2.6- Cell division, cell diversity and cellular organisation Flashcards Preview

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Flashcards in 2.6- Cell division, cell diversity and cellular organisation Deck (59)
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1

What is the cell cycle?

The process that all body cells in multicellular organisms use to grow and divide

2

What are the two periods in the cell cycle called?

Interphase and M Phase (M phase involves mitosis and cytokinesis)

3

What occurs in interphase?

Cell growth and DNA replication

4

What occurs in M phase?

Mitosis and cytokinesis

5

What are the three growth stages of interphase?

G1,S,G2

6

What occurs during G1?

Cell grows and new organelles and proteins are made

7

What occurs during the synthesis phase?

Cells replicate DNA ready to divide by mitosis

8

What occurs during G2?

Cell keeps growing and proteins needed for cell division are made

9

What occurs at the G1 checkpoint?

That cell checks that the chemicals needed for replication are present and for any damage to the DNA (this occurs before entering S phase)

10

What occurs at the G2 checkpoint?

The cell checks whether all the DNA has been replicated without any damage. If it has the cell can enter mitosis.

11

What are the four stages of mitosis?

Prophase, metaphase, anaphase, telophone,

12

What occurs during prophase?

-The chromosomes condense, getting shorter and fatter.
-Centrioles start moving towards opposite ends of the cell
-The nuclear envelope breaks down and chromosomes lie free in the cytoplasm

13

What occurs during metaphase?

What occurs during metaphase?

14

What occurs during anaphase?

-The centromeres Divide separating each pair of chromatids
-The spindles contract pulling chromatids towards opposite ends of the cell

15

What occurs during telophase?

-The chromatids reach the opposite poles of the spindle and uncoil and become long and thin again (they are now called chromosomes again)
-A nuclear envelope forms around each group of chromosomes so there are now two new nuclei

16

What is cytokinesis?

Where the cytoplasm divides. In animal cells, a cleavage furrow forms to divide the cell membrane. There are now two daughter cells that are genetically identical to each other.
Cytokinesis is a separate process to mitosis

17

What occurs during interphase?

-The cell carries out normal functions but also prepared to divide
-The cells DNA is unravelled and replicated to double its genetic content
-The organelles are also replicated so it has spare ones and it's ATP content is increased

18

How can you observe the cell cycle and mitosis?

You can stain chromosomes (using Giemsa stain) so that you can see them under a microscope and watch what happens during mitosis.

19

What does meiosis produce?

Gametes for sexual reproduction

20

Why are cells produced in meiosis genetically different to each other?

Each new cell ends up with a different combination of chromosomes

21

What are haploid cells?

Cells with half the normal number of chromosomes

22

How many divisions in meiosis?

2, meiosis I and meiosis II

23

What happens in prophase 1?

The chromosomes condense
The chromosomes and arrange themselves into homologous has and crossing over occurs
Centrioles style after the ends of the cell
The nuclear envelope breaks down

24

What happens in metaphase 1?

The homologous pairs line up across the centre of the cell and attach to spindle fibres

25

What happens in anaphase 1?

The spindles contracts, separating the homologous pairs

26

What happens in telophase 1?

A nuclear envelope forms around each group of chromosomes

27

What happens in prophase 2?

The chromosomes condense
The chromosomes and arrange themselves into homologous has and crossing over occurs
Centrioles style after the ends of the cell
The nuclear envelope breaks down

28

What happens in metaphase 2?

The homologous pairs line up across the centre of the cell and attach to spindle fibres

29

What happens in anaphase 2?

The pairs of sister chromatids are separated and each new daughter cell inherits one chromatid from each chromosome
Four genetically different daughter cells are produced(gametes)

30

What is the overall aim of meiosis?

The half the chromosome number(reduction division)- this occurs during meiosis 1