DNA Replication and Protein synthesis
DNA Replication
Protein synthesis
General idea of DNA
The structure of nucleotide
In every cell has chromosomes which contain DNA.
DNA stands for deoxyribonucleic acid
It is a molecule that forms the genetic material of all living organisms which control our characteristics.
Nucleic acids carry the genetic code which determines the order of the amino acids in each protein that a cell makes.
Calls can only make a particular protein if they have nucleic acid with the correct code.
Nucleic acid is a long chain of smaller units, called nucleotides
There are two types of nucleic acid
Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)
The chain is held together because the phosphate group of each nucleotide is linked to the sugar of the next.
Bases always pair in a precise way. One member of each pair is a Purine and the other is a Pyrimidine
Double helix
2.The hydrogen bonds break down
- Free mRNA nucleotides pair with the exposed DNA bases.
- The DNA helix unwinds where it is to be copied
- A molecule of mRNA moves into the cytoplasm
- A ribosome becomes attached to its ‘start’ codon
- small molecules of transfer RNA (tRNA) bring individual amino acids to the ribosome
- The ribosome moves along the mRNA 3 bases at a time
- The ribosome will link amino acid to form a protein
New cells must have the same DNA code as their parents
- The double helix of each molecule unwinds
- The weak hydrogen bonds between DNA bases easily break down
- The molecule then becomes two separate chains of nucleotides with unpaired bases
- Then Free DNA nucleotides pair with the unpaired bases in each of the separate DNA chains
- The newly paired nucleotides are joined together by DNA polymerase
- Two new DNA molecules are being formed that are exact copies of the old ones.