KA1 - Division And Differentiation In Human Cells

Question 1

Define somatic cells

Answer 1

Somatic cells are any cell in the body other than the cells involved in reproduction

Question 2

Define germline cells

Answer 2

Germline cells involve the gametes and the stem cells that divide to produce the gametes

Question 3

How do somatic cells divide?

Answer 3

Somatic cells divide by mitosis to form more somatic cells.

Question 4

What does mitosis maintain?

Answer 4

The diploid chromosome number

Question 5

How many chromosomes do diploid cells have?

Answer 5

Diploid cells have 23 pairs of homologous chromosomes

Question 6

How to germline cells divide?

Answer 6

The nucleus of a germline cell can divide by mitosis to produce more germline cells

Question 7

How do germline stem cells divide?

Answer 7

Germline stem cells can divide by meiosis to produce haploid gametes

Question 8

What 2 divisions does germline cells undergo to produce haploid gametes?

Answer 8

Separating homologous chromosomes

Separating chromotides

Question 9

How many chromosomes do haploid gametes contain?

Answer 9

Haploid gametes contain 23 single chromosomes

Question 10

Define cellular differentiation

Answer 10

Cellular differentiation is the process by which a cell becomes specialised

Question 11

How do unspecialised cells develop a specialised function?

Answer 11

The cell expresses certain genes to produce proteins characteristics for that type of cell

Question 12

What are stem cells?

Answer 12

Stem cells are unspecialised somatic cells that have the ability to differentiate into a diverse range of specialised cells

Question 13

What are the 2 types of stem cell?

Answer 13

Embryonic

Tissue

Question 14

Why are embryonic stem cells described as pluripotent?

Answer 14

Cells in the very early embryo can differentiate into all of the cell types that make up that individual

Question 15

What allows embryonic stem cells to differentiate into any type of cell?

Answer 15

All the genes in embryonic stem cells can be switched on so these cells can differentiate into any type of cell

Question 16

Why are tissue stem cells described as multipotent?

Answer 16

Tissue stem cells can differentiate into all of the cell types found in a particular tissue type and are said to be multipotent

Question 17

Give an example of the differenciation of tissue stem cells

Answer 17

For example, blood stem cells located in bone marrow can give rise to red blood cells, platelets, phagocytes and lymphocytes.

Question 18

Give examples of research involving stem cells

Answer 18

How cell processes work such as cell growth, differentiation and gene regulation work.

The study of diseases and their development.

Drug testing.

Question 19

Give examples of therapeutic uses of stem cells

Answer 19

Treatment of disease e.g. heart disease

Regeneration of damaged skin for burns patients

Cornea repair

Question 20

How are stem cells used outside the body?

Answer 20

Stem cells from the embryo can self renew, under the right conditions in the lab

Question 21

Give an ethical issue for the use of stem cells

Answer 21

Embryonic stem cells have the potential to discover cures for diseases for which there are currently none and can be used in the treatment of injury

Question 22

Give an ethical issue against the use of stem cells

Answer 22

Destruction of an embryo which could be a potential life

Question 23

How do tumours form?

Answer 23

Cancer cells divide excessively because they do not respond to regulatory signals. This results in a mass of abnormal cells called a tumour.

Question 24

How to secondary tumours form?

Answer 24

Cells within a tumour may fail to attach to each other, spreading through the body where they may form secondary tumours