Division and Differentiation in Human Cells

Question 1

Where are Somatic Cells found?

Answer 1

Any body cells other than those involved in reproduction

Question 2

What do Somatic Cells do?

Answer 2

Divide by mitosis to form more Somatic Cells

Question 3

What are Germline Cells?

Answer 3

Gametes

Question 4

What do Germline Stem Cells do in relation to Gametes?

Answer 4

Divide to form Gametes

Question 5

What do Germline Stem Cells do?

Answer 5

Divide by mitosis to form more Germline Stem Cells

Question 6

What do Germline Stem Cells do when divided?

Answer 6

They maintain diploid chromosome complement - 23 homologous pairs

Question 7

Germline Stem Cells divide by what to produce what?

Answer 7

Meiosis to produce haploid gametes by undergoing two divisions

Question 8

What happens during meiosis?

Answer 8

Firstly the homologous chromosomes separate and secondly separating chromatids, producing 23 single chromosomes in each haploid cell

Question 9

What is Cellular Differentiation?

Answer 9

This is the process by which a cell develops more specialised cells functions by selective gene expression meaning only a fraction of the genes remain switched on so only those are expressed producing the characteristics specific proteins

Question 10

What are stem cells?

Answer 10

Stem cells are undifferentiated somatic cells that can divide to either make copies of themselves or differentiate into specialised cells

Question 11

What are the two types of stem cells?

Answer 11

Embryonic Stem Cells and Tissue (Adult) Stem Cells

Question 12

Describe embryonic stem cells

Answer 12

Come from a very early embryo, all the genes have the potential to be switched on so the cells can differentiate into almost any cell type (pluripotent)

Question 13

Describe tissue stem cells

Answer 13

Found in tissue and bone marrow, many of their genes are already switched off so they can only differentiate into a limited number of cells closely related to the tissue that they are found in or bone marrow can differentiate into different blood cells (multipotent) and involved in the growth, repair and renewal of cells found in that tissue

Question 14

What are the therapeutic uses of stem cells?

Answer 14

They are used in the regeneration of damaged tissue and corneal repairs. Embryo cells can self-renew, under the right conditions in the lab

Question 15

What are the research uses of stem cells?

Answer 15

They are used as model cells (genetically identical to differentiated somatic cells) to study how diseases develop or the responses to new drugs. These provide information on how cell processes such as cell growth, differentiation and gene regulation work

Question 16

What the ethical uses of stem cells?

Answer 16

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

Question 17

What do cancer cells do and what is the result of this?

Answer 17

These cells do not respond to regulatory signals and divide excessively. This results in a mass of abnormal/cancer cells which is known as a tumour

Question 18

What happens if the cells within the tumour fail to attach to each other?

Answer 18

They can spread throughout the body and form a secondary tumour