift

Question 19

What is meant by a frameshift

Answer 19

When all following triplets/codons change due to deletion of one base

Question 20

How can gene mutations cause a non-functional protein

Answer 20

• Change in DNA triplet during replication
• Change in mRNA codon
• Change in anticodon
• Different amino acid
• Change in primary structure
• Different bonding (hydrogen and ionic)
• Change in tertiary structure of protein
• Change shape of active site/variable region
• Unable to form enzyme-substrate or antigen-antibody complex

Question 22

Why may a gene mutation cause no change to primary structure

Answer 22

• DNA is degenerate
• Each amino acid is coded for by more than one codon
• Change to DNA base but not change amino acid coded for
• So no Change in primary structure
• No change to bonding
• No change to tertiary structure
• Can still form complex

Question 23

What is an example of a chromosome mutation

Answer 23

Chromosome non-disjunction

Question 24

What is meant by chromosomes non-disjunction

Answer 24

When chromosomes don’t separate properly in Meiosis I or II

Question 25

What is the result of chromosomes non-disjunction

Answer 25

An uneven number of chromosomes in the gametes

Question 26

What is an example of a disease caused by chromosome non-disjunction

Answer 26

Down’s syndrome