4.3 Genetic Diversity: Mutations & Meiosis

Question 1

What is a substitution mutation?

Answer 1

When one base is changed for another

Question 2

What is an insertion/addition mutation?

Answer 2

When one or more nucleotides are added into the DNA

Question 3

What is a deletion mutation?

Answer 3

When one or more nucleotides are deleted from DNA

Question 4

What is a point mutation?

Answer 4

When a single base pair is altered

Question 5

What is a frameshift?

Answer 5

A knock on effect causing every amino acid after to be incorrect

Question 6

Why are frameshifts caused?

Answer 6

Bases are read 3 at a time in a non-overlapping frame

Question 7

What is the result of a frameshift?

Answer 7

The bonds will form in different places and the tertiary structure of the protein will be incorrect

Question 8

What is meant by a silent mutation?

Answer 8

No change has been made to the primary structure

Question 9

How can a mutation be silent?

Answer 9

Degenerate code means multiple codons can code for the same amino acid

Question 10

What is a mutagen?

Answer 10

Something that increase chances of a mutation

Question 11

What is in cells to help prevent mutations?

Answer 11

Enzymes that check the DNA after replication

Question 12

What will happen to the cell of a healthy person if there is a mistake in DNA?

Answer 12

Apoptosis - programmed cell death
OR
There are enzymes that can fix small mistakes

Question 13

What is apoptosis?

Answer 13

Programmed cell death

Question 14

What is the consequence of cancer patients who don’t have the working enzymes to cause programmed cell death?

Answer 14

Cell will not undergo apoptosis
Means uncontrolled cell division and tumour growth

Question 15

Give examples of mutagens.

Answer 15

Alcohol
Benzene
UV light
x-rays

Question 16

What is the role of meiosis?

Answer 16

Create gametes

Question 17

What is started with in meiosis?

Answer 17

Germ line cells

Question 18

How many chromosomes do germ line cells have?

Answer 18

46

Question 19

What is a homologous pair of chromosomes?

Answer 19

Chromosomes that code for the same gene

Question 20

Where does each chromosome in an homologous pair come from?

Answer 20

One from each parent

Question 21

Are homologous chromosomes identical?

Answer 21

No they can contain different alleles (different versions of the same gene)

Question 22

How do chromosomes line up during the first division of meiosis?

Answer 22

In their homologous pairs down the centre of the cell

Question 23

Why is it important homologous pairs line up the centre of the cell during the first stage of meiosis?

Answer 23

As one from each pair needs to end up in a daughter cell

Question 24

What process can occur when homologous pairs are lined up in pairs during the first stage of meiosis?

Answer 24

Crossing over when chromosomes in homologous pairs can swap one or more alleles

Question 25

Why does crossing over increase variation?

Answer 25

Creates new combinations of alleles

Question 26

What has happened by the end of division one in meiosis?

Answer 26

DNA chromosomes have been halved from 46 to 23

Question 27

How does the amount of gametes produced in parents create increased variation?

Answer 27

Random fertilisation

Question 28

What is random segregation?

Answer 28

The allocation of gene copies is random with one of two gene copies being distributed to each gamete