20.6 - protein synthesis

Question 1

The process of protein synthesis is called

Answer 1

translation

Question 2

what is translation

Answer 2

It involves translating the genetic information from the sequence of nucleotides into the sequence of amino acids in the primary structure of a protein.

Question 3

Each mRNA has a _______ followed by the sequences that carry the information for the order of the_________ that will be produced in the process of _____.

Answer 3

short untranslated region
amino acids in the protein
translation

Question 4

That genetic information is the

Answer 4

sequence of codons along the mRNA

Question 5

The decoding process is carried out by

Answer 5

tRNA molecules

Question 6

translation is carried out on

Answer 6

ribosomes

Question 7

what are ribosomes

Answer 7

complexes of ribosomal RNA (rRNA) and proteins.

Question 8

each ribosome is made up of two subunits:

Answer 8

a small and a large ribosomal subunit

Question 9

In eukaryotic cells, the small ribosomal subunit contains

Answer 9

one rRNA molecule and thirty-three different ribosomal proteins

Question 10

the large subunit contains

Answer 10

three rRNA molecules and about forty-nine different proteins.

Question 11

Protein synthesis involves the simultaneous action of many ribosomes on a

Answer 11

single mRNA molecule

Question 12

These complexes of many ribosomes along a single mRNA are known as

Answer 12

polyribosomes or polysomes

Question 13

Each ribosome synthesizes what

Answer 13

one copy of the protein molecule encoded by the mRNA. Thus, many copies of a protein are simultaneously produced

Question 14

The molecule that decodes the information in the mRNA molecule into the primary structure of a protein is

Answer 14

transfer RNA (tRNA).

Question 15

the tRNA must ____ bind ____, and only ___, specific _____.

Answer 15

covalently
one one
amino acid

Question 16

There is at least one transfer RNA for each

Answer 16

amino acid

Question 17

All tRNA molecules have the sequence ____ at their 3’ ends

Answer 17

CCA

Question 18

The CCA is the site where the amino acid will be __________

Answer 18

covalently attached to the tRNA molecule.

Question 19

Each tRNA is specifically recognized by the active site of an enzyme called an

Answer 19

aminoacyl tRNA synthetase

Question 20

aminoacyl tRNA synthetase also recognizes the correct amino acid and covalently links the amino acid to the

Answer 20

3′ end of the tRNA molecule

Question 21

The resulting structure is called an

Answer 21

aminoacyl tRNA.

Question 22

The covalently bound amino acid will be transferred from the tRNA to a

Answer 22

growing polypeptide chain during protein synthesis.

Question 23

the tRNA must be able to recognize the

Answer 23

appropriate codon on the mRNA that calls for that amino acid.

Question 24

Second, the tRNA must be able to recognize the appropriate codon on the mRNA that calls for that amino acid. This is mediated through a sequence of three bases called the

Answer 24

anticodon

Question 25

where is the anticodon located

Answer 25

at the bottom of the tRNA cloverleaf

Question 26

The anticodon sequence for each tRNA is complementary to the

Answer 26

codon on the mRNA that specifies a particular amino acid.

Question 27

___________ will bring the correct amino acid to the site of protein synthesis.

Answer 27

the anticodon-codon complementary hydrogen bonding

Question 28

The first stage of protein synthesis is

Answer 28

initiation

Question 29

Proteins called ______ assist in the formation of a translation complex composed of an______________________________________-

Answer 29

initiation factors | mRNA molecule, the small and large ribosomal subunits, and the initiator tRNA.

Question 30

This initiator tRNA recognizes the codon ____ and carries the amino acid _____.

Answer 30

AUG | methionine

Question 31

The ribosome has two sites for binding

Answer 31

tRNA molecules

Question 32

The first site, called the

Answer 32

peptidyl tRNA binding site (P-site)

Question 33

what does the peptidyl tRNA binding site (P-site) hold

Answer 33

holds the peptidyl tRNA, the growing peptide bound to a tRNA molecule

Question 34

The second site, called the

Answer 34

aminoacyl tRNA binding site (A-site)

Question 35

what does the aminoacyl tRNA binding site (A-site) hold

Answer 35

holds the aminoacyl tRNA carrying the next amino acid to be added to the peptide chain.

Question 36

Each of the tRNA molecules is hydrogen bonded to the

Answer 36

mRNA molecule by codon-anticodon complementarity.

Question 37

The entire complex is further stabilized by the fact that the mRNA is also bound to the

Answer 37

ribosome

Question 38

The second stage of translation is

Answer 38

chain elongation

Question 39

chain elongation occurs in

Answer 39

three steps that are repeated until protein synthesis is complete.

Question 40

We enter the action after a ______ has already been assembled, and a _______ occupies the P-site

Answer 40

tetrapeptide | peptidyl tRNA

Question 41

The first event in elongation is the

Answer 41

binding of an aminoacyl-tRNA molecule to the empty A-site.

Question 42

Next in elongation, ___ bond formation is catalyzed by a catalytic region of the ______.

Answer 42

Peptide | 28S rRNA

Question 43

next, peptide bond formation is catalyzed by a catalytic region of the 28S rRNA. This is another example of a ribozyme, which is called

Answer 43

peptidyl transferase

Question 44

Now the peptide chain is shifted to the ____ that occupies the __-site

Answer 44

tRNA | A

Question 45

Finally, the ______ falls away, and the ribosome changes positions so that the next codon on the ______ occupies the _____

Answer 45

tRNA in the P-site mRNA A-site

Question 46

his movement of the ribosome is called

Answer 46

translocation

Question 47

The process shifts the new peptidyl tRNA from the

Answer 47

A-site to P-site

Question 48

The chain elongation stage of translation requires the hydrolysis of ____________ Several ________ factors are also involved in this process.

Answer 48

GTP to GDP and Pi | elongation

Question 49

The last stage of translation is

Answer 49

termination

Question 50

There are three termination codons

Answer 50

UAA, UAG, and UGA

Question 51

UAA, UAG, and UGA have no

Answer 51

no corresponding tRNA molecules

Question 52

When one of these “stop” codons is encountered, translation is

Answer 52

terminated

Question 53

A_____- factor binds the empty A-site

Answer 53

release

Question 54

The peptidyl transferase that had previously catalyzed peptide bond formation hydrolyzes the

Answer 54

ester bond between the peptidyl tRNA and the last amino acid of the newly synthesized protein

Question 55

At this point, the tRNA, the newly synthesized peptide, and the two ribosomal subunits are

Answer 55

released

Question 56

The peptide that is released following translation is not necessarily in its

Answer 56

final functional form

Question 57

In some cases, the peptide is _______ cleaved before it becomes functional.

Answer 57

proteolytically