Translation

Question 1

what are three main things needed to translate mRNA into protein?

Answer 1

ribosomes, amino acids, and transfer RNA

Question 2

what are the two subunits of the ribosome?

Answer 2

The 30S and 50S

Question 3

how does the ribosome read the RNA

Answer 3

5’ to 3’

Question 4

what are four general things that must happen before the polypeptide becomes a functional protein?

Answer 4

folding, joining with other subunits, identification tags added, and certain proteins cleaved from it

Question 5

define the wobble hypothesis

Answer 5

tells us that the third nucleotide in the anticodon, when bound to the mRNA, does not have the same confines as the other two, allowing for non-specific base pairing. Therefore, codons with differing third nucleotides can code for the same amino acid

Question 6

how many tRNAs are responsible for the 61 different codons?

Answer 6

45

Question 7

what is the the role of tRNA?

Answer 7

It is responsible for carrying specific amino acids to the ribosome, each amino acid corresponding to a specific anticodon on the bottom of the tRNA

Question 8

what is the name of the enzyme that binds tRNA to its corresponding amino acid?

Answer 8

aminoacyl-tRNA synthetase

Question 9

what exactly does the enzyme do to the aa and the tRNA?

Answer 9

forms a covalent bond between the two

Question 10

what is the driving source of energy for aminoacyl-tRNA synthetase?

Answer 10

ATP

Question 11

where is the covalent bond made between the amino acid and tRNA?

Answer 11

on the 3’ end of the tRNA

Question 12

what role does the 30S subunit play at the beginning?

Answer 12

It attaches to the mRNA strand at the start codon

Question 13

where does the 30S subunit attach to the mRNA?

Answer 13

5’ Gcap

Question 14

where will the beginning of translation always begin

Answer 14

in the cytosol

Question 15

what are the three sites on the ribosome?

Answer 15

A, P, E

Question 16

where is the tRNA received and matched with its appropriate codon?

Answer 16

A site

Question 17

where do the peptide bonds form and the polypeptide snake out of?

Answer 17

P site

Question 18

what elongation initiation factor is responsible for joining the new amino acid on the trna to the polypeptide chain?

Answer 18

peptidyl transferase

Question 19

what is the difference between the n terminus and the C terminous

Answer 19

N terminus is the end that comes out first, the c terminus is at the end of the polypeptide strand

Question 20

where are ribosomes manufactured

Answer 20

in the nucleolus

Question 21

What is already part of the 30S subunit of the ribosome, allowing the subunit to find the start codon?

Answer 21

the anitcodon with methianie

Question 22

what happens when a stoop codon is reached?

Answer 22

a release factor with corresponding anticodon binds at the E site

Question 23

What makes the release factor able to release the polypeptide?

Answer 23

When transferase releases peptide bond on the previous tRNA, it tries to give it to the release factor, but it cant. So, the peptide is free to float away from the ribosome

Question 24

How many aminoacyl transferases are there? Why?

Answer 24

20. They need 20 because each amino acid is different and needs its own trnasferase to be able to move it

Question 25

what is a big difference between euk and prok in regards to translation?

Answer 25

Eukaryotes can never carry out transcription and translation at the same time, while prok. can!

Question 26

What signals the enzyme that takes the ribosome and mRNA to the ER?

Answer 26

signal peptide, made up of the first couple peptides synthesized in the chain

Question 27

what is the protein family called that comes, recognizes the siganl peptide, and transports it to the ER?

Answer 27

signal recognition proteins

Question 28

what happens once the recognition proteins bind to the signal peptide?

Answer 28

translation gets paused until the system reaches the ER

Question 29

Once the ribosome reaches the ER, then what happens?

Answer 29

the signal recognition protein binds to an integral protein, and the way it binds also lines up the ribosome right on the opening of the integral protein

Question 30

Once the signal recognition protein has bound to the pore, what does it do with the signal peptide?

Answer 30

It hands it over to the pore, and the pore anchors the signal (n terminus) to itself

Question 31

Once the n terminus has been secured by the pore, and the ribosome is lined up, what will happen then?

Answer 31

The ribosome will once again contiue transcription, but this time the polypeptide will elongnate inside the ER

Question 32

just before the ribosome finishes translation of sequence, what occurs?

Answer 32

a protein in the pore called peptidase cuts the peptide bond between the signal peptide and the first meaningful amino acid to the protein

Question 33

What is important to remember in the relationship between the ribosome and the ER pore?

Answer 33

They are never attached to each other, just lined up

Question 34

What is the initiation step to allow the making of a transmembrane protein

Answer 34

a seqeunce of polypeptides is recognized by the transmembrane protein, or pore.

Question 35

What is the result of the initiation step in regards to making a transmembrane protein

Answer 35

a hydrophobic stop-transfer protein allows no more peptide through, and the rest of the polypeptide is translated and kept outside the ER membrane

Question 36

why are chaperones needed?

Answer 36

polypeptides floating freely in the cytosol are vulnerable to degradation. chaperones keep that from happening

Question 37

what are the two types of chaperones?

Answer 37

large and small

Question 38

What are the characteristics of small chaperones? (2)

Answer 38

small chaperones interact directly with the protein | they maintain the structure of the polypeptide

Question 39

what are the characteristics of large chaperones?

Answer 39

They completely engulf the polypeptide, creating a safe environment for the pp to begin folding

Question 40

where does sorting occur in the golgi?

Answer 40

the last systernae

Question 41

What are three postranslational additions to proteins?

Answer 41

glycocilation, acetylation, and lipidation

Question 42

What is added to a protein if it is found to be faulty?

Answer 42

ubiquitone, which will send it to degradation

Question 43

what are the two pathways by which proteins are secreted out of the cell?

Answer 43

constitutive and regulated

Question 44

what kind of proteins are using the constitutive pathway?

Answer 44

Those that help maintain normal function, and plasma membrane proteins

Question 45

what substances use the regulated pathway?

Answer 45

chemical messengers, such as insulin

Question 46

what signals the release of vesicles in the regulatory pathway?

Answer 46

calcium

Question 47

where do the regulated vesicles hang out?

Answer 47

they are docked on proteins just below the plasma membrane

Question 48

Define point mutation

Answer 48

Where one nucleotide is changed in a sequence

Question 49

what can cause mutations?

Answer 49

UV rays, free radicals, and exposure to dangerous chemicals

Question 50

what is a missense mutation?

Answer 50

a point mutation that changes the codon so that it codes for different amino acid than it was supposed to

Question 51

what is a nonsense mutation?

Answer 51

a point mutation that changes a codon into a stop codon

Question 52

What is a silent mutation

Answer 52

A point mutation that results in third nucleotide in codon being switched, but the codon still codes for the same amino acid

Question 53

what is frame shift mutation?

Answer 53

insertion or deletion of a single nucleotide, causing the reading frame to shift over one nucleotide