Mitosis and meiosis Flashcards

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1
Q

What is mitosis used for?

A

Asexual reproduction
Growth
Tissue repair
Repair cells

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2
Q

What happened in prophase in mitosis?

A
  • The nuclear envelope and nucleolus breaks down
  • The centrioles duplicate and go to opposite poles
  • The DNA condenses into 2 identical chromatids
  • Spindle fibres made from tubulin are made from the centrioles in animal cells
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3
Q

What happened in metaphase in mitosis?

A
  • The chromatids move into the middle down the equator of the cell or the metaphase plate
  • The spindle fibres attach to the centromeres on the chromatids
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4
Q

What happened in anaphase in mitosis?

A
  • The centromere divides and the sister chromosomes are dragged to opposite poles.
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5
Q

What happened in telophase in mitosis?

A
  • A nuclear envelope is made around the chromosomes and they unravel
  • The cell membrane starts to split
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6
Q

What happens in cytokinesis after mitosis in animal cells?

A

The plasma membrane folds inwards and ‘nips in’ the cytoplasm

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7
Q

What is meiosis used for?

A

Sexual reproduction

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8
Q

What happened in prophase I in meiosis?

A
  • The nuclear envelope and nucleolus breaks down
  • The centrioles duplicate and go to opposite poles
  • The DNA condenses
  • Spindle fibres made from tubulin are made from the centrioles in animal cells
  • The homologous pairs of chromosones form bivalents and exhange alleles
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9
Q

What happened in metaphase I in meiosis?

A
  • The homologous pairs of chromosones are opposite to each other on the equator
  • The spindle fibres connect to the centromeres of the chromatids
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10
Q

What happened in anaphase I in meiosis?

A

The homologous chomosones are dragged to the opposite poles by the motor proteins on the tubulin spindle fibres

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11
Q

What happened in telophase I in meiosis in animal cells?

A
  • A nuclear envelope is made around the chromosomes and they unravel
  • The cell membrane starts to split into 2 not genetically identical daughter cells with 1/2 the number of chromosomes from the original
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12
Q

What happened in telophase I in meiosis in plant cells?

A
  • A nuclear envelope is made around the chromosomes and they unravel
  • The cell membrane starts to split into 2 not genetically identical daughter cells with 1/2 the number of chromosomes from the original
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13
Q

What happens in telophase II in meiosis in plant cells?

A
  • A nuclear envelope is made around the chromosomes and they unravel
  • The cell membrane starts to split into a ‘tetrad’ of 4 haploid daughter cells with half the number of chromosomes as the 1st cell
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14
Q

What are the similarities between mitosis and meiosis?

A

Mitosis and meiosis 2 are similar in what happens

Both have the same interphase

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15
Q

What happens in cytokinesis in plant cells?

A

An end plate is formed from where the equator of the spindle was, and new plasma membrane and cellulose cell wall are laid down on either side along the end plate

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16
Q

What are the differences between mitosis and meiosis?

A

In mitosis the DNA isn’t exchanged
Mitosis only splits once, meiosis twice
Mitosis makes genetically identical daughter cells
Mitosis makes 2 cells, meiosis makes 4

17
Q

What happens in cytokinesis after mitosis in plant cells?

A

An end plate forms at the equator and a new plasma membrane and cell wall material are laid down on either side along this plate

18
Q

What is the benefit of the chromatids exchanging information in meiosis?

A

To achieve more diversity and to swap alleles

19
Q

What is independant assortment?

A

When the homologous chromosome pairs line up on the equator independent of one another

20
Q

What is independent assortment?

A

Each homologous pair lined up on the equator independently of all other pairs randomly.

21
Q

How does variation occur in meiosis?

A
  • Crossing over
  • Mutation
  • Random fertilisation
  • independant assortment
22
Q

Why is fertilisation random?

A

It isn’t known which sperm will fertilise the egg and which egg will come out

23
Q

How do you find the number of variations in a cell without crossing over?

A

2 to the power of the number of pairs of chromosomes

24
Q

Why is variation important?

A

To provide a wide variety of types of people to be able to adapt to different environments

25
Q

Where is the genetic material crossed over in meiosis 1?

A

The chiasmata

26
Q

What happens in cytokinesis after meiosis in plant cells?

A

An end plate is formed from where the equator of the spindle was, and new plasma membrane and cellulose cell wall are laid down on either side along the end plate

27
Q

Homologous pair of chromosome meaning

A

a pair of chromosomes that code for the same genes but have different alleles

28
Q

Sister pair of chromatids meaning

A

A pair of chromatids that are exactly the same. from the same chromatid

29
Q

centromere meaning

A

Where two chromatids are attatched

30
Q

Cytokinesis in plant cells

A

Due to the celll wall instead of the cell nipping in vesicles assemble where the equator was. The vesicles then fuse which splits the cell. The vesicles undergo lysis then wall is made.

31
Q

bivalent

A

A pair of homolohous chromosones

32
Q

chiasmata

A

the place where the homo chromosones are attatched when swapping.

33
Q

Prophase II

A

The chromosones condense again and the sister pairs of chromatids pair up
all other things happen as normal e.g nucleolus bye

34
Q

Metaphase II

A

the spindle fibres attatch to the centromere of each chromone.
independent assortment can happen because the sister chromatids can be randomly arranged so DNA can be different

35
Q

anaphase II

A

The sister chromatids are pulled apart