Ch2 Cell division Flashcards
Cell cycle stage 1
Cells grow bigger, increase in their mass and carry out normal activities
They replicate DNA to form 2 copies of each chromosome ready for division
Also increase sub-cellular structures(mitochondria, ribosomes and chloroplasts)
Cell cycle stage 2
Mitosis
one set of each chromosome is pulled to each end of the dividing cell
Nucleus divides
Cell cycle stage 3
Cytoplasm and cell membrane also divides to form two identical daughter cells
How many chromosomes in a body cell
46 (23 pairs)
Differentiation in plants
plant cells retain ability to differentiate all their lives
stem cells are formed at plant meristems(active regions at stem and roots)
Differentiation in animals
stem cells become specialised early in life and do not change
Use of stem cells in plants
Cloning:
grow more plants of rare species to save from extinction
clone crops with desired features
large population of identical plants for research
Stem cells
unspecialised cells with the potential to differentiate into different types of specialised cells in the body.
Uses of stem cells in medicine
Could produce nerve cells to treat paralysis
Insulin-producing cells to treat diabetes
Therapeutic cloning
Therapeutic cloning
an embryo is produced with the same genes as
the patient
Stem cells from the embryo are cultured and made to differentiate into specialised tissues
Cannot be rejected by the patient’s body because it is a perfect match
Finding stem cells
adult bone marrow
embryonic cells
Problems with stem cells
embryonic stem cells
- ethical argument, can’t give permission and violation of human rights
- religion- can’t interfere with human reproduction
- research is slow, expensive and difficult
- could cause cancer
adult stem cells
- might transfer viruses
- more likely to be rejected
