Cell division

Question 1

What are chromosomes made up of?

Answer 1

DNA molecules combined with proteins - they contain genes which provide the instructions for protein synthesis

Question 2

What is a gene?

Answer 2

A section of DNA which codes for a protein

Question 3

How many chromosomes are found in the nucleus of human body cells?

Answer 3

46 - 23 pairs

Question 4

What are the three main stages of the cell cycle?

Answer 4

1) Replication of DNA
2) Mitosis
3) Division of the cell

Question 5

Why is mitosis important?

Answer 5

• produces identical cells which all have the same genetic information
• produces additional cells for growth and repair

Question 6

Describe the first stage of the cell cycle

Answer 6

longest stage - cells grow and increase in mass, replicate DNA, and synthesise more organelles (e.g. mitochondria, ribosomes)

Question 7

Describe the second stage of the cell cycle

Answer 7

Each chromosome in a pair is pulled to opposite sides of the cell , then the nucleus divides

Question 8

Describe the third stage of the cell cycle

Answer 8

the cytoplasm and cell membrane divide - two identical daughter cells are released

Question 9

What is a stem cell?

Answer 9

An unspecialised cell which is capable of differentiating into other cell types and of self-renewal

Question 10

What is funtion of stem cells in embryos?

Answer 10

Embryonic stem cells can replicate themselves and differentiate into many other types of cells
Embryotic stem cells may be able to treat conditions such as paralysis and diabetes by dividing to replace damaged cells

Question 11

what is the function of stem cells in adult bone marrow?

Answer 11

adult stem cells can differentiate into several cell types to replace dead or damaged tissues
for example, bone marrow stem cells can form many different types of blood cells

Question 12

what is the function of stem cells in plant meristems

Answer 12

meristem cells retain the ability to differentiate into any type of plant cell throughout their lifespan - they can differnetiate into any cell that’s required by the plant

Question 13

what is theraputic cloning?

Answer 13

A cloning method where an embryo is produced with the same genetic makeup as the patient. the stem cells from the embryo will not be rejected by the patient’s immune system, so can be used to treat different medical conditions

Question 14

what are the advantages of cloning plants with meristem stem cells?

Answer 14

• can help protect rare plants from going extinct
• can produce large numbers of plants with a favourable characteristic
• can produce identical plants for research

Question 15

what are the issues assosiated with embryonic stem cells?

Answer 15

• many embryonic stem cells are sourced from aborted embryos - some people have an ethical/religious objection
• development of stem cell therapies are slow, expensive, and difficult
• adult stem cells infected with a virus can transfer infections to patients
• if donor stem cells do not have a similar genetic makeup to the patient, an immune response can be triggered (rejection)