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BIOLOGY, M5 2017 HSC 13 MC

A section of DNA has the following nucleotide sequence.

`text{AGG  TCT  CAG  ATC}`

What is the nucleotide sequence of the newly-made strand following DNA replication?

  1. `text{AGG  TCT  CAG  ATC}`
  2. `text{AGG  UCU  CAG  AUC}`
  3. `text{UCC  AGA  GUC  UAG}`
  4. `text{TCC  AGA  GTC  TAG}`
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`D`

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→ Adenine `text{(A)}` pairs with thymine `text{(T)}` and cytosine `text{(C)}` pairs with guanine `text{(G)}` as bases on complementary strands of DNA.

`=>D`


♦ Mean mark 49%.

BIOLOGY, M5 2022 HSC 28b

Describe the process of DNA replication.   (3 marks)

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  1. DNA helicase ‘unwinds’ DNA by breaking hydrogen bonds between the bases.
  2. Binding proteins are added to each strand to prevent them reattaching. 
  3. RNA primase adds RNA primers which act as a promoter region for DNA polymerase.
  4. DNA polymerase adds complementary nucleotides in the 5′ to 3′ direction of each strand.
  5. Exonuclease removes RNA primers, and DNA polymerase adds complementary nucleotides.
  6. DNA ligase reattaches sections together.

 
→ This produces 2 identical DNA molecules, which are also identical to the original.

Show Worked Solution
  1. DNA helicase ‘unwinds’ DNA by breaking hydrogen bonds between the bases.
  2. Binding proteins are added to each strand to prevent them reattaching. 
  3. RNA primate adds RNA primers which act as a promoter region for DNA polymerase.
  4. DNA polymerase adds complementary nucleotides in the 5′ to 3′ direction of each strand.
  5. Exonuclease removes RNA primers, and DNA polymerase adds complementary nucleotides.
  6. DNA ligase reattaches sections together.

 
→ This produces 2 identical DNA molecules, which are also identical to the original.


♦ Mean mark 47%.

BIOLOGY, M5 2022 HSC 28a

Soon after the discovery of the structure of DNA, scientists began investigating how DNA replicated. Three models were proposed.
 

Identify which of the models above is currently accepted.   (1 mark)

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→ Model 2 is correct.

→ Each replicated copy contains 1 original strand and 1 new strand.

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→ Model 2 is correct.

→ Each replicated copy contains 1 original strand and 1 new strand.