DNA Structure and Replication

Question 1

Nucleotide structure

Answer 1

Nucleotides are made of deoxyribose sugar, nitrogen containing bases and a phosphate

Question 2

Sugar phosphate bonds

Answer 2

Link together nucleotides, known as the backbone

Question 3

DNA structure

Answer 3

DNA is double stranded with the two strands running in opposite directions (5’-3’ and 3’-5’), this is known as an antiparallel arrangement.

Question 4

When does DNA replication occur?

Answer 4

Takes place prior to cell division (mitosis and meiosis)

Question 5

What does DNA replication require?

Answer 5

• DNA to act as a template
• Primer
• Enzymes including DNA Polymerase
• Free nucleotides
• ATP for energy

Question 6

DNA polymerase

Answer 6

The enzyme that carries out replication (only builds in the 5’ to 3’ direction)

Question 7

DNA template

Answer 7

Templates are used in a 3’ to 5’ direction. During replication, each DNA strand is used as a template to synthesise a second DNA strand.

Question 8

DNA replication step 1

Answer 8

DNA unwinds and unzips by DNA polymerase

Question 9

DNA replication step 2

Answer 9

Primer attaches

Question 10

DNA replication step 3

Answer 10

Free nucleotides by polymerase attach to make a new DNA strand

Question 11

Lagging strand direction

Answer 11

Travels in a 3’ to 5’ direction

Question 12

Leading strand direction

Answer 12

Travels in a 5’ to 3’ direction

Question 13

DNA ligase

Answer 13

Enzyme that joins together DNA fragments. Present on the lagging strand.

Question 14

Primer

Answer 14

Short complementary strand of DNA

Question 15

DNA replication`

Answer 15

Formation of copies of DNA molecules