Unit 1: human cells- Division and differentiation in human cells

Question 1

What are somatic cells?

Answer 1

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

Question 2

Why do somatic cells divide?

Answer 2

Somatic cells divide during growth and repair to increase and maintain total cell numbers.

Question 3

What are stem cells?

Answer 3

Stem cells are undifferentiated cells that have a unique property in that they not only make new copies of themselves (self renew), but can also differentiate to become a range of specific cell types.

Question 4

What is Cellular Differentiation?

Answer 4

Cellular Differentiation is a process by which a cell expresses certain genes to produce proteins characteristic for that cell type. This allows a cell to carry out specialised functions.

Question 5

What do differentiated cells only have a few of and what does this mean for the cell?

Answer 5

Differentiated cells only have a few genes switched on and those that are not required for that specific cells function are switched off, meaning only the proteins that the cell requires to function are produced.

Question 6

Where are adult tissue stem cells found?

Answer 6

Adult tissue stem cells are found in the tissue of adults and children, including the skin and bone marrow.

Question 7

Are adult tissue stem cells capable of dividing into a wide range of differentiated cells?

Answer 7

No they are only capable of dividing into a LIMITED range of differentiated cells.

Question 8

Can adult tissue stem cells be used successfully in bone marrow transplants?

Answer 8

Yes.

Question 9

Where are embryonic stem cells found?

Answer 9

In the inner cell masses of early embryos (blastocyst).

Question 10

Are embryonic stem cells capable of dividing into a wide range of differentiated cells?

Answer 10

Yes.

Question 11

What is the meaning of multipotent?

Answer 11

Cells that have the ability/are capable of giving rise to a limited number of cell types.

Question 12

What is the meaning of pluripotent?

Answer 12

Cells that have the ability/are capable of developing into ALL types of cells.

Question 13

What is an example of a multipotent cell?

Answer 13

Adult tissue stem cell.

Question 14

What is an example of a pluripotent cell?

Answer 14

Embryonic stem cells.

Question 15

Why are embryonic stem cells capable of differentiating into any specialised cell type?

Answer 15

They are pluripotent.

Question 16

Why do adult tissue need stem cells?

Answer 16

To maintain cell numbers, by repairing/replacing damaged cells within the tissues or organs where they are found.

Question 17

Where is the location of the tissue stem cells which develop into blood cells?

Answer 17

Bone marrow.

Question 18

What are germline cells?

Answer 18

A lineage of cells that divide to form/produce gametes.

Question 19

Are germline cells diploid or haploid?

Answer 19

Diploid.

Question 20

How many pairs of chromosomes do germline cells have?

Answer 20

23 pairs of homologous chromosomes.

Question 21

How do germline cells divide to produce more germline cells?

Answer 21

By mitosis.

Question 22

What is the process of division called that germline cells undergo to produce haploid gametes?

Answer 22

Meiosis.

Question 23

What are examples of somatic cells?

Answer 23

All body cells of an organism - apart from the sperm and egg cells, like red blood cells, muscle cells and hair cells.

Question 24

What are example of gametes?

Answer 24

Egg and sperm.

Question 25

How do somatic cells divide and why is this important?

Answer 25

Somatic cells divide by mitosis so the daughter cells obtain all of the genetic info they need to function and so no genetic info is lost.

Question 26

How many chromosomes do haploid cells have?

Answer 26

23.

Question 27

How many chromosomes do diploid cells have?

Answer 27

46.

Question 28

Why can embryonic stem cells differentiate into any cell type?

Answer 28

All the genes in embryonic stem cells are switched on, so these cells can differentiate into any cell type.

Question 29

What are adult tissue stem cells involved in and why is this?

Answer 29

Adult tissue stem cells are involved in the growth, repair and renewal of the cells found in that tissue, as they are multipotent.

Question 30

What do the therapeutic uses of stem cells include?

Answer 30

Therapeutic uses involve the repair of damaged or diseased organs or tissue. For example Bone marrow transplants and skin grafts.

Question 31

Describe 2 ways how stem cells are used therapeutically in bone marrow transplants?

Answer 31

Bone marrow transplants are most common in leukaemia and can be done in 2 ways.

1) A stem cell transplant - This involves using healthy stem cells from blood or bone marrow of one person –ideally a close family member with the same or similar tissue type - and transferring them to another person.
2) Cord blood - This involves taking blood from umbilical cord and placenta which is rich in stem cells and are donated from people after birth of their new born baby. The blood after testing can then be transplanted into leukaemia sufferers etc.

Question 32

Describe 2 ways how stem cells are used therapeutically in skin grafts?

Answer 32

1) Using embryonic stem cells which are manipulated to differentiate into skin cells
2) Taking sections of healthy skin from other places of the body and placing them on required area.

Question 33

What can stem cell research be used for?

Answer 33

1) Providing info on how cell processes work.
2) Drug testing.
3) Researching how diseases work.

Question 34

What is the cut off time by which embryos are either used or destroyed?

Answer 34

14 days.

Question 35

Why are embryos that are passed 14 days old not used for research?

Answer 35

After 14 days, the nervous system starts to develop.

Question 36

Why are people against stem cell research and what is the opposing argument?

Answer 36

Against;
People believe that it is wrong to create a human life simply for the purpose of scientific research

For;
The fact that embryonic stem cells have the potential to discover cures for diseases or which thee are currently none.