Bio

Chromosome - Carry Genes that contain the instructions for making both new cells and organs

A gene is a small packet of information that controls a characteristic of your body

DNA- The unique molecule that makes up your chromosomes.

46 chromosomes in the nucleus of your body cells. They are arranged in 23 pairs.In each pair, one chromosome is from father one from the mother.

Cells divide in a series of stages called the cell cycle.  describe the stages of the cell cycle, including mitosis.

During the cell cycle, the genetic material is doubled and then divided into two identical cells.

Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria.

The DNA replicates to form two copies of each chromosome.

In mitosis one set of chromosomes is pulled to each end of the cell and the nucleus divides.

Finally, the cytoplasm and cell membranes divide to form two identical cells. 

Cell division by mitosis is important for the growth and development of multicellular organisms.

Size increase is brought about by increasing the number of cells.

Only stems cells can differentiate into different cell types. Other animal cell functions remain fixed.

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

Some animal differentiated cells (red blood cells) cannot divide mitosis so adult stem cells replace dead cells. Nerve cells do not divide and once differentiated they are not replaced by stem cells. 

In a mature adult little or no growth takes place. Cell division is restricted to repair and replacement of damaged them. Each differentiated cell divides only to make more of the same cells.

In plant cells, mitosis takes place throughout life in the meristems found in the shoot and root tips. Undifferentiated cells are formed at active regions in the meristems mitosis takes place almost continuously.

Many plant cells retain the ability to differentiate throughout life. 

Where growth occurs Mainly at shoot and root tips and in special growth zones like buds 

How growth occurs Size increase often caused by increasing the size of cells by absorbing water into the vacuole.

Even when plant cell differentiates it can re-differentiate and become a completely different type of cell.Unlike animal cell 

A stem cell is an undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation.

Students should be able to describe the function of stem cells in embryos, in adult animals and in the meristems in plants.

Stem cells from human embryos can be cloned and made to differentiate into most different types of human cells.

Stem cells from adult bone marrow can form many types of cells including blood cells. Meristem tissue in plants can differentiate into any type of plant cell, throughout the life of the plant. Knowledge and understanding of stem cell techniques are not required. Treatment with stem cells may be able to help conditions such as diabetes and paralysis.

For

Embryonic Stem cells can be cloned and made to differentiate into many types of cell.

Treatment with stem cells may be able to help conditions such as paralysis and diabetes.

Therapeutic cloning: same genetic information as a patient means same genes and stem cells won't get rejected by the immunue system.

Against:

Human embryos have the potential for life. Embryos rights. Why trade its life just to cure someone else?

Money should be spent elsewhere rather than on funding stem cell research.