Translation

Question 1

DNA - RNA
RNA - ?

Answer 1

protein

Question 2

what is the point of translation?

Answer 2

to make a polypeptide that corresponds to the sequence in the mrna

Question 3

what are the components of translation?

Answer 3

1. mrna
2. ribosomes
3. trna
4. aminoacyl-trna synthetase
5. various protein factors

Question 4

ribosomes are made up of?

Answer 4

they are made up of ribosomal rna and proteins.
in shape they have 2 subunits: large and small subunit

Question 5

the subunit numbers?

Answer 5

small subunit: 40s
large subunit: 60s
together: 80s

Question 6

where is the ribosome assembled in eukaryotes?

Answer 6

in eukaryotes the ribosome is assembled in the nucleus

Question 7

once the ribosomes are made, they move into?

Answer 7

the cytoplasm

Question 8

the subunits are found where? they come together when?

Answer 8

the subunits are found free in the cytoplasm, they only come together when translation occurs.

Question 9

what are the 4 sites on the ribosome that are important for protein synthesis?

Answer 9

• one mrna binding site
• 3 trna binding sites
  APE
  Aminoacyl trna binding site, peptidyl trna binding site, exit site

Question 10

what is trna?

Answer 10

trna is transfer rna. it is the carrier of amino acids.
- the trna binds to a specific amino acid and brings it to the mrna based upon the appropriate codon.

Question 11

there is a specific trna molecule?

Answer 11

for each codon

Question 12

what is an anticodon?

Answer 12

an anticodon is a nucleotide triplet that base pairs with a complementary sequence on the mrna.

Question 13

what is aminoacyl trna synthetase?

Answer 13

this is the enzyme responsible for attaching the correct amino acid to its corresponding trna molecule. 20 different kinds.

Question 14

once the amino acid is attached, the trna is called?

Answer 14

an aminoacyl trna or charged trna

Question 15

there are various protein factors required for?

Answer 15

initiation, elongation, and termination.
examples: ifs, efs, release factors

Question 16

the translation initiation codon is 5’ aug 3’ by way of genetic code, this codon codes for?

Answer 16

methionine

Question 17

what does the initial assembly require?

Answer 17

• mrna
• small ribosomal subunit
• initiator trna met

Question 18

once assembled, what next?

Answer 18

the large subunit comes in and binds.
= translation initiation complex

Question 19

what position is trna met in?

Answer 19

p site.

Question 20

step 2: elongation

Answer 20

• trna met is in p site
• a site is open

Question 21

there are 3 phases of elongation?

Answer 21

first: aminoacyl trna binding. incoming aminoacyl trna is bought to the a site of the ribosome.
then: transpeptidation reaction: the formation of a peptide bond between the amino group of the new amino acid in the a site and the carboxyl group of the amino acid on the growing chain.
then: translocation: the ribosome moves one codon along the mrna. the trna in the p sie moves to the e site and the trna in the a site moves to the p site and a nre trna enters the a site

Question 22

what are polyribosomes?

Answer 22

string of ribosomes along the mrna.
allows the cell to make many copies of a polypeptide quickly.

Question 23

how does the ribosome know when to stop?

Answer 23

elongation proceeds until one of the three possible stop codons are reached. they are recognized by proteins called release factors which bind to the codon and trigger the release of the polypeptide from the trna.

Question 24

what happens to the released polypeptides?

Answer 24

the released polypeptides are then folded into their 3d conformation.

Question 25

correct folding is aided by ?

Answer 25

proteins called molecular chaperones

Question 26

polypeptide vs protein?

Answer 26

a polypeptide refers to the immediate polymerization of amino acids.
a protein is a polypeptide or several that has folded itself into a functional conformation