Cell Biology - Cell division

Question 1

What do chromosomes carry?

Answer 1

A large number of genes made of DNA molecules.

Question 2

What is the cell cycle?

Answer 2

When body cells divide to form 2 genetically identical daughter cells by going through a series of stages.

Question 3

What is the function of a gene.

Answer 3

To code for a specific protein.

Question 4

What happens in the initial growth/ stage 1 of the cell cycle?

Answer 4

• Cell grows bigger.
• Extra sub-cellular structures are produced.
• Cells chromosomes are replicated.

Question 5

What happens in stage 2 (mitosis) of the cell cycle?

Answer 5

• The 2 sets of chromosomes are pulled to opposite ends of the cell.
• The nucleus divides to form 2 nuclei.

Question 6

What happens in stage 3 of the cell cycle?

Answer 6

Cytoplasm and cell membrane divide to form 2 genetically identical daughter cells.

Question 7

What is a stem cell?

Answer 7

An undifferentiated cell that can develop into one or more types of specialised cell.

Question 8

What are the 3 types of stem cells?

Answer 8

Adult, embryonic, plant meristem.

Question 9

Where is the adult stem cell found?

Answer 9

Bone marrow.

Question 10

What can adult stem cells differentiate into?

Answer 10

Certain types of cells - bone marrow to different types of blood cells.

Question 11

What are the advantages of using adult stem cells?

Answer 11

• Fewer ethical issues = adults can consent to have their stem cells removed and used.
• Relatively safe to use as treatment and donors recover quickly.
• Already an established technique for treating diseases e.g. leukaemia.

Question 12

What are the disadvantages of using adult stem cells?

Answer 12

• Requires a donor, potentially meaning a long wait time to find someone suitable.
• Can only differentiate into certain types of cells so can only be used to treat few diseases.

Question 13

Where are embryonic stem cells found?

Answer 13

Early human embryos.

Question 14

What can embryonic stem cells differentiate into?

Answer 14

Any type of specialised cell in the body.

Question 15

What are the advantages of using embryonic stem cells?

Answer 15

• Can treat a wide range of diseases.
• May be possible to grow whole replacement organs.
• No donor needed = don’t need to wait.

Question 16

What are the disadvantages of using embryonic stem cells?

Answer 16

• Ethical issues as the embryo is destroyed and each embryo is potential human life.
• Risk of transferring viral infections to patient.
• Newer treatment so relatively under-researched.

Question 17

Where are plant meristems found?

Answer 17

Meristem regions in the roots and shoots of plants.

Question 18

What can plant meristems differentiate into?

Answer 18

Into all cell types and can be used to create clones of whole plants.

Question 19

What are the advantages of using plant meristems?

Answer 19

• Rare species of plants can be cloned to prevent extinction.
• Plants with desirable traits can be cloned to produce large numbers of identical plants.
• Fast and low-cost production of large numbers of plants.

Question 20

What are the disadvantages of using plant meristems?

Answer 20

Cloned plants are genetically identical, so a whole crop is at risk of being destroyed by a single disease or genetic defence.

Question 21

What is therapeutic cloning?

Answer 21

• Cells from a patient’s own body are used to create a cloned early embryo of themselves.
• Stem cells from this embryo can be used for medical treatments and growing new organs.
• The stem cells have the same genes as the patient so are less likely to be rejected when transplanted.