1. 7.3 Translation Understanding:
Initiation of translation involves assembly of the components that carry out the process
Synthesis of the polypeptide involves a repeated cycle of events
Disassembly of the components follows termination of translation
Free ribosomes synthesize proteins primarily within the cell
Bound ribosomes synthesize proteins primarily for secretion or for use in lysosomes
Translation can occur immediately after transcription in prokaryotes
The sequence and number of amino acids in the polypeptide is the primary structure
The secondary structure is the formation of alpha helixes and beta pleated sheets
The tertiary structure is the further folding of the polypeptide
The quaternary structure exists in proteins with more than one polypeptide chain
Applications:
tRNA-activating enzymes illustrate enzyme-substrate specificity and the role of phosphorylation
Skills:
The use of molecular visualization software to analyse the structure of eukaryotic ribosomes and a tRNA molecule
Identification of polysomes in an electron micrograph
Nature of science:
Developments in scientific research follow improvements in computing

2. Subunits (one large, one small)
Draw and Label…
Ribosome
Subunits (one large, one small)
Three tRNA binding sites and their uses
mRNA binding site
tRNA
CCA base sequence at 3’ end (amino acid attaches)
Anticodon loop
Bases
Hydrogen bonds
Skills:
The use of molecular visualization software to analyse the structure of eukaryotic ribosomes and a tRNA molecule

3. Subunits
A site: Holds tRNA carrying next amino acid to be added (incoming) P site: Holds tRNA carrying the growing polypeptide chain E site: tRNA has lost its amino acid and is discharged
Skills:
The use of molecular visualization software to analyse the structure of eukaryotic ribosomes and a tRNA molecule

4. tRNA
Loops created by base pairing Anticodon loop matches codon on mRNA H bonds between bases ACC region carries specific amino acid (depends on anticodon)
Skills:
The use of molecular visualization software to analyse the structure of eukaryotic ribosomes and a tRNA molecule

5. Initiation mRNA binds to small ribosomal subunit at mRNA binding site
Initiator tRNA molecule carrying methionine (amino acid) binds at start codon ‘AUG’ at the P site
Large ribosomal subunit binds to small one
Another tRNA binds at the A site
Peptide bond forms between amino acids in P and A site and remains on the tRNA molecule at the A site
Understanding:
Initiation of translation involves assembly of the components that carry out the process

6. Ribosome moves along the mRNA molecule
Elongation
Ribosome moves along the mRNA molecule
tRNA moves from P site to E site and leaves the ribosome
tRNA in the A site moves to the P site
Allows next tRNA to bind to the A site
Movement of tRNAs from one site to another = translocation
Understanding:
Synthesis of the polypeptide involves a repeated cycle of events

7. Process continues until a stop codon is reached
Termination
Process continues until a stop codon is reached
Release factor fills the A site (no amino acid carried)
Polypeptide is released
Components disassemble
Understanding:
Disassembly of the components follows termination of translation

8. Translation
Initiation
Elongation
Termination

9. Endoplasmic reticulum
Ribosomes
Different ribosomes used to synthesize proteins bound for different destinations
Type of ribosome
Proteins used in/at:
Free
Cytoplasm
Mitochondria
Chloroplasts
Bound to ER
Endoplasmic reticulum
Golgi apparatus
Lysosomes
Plasma membrane
Outside of cell
Understanding:
Free ribosomes synthesize proteins primarily within the cell
Bound ribosomes synthesize proteins primarily for secretion or for use in lysosomes

10. Polysomes
Many ribosomes attached to a single mRNA molecule Appear as beads on a string Able to see them using an electron microscope
Skills:
Identification of polysomes in an electron micrograph

11. Polypeptide Structures
Presentations for polypeptide structure
Create presentations or videos for the following polypeptide structures. Presentations on Monday:
Primary structure and secondary structure
Tertiary structure and quaternary structure
Fibrous and globular proteins
Understanding:
The sequence and number of amino acids in the polypeptide is the primary structure
The secondary structure is the formation of alpha helixes and beta pleated sheets
The tertiary structure is the further folding of the polypeptide
The quaternary structure exists in proteins with more than one polypeptide chain

12. Polypeptide Structures Organizational structure
Description
Primary
Secondary
Tertiary
Quaternary
Fibrous and globular proteins