The nucleus of a cell contains
Chromosome made of DNA
Each chromosome carries
Hundreds to thousands of genes
Different genes contain
The code to make different protein and do control the development of different characteristics
In body cells chromosomes are found in
Pairs
One from each parent
Different species have different numbers of
Pairs of chromosome
Humans 23
Dogs 39
Cell cycle
Series of changes involving growth and division
Mitosis
When the cell divides into two identical cells
Before a cell can divide it needs to
Grow and increase the number of sub cellular structures
Such as ribosomes and mitochondria
When the cell divides
Dna replicates si two two copies of each chromosome
Genetic material is doubles
3 steps of mitosis
1- one set of chromosomes is pulled to each end of the cell
2- the nucleus divides
The cytoplasm and cell membranes divide to form two identical cell
Mitosis is important for
Growing and development of multi cellular organisms
Repairing damaged tissue
Asexual reproduction
Undifferentiated
Not yet become specialised
Stem cells
Divide to make different types of cells
Stem cells are found in
Human embryos
In the umbilical chord
Some organs and tissues
Stem cells from human embryos are called
Embryonic stem cells
Can make all types of cells
Adult stem cells are found in
Some organs and tissues
Can only make certain types of cells and there capacity to divide is limited
Difficult to find and isolate
Stem cells are useful for
Replacing damaged cells
Treating conditions
Therapeutic cloning
A cloned embryo of the patient may be made and used as a source of stem cells
Stem cells from the cloned embryo will not be d
Rejected
Concern for using stem cells
Risks such as the transfer or viral infection
Ethical or religious objections
Stem cells in plants are found in
Meristems
Meristems allow
Plants to make new cells for growth
Stem cells can be used to produce
Clones of plants quickly
Stem cells in plants useful
Protect from extinction- cloned
Disease resistance in large numbers of identical crop plants