1.1 Differentiation & Stem Cells Flashcards
What is differentiation?
Differentiation is the process by which an unspecialised cell becomes altered and adapted to perform a particular function
What happens once a cell becomes differentiated
It only expresses the genes that produce the proteins characteristic for that type of cell
List some examples of specialised cells
Ciliated epithelial cell - cilia gently sweep mucus upwards and away from the lungs
Nerve cell - long which allows it to carry electrical impulses
Red blood cell - biconcave shape presents a large absorbing surface area for the absorption of oxygen
Goblet cell - produces mucus
List some examples of tissue
Muscle tissue, connective tissue, epithelial tissue, nervous tissue
Define stem cell
A stem cell is an unspecialised cell that can divide to make copies of themselves (self-renew) and/or differentiate into specialised cells
What are the two main types of stem cell
Embryonic and tissue (adult) stem cells
Where are embryonic stem cells derived from
An embryo that is about 4-5 days old, known as a blastocyst
What does pluripotent mean
The embryonic stem cells can develop into any of the 200 plus cell types of the adult body
What are ethical issues with the use of embryonic stem cells
It involves the destruction of embryos which many believe to be unethical as it has the potential to grow into a baby. However once the time for keeping spare embryos is up they are destroyed anyway.
Where can adult (tissue) stem cells be found
The skin, muscle, intestine and bone marrow
What are adult (tissue) stem cells said to be
Multipotent
What does multipotent mean
They have the ability to divide into only several distinct cell types, usually similar to the tissue that surrounds them ( they give rise to a more limited range of cell types )
What are ethical issues with the use of adult tissue stem cells
Not controversial. Doesnt require the destruction of an embryo. The patients own stem cells can be harvested for use - rejection of tissue will not be an issue
What are therapeutic applications of stem cells?
Bone marrow transplatation, skin grafts and corneal grafts
What are future developments of stem cells
Heart muscle - repairing damaged heart muscle after a heart attacm
Bladder - building a new bladder in a laboratory if a patients bladder has been damaged due to injury or disease
What can stem cells be used as
They can be used as model cells to study how diseases develop and for drug testing
What is a somatic cell
A somatic cell is a differentiated cell that forms different types of tissue that exist
What cells are somatic
All body cells are somatic like skin, nerve and muscle cells.
Somatic cells are (diploid/gamete)
Diploid
What do somatic cells divide by mitosis to form
More somatic cells
What is a germline cell
A germline cell is a cell that will become a gamete or a cell that produces gametes
What happens when cancer cells divide uncontrollably
A mass of abnormal cells
What happens if cancer cells do not respond to regulatory signals
They may fail to attach to each other
What happens if cancer cells fail to attach to each other
They can spread through the body and form secondary tumours
What is a tumour
A mass of abnormal cells that divide uncontrollably
What are the two types of tumour
A benign tumour and a malignant tumour
What metastasise mean?
To spread around the body
Does a benign tumour metastasise?
No
What are examples of benign tumours
Moles and warts
Are benign tumours harmful and can they be removed
Benign tumours dont normally cause problems and can be removed by surgery
What is a malignant tumour
A tumour that can spread to other parts of the body
What happens to the cells in malignant tumours
The cells are cancerous. The cells do not respond to regulatory signals which causes them to fail to attach to each other. They can them spread around the body forming secondary tumours
What does the risk of cancer increase with
Age
How can the risk of cancer be increased by
Agents such as cigarette smoke, polltion and ultraviolet radiation
