Translation

Question 1

Translation

Answer 1

The synthesis of a polypeptide using information from mRNA

-Occurs at the ribosome
-Nucleotide sequence—>Amino acid sequence

Question 2

Transfer RNA (tRNA)

Answer 2

Key player in translating mRNA to an amino acid sequence

-Has a anticodon region (complementary and antiparallel to mRNA)
-Carries the amino acid that mRNA codes for

When tRNA carries an amino acid it is “charged”

SEE PHOTO IN CAMERA ROLL

Question 3

Ribosomes

Answer 3

Where translation occurs

-Has two subunits: small and large
-Prokaryotic and eukaryotic ribosomal subunits differ in size

Large subunit
Has three sites A, P, E
A site: Amino acid site
-Holds the next tRNA carrying an amino acid
P site: Polypeptide site
-Hilds the tRNA carrying the growing polypeptide chain
E site: exit site

Question 4

Step 1: Initiation

Answer 4

Begins when small ribosomal subunit binds to the mRNA and a charges tRNA binds to the start codon
-The tRNA carries methionine
-The large subunit binds

Question 5

Step 2: Elongation

Answer 5

Starts when the next tRNA comes into the A site
-mRNA is moved through the ribosomes and its codons are read

Each mRNA codon codes for a specific amino acid

1. Codon recognition: the appropriate anticodon of the next tRNA goes to the A site
2. Peptide bond formation: peptide bonds are formed that transfer the polypeptide to the A site tRNA
3. Translocation: the tRNA in the A site moves to the P site. The tRNA in the P site goes to the E site. The site is open for the next tRNA

Question 6

Termination

Answer 6

Occurs when a stop codon in the mRNA reaches the A site of the ribosome

Stop codons do not code for amino acids

1. The stop codon signals for a release factor
   -Hydrolyzes the bond that holds the polypeptide to the P site
   -Polypeptide releases
   -All translational units disassemble

Question 7

Protein Folding

Answer 7

As translation takes place the growing polypeptide chain be to coil and fold

-Genes determine the primary structure (primary structure determines the final shape)
-Some poly peptides require chaperone proteins to fold correctly and some require modification before it can be functional in the cell

Four structures of protein folding
1. Primary
2. Secondary
3. Tertiary
4.Quaternary