Cell Continuity

Question 1

How many steps does it take to form a new cell?

Answer 1

3

Question 2

What are chromosomes?

Answer 2

• Structure in the nucleus

- Made of DNA & Protein

Question 3

What is the chromatin like when it is not dividing?

Answer 3

Long thin threads

Question 4

What is the chromatin like when it is dividing?

Answer 4

Chromatin forms a number of clearly distinguishable chromosomes

Question 5

How many chromosomes does humans have?

Answer 5

46

Question 6

What are genes?

Answer 6

A section of DNA that contains the instructions for the formation of protein

Question 7

What is a haploid cell?

Answer 7

A haploid cell has one set of chromosomes.

Question 8

What letter symbolises a haploid cell?

Answer 8

The letter ‘n’

Question 9

What two human cells are examples of haploid cells?

Answer 9

Eggs and sperm

Haploid n=23

Question 10

What is a diploid cell?

Answer 10

A diploid cell has two sets of chromosomes

Question 11

Chromosomes are in pairs in diploid cells, what are these pairs called?

Answer 11

Homologous pairs.

Question 12

How is diploid symbolised?

Answer 12

‘2n’

Question 13

In diploid cells, where does each pair come from?

Answer 13

One comes from the mother and one comes from the father

Question 14

What is cell cycle?

Answer 14

Describes the life of a cell

Question 15

What is the period in the cycle were the cell is not dividing called?

Answer 15

Interphase

Question 16

What is the period when a cell divides called?

Answer 16

Mitosis

Question 17

What % of a cell’s life is in interphase?

Answer 17

90%

Question 18

What is happening at the start of interphase?

Answer 18

• Cell is very active
• Produces new organelles eg. mitochondria, chloroplasts
• Chemicals needed for growth eg. enzymes and proteins

Question 19

What is happening at the end of interphase?

Answer 19

• Chromosomes make identical copies of themselves

- Double stranded chromosome

Question 20

What is the next phase after interphase?

Answer 20

Prophase

Question 21

Describe what happens in prophase.

Answer 21

• The chromatin contracts
• Chromosomes become visible as a double stranded structure
• Spindle fibres appear in cytoplasm
• Nucleolus disappears
• Nuclear membrane starts to break down

Question 22

What phase comes after prophase?

Answer 22

Metaphase

Question 23

Describe Metaphase.

Answer 23

• Nuclear membrane is broken down
• Chromosomes line up across the centre of the cell.
• Spindles fibres from each pole attach to each chromosome at the centromere.

Question 24

What phase follows the metaphase?

Answer 24

Anaphase

Question 25

Describe anaphase.

Answer 25

- Spindle fibres contract - One chromosome from each double-stranded chromosome is pulled to opposite poles of the cell - The four chromosomes pulled to each pole have identical sets of genes

Question 26

What follows anaphase?

Answer 26

Telophase

Question 27

Describe telophase.

Answer 27

- The four chromosomes at each pole elongate to form chromatin - The spindle fibres break down - The nucleolus re-form - A nuclear membrane forms around the chromatin at each pole.