DNA Structure

Question 1

What are the two types of Nucleic acid and what are the differences between them?

Answer 1

• DNA + RNA

- Deoxyribose sugar vs ribose sugar

Question 2

What are the names of the 5 nucleotide bases?

Answer 2

• Adenine
• Thymine
• Uracil
• Guanine
• Cytosine

Question 3

Which bases bond with each other?

Answer 3

• Adenine bonds with thymine (Uracil in RNA)

- Guanine bonds with cytosine

Question 4

What are the pyrimidines and how many rings do they have?

Answer 4

• cytosine
• Thymine
• Uracil
• single ring

Question 5

What are the purines and how many rings do they have?

Answer 5

• Adenine
• Guanine
• 2 rings

Question 6

What is the name of the bonds that join nucleotide monomers?

Answer 6

Phosphodiester bonds

Question 7

Explain the formation of the phosphodiester bond:

Answer 7

The Hydroxyl group (OH) on carbon 3 of one nucleotide reacts with the phosphate group attached to carbon 5 on another nucleotide

Question 8

Which direction are DNA and RNA strands synthesized in?

Answer 8

5’-3’ direction

Question 9

What is the name for the model of DNA replication?

Answer 9

Semi- conservative model of replication

Question 10

What enzyme repairs replication errors during replication?

Answer 10

exonuclease

Question 11

What enzyme repairs DNA replication errors after replication?

Answer 11

Endonuclease

Question 12

What is the error rate of DNA polymerase III

Answer 12

1 in 10^8-10^10 base pairs

Question 13

How does DNA pol III “proofread”

Answer 13

3’-5’ (of template strand) exonuclease activity of pol III removes incorrect bases during replication

Question 14

How does DNA repair after replication occur?

Answer 14

• damage, including some flanking regions is removed by an endonuclease
• A DNA polymerase makes new DNA
• DNA Ligase joins ends of new stand with pre-existing strand

Question 15

Why is correcting DNA errors so important?

Answer 15

• replication is semiconservative
• mistake becomes template strand
• newly replicated strand will also be incorrect
• All strands based off this template strand with continue to be incorrect

Question 16

What are the Key details of the polymerase chain reaction (PCR) (4)

Answer 16

• in vitro method of making multiple DNA copies so that there is enough DNA material to work with
• Only targeted regions are copied
• causes rapid exponential increase of DNA molecules
• Utilizes heating and cooling to maximize enzyme activity

Question 17

What are the uses of PCR? (4)

Answer 17

• Medical applications
• Forensic applications
• Infectious Disease detection and identification
• Molecular biology research applications

Question 18

What are the basic steps of PCR?

Answer 18

• temperature increased to denature ( separate) DNA strands
• Temp decreased to allow primers to base pair to complementary DNA template
• Polymerase extends primer to form nascent DNA strand
• repeat up to 35 times

Question 19

What are the differences in DNA replication in vivo and in vitro?

Answer 19

• in vivo has RNA primer, in vitro has DNA primer
• in vivo has primer synthesized by primase, in vitro has completed primer added
• in vivo has a leading and lagging (discontinuous) strand, in vitro has 2 continuous strands
• in vivo uses multiple enzymes and proteins, in vitro only uses heat stable DNA polymerase