HOW PROTEINS ARE MADE BY THE CELL What is a protein and why is it important for living systems?

Your body is made up of trillions of cells, of all different kinds: muscle cells, brain cells, blood cells, and more. Inside those cells, proteins are allowing your body to do what it does: break down food to power your muscles, send signals through your brain that control the body, and transport nutrients through your blood. Proteins are building blocks, they make up all that you are.

Proteins are made in two processes: Transcription Making an mRNA copy of DNA Translation Making a protein from the mRNA copy

Transcription 1. Only a segment (gene) of one of the strands of DNA is used as a template to create a strand of mRNA 2. Requires the enzyme RNA polymerase 3. Transcription always starts at a region called the promoter.

4. Introns are segments of DNA that do not contain genes (they get cut out of mRNA). Exons are segments that contain genes (they stay in the mRNA). 5. Each 3 bases on the final mRNA is a codon, it corresponds to an amino acid (see codon chart). many amino acids make a protein!

Translation 1. mRNA leaves the nucleus and goes to a ribosome in the cytoplasm. 2. The ribosome adds individual amino acids to form a protein. The sequence of amino acids change the shape of the protein which determines its function (hair, enzymes, skin, muscles etc)

3. tRNA molecules bring the amino acids to the ribosome to add to the growing protein. 4. Anticodons on the tRNA molecules match up using the base pairing rules. This is how the ribosome makes sure the correct amino acid is added to the growing protein.

The steps in translation

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amino acids DNA tRNA protein anticodon ribosome mRNA codon Label the image....