Biology - B2 - Cell division

- In body cells,chromosomes are found in pairs

- Body cells divide in a series of stages called the cell cycle

- During the cell cycle the genetic material is doubled 

-It then provides into two identical nuclei in a process called mitosis

- Before a cell can divide it needs to grow, replicate the DNA to form two copies of each chromosome and increase the number of sub cellular structures

-In mitosisone set of chromosomes is pulled toeach end of the cell  and the nucleus divides

- Finally the cytoplasm and cell membranes divide to form two identicalc cells.

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

-In plant cells, mitosis takes place throughout life in the meristems found in the shoot and root tips

-Many types of plant  cells retain the ability to differentiate throughout life

-Most types of animal cell differentiate at an early stage of development

- Cells produced by mitosis are gentically identical to the parent cell

- Producing identical off spring is known as cloning

- It is difficult to clone animals as because as you have seen most animals differentiate permanently early in embryo development

-The cells cannot change back.

-Embroyonic stems cells (from human embroyos) and adult stem cells (from adult bone marrow) can be cloned and made to differentiate intomany different types of cells.

- Treatment with stem cells may be able to hep conditions such as parlysis and diabetes 

- Stem cells from plant meristems are used to produce new plant clones quickly and economically for research, horticulture and agriculture.

- An egg and sperm fuse to form a zygote a single new cell

-That cell divides and becomes a hollow ball of cells- the embroyo . 

- The inner cells of this ball are the embroyinc stem cells. 

(Horticulture is the art or practice of gardening  and management.)

-Treatment with stem cells from embryos or adult cell cloning, may be able to help with conditions such as diabietes 

- In theraputic cloning is produced with the same genes as the patient so the stem cells produced are not rejected and may be used for medical treatment

- The use of stem cells has some potential risks and some people have ethical and religous objections

- Currently in the Uk reserach is being made to treat 

- spinal cord after injuries, diabites , heart after damage in a heart attack,eyesight in the blind,damaged after bone and cartilage

- It is not known how many of these hopes will be fufilled only time will tell!