1. Protein Synthesis
9 Biology

2. Terminology DNA Protein synthesis mRNA tRNA rRNA RNA polymerase
Helicase
Codon
Anti-codon
Ribosome
E.R.
Polypeptide
Amino acid
Triplet

3. Proteins are synthesized:
To make Communication molecules
Signals on cell membrane
To make Antibodies
Fight pathogens
To make Transport molecules
Protein channels in cell membranes
To make Enzymes
Catalyze reactions

4. How do the proteins get synthesized?
Protein “recipe” is on DNA
Order of the nitrogenous bases dictates the protein made
DNA has the information, but cannot leave the nucleus.
mRNA is used to copy the protein recipe, take it out of the nucleus, and have it translated by ribosomes and tRNA

5. RNA-Ribonucleic Acid RNA is: 3 Types: Single stranded Has base pairing
BUT
Has no Thymine
Uses Uracil instead
So…
A pairs with U
G pairs with C
3 Types:
mRNA- messenger RNA
tRNA- transfer RNA
rRNA- ribosomal RNA
Ribosomes are made of rRNA, and are synthesized in the nucleolus

6. Protein Synthesis Step 1: Transcription
DNA molecule uses helicase to unzip in the area where the protein recipe is
mRNA copies the DNA strand using RNA polymerase and with A,U,G,C in the proper complementary order

7. Protein Synthesis Step 2: Translation
mRNA leaves the nucleus and heads for a ribosome
Ribosome puts mRNA strand( codon) in contact with tRNA (anti-codon)
tRNA encodes for amino acids using “triplets” of code
3 bases= 1 amino acid

8. Protein Synthesis Step 3:
Amino acids form a polypeptide chain protein
Protein assumes its folding pattern
It will be used in cell or exported for use outside the cell
Protein translated in cytoplasm used in cell
Protein translated in E.R. exported

9. How Code on DNA Becomes Protein
Order of nitrogenous bases encodes for proteins-
Change base sequence, change the protein made
Protein expression is visible:
Eye color
Height
Physical features
Protein expression is also invisible:
Enzyme action
Antibody generation
Cell signalling
Order of bases on DNAcopied by mRNAtranslated to protein by tRNA and ribosomes