Cell division Flashcards

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1
Q

What are the 3 parts of interphase?

A

G1, S, G2

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2
Q

What happens in G1?

A

Organelles replicate

Cell grows in size

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3
Q

What happens in S?

A

DNA is replicated in the nucleus

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4
Q

What happens in G2?

A

Energy stores are increased

Cell continues to grow in size

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5
Q

What is checked at the G1 checkpoint?

A
  • Cell size
  • Nutrients
  • Growth factors
  • DNA damage
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6
Q

What is checked at the G2 checkpoint?

A
  • Cell size
  • DNA replication
  • DNA damage
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7
Q

What is G0?

A

Where the cell leaves the cycle

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8
Q

What are 3 common reasons why cells enter G0?

A

The cell has differentiated
The cell is old
The cell is damaged

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9
Q

What are senescent cells?

A

Old cells that stop dividing

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10
Q

What is cytokinesis?

A

Where the cytoplasm divides and two cells are produced

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11
Q

What is the spindle assembly check point?

A

Where it is checked that all chromosomes are attached to spindle fibres and aligned

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12
Q

What is the spindle assembly check point also known as?

A

The metaphase checkpoint

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13
Q

What would the indefinite replication of cells lead to?

A

Increased frequency of mutation = increased likelihood of harmful mutation

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14
Q

What does mitosis produce?

A

Two identical daughter cells

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15
Q

How are chromatids produced?

A

When a chromosomes is converted into two identical chromatids

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16
Q

What is the centromere?

A

The centre point where two chromatids join to form a chromosome

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17
Q

What are the four stages of mitosis?

A

Prophase, Metaphase, Anaphase and Telophase

18
Q

What happens to the nucleolus during prophase?

A

It disappears

19
Q

What do chromatin fibers do during prophase?

A

Coil and condense to form chromosomes

20
Q

What happens in animal and but not plant cells during prophase to do with centrioles?

A

Centrioles move to opposite poles of the cell

21
Q

What has happened by the end of prophase?

A

The nuclear envelope has disappeared

22
Q

What happens during metaphase?

A

Chromosomes line up along the metaphase plate equator

23
Q

What is the metaphase plate?

A

The (invisible) line through the centre of the cell, where chromosomes line up (during metaphase)

24
Q

What happens during anaphase to centromeres?

A

Centromeres holding the chromatids together in each chromosomes divide

25
Q

What happens to chromatids in anaphase?

A

The chromatids are separated by the shortening of spindle fibres, and are pulled to opposite poles of the cell

26
Q

What happens during telophase?

A

Two new sets of chromosomes gather at each pole of the cell
The nuclear envelope reforms around these two groups of chromosomes
The chromosomes begin to uncoil and the nucleolus is formed

27
Q

What happens in cytokinesis in animal cells?

A
  • Cleavage furrow forms around the middle of the cell

- Cytoskeleton pulls cell surface membrane inwards until it is close enough to fuse around the middle, forming two cells

28
Q

What happens in cytokinesis in plant cells?

A

Vesicles gather along the middle of the cell, and fuse with one another and the cell surface membrane to form two separate cells

29
Q

What are homologous chromosomes?

A

Chromosomes from different parents that are similar and pair up together

30
Q

Overview of meiosis 1

A

Reduction division- the pairs of homologous chromosomes are separated into two cells- each will contain 23 chromosomes

31
Q

Overview of meiosis 2

A

Similar to mitosis- the pairs of chromatids present in each cell are separated, forming two more cells (4 total overall)

32
Q

What is haploid?

A

A cell with 23 chromosomes

33
Q

What is the main thing that occurs in prophase 1 of meiosis?

A

Crossing over, where genes are swapped between homologous chromosomes

34
Q

What is formed from crossing over?

A

Bivalents

35
Q

What is the main thing that occurs in metaphase 1 of meiosis?

A

Homologous chromosomes line up in pairs along the metaphase plate- independent assortment occurs

36
Q

What is independent assortment?

A

The orientation and location of each homologous pair on the metaphase plate equator is random and independent of any other homologous pair, meaning there are many different combinations that can occur

37
Q

What does independent assortment and crossing over result in?

A

Genetic variation

38
Q

What are the main difference between anaphase 1 in meiosis and anaphase in mitosis?

A

In anaphase of mitosis, chromatids are pulled to opposite poles, whereas in meiosis 1, homologous chromosomes are pulled to opposite poles

39
Q

What happens in telephase 1 of meiosis?

A

The nuclear membrane reforms around the different sets of chromosomes
The cell undergoes cytokinesis

40
Q

What are the 4 final products of meoisis?

A

4 non-identical daughter cells

41
Q

What is meiosis 2 very similar to?

A

Mitosis