Tissue renewal, stem cells and cancer

Question 1

What are the gene defects present in cancer cells?

Answer 1

Proliferation genes (proto-oncogenes) and anti-proliferation genes. There is usually activating mutations in the proliferation genes and inactivation mutations in the anti-proliferation genes.

Question 2

What do oncogenes do?

Answer 2

They promote inappropriate cell proliferation.

Question 3

What factors contribute to inappropriate cell proliferation?

Answer 3

Normal protein in a cell not normally expressing a protein, normal protein being made in excess and mutant protein that is always in the active state.

Question 4

What can inactivation of RB/CIP result in?

Answer 4

Inappropriate progress into S phase and both factors are therefore tumour suppressors.

Question 5

What does the dermis provide?

Answer 5

Mechanical support.

Question 6

Where is the dermis located?

Answer 6

Below the epidermis.

Question 7

Where is the hypodermis located?

Answer 7

Below the dermis.

Question 8

What types of tissue makes up the dermis?

Answer 8

Loose conenctive tissue and dense connective tissue. The dense connective tissue lies below the loose connective tissue.

Question 9

What cells is the epidermis made up of?

Answer 9

Keratinocytes and melanocytes, as well as Langerhans cells that are involved in immune responses.

Question 10

What are the three key factors that maintain tissue organisation?

Answer 10

Cell communication, selective cell to cell adhesion and cell memory.

Question 11

How does the rate of cell and renewal tissue vary across different tissues?

Answer 11

Neurons never renew, bones take many years, epidermal takes months, erythrocytes take months and gut epithelial only take a few days.

Question 12

What is essential for tissue renewal?

Answer 12

Stem cells.

Question 13

What are multipotent stem cells?

Answer 13

Can give rise to specialised cell types within a specific tissue or organ.

Question 14

What are unipotent stem cells?

Answer 14

Can only develop into one cell type - lowest undifferentiation of all the cell types.

Question 15

What are oligopotent stem cells?

Answer 15

The ability of progenitor cells to give rise to a few cell types.

Question 16

What is gut epithelium made up of?

Answer 16

A single layer folded in the small intestine into crypts and villi.

Question 17

What controls stem cell renewal and the production of differentiated cell types?

Answer 17

Cell signalling.

Question 18

What are hematopoietic stem cells?

Answer 18

Stem cells in the bone marrow that give rise to all types of blood cells. They are multipotent stem cells.

Question 19

How can stem cells be used to treat blood disorders?

Answer 19

Some leukemias - the patients faulty bone marrow cells can be destroyed and replaced by donor bone marrow.

Question 20

What are induced pluripotent stem cells?

Answer 20

They are adult cells that have been reprogrammed using transcription factors to pluripotent cells.

Question 21

What are the benefits of induced pluripotent stem cells?

Answer 21

They can avoid problems of immune rejection, they avoid ethical problems associated with deriving ES cells from human embryos.

Question 22

What did John Gurdon do?

Answer 22

He showed that a nucleus from an adult frog could replace the nucleus of a frog egg and result in the development of a tadpole - a clone.

Question 23

What is a benign tumour?

Answer 23

Excess growth of cells within their original tissue.

Question 24

What is a malignant tumour?

Answer 24

Cells that invade surrounding tissues.

Question 25

How are benign and malignant tumours formed?

Answer 25

A series of mutations in genes that normally regulate cell proliferation, survival and organisation within tissues.

Question 26

What are metastases?

Answer 26

Cells that can break through boundaries and enter the bloodstream and colonise distant sites in the body.