Translation

Question 1

What is the central dogma of molecular biology?

Answer 1

DNA replicates into DNA
DNA is transcribed into RNA
RNA is translated into proteins

Question 2

What is the genetic code?

Answer 2

Ribonucleotide language on mRNA

Question 3

What is the role of tRNA?

Answer 3

Interprets mRNA code in AA by its anticodon loop

Question 4

What are the three stop codons?

Answer 4

UAA
UGA
UAG

Question 5

What is the start codon and what does it code for?

Answer 5

AUG

Methionine

Question 6

What are the four properties of the genetic code?

Answer 6

Universal
Unambiguous
Degenerate/redundant
Non-overlapping and continuous

Question 7

What is the open reading frame?

Answer 7

Genetic code from start codon to stop codon

Question 8

What are the 5 mutations in nucleotide sequence?

Answer 8

Base substitution/point mutations
Frame shift mutations
Splice site mutations
Trinucleotide repeat expansion
Large segment deletion

Question 9

What are the three point mutations?

Answer 9

Silent
Missense
Nonsense

Question 10

What is a silent mutation?

Answer 10

Same AA

Question 11

What is a missense mutation?

Answer 11

Different AA

Question 12

What is a nonsense mutation?

Answer 12

Premature stop codon

Question 13

What is a frame shift mutation?

Answer 13

Deletion or insertion of 1-2 nucleotides
OR
Deletion of insertion of 3 nucleotides

Question 14

What are the requirements of translation?

Answer 14

mRNA
AAs
tRNA
Ribosomes
Translation factors
Energy

Question 15

How does AA attach to tRNA?

Answer 15

Attaches to CCA at 3’ end

Question 16

What is the wobble hypothesis?

Answer 16

Many tRNAs can pair to same codon as last nucleotide of codon (first in tRNA) is in a wobble position

Question 17

What is the function of the small subunit of ribosomes?

Answer 17

Binds to mRNA
Correct base-pairing between codon and anticodon

Question 18

What is the function of the large ribosomal subunit?

Answer 18

Catalytic peptidyl transferase activity of 23S rRNA in prokaryotes and 28s in eukaryotes - peptide bond formation

Question 19

What are the three binding sites for tRNA and their functions?

Answer 19

A - accepts new tRNA and matches to codon
P - formation of peptide bonds
E - exit site

Question 20

What are the translation factors?

Answer 20

Initiation factors (IFs)
Elongation factors (EFs)
Termination Factors (RFs)

Question 21

What is used for energy in translation?

Answer 21

GTP
ATP

Question 22

What are the 4 steps of translation?

Answer 22

Preinitiation
Initiation
Elongation
Termination

Question 23

What does polycistronic mean?

Answer 23

Multiple coding regions on one mRNA seen in prokaryotes

Question 24

What does monocistronic mean?

Answer 24

One coding region on mRNA - only option in eukaryotes

Question 25

What is pre-initiation and its energy requirements?

Answer 25

Activation of AA - aminoacylated tRNA Two high energy bonds from ATP

Question 26

What is initiation?

Answer 26

mRNA and met-tRNA bind to ribosome Formyl added to met-tRNA in prokaryotes at start codon only

Question 27

What is elongation in translation?

Answer 27

Successive cycles of active tRNA binding and peptide bond formation until stop codon is reached

Question 28

What is termination?

Answer 28

Once stop codon is reached, mRNA and tRNA dissociate, ribosome subunits are recycled

Question 29

What is the Shine-Dalgarno sequence?

Answer 29

Initiation site in prokaryotes upstream of start codon that binds to 16S rRNA of small subunit Is then bound with IFs

Question 30

How many and what type of energy bonds are required for translation in prokaryotes?

Answer 30

2 ATP 2 GTP +1 GTP for termination Extra needed in eukaryotes

Question 31

Where to the products go from translation on free ribosomes?

Answer 31

Nucleus Mitochondria Peroxisomes Stay in cytosol

Question 32

Where to the products go from translation on rER?

Answer 32

Exported from cell Plasma membrane Lysosomes

Question 33

What is the signal for translation in eukaryotes?

Answer 33

Kozak sequence - ACCAUGG

Question 34

What is the function of eIF4?

Answer 34

Binds to the 5' cap of mRNA which allows preinitiation complex to bind forming initiation complex

Question 35

How are proteins folded?

Answer 35

By chaperones, concurrent with translation Misfolded proteins are either refolded are degraded

Question 36

What is the function of protein targeting and how does it work?

Answer 36

Specific AA sequences direct proteins Secretory or non-secretory paths to destinations

Question 37

What is added to proteins destined for lysosome?

Answer 37

M6P

Question 38

What are some inhibitors of prokaryotic protein synthesis?

Answer 38

Streptomycin Neomycin Puromycin Chloramphenicol Erythromycin

Question 39

What are some inhibitors of eukaryotic protein synthesis?

Answer 39

Diphtheria toxin Pseudomonas Ricin Cycloheximide Shiga and shiga-like toxin