Cell division and stem cells

Chromosone

Linear arrangements of genes

Why do chromosomes come in pairs

One gene from each parent

What does a gene code for?

Charecteristics

Allele

Different version of the same gene eg. Blue eyes

Stem cells

Undifferentiated cells that can differentiate into any other type of cell

2 sources of stem cells

• embryonic tissue

• Adult stem cells that occur in some tissue

Stem cell uses

Replaced damage or diseased tissue and so have many medical applications

Benefits of using your own stem cells

• no rejection

• No need to find a donor

• No concern about using embryonic tissue

Benefits of embryonic cells

Embryonic stem cells can differentiate into a wider range of cell types

Issues of Embryonic cells

• waste of ‘potential life.’

Clinical issues associated with the use of stem cells

• no guarantee how successful eg. Stem cells used in Parkinson’s disease to replace nerve cells

• Difficulty in finding suitable donors

• Mutated stem cells can behave like cancer sells

Ethical issues associated with the use of stem cells

• one source is produced by IVF, potential life

• At what stage is an embryo regarded a person?

Social issues associated with stem cells in medicine

• risks could out way benefits

• Patients could be exploited by paying for expensive treatments, given false hope

Mitosis uses

• growth

• Replace cells

• Repair cells

Mitosis

• Mitosis mother cell has 4 chromosomes (2 pairs)

• Produces 2 daughter cells, genetically identical

• Has the same no. Chromosomes as the mother cell (4)

Problems of mitosis

Cancer is a result of uncontrollable mitosis

Use of meisos

Formation of sex cells, gametes

Meisos

• Mother cell has 4 chromosomes [2 pairs - diploid]

• 2 divisions

• 4 new cells have formed

• Each cells has half the chromosomes as the mother - haploid

• Cells are not genetically identical