Tissue renewal, stem cells and cancer Flashcards
What are the gene defects present in cancer cells?
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.
What do oncogenes do?
They promote inappropriate cell proliferation.
What factors contribute to inappropriate cell proliferation?
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.
What can inactivation of RB/CIP result in?
Inappropriate progress into S phase and both factors are therefore tumour suppressors.
What does the dermis provide?
Mechanical support.
Where is the dermis located?
Below the epidermis.
Where is the hypodermis located?
Below the dermis.
What types of tissue makes up the dermis?
Loose conenctive tissue and dense connective tissue. The dense connective tissue lies below the loose connective tissue.
What cells is the epidermis made up of?
Keratinocytes and melanocytes, as well as Langerhans cells that are involved in immune responses.
What are the three key factors that maintain tissue organisation?
Cell communication, selective cell to cell adhesion and cell memory.
How does the rate of cell and renewal tissue vary across different tissues?
Neurons never renew, bones take many years, epidermal takes months, erythrocytes take months and gut epithelial only take a few days.
What is essential for tissue renewal?
Stem cells.
What are multipotent stem cells?
Can give rise to specialised cell types within a specific tissue or organ.
What are unipotent stem cells?
Can only develop into one cell type - lowest undifferentiation of all the cell types.
What are oligopotent stem cells?
The ability of progenitor cells to give rise to a few cell types.
What is gut epithelium made up of?
A single layer folded in the small intestine into crypts and villi.
What controls stem cell renewal and the production of differentiated cell types?
Cell signalling.
What are hematopoietic stem cells?
Stem cells in the bone marrow that give rise to all types of blood cells. They are multipotent stem cells.
How can stem cells be used to treat blood disorders?
Some leukemias - the patients faulty bone marrow cells can be destroyed and replaced by donor bone marrow.
What are induced pluripotent stem cells?
They are adult cells that have been reprogrammed using transcription factors to pluripotent cells.
What are the benefits of induced pluripotent stem cells?
They can avoid problems of immune rejection, they avoid ethical problems associated with deriving ES cells from human embryos.
What did John Gurdon do?
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.
What is a benign tumour?
Excess growth of cells within their original tissue.
What is a malignant tumour?
Cells that invade surrounding tissues.
How are benign and malignant tumours formed?
A series of mutations in genes that normally regulate cell proliferation, survival and organisation within tissues.
What are metastases?
Cells that can break through boundaries and enter the bloodstream and colonise distant sites in the body.
