Unit 2 - Structure & replication of DNA

Question 1

What does DNA stand for?

Answer 1

Deoxyribose nucleic acid

Question 2

What composes DNA?

Answer 2

2 Strands of repeating units (nucleotides)
Nucleotides composed of (Deoxyribose Sugar) ,(Phosphate) and (Base)
///Strong chemical bond between Dexoxyribose and Phosphate forms a sugar phosphate backbone

Question 3

How are bases (A-T / C-G) bonded?

Answer 3

Joined together by weak hydrogen bonds

Question 4

Antiparallel structure?

Answer 4

2 Strands run in opposite directions
One end has deoxyribose 3-prime and the other phosphate 5-prime
Double strands twist into double helix

Question 5

Before cell division, what replicates DNA?

Answer 5

DNA Polymerase

Question 6

What is required for DNA replication?

Answer 6

Primers (short nucleotide strand which binds to 3-prime )
Nucleotides
Enzymes (DNA polymerase and sometimes ligase)
ATP

Question 7

How does DNA replicate?

Answer 7

1. DNA unwinds
2. Hydrogen bonds break
3. Primer bonds to a 3-prime to start replication
4. DNA Polymerase adds complementary nucleotides to template strands from primer onwards = replication can only occur from 3 to 5 on parent strand

Question 8

Leading Strand?

Lagging Strand?

Answer 8

Leading strand is repeated continuously

Lagging strand has nucleotides which only add to 3 prime so its replicated with many primers

Question 9

What does PCR stand for?

Answer 9

Polymerase Chain Reaction

Question 10

What does PCR do?

Answer 10

Amplifies DNA using complementary primers for specific target sequences

Question 11

What happens in PCR?

Answer 11

1. DNA heated between 92 and 98°C- to denature DNA and separate 2 strands.
2. Cooled to 50-65°C to allow primers to bind to target sequences.
3. Heated to 70-80°C for heat tolerant DNA polymerase to replicate the region of DNA

Question 12

Practical uses of PCR?

Answer 12

Help solve crimes

Diagnose genetic disorders