Cell Division

Question 1

Chromosome

Answer 1

Strips of of tightly coiled DNA in a threadlike structure found in the nucleus.

Question 2

Gene

Answer 2

Sections of DNA that code for a particular protein/characteristic.

Question 3

DNA

Answer 3

Unique molecules with a double helix shape that make up chromosomes.

Question 4

How many chromosomes do humans have?

Answer 4

Humans have 46 (23 pairs) chromosomes found in the nucleus of their body cells.

Question 5

Mitosis

Answer 5

Mitosis is a type of cell division that results in two identical daughter cells.

Question 6

What has to happen before a cell can divide?

Answer 6

Organelles and DNA have to be replicated. This process takes up most of the cell cycle.

Question 7

What happens during cytokinesis?

Answer 7

The cytoplasm and cell membrane divide.

Question 8

Differentiation

Answer 8

The process by which cells become specialised for a specific function.

Question 9

Stem cells

Answer 9

Undifferentiated cells.

Question 10

Plant stem cells

Answer 10

Plant cells can differentiate their whole lives. This makes cloning easier in plants than animals. Stem cells are found in the meristems-active areas- the stems and roots. Plant stem cells are totipotent and can differentiate and redifferentiate into any cell in the plant.

Question 11

Embryonic stem cells

Answer 11

Embryonic stem cells differentiate to form all the specialised cells in your body. They are totipotent (have the potential to become any cell) but cannot redifferentiate once they are specialised.

Question 12

Adult stem cells

Answer 12

Adult stem cells are undifferentiated cells found throughout the body that divide to replace and repair dead and damaged tissues. They are found in areas such as the skin and bone marrow. They are multipotent (can only differentiate into a few cell types) and cannot change back.

Question 13

Therapeutic cloning

Answer 13

The production of embryonic stem cells for use in replacing or repairing damaged tissues or organs, achieved by transferring a nucleus from the patient’s body cell into the donor’s egg whose nucleus has been removed.

Question 14

Problems with therapeutic cloning

Answer 14

Come from aborted embryos- religious and ethical issues
Progress in developing therapeutic cloning is slow, expensive and difficult.
Scientists have only been using them for 20 years-it isn’t fully understood.
Embryonic stem cells divide rapidly- may cause cancer.

Question 15

Adult stem cell transplantation

Answer 15

Taking adult stem cells from the donor’s bone marrow then inserting them in an area of the patients body. The stem cells will redifferentiate and produce healthier blood cells.

Question 16

Issues with adult stem cell transplantation

Answer 16

They have a much more limited range of potential cell types (multipotent)
Risk that the stem cells may carry viruses that will be transferred to the patient
Can be rejected by the body because they have different DNA, so the patient has to be put on dangerous immunosuppressant drugs to stop this.