B2 - Cell division

Explain the process of Cell cycle

Stage 1: Cells grow bigger, increase in mass. They replicate their DNA to form two copies of each chromosome ready for cell division. Sub-cellular structures are also increased to get ready to divide.

Stage 2: Mitosis - one set of chromosomes is pulled to each side of the dividing cell and the nucleus splits

Why is mitotic cell division important?

Mitotic cell division is important in the growth, repair and development of multicellular organisms

Where does mitosis occur most frequently in plants?

the roots and stems of the leaves, which is known as the meristems. In these places, mitosis happens almost continously.

What is the difference between plant and animal cells when it comes to differentiation and mitosis?

Animal cells differentiate at an early stage of development. Most specialised cells can divide by mitosis but can only form the same type of cell.

Plant cells retain the abillity to differentiate throughout life as plants are growing all through their lives. Plants cells produced from mitosis do not differentiate until they're in their final position in the plant. Even then, the differentiation is not permanent.

What is an embryonic stem cell?

embryonic stem cells are stem cells orignated from an embryo. They can differentiate into any type of cell

Where are embryonic stem cells formed from

When an egg and a sperm cell fuse to form a zygote, a single new cell. That cell keeps dividing and becomes a hollow ball of cells called an embryo. The inner cells of this ball are embryonic stem cells.

Where are adult stem cells formed?

Bone marrow is a good source of adult stem cells

What is different about adult stem cells compared to embryonic stem cells

Adult stem cells can only differentiate into types of blood cells

Why is plant cloning using stem cells from meristems important?

- save a plant from extinction
- use it for medicine
- agriculture (producing disease resistant crops)
- horticulture (selling plants)

What are disadvantages of embryonic stem cells?

- May kill the embryo
- religious and moral objections
- expensive and difficult to control

What are disadvantages of adult stem cells

- limited diseases it could treat
- stem cells may be rejected

What is therapeutic cloning?

Using adult stem cells from an adult to produce an early embryo of themselves. Then, the embryonic stem cells from the embryo could be used to treat the original patient. These stem cells wouldn't be rejected.

How do bacteria divide and explain the process?

Through binary fission.

first the genetic material is replicated and the cell grows in size.

The two large circular strands of DNA move to either side of the cell but the plasmids are arranged randomly .

A cell wall grows down the middle and the two halves pull apart.