03 Nucleic acids - DNA and RNA

Question 1

How many bases per turn in DNA?

Answer 1

10.4 bases per turn

Question 2

Angle of rotation per base?

Answer 2

36˚

Question 3

Name of ribonucleotides

Answer 3

adenylate, uridylate, guanylate, cytidylate

Question 4

Name of deoxyribonucleotides

Answer 4

deoxyadenylate, deoxythymidylate, deoxyguanylate, deoxycytidylate

Question 5

Name of nucleosides (RNA)

Answer 5

adenosine, uridine, guanosine, cytidine

Question 6

Name of nucleosides (DNA)

Answer 6

deoxyadenosine, deoxythymidine, deoxyguanosine, deoxycytidine

Question 7

Types of RNA

Answer 7

⎼ Messenger RNA - mRNA
⎼ Transfer RNA - tRNA
⎼ Ribosomal RNA - rRNA
⎼ Single guide RNA - sgRNA
⎼ Small nuclear RNA - snRNA
⎼ Small interference RNA – siRNA

Question 8

What is CRISPR-Cas9?

Answer 8

enzyme which generates breaks in double stranded DNA at two target sites, allowing gene editing

Question 9

Where can reverse transcription occur?

Answer 9

viruses (e.g. HIV)

Question 10

Direction of mRNA is 5’->3’, what is the direction of the corresponding polypeptide?

Answer 10

amino terminus -> carboxyl terminus

Question 11

What ion is required for DNA replication, transcription and translation?

Answer 11

Magnesium

Question 12

What is the cleavage signal?

Answer 12

AAUAAA

Question 13

How is the nascent RNA processed to become a mature mRNA?

Answer 13

• 5’ capping
• polyadenylation
• splicing

Question 14

Addition of poly(A) tail is done by?

Answer 14

poly(A) polymerase

Question 15

Which type of enzyme cleaves the mRNA?

Answer 15

Endonucleases

Question 16

What is the adaptor between mRNA and protein?

Answer 16

tRNA

Question 17

What is the enzyme that attaches the appropriate amino acid onto its corresponding tRNA?

Answer 17

aminoacyl tRNA synthetase

Question 18

What is a histone octamer made of?

Answer 18

2 copies of H2A, H2B, H3, H4

Question 19

What are the core histone proteins?

Answer 19

H2A, H2B, H3, H4

Question 20

DNA wraps around histone octamers to form a?

Answer 20

nucleosome

Question 21

What is the structure of chromatin?

Answer 21

Beads-on-a-string form

Question 22

From nucleosome to chromatid

Answer 22

~75000 bp -> 1 loop
6 loops -> 1 rosette
30 rosettes -> 1 coil
10 coils -> chromatid

Question 23

Function of activator proteins

Answer 23

bind to enhancers -> cause DNA to bend -> bring them near a gene promoter -> increase transcription

Question 24

What are enhancers?

Answer 24

short region of DNA which can be bound by proteins to increase transcription

Question 25

What is an insulator?

Answer 25

stop the enhancers from binding to the promoter if a protein CTCF binds to it

Question 26

What is methylation?

Answer 26

addition of methyl group to C nucleotides to prevent CTCF from attaching to the insulator -> allowing enhancers to bind to the promoter

Question 27

What is the use of the protein complex containing transcription factors?

Answer 27

makes it easier for RNA polymerase to attach to the promotor and start transcribing a gene

Question 28

What does cDNA microarray do?

Answer 28

measure expression levels of genes (& detect cancer)