4.3 Genetic diversity Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What does meiosis produce?

A

Haploid gametes - genetically different

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Where does meiosis take place?

A

Sex organs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why is it important that gametes are haploid?

A

So they can fuse together during fertilisation forming a diploid zygote

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a chiasmata?

A

The point where the chromosomes join during crossing over

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the full sequence of meiosis?

A

Interphase
Meiosis 1
Cytokinesis 1
Meiosis 2
Cytokinesis 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens to the chromosomes during meiosis?

A

The no. Of chromosomes in each cell produced is decreased by half

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What happens during meiosis 1?

A

Separation of bivalents
Produces 2 haploid daughter cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens during meiosis 2?

A

Separation of sister chromatids
Produces 4 haploid daughter cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What happens during prophase 1 in meiosis 1?

A

The chromosomes condense and become visible arranged as bivalents
The nuclear membrane breaks down
Spindle fibres same as mitosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens during metaphase 1 of meiosis 1?

A

The bivalents align at the equator of the spindle apparatus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens during anaphase 1 of meiosis 1?

A

Spindle fibres shorten
Bivalents move to opposite poles - chiasmata break

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What happens during prophase 2 of meiosis 2?

A

Chromosomes condense and become visible again
Nuclear membrane breaks down
Spindle fibres develop

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What happens during metaphase 2 of meiosis 2?

A

The chromosomes are aligned on the equator or the spindle apparatus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How do the chromosomes align on the equator differently in meiosis 2 to meiosis 1?

A

The chromosomes align at right angles during meiosis 2 to the way they were aligned in meiosis 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What happens in anaphase 2 in meiosis 2?

A

The centromere of each chromosome divides and the sister chromatids are separated
Spindle fibres shorten

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does it mean that meiosis is reduction division?

A

The no. Of chromosomes half

17
Q

How does meiosis increase genetic diversity?

A

Crossing over
Random fusion of gametes
Independent segregation

18
Q

How do you calculate the number of genetically different gametes produced by independent segregation?

A

2 to the power of n
Where n is the no. Of homologous chromosome paira

19
Q

What is random fusion of gametes?

A

Lots of genetically different gametes produced
We cannot predict which male gamete will fuse with which female gamete- random fusion

20
Q

How does random fusion of gametes create genetic diversity?

A

each parent is genetically different
produces gametes which have a unique combination of alleles
fertilisation = the zygote has an unique combination of alleles

21
Q

How does crossing over happen?

A

chromosomes condense and tangle during Prophase 1
they cross over to form Chiasmata - the genetic info is swapped if chromosomes are heterozygous
each chromosome then has a new combination of alleles - recombinant chromosomes

22
Q

What are recombinant chromosomes?

A

the new combination of alleles after crossing over are not present in either pair of parent chromosomes

23
Q

What is independant segregation?

A

The random separation of homologous chromosomes in meiosis 1 that produces genetic variation

24
Q

How do the chromosomes become tangled?

A

when the bivalents condense and they supercoil close to each other

25
Q

What is genetic diversity?

A

the total number of different alleles in a population - the greater no. of different alleles, the greater genetic diversity

26
Q

Why will induvidual’s do better in environment changes with genetic diversity?

A

theres a wider range of alleles so a wide range of characteristics, so a greater probablitity that an induvidual will have a characteristic to suit the environment