02/20 translation

Question 1

How many ribosomes are in prokaryotes?

Answer 1

one ribosome, 70S

Question 2

Where is the ribosome for prokaryotes found

Answer 2

in the cytoplasm

Question 3

How many ribosomes are in eukaryotes

Answer 3

there are two ribosomes

Question 4

what are the two types of ribosomes in eukaryotes

Answer 4

One of them is in the cytoplasm (80S), and the other is found in organelles like the mitochondria. it is 70S and acts like a prokaryotic ribosome

Question 5

what is the difference between the two ribosomes in eukaryotes

Answer 5

the 80S is eukaryotic functioning and the other is 70S and found in the mitochondria, it acts like a bacterial ribosome

Question 6

what are the subunits for bacterial ribosomes?

Answer 6

larger subunit: 50S and smaller subunit is 30S

Question 7

true or false, the holocomplex for the bacterial ribosome is 80S

Answer 7

false, the subunits are not additive and instead. meld together to form 70S

Question 8

where are the ribosomes for eukaryotic organisms found

Answer 8

in the cytoplasm outside the nucleus

Question 9

what are the subunits of the eukaryotic ribosome

Answer 9

the 40s and 60s

Question 10

what is the holocomplex of the eukaryotic ribosome

Answer 10

the 80S

Question 11

what RNA is important in the small subunits of bacterial and eukaryotic ribosomes

Answer 11

16sRNA in p and 18sRNA in e

Question 12

what type of ribosome is found in the mitochondria

Answer 12

70S, the bacterial ribosome due to its circular DNA

Question 13

what are the three critical ribosome sites

Answer 13

P site (peptidyl)
A site ( aminoacyl site)
E site (Exit site)

Question 14

where does the charged tRNA enter

Answer 14

the A site

Question 15

where is the growing polypeptide chain

Answer 15

the P site

Question 16

after the tRNA in the P site has transferred its polypeptide chain and translocates to the E site, what happens to the uncharged tRNA

Answer 16

it leaves the ribosome to be recharged by aminoacyl tRNA synthetase

Question 17

go review the process lol

Question 18

where is the first initiator tRNA added

Answer 18

it is added at the P site, this is the only one that does this

Question 19

in bacterial translation, what is the purpose of the 5’ UTR?

Answer 19

it is the ribosomal binding site

Question 20

initially, the ribosome subunits are

Answer 20

uncoupled

Question 21

what does the stop codon do

Answer 21

a release factor (protein) will bind at the A site, not an amino acid

Question 22

what is post-translational modification

Answer 22

the polypeptide will form its tertiary structure and may be modified

Question 23

as the polypeptide chain is formed, does it remain in its primary state

Answer 23

no, it begins its secondary folding immediately

Question 24

What is the role of the 16aRNA component of the 30s subunit?

Answer 24

it binds complementary to the mRNA ribosomal binding site and attaches the mRNA to the 30s subunit

Question 25

does the 18sRNA component of the 40s RNA in eukaryotes bind to the ribosomal binding site

Answer 25

no, there is no ribosomal binding site

Question 26

how does the first tRNA bind at the P site and not the A site?

Answer 26

the initiation factors bind to the smaller subunit and block the E and A sites so only the P site can b accessed

Question 27

after the mRNA binds to the 30S ribosomal subunit and the initiation factors bind, what occurs

Answer 27

the initiator tRNA binds at the P site followed by the larger 50S subunit

Question 28

True or false; both prokaryotic and eukaryotic translation initiation uses the small unit of the ribosome to bind to a ribosomal binding sequence near the start codon

Answer 28

false only prokaryotics do this. Eukaryotics have a scanning process where the ribosome seeks out the best AUG start codon after attaching to the 5' Cap

Question 29

how is initiation of trnaslationdifferent for eukaryotic cells

Answer 29

the ribosome will attach through the 5' cap and scan through the 5' UTR until it finds an AUG with a good consensus sequence

Question 30

is every AUG considered a start codon in eukaryotic translation

Answer 30

no, usually the start AUG codon is the first one after the 5' cap but it depends on the consensus sequence

Question 31

what are kozak rules

Answer 31

usually the start codon is the first AUG after the 5' cap but there is an optimal consensus sequence

Question 32

which has a faster elongation process

Answer 32

prokaryotes are generally faster

Question 33

what energy source is used for elongation of polypeptides

Answer 33

GTP

Question 34

what creates the covalent bond between the previous polypeptide chain and the new amino acid

Answer 34

peptidyl transferase forms a peptide bond

Question 35

what is the peptidyl transferase

Answer 35

it is a ribozyme on the large ribosomal subunit, it forms a peptide covalent bond

Question 36

if a protein was boiled, what happens to the covalent bonds (e.g, cysteine disulfide bridges)

Answer 36

they remain intact

Question 37

what is the reading frame

Answer 37

The reading frame describes how everything downstream of the AUG start codon is read in NON overlapping sets of 3

Question 38

what is the high fidelity of translation determined by

Answer 38

the proper charging of tRNA through tRNA synthetase and its covalently modified bases and through anti-codon/ codon matching

Question 39

What are the nonsense/ stop codons

Answer 39

they are codons that are not recognized by tRNAs but rather are recognized by release factor proteins that bind in the A site

Question 40

where do release factor proteins bind in the ribosome

Answer 40

they bind in the A site of the ribosome

Question 41

what is a polyribosome

Answer 41

an mRNA transcript with many bound ribosomes performing translation

Question 42

what organisms can form polyribosomes

Answer 42

both prokaryotes and eukaryotes

Question 43

what is coupling

Answer 43

coupling is the process where translation begins before transcription is done IN BACTERIA THIS DOESNT OCCUR IN EUKARYOTES

Question 44

can eukaryotes couple transcription and tranlsation

Answer 44

no! only prokaryotes