Lecture 6- Transcription/Translation

Question 1

What are the 4 bases for RNA?

Answer 1

Adeneine - Uracil
Guanine - Cytosine

Question 2

What type of sugar does RNA have?

What type of group is on the 2’ carbon of RNA?

Answer 2

Ribose

Hydroxyl (OH-)

Question 3

In what two ways does the hydroxyl group affect RNA?

Answer 3

1. Interferes with the double strand (causing RNA to be single stranded)
2. Makes RNA less stable than DNA (phosphate backbone is more susceptible to hydrolysis)

Question 4

What type of bonds make up the sugar backbone of RNA?

Answer 4

Phosphodiester bonds

Question 5

True or false: because RNA is single stranded, it cannot form complex structures?

Answer 5

FALSE

Hydrogen bonds can help fold single strand RNA into secondary structures

Question 6

In secondary structure of RNA, what two ribozyme catalytic activity exists?

Answer 6

rRNA (ribosomal RNA)
snRNP (small nuclear ribonucleoproteins)

Question 7

What are the four main types of RNA?

Answer 7

mRNA- messanger
tRNA- transfer
rRNA- ribosomal
snRNA- small nuclear

Question 8

What is the role of mRNA?

Answer 8

Forms template for protein synthesis

Question 9

What is the role of tRNA?

Answer 9

Carries activated amino acids to ribosomes for protein synthesis

Question 10

What is the role of rRNA?

Answer 10

Structural core of ribosomes

Question 11

What is the role of snRNA?

Answer 11

Involved in the processing of DNA and RNA within the nucleus

Question 12

What type of RNA is eventually translated into a protein?

Answer 12

mRNA

Question 13

What type of RNA matches mRNA code to appropriate amino acids?

Answer 13

tRNA

Question 14

_____ reads mRNA and translate to proteins

Answer 14

Ribosomes

Question 15

Ribosomes are made up of ____ and _____.

Answer 15

RNA and Proteins

Question 16

What is the site of protein synthesis in the cell?

Answer 16

The ribosome

Question 17

Where is the TATA box located?

Answer 17

In the promoter region upstream from gene (5’ end)

Question 18

Why is it called a TATA box?

Answer 18

Contains sequences of thymines and adenines

Question 19

What are the four steps for transcription initiation?

Answer 19

1. Transcription factors (nuclear proteins) bind to the TATA box in promoter region
2. Transcription factors recruit RNA polymerase
3. RNA polymerase binds to DNA sequence and is activated
4. Transcription begins

Question 20

How is RNA polymerase different than DNA polymerase?

Answer 20

RNA polymerase can unwind DNA, but DNA polymerase cannot in DNA replication (helicase must do this)

Question 21

Does RNA polymerase require a primer?

Answer 21

No

Question 22

What direction does RNA polymerase read and synthesize?

Answer 22

Reads 3’ to 5’
Synthesizes 5’ to 3’

Opposite ways of DNA polymerase

Question 23

True or false: RNA polymerase catalyzes phosphodiester bonds

Answer 23

True!

Question 24

What type of RNA polymerase makes rRNA?

Answer 24

RNA Polymerase 1

Question 25

What type of RNA polymerase makes mRNA and snRNA?

Answer 25

RNA Polymerase 2

Question 26

What type of RNA polymerase makes rRNA, tRNA, and snRNA?

Answer 26

RNA Polymerase 3

Question 27

Where are mRNA, tRNA, and rRNA made? Endoplasmic reticulum Ribosome Nucleus Cytoplasm

Answer 27

Nucelus

Question 28

Where do mRNA, tRNA, and rRNA function? Endoplasmic reticulum Ribosome Nucleus Cytoplasm

Answer 28

Cytoplasm

Question 29

What are three post-transcriptional modifications?

Answer 29

5' capping 3' poly adenylation Spicing

Question 30

What are the two main functions of 5' capping?

Answer 30

1. Protects mRNA from 5' to 3' exonuclease degradation 2. Region where ribosomes can bind

Question 31

What is the main function of 3' Poly adenylation?

Answer 31

Protects from 3' to 5' exonuclease degradation

Question 32

What are non-coding regions called?

Answer 32

Introns

Question 33

What are codes for proteins called?

Answer 33

Exons

Question 34

What happens in mRNA splicing?

Answer 34

Spliceosome made of snRNPs removes introns and ligates exons together

Question 35

What happens in alternative splicing?

Answer 35

Because of splicing different combinations of exons, multiple protein possibilities can form from one gene

Question 36

How/which direction is mRNA read?

Answer 36

mRNA reads 5' to 3' Bases are read in triplets (codons)

Question 37

What is the start codon?

Answer 37

AUG

Question 38

What are the 3 stop codons?

Answer 38

UAA- u are annoying UGA- u go away UAG- u are gone

Question 39

Since most amino acids have multiple codons, what does this lead to?

Answer 39

Wobble effect

Question 40

What is the wobble hypothesis?

Answer 40

Since only the first two codons are precisely paired with the anticodon, an exact tRNA match is not required for the third codon, which leads to wobbling

Question 41

What is a frameshift mutation?

Answer 41

All codons after mutation are different

Question 42

What is a point mutation?

Answer 42

Single base added, deleted, or changed

Question 43

What is a missense mutation?

Answer 43

Changed base causes different amino acid

Question 44

What is a nonsense mutation?

Answer 44

Changed base causes premature stop codon

Question 45

What is a silent mutation?

Answer 45

Changed base has no effect

Question 46

What are anti-codons in tRNA?

Answer 46

Complementary bases of codons *EX: the codon AUG has the anti-codon UAC*

Question 47

What happens to the tRNA after the anti-codon binds to the appropriate codon?

Answer 47

tRNA releases its amino acid

Question 48

What do both the small subunit and large subunit contain?

Answer 48

rRNA and proteins

Question 49

What are the two main functions that the small subunit carries out?

Answer 49

1. Binds and reads mRNA 2. Recruits the large ribosomal subunit when it finds AUG

Question 50

What are the two main functions that the large subunit carries out?

Answer 50

1. Acts as a docking site for tRNAs (APE) 2. Catalyzes peptide bonds between amino acids released from tRNAs

Question 51

What are the four main steps for translation initiation?

Answer 51

1. Small ribosomal subunit binds mRNA 2. tRNA with anticodon UAC binds AUG start codon at P site 3. Large subunit is recruited 4. New tRNA binds codon at A site

Question 52

What site does tRNA with anticodon UAC bind AUG start codon?

Answer 52

P site

Question 53

What site does new tRNA bind codon?

Answer 53

A site

Question 54

RNA polymerase binds to the transcription factors at the Promoter region 3' poly A tail Spliceosome Replication fork

Answer 54

Promoter region

Question 55

A mismatch between the third base of the codon and the anticodon is referred to as A point mutation Missense mutation Wobble pairing Frameshift mutation

Answer 55

Wobble pairing

Question 56

Which of the following is not a function of RNA polymerase? Unwinds DNA Reads template strand 3' to 5' Synthesizes RNA strand 5' to 3' Catalyzes peptide bonds

Answer 56

Catalyzes peptide bonds

Question 57

Abnormalities in which of the following will most directly impair spliceosome function? snRNA tRNA rRNA None of the above

Answer 57

snRNA

Question 58

Abnormalities in the RNA polymerase 2 can lead to defective mRNA tRNA rRNA More than one answer is correct

Answer 58

mRNA

Question 59

A point mutation that introduces a premature stop codon is classified as a ________ mutation Silent Frameshift Nonsense Missense

Answer 59

Nonsense

Question 60

When do ribosomes stop moving along mRNA?

Answer 60

When they encounter a stop codon in the A site

Question 61

Since there are no tRNAs with anticodons for stop codons _______ ________ bind to stop codon

Answer 61

Releasing factors

Question 62

What is the charged substrate called to hold tRNA, ATP, and the amino acid? *think enzyme name*

Answer 62

Aminoacyl-tRNA synthetase

Question 63

Where does tRNA drop the amino acid?

Answer 63

At the ribosome

Question 64

What are three examples of reversible modifcations?

Answer 64

1. Phosphorylation 2. Ubiquitylation 3. Glycosylation *Think PUG*

Question 65

What is an example of an irreversible modification?

Answer 65

Proteolysis