Cell Division - Mitosis

Question 1

What are the two types of cell division?

Answer 1

1. Mitosis
2. Meiosis

Question 2

In mitosis what does the parent cell divide to produce?

Answer 2

Two genetically identical daughter cells

Question 3

What does the cell cycle consist of?

Answer 3

A period of cell growth and DNA replication called interphase. Mitosis happens after that. Interphase is divided into three separate growth stages. These are called G1, S and G2

Question 4

Explain G1

Answer 4

Cell grows and new organelles and proteins are made

Question 5

Explain S

Answer 5

Cell replicates its DNA, ready to divide by mitosis

Question 6

Explain G2

Answer 6

Cell keeps growing and proteins needed for cell division are made

Question 7

What are the four stages of mitosis?

Answer 7

1. Prophase
2. Metaphase
3. Anaphase
4. Telophase

Question 8

Explain interphase

Answer 8

Cell carries out normal functions but prepares to divide. DNA is unravelled and replicated, to double its genetic content. The organelle are replicated and the ATP content is increased

Question 9

Explain prophase

Answer 9

The chromosomes condense, getting shorter and fatter. Tiny bundles of protein called centrioles start moving to opposite ends of the cell, forming a network of protein fibres called the spindle. The nuclear envelope breaks down and chromosomes lie free in the cytoplasm

Question 10

Explain metaphase

Answer 10

The chromosomes (each with two chromatids) line up along the middle of the cell and become attached to the spindle by their centromere

Question 11

Explain anaphase

Answer 11

The centromeres divide, separating each pair of sister chromatids. The spindles contract, pulling chromatids to opposite poles of the spindle, centromere first, making the chromosomes appear v-shaped

Question 12

Explain telophase

Answer 12

The chromatids reach opposite poles of the spindle, they uncoil and become long and thin again. A nuclear envelope forms around each group of chromosomes, so there are now two nuclei. The cytoplasm decides (cytokinesis). There are now two daughter cells that are genetically identical to each other and the daughter cell

Question 13

Cancer is the result of uncontrolled cell division, explain

Answer 13

Mitosis and the cell cycle are controlled by genes. If there’s a mutation in the gene that controls cell division, the cell grows out of control. The cells keep dividing to form a tumour. Cancer is a tumour that invades surrounding tissue

Question 14

What are some treatments for caner designed to do?

Answer 14

To control the rate of cell division in tumour cells by disrupting the cell cycle. This kills the tumour cells

Question 15

Do cancer treatments distinguish between normal cells and tumour cells?

Answer 15

No, they also kill normal body cells that are dividing. However, tumour cells divide much more frequently than normal cells, so the treatments are more likely to kill tumour cells

Question 16

Give two examples of cancer treatments

Answer 16

1. G1 - some chemical drugs prevent the synthesis of enzymes needed for DNA replication, so the cell is unable to enter the S phase, disrupting the cell cycle forcing the cell to kill itself
2. S phase - radiation and some drugs damage DNA. At several points in the cell cycle the DNA in the cell is checked for damage,. If severe damage is detected the cell will kill itself, preventing further tumour growth