Transcription & Translation

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Protein synthesis  

The process of how and when proteins are made in a cell.

to make proteins two things must happen:

1. The instructions from the code must be carried from the DNA in the nucleus to the ribosomes (Transcription).

2. Amino acids must be brought to the ribosome to be built up into a protein (Translation).

^^ both stages are carried out by a chemical called RNA (ribonucleic acid).

RNA has a similar structure to DNA, but the RNA molecule is a single strand



DNA (Deoxyribonucleic  acid) - A double helix of paired bases, it is a chemical made up of genes.

it contains all the instructions to put an organism together and make it work.

its found in the nucleus of an animal and plant cells, in really long molecules called chromosomes.

A DNA molecule has 2 strands coiled together in the shape of a double helix(two spirals).

each of the two strands is made up of lots of small groups called nucleotides.

each nucleotide contains a small molecule called a base.

DNA has just four different bases - Adenine (A), Cytosine (C), Guanine (G) and Thymine (T).

The bases are paired and are always paired up in the same way - 

Its always A+T and C+G This is called complementary base-pairing. 

DNA controls the production of proteins in a cell.

DNA molecules contain a genetic code which determines which proteins are built.

the proteins include enzymes that control all the reactions going on in the body.


Gene - a section of DNA that 'codes' for a particular protein.

proteins are made up of chains of molecules called amino acids. Each different protein has its own particular order of amino acids ( there are about 20 amino acids).

This gives each protein a different shape, which means each protein can have a different function.

Its the order of the bases in a strand of DNA that decides the order of amino acids.

Each amino acid is coded for by a sequence of three bases in the strand of DNA.

proteins are made from 20 different amino acids, all found in the cytoplasm of cells.

they're stuck together to make proteins, following the order of the code in the DNA.

amino acids - ( think of them as words and think of proteins as sentences, amino acids make up proteins).proteins are assembled from amino acids in the cytoplasm at structures called ribosomes.


Transamination is when our body changes amino acids when we dont get the right amount from our diet, it happens in the liver.

DNA also detemines which genes are switched on or off - and so which proteins the cell produces e.g haomoglobin or keratin. that in turn determines what type of cell it is, e.g red blood cell, skin cell.


DNA is found in the cell nucleus and can't move out of it because its really big.


heidi wright


helpful thanks x

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