KH 02

Question 1

What is the central dogma of molecular biology?

Answer 1

DNA makes RNA makes protein

Question 2

What does replication involve?

Answer 2

DNA synthesis

Question 3

What does transcription involve?

Answer 3

RNA synthesis

Question 4

What does translation involve?

Answer 4

Protein synthesis

Question 5

What is the biopolymer, template and enzyme for replication?

Answer 5

DNA, DNA, DNA polymerase

Question 6

What is the biopolymer, template and enzyme for transcription?

Answer 6

RNA, DNA, RNA polymerase

Question 7

What is the biopolymer, template and enzyme for translation?

Answer 7

Protein, mRNA, ribosome

Question 8

Most enzymes, including DNA and RNA polymerase, are _____.

Answer 8

proteins

Question 9

What is the ribosome made of?

Answer 9

It has protein and RNA components. Both contribute to its enzymatic function

Question 10

In transcription, what does the template?

Answer 10

The template, the exposed DNA strand, specifies RNA sequence by Watson-Crick base-pairing

Question 11

What are rNTPs? ***

Answer 11

Ribonucleoside triphosphates

Question 12

In transcription, is there a direct or indirect interaction of the template with the incoming monomer (rNTP)?

Answer 12

Direct

Question 13

How do rNTPs diffuse?

Answer 13

Randomly. RNA polymerase will only link incoming rNTP to growing chain if it forms the perfect Watson-Crick base pair

Question 14

RNA molecules are always synthesized in the ___ direction

Answer 14

5′ -› 3′

Question 15

In transcription, is the nascent RNA chain parallel or antiparallel?

Answer 15

Antiparallel

Question 16

In transcription, at which end does the chain grow?

Answer 16

The 3’ end

Question 17

The polymerization catalyzes an attack of the ___ on the _____ of the incoming rNTP. Bêta and gamma _____ are dropped.

Answer 17

3’ -OH, alpha phosphate, diphosphate

Question 18

The sequence of RNA transcribed from a region of DNA corresponds to the sequence of the _____.

Answer 18

non-template strand

Question 19

The non-template strand and the new RNA strand are both _____ to, and _____ with, the template DNA strand

Answer 19

complementary, antiparallel

Question 20

The template DNA strand is exposed by local unwinding of duplex DNA by _____.

Answer 20

helicase (associated with the RNA polymerase)

Question 21

What moves along the DNA with RNA polymerase during transcription?

Answer 21

The transcription bubble

Question 22

What happens after the DNA is unwound in the transcription bubble?

Answer 22

The original DNA duplex
re-forms behind the RNA
polymerase. The re-forming duplex behind
polymerase “kicks
out” the newly-synthesized
RNA strand.

Question 23

How does the RNA polymerase move along the DNA?

Answer 23

Unidirectionally

Question 24

During transcription, the displaced single-stranded
RNA exits through a channel
in the polymerase, __ end first.

Answer 24

5’

Question 25

What are the names of the DNA sequences that facilitate the initial binding of RNA polymerase to the DNA during transcription?

Answer 25

Promoters

Question 26

How does the RNA polymerase stop the DNA transcription?

Answer 26

Certain DNA sequences destabilize the attachment of RNA polymerase to the DNA as it moves. The RNA polymerase falls off the DNA and releases the completed RNA chain.

Question 27

What are the similarities between DNA replication and transcription?

Answer 27

1. Template = DNA 2. DNA duplex locally unwound by a helicase at initiation sites to expose template 3. New strand synthesized 5’ to 3’ antiparallel to template. Chain growth at 3’ end 4. Monomers = nucleoside triphosphates 5. Direct interaction (Watson‐Crick base pairing) between template DNA and incoming monomer 6. Attack of 3’‐OH on alpha phosphate of incoming dNTP. Bêta and gamma diphosphate “dropped”

Question 28

What are the differences between DNA replication and transcription?

Answer 28

1. Transcription: Monomer = rNTPs / Replication: Monomer = dNTPs 2. Transcription: Start and stop sites on template / Replication: Start sites (origins), but no stop sites 3. Transcription: Newly synthesized strand (RNA) separates from template strand. / Replication: Newly synthesized strand (DNA) never separates from template strand. 4. Transcription: Only one of the original DNA strands is a template strand. / Replication: Both of the original DNA strands independently serve as template strands. 5. Transcription: We start with one molecule of double‐ stranded DNA and we end with one molecule of double‐stranded DNA (plus the RNA molecule produced). / Replication: We start with one molecule of double‐stranded DNA and we end with two molecules of double‐ stranded DNA

Question 29

What do the 5' and 3' ends in an mRNA sequence respectively correspond to in the protein sequence?

Answer 29

NH2.....COOH

Question 30

Nucleotides are "read" into amino acids as 3-character words called _____.

Answer 30

codons

Question 31

How many 3-nucleotide codons are there?

Answer 31

64

Question 32

What is the genetic code?

Answer 32

A dictionary of 3-nucleotide codons and their corresponding amino acids. It is a 4 x 16 table.

Question 33

What are the 3 STOP codons (terminaison codons), that do not code for any amino acid?

Answer 33

UAA, UAG, UGA (Stop)

Question 34

What is the start codon?

Answer 34

AUG (Methionine or Met)

Question 35

Can the STOP codon be present within the protein chain?

Answer 35

No

Question 36

Can the START codon (Met) be present within the protein chain?

Answer 36

Yes

Question 37

All proteins start their synthesis with ___.

Answer 37

Met

Question 38

There is a _____ interaction of template with next monomer molecule to be incorporated in replication and transcription.

Answer 38

direct

Question 39

There is an _____ interaction between template and next monomer to be incorporated (amino acid) in translation

Answer 39

indirect

Question 40

tRNA acts as an _____ between template and growing chain

Answer 40

adaptator

Question 41

What are the respective energized monomers for replication, transcription and translation?

Answer 41

dNTP, rNTP and aminoacyl tRNA