Unit 1.2 - Structure + Replication Of DNA

Question 1

Describe the structure of DNA

Answer 1

• Made up of nucleotides (deoxyribose sugar, phosphate and base)
• Sugar phosphate backbone
• Base pairing ( A+T and G+C)
• Base pairs held together by hydrogen bonds
• Double stranded anti parallel structure
• Deoxyribose at 3’ end and phosphate at 5’ ends of each strand
• Forming a double helix

Question 2

What happened prior to cell division?

Answer 2

DNA is replicated by a DNA polymerase is DNA polymerase needs primers to start replication

Question 3

What is a primer?

Answer 3

A short strand of nucleotides which binds to the three prime end of the templates DNA strand allowing polymerase to add DNA nucleotides

Question 4

What are some practical applications of PCR?

Answer 4

DNA can be amplified to help solve crimes, settle paternity suits and diagnose genetic disorders

Question 5

What is PCR?

Answer 5

PCR amplifies DNA using complimentary primers for specific target sequences

Question 6

Describe DNA replication

Answer 6

• DNA is unwound and hydrogen bonds between bases are broken to form two template strands
• DNA polymerase adds DNA nucleotides using complimentary base pairing to the deoxyribose three prime end of the new DNA strand which is forming
• DNA polymerase can only add DNA nucleotides in at five prime to 3 prime direction
• Resulting in the leading Strand being replicated continuously and the lagging strand is being replicated in fragments
• Fragments of DNA are joined together by ligand

Question 7

Describe the amplification of DNA sequences in PCR

Answer 7

• DNA is heated to between 92 and 98° to separate the complimentary strand
• It’s them cooled to between 50 and 65° to allow primers to bind to specific target sequences
• It is then heated to between 70 and 80° for heat tolerant DNA polyamory is to replicate the region of DNA
• Repeated cycles of heating and cooling amplify the region of DNA