UNIT 1 - KA1
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What is a stem cell
Stem cells are sites of production of specialised cells. They have the potential to become specialised cells and are involved in growth and repair.
Why is cell division necessary
Cell division is necessary to allow organisms to grow or to replace damaged cells and repair tissues
What is a somatic cell
Somatic cells are differentiated body cells that are NOT GAMETES, they are found throughout the body
What process do somatic cells divide by and what type of cells do they form?
Somatic body cells divide by mitosis/cell division to produce genetically identical diploid daughter cells. Somatic cells are diploid (23 pairs of homologous chromosomes =46)
What is a germline cell
A germline cell is a cell that can divide to produce: a) more (diploid) germline cells OR b) (haploid) gametes - sex cells
Where are germline cells found
They are found in the OVARIES in females and the TESTES in males
What processes do germline stem cells divide by and what types of cells do they form?
When germline cells divide, there are two possible options: • division by MITOSIS (to make germline cells) • division by MEIOSIS (to make more gametes)
Germline stem cells - MITOSIS
The nucleus of a germline stem cell can divide by mitosis to maintain the chromosome number
How many chromosomes do diploid cells have
Diploid cells have 46 chromosomes
Germline stem cells - MEIOSIS
The nucleus of a germline stem cell can divide by meiosis, it undergoes two divisions firstly separating the homologous chromosomes and secondly separating the chromatids
How many chromosomes do haploid cells have
Haploid gametes contain 23 single chromosomes
What Is cellular differentiation
Differentiation is the process by which a cell expresses certain genes to produce proteins characteristics for that type of cell
Why does cellular differentiation need to take place?
Cells become differentiated so that different cells become specialised to carry out specific functions, rather than all cells carrying out all functions. SAVES energy and resources
From what type of cells do specialised cells form?
Stem cells
What are embryonic stem cells , what can they do and what is the word used to describe this
cells in the very early embryo can differentiate into all the cell types that makeup the individual so are pluripotent
Explain why cells in the very early embryo can do what they do
All the genes in embryonic stem cells can be switched on so these cells can differentiate into any type of cell
What is a tissue (adult) stem cell
Tissue (adult) stem cells are involved in the growth repair and renewal of the cells found in that tissue e.g. skin they are multipotent
What does multi potent mean when referring to tissue stem cells
Multi potent- they can differentiate into all of the types of cell found in a particular tissue (not the same as pluripotent)
What is the main difference between embryonic and tissue stem cells
Embryonic stem cells have the potential to differentiate into any type of blood cell, tissue stem cells can only differentiate into cells from the tissue they are found in. (More potential from embryonic)
What do therapeutic uses of stem cells involve
Therapeutic uses of stem cells involves the repair of damaged or diseased organs or tissues
Two therapeutic uses for stem cells
1- repair of cornea (eye) 2- regeneration of damaged skin (burns/injury)
What does stem cell research provide information of
Stem cell research provides information on how cell processes such as cell growth, differentiation and gene regulation work
Stem cells are used as models in research for:
1- study how diseases develop 2- used for drug testing
Why may there be ethical concerns about using embryonic stem cells
There may be ethical concerns of using embryonic stem cells as it involves destruction of embryos