The Genetic Code and Protein Synthesis

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The Genetic Code and Protein Synthesis

Genetic code is the sequence of organic bases on the double strands of

DNA. These bases line up in a particular order to code for things like

eye colour, hair colour and height. Every person has an individual

genetic code and no two persons are exactly the same.

DNA replicates in a semi-conservative manner. The two strands are

separated by an enzyme called Helicase and both become templates for

new DNA. Each strand then attracts new organic bases to the ones

already present e.g. If the code on one strand was TGACACCCTGGTAGCAGT,

then the attracted organic bases would be ACTGTGGGACCATCGTCA. Another

enzyme called DNA Polymerase holds the amino acids in place, while the

sugar-phosphate back-bone is formed. One final enzyme- ligase- fixes

any broken bits of the DNA together.

Messenger RNA is made in a very similar way to DNA, except Thymine is

replaced by Uracil. Messenger RNA is also formed from a template

strand of DNA. This process is known as transcription. Helicase

unwinds the double strand, then organic bases line up next to the

corresponding bases on the DNA. It then peels away from the DNA and

exits through pores in the nuclear envelope into the cytoplasm. Once

in the cytoplasm it attaches to a ribosome, which causes amino acids

to assemble in the right order. The DNA then winds back up into its

original shape.

Transfer RNA helps the amino acids to assemble along the strand. They

also transfer amino acids to the ribosome. Amino acids attach to one

end of the tRNA and the tRNA binds to the mRNA. Cells posses over 20

types of tRNA which are all that is needed. The tRNA lines up with

corresponding bases on the mRNA, which is called a codon. The end on

the tRNA is called an anticodon.

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