DNA needs to replicate in order for chromosomes to be copied – giving identical genetic code to every new cell that’s made.

DNA needs to replicate in order for chromosomes to be copied – giving identical genetic code to every new cell that’s made. Base pairs allow DNA to replicate – it is controlled by enzymes.

DNA needs to replicate in order for chromosomes to be copied – giving identical genetic code to every new cell that’s made. Base pairs allow DNA to replicate – it is controlled by enzymes. Two identical DNA molecules result from replication, each having one original strand and one new strand (this is the semi- conservative replication model)

1.DNA helix unwinds 2.Hydrogen bonds between the base pairs break (unzips)

1.DNA helix unwinds 2.Hydrogen bonds between the base pairs break (unzips) 3.Nucleotides from within the nucleus assemble opposite each open strand, using energy from ATP to join together.

1.DNA helix unwinds 2.Hydrogen bonds between the base pairs break (unzips) 3.Nucleotides from within the nucleus assemble opposite each open strand, using energy from ATP to join together. 4.One strand is copied in a straightforward manner, and the other is copied in the opposite direction

1.DNA helix unwinds 2.Hydrogen bonds between the base pairs break (unzips) 3.Nucleotides from within the nucleus assemble opposite each open strand, using energy from ATP to join together. 4.One strand is copied in a straightforward manner, and the other is copied in the opposite direction 5.New nucleotides bond to the corresponding base (A – T, C – G )

1.DNA helix unwinds 2.Hydrogen bonds between the base pairs break (unzips) 3.Nucleotides from within the nucleus assemble opposite each open strand, using energy from ATP to join together. 4.One strand is copied in a straightforward manner, and the other is copied in the opposite direction 5.New nucleotides bond to the corresponding base (A – T, C – G ) 6.The two new DNA molecules are identical

Occurs prior to cell division (mitosis/meiosis) in what is known as interphase.

It is called semi-conservative because it is half old DNA and half new.

Cells divide by mitosis for growth, and to replace worn or injured cells.

Mitosis produces two daughter cells that are genetically identical to the parent cell so it can continue functioning in the same way.

Cells divide by mitosis for growth, and to replace worn or injured cells. Mitosis produces two daughter cells that are genetically identical to the parent cell so it can continue functioning in the same way. Takes place rapidly when new cells are forming – zygote, embryo, infant and young organism or in plants coming out of dormancy.

Cells divide by mitosis for growth, and to replace worn or injured cells. Mitosis produces two daughter cells that are genetically identical to the parent cell so it can continue functioning in the same way. Takes place rapidly when new cells are forming – zygote, embryo, infant and young organism or in plants coming out of dormancy. High rate of mitosis is needed for repairs after tissue damage – human bone marrow and lymph nodes divide rapidly to form replacement cells.

Some areas of the body are constantly producing new cells – eg skin cells; therefore having a greater mitotic rate than other parts of the body.

The rate of mitosis is influenced by temperature (due to enzyme activity), availability of essential nutrients (phosphorus is needed for DNA replication), the presence of mutation- promoting chemicals (mutagens) and/or carcinogens (cancer causing chemicals).