DNA and genetic coding

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DNA and genetic coding

The nucleus contrains genes. Each gene is section of a chromosome made of DNA and it also codes for a particlar protein. 

NUCLEUS - central part of a cell, 'the brain'.                                                                        

GENES - section of DNA that codes for a particular characteristic.                                      

DNA - molecule found in all body cells, in the nucleus. It is a sequence which  determines how our bodies are made and gives each one of us a  unique genetic code.                      

CHROMOSOME - thread-like structures in the cell nucleus that carry genetic information. 

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DNA and genetic coding

DNA is made of two strands interwinding (coiled) which form a double helix, each strand contains chemicals which are called bases. There are four different types of bases, a cross link is formed between the strands which is made up of pairs of bases. Each gene contains a different sequence of bases.

Proteins are made in the cytoplasm but DNA cannot leave the nucleus. This means a copy of the gene has to made, this means it can leave the nucleus and therefore carry the code to the cytoplasm.

The four bases in DNA are called A, T, C and G. The cross link that holds the two strands of double helix, are between the two pairs every time, this is known as complementary base paring, the two pairs are A-T and G-C. 

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DNA and genetic coding

The DNA base code also controls which protein is made, this is due to the fact the base sequence in the DNA codes for the amino acid sequence in the protein, Each amino acid is coded for by a sequence of three bases. 

The code needed to produce a protein is carried from the DNA to the ribosomes by a molecule called messenger RNA or mRNA.

Many of the proteins that are made are enzymes, which can control the activity of the cell.

AMINO ACIDS - small molecules from which proteins are built.

MOLECULE - two or more atoms which have been chemically combined.

MESSENGER RNA - copy of a section of DNA used to carry the gene code to the ribosomes.

ENZYMES - biological catakysts that increase the speed of a chemical reaction. 

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