Human Cells: Key Area 1.1

Question 1

What is cellular differentiation?

Answer 1

The process by which a cell develops more specialised functions by expressing the gene characteristics of that type of cell.

Question 2

What are stem cells?

Answer 2

Unspecialised somatic cells that can divide to make copies of themselves and to make cells that differentiate into specialised cells of one or more types

Question 3

Early embryo facts.

Answer 3

• They are pluripotent and can make almost all of the differentiated cell types of the body
• They can be cultured in the laboratory to give a supply of embryonic stem cells

Question 4

What are tissue(adult)stem cells

Answer 4

They are multi potent as they can make almost all of the cell types found in a particular tissue type.
They are invoked in the growth hand repair and renewal of the cells found in that tissue.

Question 5

What can adult stem cells in bone marrow differentiate into?

Answer 5

• Red blood cells
• Platelets
• Phagocytes
• Lymphocytes

Question 6

What are somatic cells?

Answer 6

Diploid cells and contain two sets of homologous chromosomes. Mutations in somatic cells are not passed to offspring

Question 7

What are diploid cells?

Answer 7

Have 23 pairs of homologous chromosomes.

Question 8

How do somatic cells divide?

Answer 8

By mitosis to form more somatic cells, which differentiate to form different body tissue types such  as: 
• Epithelial
• Connective 
• Muscle
• Nervous tissue

Question 9

How do germline cells divide?

Answer 9

By mitosis to produce more germline cells or by meiosis to produce haploid gametes. Mutations in germline cells can be passed to offspring.

Question 10

How are stem cells used in research? Provide examples.

Answer 10

Research and therapeutic uses. Focus on areas such as the repair of damaged of diseased organs or tissues, for example corneal transplants and skin grafts for burns. They can also be used as model cells to study how diseases develop or for drug testing.

Question 11

What are some ethical issues related to stem cell use?

Answer 11

• Destruction of a human embryo
• Is there a possibility of stem cells being used eugenically?
• Could stem cells become part of ca commercial trade in biological material?

Question 12

What are the regulations of embryonic stem cell use?

Answer 12

• Researchers must be granted a licence
• Embryos cannot be used beyond 14 days of development
• Human embryos cannot he implanted into another species

Question 13

How are tumours formed?

Answer 13

Cancer cells divide excessively to produce a mass of abnormal cells

Question 14

How can secondary rumours be formed?

Answer 14

Cancer cells do not respond to regulatory signals and may fail to attach to each other. If cancer cells fail to attach to each other they can spread through the body to form secondary tumours