Translation

Question 1

export of mRNA from nucleus to cytoplasm

Answer 1

requires:
1) nuclear export receptor
2) CBC (cap-binding complex)
3) energy

Question 2

nuclear export receptor

Answer 2

a complex of proteins that attaches to mature mRNA and aids in transporting mRNA out of nucleus into cytoplasm for translation

Question 3

where in the cell does translation occur

Answer 3

in the cytoplasm

Question 4

eIF4G and eIF4E

Answer 4

displace the CBC (cap-binding complex) from mRNA transcript in the cytosol; bind to the proteins bound to poly-A tail

Question 5

wobble base

Answer 5

there is some redundancy at the third position of a codon, so changes in the 3rd position can sometimes still encode for the same amino acid

Question 6

what are the 3 stop codons

Answer 6

UAA, UGA, UAG
(U Are Annoying, U Go Away, U Are Gone)
*indicate the end of translation

Question 7

what is the start codon

Answer 7

AUG (codes for methionine)

Question 8

silent (synonymous) mutations

Answer 8

change in a codon sequence that does NOT change what amino acid is coded for

Question 9

non-sense mutation

Answer 9

a point mutation that changes a codon that should code an amino acid to a STOP codon

Question 10

mis-sense (conservative) change

Answer 10

mutation that causes an amino acid to change to a different but similar amino acid (may or may not change the protein function)

Question 11

mis-sense (non-conservative) change

Answer 11

mutation that causes an amino acid to change to a different but NOT similar amino acid
-ex. hydrophobic aa to a charged aa

Question 12

reading frame

Answer 12

critical for proper translation; determines where you would start in the sequence; changes in the reading frame can completely alter the amino acid sequence

Question 13

frameshift mutation

Answer 13

insertion or deletion, which shifts the reading frame and changes the amino acid sequence

Question 14

tRNA key components

Answer 14

1) anticodon (anneals to mRNA with reverse complement)
2) CCA at 3’ end (where the amino acid is bound)

Question 15

activation of tRNA

Answer 15

aminoacyl-tRNA synthetases add the amino acid to the tRNA; specific to the AMINO ACID (not to the codon)

Question 16

subunits of prokaryote ribosome

Answer 16

50S and 30S

Question 17

subunits of eukaryote ribosome

Answer 17

60S and 40S

Question 18

small subunit of ribosome

Answer 18

matches the mRNA with the tRNA anti-codons
*binds mRNA first

Question 19

large subunit of ribosome

Answer 19

catalyzes the peptide bond formation between amino acids on the growing chain

Question 20

what are ribosomes made of

Answer 20

ribonucleoproteins (RNA and proteins)
***ribosomes assembled in the nucleolus

Question 21

locations of ribosomes in the cell

Answer 21

1) free ribosomes (in cytoplasm)
2) ER-bound ribosomes

Question 22

large subunit - 3 sites

Answer 22

A site, P site, E site

Question 23

A (aminoacyl) site of large subunit

Answer 23

where the new tRNA, bound to an amino acid, comes into the ribosome

Question 24

P (peptidyl) site of large subunit

Answer 24

where the peptide bond is formed; growing peptide chain is here

Question 25

E (exit site) of large subunit

Answer 25

where the old tRNA (without its amino acid) leaves the ribosome

Question 26

peptidyl transferase

Answer 26

the enzyme that catalyzes peptide bond formation between amino acids on growing polypeptide chain

Question 27

translation initiation

Answer 27

1) small subunit associates with initiator tRNA and eIF2 and binds to 5’ end of mRNA
2) small subunit moves along the mRNA until it reaches a start codon
3) large subunit binds and initiator tRNA enters the P-site
4) a new tRNA enters the A site; a peptide bond forms between Met and the new aa, causing large subunit to shift, such that:
-initiator tRNA moves to E site (and leaves)
-tRNA from A site moves to P site, holding the polypeptide chain
-a new tRNA can enter the A site

Question 28

translation termination

Answer 28

1) release factor binds to the A site once a stop codon is encountered
2) water is transferred to the peptide chain, releasing it from the ribosome
3) ribosome complex dissociates

Question 29

inhibitors of transcription or translation

Answer 29

important for drug development or treatment of disease (some could affect prokaryotes, eukaryotes, both, etc)