UNIT 1 - KA1

Question 1

What is a stem cell

Answer 1

Stem cells are sites of production of specialised cells.

They have the potential to become specialised cells and are involved in growth and repair.

Question 2

Why is cell division necessary

Answer 2

Cell division is necessary to allow organisms to grow or to replace damaged cells and repair tissues

Question 3

What is a somatic cell

Answer 3

Somatic cells are differentiated body cells that are NOT GAMETES, they are found throughout the body

Question 4

What process do somatic cells divide by and what type of cells do they form?

Answer 4

Somatic body cells divide by mitosis/cell division to produce genetically identical diploid daughter cells.

Somatic cells are diploid (23 pairs of homologous chromosomes =46)

Question 5

What is a germline cell

Answer 5

A germline cell is a cell that can divide to produce:

a) more (diploid) germline cells OR
b) (haploid) gametes - sex cells

Question 6

Where are germline cells found

Answer 6

They are found in the OVARIES in females and the TESTES in males

Question 7

What processes do germline stem cells divide by and what types of cells do they form?

Answer 7

When germline cells divide, there are two possible options:

• division by MITOSIS (to make germline cells)
• division by MEIOSIS (to make more gametes)

Question 8

Germline stem cells - MITOSIS

Answer 8

The nucleus of a germline stem cell can divide by mitosis to maintain the chromosome number

Question 9

How many chromosomes do diploid cells have

Answer 9

Diploid cells have 46 chromosomes

Question 10

Germline stem cells - MEIOSIS

Answer 10

The nucleus of a germline stem cell can divide by meiosis, it undergoes two divisions firstly separating the homologous chromosomes and secondly separating the chromatids

Question 11

How many chromosomes do haploid cells have

Answer 11

Haploid gametes contain 23 single chromosomes

Question 12

What Is cellular differentiation

Answer 12

Differentiation is the process by which a cell expresses certain genes to produce proteins characteristics for that type of cell

Question 13

Why does cellular differentiation need to take place?

Answer 13

Cells become differentiated so that different cells become specialised to carry out specific functions, rather than all cells carrying out all functions. SAVES energy and resources

Question 14

From what type of cells do specialised cells form?

Answer 14

Stem cells

Question 15

What are embryonic stem cells , what can they do and what is the word used to describe this

Answer 15

cells in the very early embryo can differentiate into all the cell types that makeup the individual so are pluripotent

Question 16

Explain why cells in the very early embryo can do what they do

Answer 16

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

Question 17

What is a tissue (adult) stem cell

Answer 17

Tissue (adult) stem cells are involved in the growth repair and renewal of the cells found in that tissue e.g. skin they are multipotent

Question 18

What does multi potent mean when referring to tissue stem cells

Answer 18

Multi potent- they can differentiate into all of the types of cell found in a particular tissue (not the same as pluripotent)

Question 19

What is the main difference between embryonic and tissue stem cells

Answer 19

Embryonic stem cells have the potential to differentiate into any type of blood cell, tissue stem cells can only differentiate into cells from the tissue they are found in. (More potential from embryonic)

Question 20

What do therapeutic uses of stem cells involve

Answer 20

Therapeutic uses of stem cells involves the repair of damaged or diseased organs or tissues

Question 21

Two therapeutic uses for stem cells

Answer 21

1- repair of cornea (eye)
2- regeneration of damaged skin (burns/injury)

Question 22

What does stem cell research provide information of

Answer 22

Stem cell research provides information on how cell processes such as cell growth, differentiation and gene regulation work

Question 23

Stem cells are used as models in research for:

Answer 23

1- study how diseases develop
2- used for drug testing

Question 24

Why may there be ethical concerns about using embryonic stem cells

Answer 24

There may be ethical concerns of using embryonic stem cells as it involves destruction of embryos

Question 25

Why do cancer cells divide excessively

Answer 25

Cancer cells divide excessively because they do not respond to regulatory signals (don’t switch off)

Question 26

What is a tumour

Answer 26

A tumour is a mass of abnormal cells

Question 27

How may secondary tumours form

Answer 27

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

Question 28

Tissue stem cells found in bone marrow will develop into these 4 specialised cells

Answer 28

• red blood cell
• phagocyte
• lymphocyte
• platelet

Question 29

What is a germline cell

Answer 29

Germline cells are gametes (sperm and ova) and the stem cells that divide to form gametes

Question 30

Red blood cell

Answer 30

Genes expressed : genes for haemoglobin production

Question 31

Platelet

Answer 31

Gene expressed : genes for healing associated proteins

Question 32

Phagocyte

Answer 32

Genes expressed : genes for digestive enzymes

Question 33

Lymphocytes

Answer 33

Genes expressed : genes for killing proteins and cytokines

Question 34

Somatic cell - course spec definition

Answer 34

A somatic cell is any cell In the body other than cells involved in reproduction

Question 35

What can happen to stem cells in the lab

Answer 35

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

Question 36

The ethical issues of using embryonic stem cells

Answer 36

Use of embryonic stem cells can offer effective treatments for disease and injury however it involves destruction of embryos