Download Biology Summary Sheet

Biology: Key Area 4
Summary Sheet
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Chromosomes are located in the nucleus of a cell.
Genes are located on chromosomes and are made of DNA.
DNA is a molecule that consists of two strands connected together
by bases.
DNA is described as a double-stranded helix.
There are 4 bases named; adenine (A), thymine (T), guanine (G) and
cytosine (C).
Bases always pair together in the same way; A with T, and G with C.
This is known as complementary base pairing.
The bases make up the genetic code.
DNA contains the genetic information for making proteins.
Proteins are made up of amino acids.
A group of three bases on the DNA strand form a triplet of bases
which codes for different amino acids.
The type of protein made is determined by the sequence of bases
on the DNA, as this determines the order of the amino acids.
The order of amino acids then determines which proteins are
formed.
There is no way for DNA (containing the information to make
proteins) to leave the nucleus so a copy of it’s code must be taken.
Messenger RNA (mRNA) is a molecule that carries a copy of the
code from the DNA in the nucleus to a ribosome in the cytoplasm.
From this copied code, the correct amino acids are joined together.
The amino acids join together in a long chain and eventually a
protein is formed.