Lecture 13 and 14

Question 1

What is transfer RNA?

Answer 1

An adapter RNA molecules that interfaces with single amino acids

Question 2

What is mRNA?

Answer 2

An RNA transcript of DNA code

Question 3

What is ribosomal RNA?

Answer 3

Aligns the message in a ribosome so the codons can be coded

Question 4

What does rRNA play a role in catalysing?

Answer 4

Joining of amino-acids togehter

Question 5

mRNA is not as _____ as the original DNA is has copied

Answer 5

robust

Question 6

mRNA creates great ________ with respect to how the information is used

Answer 6

flexibility

Question 7

RNA polymerase binds with the help of the ______

Answer 7

sigma factor

Question 8

RNA creates what type of complex as it moves along the DNA?

Answer 8

Open complex

Question 9

RNA is synthesised in which direction?

Answer 9

5’ to 3’

Question 10

What recursors are used in RNA synthesis?

Answer 10

Ribonucleotide triphosphate

Question 11

What is released as the RNA is synthesised?

Answer 11

Pyrophosphate

Question 12

Bacterial genes have ______ regions.

Answer 12

Promoter

Question 13

What is rho-independent termination?

Answer 13

Mechanism for stopping transcription in prokaryotes

Question 14

How does rho-independent termination create a hairpin?

Answer 14

mRNA molecules has sequence with high proportion of C and G, which bond to one another forming RNA duplex and hairpin structure

Question 15

What happens when the mRNA molecule forms a hairpin?

Answer 15

Succeeded the hairpin is a chain of uracil, which has weak bonds with adenine, a protein on RNA polymerase binds to the hairpin structure, causing temporary lapse.

Question 16

What happens when there is a temporary lapse in mRNA transcription?

Answer 16

The hairpin structure unwinds and dissociates from RNA polymerase, terminating transcription

Question 17

What is the rho protein?

Answer 17

An ATP dependent helicase made of 6 identical subunits

Question 18

How is rho initiated?

Answer 18

Sites rich in cytosine, poor in guanine

Question 19

What direction does rho move along the molecule in?

Answer 19

5’ to 3’

Question 20

How does rho disrupt the transcriptional complex?

Answer 20

Acts as RNA/DNA helicase when it reaches transcriptional bubble

Question 21

What forms when rho protein reaches the termination signal?

Answer 21

A polypeptide loop of rho protein, stops elongation byu being inserted into RNA polymerase complex

Question 22

What enzyme catalyses attachment of tRNAs to corresponding amino acids?

Answer 22

Aminoacyl-tRNA syntetase

Question 23

The prokaryotic ribosomes consists of which subunits and what overall ribosome?

Answer 23

30S, 50S, 70S

Question 24

The eukaryotic ribosome consist of which subunits and what overall ribosome?

Answer 24

60S, 40S, 80S

Question 25

What sites make up the large subunit of the ribosome?

Answer 25

Peptidyl (P) site Aminoacyl site (A) Peptidly transferase

Question 26

What name is given to the start of polypeptide synthesis?

Answer 26

Initiation

Question 27

What is the start codon and at what end of the mRNA is it?

Answer 27

AUG | 5' end

Question 28

What is the amino acid on the initiation tRNA for prokaryotes? Eukaryotes?

Answer 28

Formalmethionine (fMet) | methionine

Question 29

What is the second stage of translation?

Answer 29

Elongation

Question 30

Ribosomes move in which direction during translation?

Answer 30

5' to 3'

Question 31

To which terminus are amino acids added?

Answer 31

C

Question 32

How many amino acids are added during translation per second?

Answer 32

2-15

Question 33

What name is given to the process that halts translation?

Answer 33

Termination

Question 34

What triggers termination?

Answer 34

Nonsense codon at 3' end of reading frame

Question 35

What happens when a nonsense codon is recongised?

Answer 35

Release factor proteins halt polypeptide synthesis

Question 36

In prokaryotes, where does the small ribosomal subunit bind?

Answer 36

Ribosome binding site, (shine dalgarno box and initiating codon)

Question 37

What is the shine dalgarno sequence?

Answer 37

Ribosomal binding site located around 8 bases upstream of start codon AUG, aligns ribosome with start codon

Question 38

What is the wobble rule?

Answer 38

Some tRNA's recognise more than one codon for amino acids they carry

Question 39

What process deletes introns?

Answer 39

Posttranscriptional splicing

Question 40

What three things happen when RNA is processed after transcription in eukaryotes?

Answer 40

5' methylated cap added 3' Poly A tail added Spliced to generate mature message

Question 41

What does the poly-A tail do?

Answer 41

Direct the RNA out of the nucleus

Question 42

How is a poly-A tail added to the 3' end?

Answer 42

Cleavage by ribonuclease | Poly-A polymerase adds A's to 3' end

Question 43

Give an example of a gene with many introns.

Answer 43

Dystrophin gene | Underlies Duchenne muscular dystrophy

Question 44

What sequences dictate where splicing occurs?

Answer 44

Splice donor, branch site, splice accpetor

Question 45

How are introns removed?

Answer 45

two sequential cuts, (loop first produced called lariat)

Question 46

What type of enzyme catalyses splicing?

Answer 46

Spliceosomes

Question 47

What enzyme ensure splicing reactions take place in concert?

Answer 47

Ribozymes (RNA molecules that act as enzymes)