Topic 1: Cell Biolgy

What is stage 1 of the cell cycle?

Cell grows in size

DNA splits forming 2 copies of each chromosome

Amount of sub-cellular structures increases

What is stage 2 of the cell cycle?

Chromosomes line up along the centre of the cell.

Cell fibres pull an arm from each chromosome to the other side of the cell.

The nucleus divides

What is stage 3 of the cell cycle?

Cell membrane and cytoplasm split.

Two identical daughter cells are formed

What is mitosis used for?

Growth

Repair/Replacement of cells

Asexual Reproduction

What is the function of a sperm cell?

Fertilisation of an egg cell

What are the adaptations of a sperm cell?

Long Tail (Flagellum): Swims to egg

Streamlined: Makes swimming easier

Many mitochondria: Provides energy for swimming

Enzymes: For digesting outer layer of cell

What is the function of a nerve cell?

To carry electrical impulses

What are the adaptations of nerve cells?

Long axon: Transfers electrical impulses faster

Dendrites: Increase the surface area of the cell and connects many neurones to each other

Myelin Sheath: insulates axon and speeds up transmission of impulses

What is the function of a muscle cell?

Contraction

What are the adaptations of muscle cells?

Lots of mitochondria: Provides energy for contraction

Protein fibres: change their length to allow contraction

What are stem cells?

Cells that can divide by mitosis to form more cells and can also differentiate into specialised cells.

What are embryonic stem cells?

After the egg and sperm cell fertilise they produce one single cell called a zygote which divide into more cells by mitosis forming an embryo.

These embryonic stem cells can differentiate into any type of cell.

What are adult stem cells?

Adult stem cells can not differentiate into absolutely anything.

Bone marrow can divide by mitosis however it can only differentiate into different types of blood cells and they can replace any damaged cells but they can not form my new tissues.

Why are plant stem cells?

Plant stem cells are found in meristem tissues which are found in the roots and shoots of the plant. Plant stem cells can differentiate into specialised cells throughout there whole life whereas embryonic stem cells disappear when they’re older.

What are stem cells in medicine used for?

They are used to treat damaged cells and replace them with new good ones. They can be used to treat things such as diabetes where the pancreas cells are damaged or paralysis where the nerve cells are damaged.

What is the risk of using embryonic stem cells?

The patients immune system can reject the cells as the cells have different genomes to the patient. Meaning the cells would be destroyed a the body would see them as foreign.

Immune system suppression medication can be given for this but it does not always work.

What are the ethical issues with using embryonic stem cells?

The embryos that are being used have the potential to become human life.

The embryos cannot consent to being used.

However other people think that curing existing people is more important than the rights of embryos.

Embryo cells are also usually unwanted cell from fertility clinics.

What are this risks of using embryonic stem cells or adult stem cells?

If stem cell is infected with a virus it can be transferred to the patient which will cause even more issues for the patient.

Stem cells divide very quickly and the division can get out of control which means they could develop into a tumour or cancer.

What is a strength of using adult stem cells?

They won’t be rejected as they are takes from the patients body.