Cells and Control - Cell Division and Stem Cells

Describe cell cycle completely.

1. Interphase - DNA spread out in long strings. Cell grows and increases amount of subcellular structures. DNA is duplicated and forms X - shaped chromosomes.

2. Mitosis

   1. Prophase - Chromosomes condense. Membrane around nucleus breaks down, exposing the chromosomes

   2. Metaphase - Chromosomes line up at centre of cell

   3. Anaphase - Spindle fibres pull chromosomes apart. Chromatids pulled to opposite ends of the cell

   4. Telophase - Membranes form around each set of chromosomes, forming 2 nuclei of 2 new cells

3. Cytokinesis - Before telophase ends, cytoplasm and cell membrane divide to form two separate cells.

   Final result: 2 genetically identical daughter cells .

Describe adaptations of the following:

1. Red blood cell

2. Nerve cell

3. Muscle cell

1. Red blood cell - contains haemoglobin which carries oxygen. Has no nucleus in order to carry more oxygen. Flat disc shape = wider surface area = absorb more oxygen in lungs

2. Nerve cell - thin and long. Contains fatty myelin sheath that increases speed at which messages can travel

3. Muscle cell - Look at the photo attached

Where are stem cells found?

Early human embryos. Bone marrow. Meristems of plants

Where can stem cells be used in medicine?

Used to treat paralysis. Embryonic stem cells can be used to produce nerve cells to replace damaged spinal tissue in paralysed people.

Used to treat diabetes. Embryonic stem cells used to produce insulin - producing cells, to replace the faulty ones in people with diabetes

Benefits and risks of using stem cells in medicine?

Issues:

Tumour development. Disease transmission. Rejection. Ethical issues.

Benefits:

Can be used in research and to cure diabetes and paralysis.