Divison And Differentiation In human Ces Flashcards
Differentiation
Differentiation is the process by which an unspecialised cell becomes altered and adapted to perform a specialised function as part of a permanent tissue.
How does a cell specialise?
By turning on or off certain genes
- some end are switched off
- genes that are vital to all living cells are expressed
- genes for specialised cell function are expressed
Unspecialised cell
An unspecialised cell is a cell which is not specialised to carry out a particular function (e.g. A stem cell)
Totipotent
Can differentiate into all cell types
Pluripotent
Can differentiate into any cell type except placenta
Multi potent
Can differentiate into a more limited range of cell types, usually from the tissue the stem cell is found in
Stem cells
Stem cells are unspecialised cells that have the ability to reproduce or differentiate into a diverse range of specialised cells
Stem cells can either …
- reproduce themselves by mitosis while remaining undifferentiated
- differentiate into specialised cell types
At the blastocyst stage, embryonic cells are described as ?
Pluripotent
Embryonic stem cells can either…
- divide into specialised cells
- put in a lab under in vitro conditions to form stem cells (embryonic stem cells) thus providing a bank of stem cells for research
Where are adult stem cells found ?
- locations such as skin or red bone marrow
- small numbers in the tissues and organs of adults and children
What are adult stem cells described as?
Multi potent. Can give rise to a limited number of cell types, closely related to the tissue in which they are normally located (those in red bone marrow could give rise to rbcs)
What are adult stem cells used for?
Growth and repair
Somatic cells
All differentiated cells derived from stem cells are called somatic cells
Somatic cells form different types of body tissue
Epithelium
Lines major body cavities, tubular structure
Connective
Bone, cartilage and blood
Bone
Consists of concentric layers of calcified material laid down around blood vessels
Blood
Connective
Muscle
Skeletal striped fibres, smooth spindle shaped involuntary and cardiac
Nervous
Composed of network of nerve cells called neurones, which receive and transmit nerve impulses, also glial cells which support and maintain the neurones
Mutations in somatic cells
Mutations will not be passed through generations as it involved in sexual reproduction
Germline cells
A cell that leads to the formation of sex cells (gametes)
Where are germline cells situated?
Testes and ovaries
Is a germline cell diploid or haploid
A germline cell, like a somatic cell is diploid, its nucleus contains 23 pairs of homologous chromosomes and is able to undergo mitosis to produce more germline cells
THEY PRODUCE HAPLOID GAMETES
What can germline cells do?
- divide by mitosis to replace themselves
Produce haploid gametes by dividing by meiosis
Why are germline cells described as immortal?
They do not die, can divide indefinitely
Will mutations be passed into offspring in germline cells?
Yes, will be passed onto offspring during sexual reproduction
Why is meiosis important
Involved in sexual reproduction
Important for sexual variation
Therapeutic uses of stem cells
Skin grafts, bone marrow transplants, cornea repair
What is a cancer?
A cancer is an uncontrolled growth of cells that do not respond to regulatory signals
What is a tumour
When cancer cells divide uncontrollably to produce a mass of abnormal cells called a tumour
Benign tumour
Remains as a discrete group of abnormal cells in one place within an otherwise normal tissue
Do not cause problems, easily removed
Malignant tumour
When some of its cells lose the surface molecules that keep them attached to the original group enter the circulatory system and spread through the body, forming secondary tumours
Agents causing cancerous damage
Smoking, pollution, ultraviolet radiation
