9 - Ribosome

Question 1

ribsome architechture

Answer 1

• largue subunit
• small subunit
• tRNA
• newly synthesized mRNA

Question 2

binding sites in the ribosome

Answer 2

• A site
• P site
• E site

Question 3

polypeptide synthesis in binding sites

Answer 3

• amino acid in tRNA (in A site) will act as the Nu- and attack the ester linkage which will connect the polypeptide to the P-site
• when a stop codon is encountered, the ester is hydrolyzed to give the C terminus (carbonyl)

Question 4

ribozyme

Answer 4

the ribosome is a ribozyme as it is a RNA synthesizing catalyst

Question 5

elongation factor (EF)

Answer 5

forms a complex with tRNA and will dissociate (along with the hydrolysis of GTP) once it is delivered to the proper A site

Question 6

sarcin-ricin loop (SRL)

Answer 6

• close to where GTP is hydrolyzed

Question 7

ricin

Answer 7

• enzyme comes from castor bean
• 1 molecule will kill the entire cell3
• 2 subunits that will dissociate from each other once it enters the cell
• the catalytic part is an enzyme that will hydrolyzes adenine base in the SRL
• hydrolyzing adenine prevents EF binding as it will not recognize
• protein synthesis will terminate
• will continue to hydrolyze and terminate protein synthesis until cell is dead

Question 8

release factor

Answer 8

• reads stop codons and will bind to A site

- similar structure as tRNA

Question 9

protein folding

Answer 9

full protein cannot fully fold until the whole chain has exited the tunnel

Question 10

erythromycin A

Answer 10

• targets exit tunnel
• blocks protein from exiting the tunnel
• protein synthesis will terminate

Question 11

exit tunnel

Answer 11

• polypeptide chains exit the tunnel to form proteins and can be targeted specifically
• diversity in different tunnels because of mutations