1.1 Division and Differentiation in Human Cells Flashcards
Describe Somatic cells
- Non sex cells
- Contain two sets of chromosomes
- Divide by mitosis to produce more somatic cells
Definition of differentiation
The cell expressing genes that are characterised for a particular types of cell
What happens to a cells once it it differentiated
It becomes specialised in structure and biochemical properties
Example of differentiation
The gene that produces the hormone insulin is only expressed in the cells of the pancreas
Describe Stem cells
Unspecialised somatic cells that divide to make copies of themselves (self renew) and differentiate into specialised cells
Properties of Tissue (adult) stem cells
- Involved in growth, repair and renewal of tissues
- Multipotent- the ability to make all cells types within a particular tissue
- eg. Blood stem cells in bone marrow can make all types of blood cells
Properties of Embryonic stem cells
- Found in the inner cells of an early embryo (blastocyst stage)
- Pluripotent- can make nearly all the cell types in the body
- Most genes are still switched on/expressed
Describe Germline cells
- Diploid cells
- Gamete mother cells (cells that make up the lining of the ovary/teste wall)
- Divides by mitosis to produce more diploid gametes
- Divides by meiosis to produce haploid gametes
What happens when a mutation occurs in germline cells
The mutation will be passed onto offspring
Main body tissue types in the body
- Epithelial (skin)
- Connective (blood, bones, cartilage)
- Muscle
- Nerve
What body organs are formed from
A variety of tissues
Benefits of stem cell research
Provides information on:
•How cell processes (differentiation, cell growth, gene regulation) work
•Used as model cells to study how diseases develop
•Used for drug testing
Theraputic uses of stem cells
- Bone marrow transplantants
- Skin grafts for burns
- Repair of damaged/diseases organs and tissues
Ethical issues of stem cell uses
- Not allowed to develop beyond 14 days (the same time the embryo would implant into the uterus)
- Ethical issues have led to regulations on the use of embryonic stem cells
Why cancer cells don’t respond to regulatory signals
- Succession of mutations on the genes that control cell division
- The genetic errors accumulate
- Control of cell division is lost
