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From DNA to protein - 3D

here is a cell the basic unit of all

living tissue in most human cells there

is a structure called the nucleus the

nucleus contains the genome in humans

the genome is split between 23 pairs of

chromosomes each chromosome contains a

long strand of DNA tightly packaged

around proteins called histones within

the DNA are sections called genes these

genes contain the instructions for

making proteins when a gene is switched

on an enzyme called RNA polymerase

attaches to the start of the gene it

moves along the DNA making a strand of

messenger RNA out of free bases in the

nucleus the DNA code determines the

order in which the free bases are added

to the messenger RNA this process is

called transcription

before the messenger RNA can be used as

a template for the production of

proteins it needs to be processed this

involves removing and adding sections of

RNA the messenger RNA then moves out of

the nucleus into the cytoplasm protein

factories in the cytoplasm called

ribosomes bind to the messenger RNA the

ribosome reads the code in the messenger

RNA to produce a chain made up of amino

acids there are 20 different types of

amino acid transfer RNA molecules carry

the amino acids to the ribosome the

messenger RNA is read 3 bases at a time

as each triplet is read a transfer RNA

delivers the corresponding amino acid

this is added to a growing chain of

amino acids once the last amino acid has

been added the chain folds into a

complex 3d shape to form the protein