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Year 10
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Higher

The structure of DNA: including nucleotides

I can describe the structure of DNA and how DNA is copied during mitosis.

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New
New
Year 10
OCR
Higher

The structure of DNA: including nucleotides

I can describe the structure of DNA and how DNA is copied during mitosis.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. DNA is made of two strands, each a long polymer of nucleotides, wound together in a double helix shape.
  2. DNA is a polymer of four different nucleotides (A, C, G and T).
  3. Nucleotides in each strand of DNA pair up in a complementary way; A pairs with T, and C pairs with G.
  4. The DNA in chromosomes is unwound & copied during interphase, then the copies separate and the cell divides by mitosis.
  5. Complementary base pairing allows an exact copy of each ‘unzipped’ DNA strand to be made from free nucleotides.

Common misconception

Students may think that each strand of DNA is the same without recognising one strand is inverted.

The slides specifically mention the second strand is inverted and this is also reinforced using diagrams of inverted nucleotides wherever possible.

Keywords

  • DNA - A polymer with a double helix structure that carries the genetic information.

  • Mitosis - A type of cell division that produces genetically identical cells.

  • Nucleotides - Individual subunits that make up DNA.

  • Polymer - A long chain of repeating subunits.

  • Complementary base pairing - Bases form pairs with one other base: A pairs with T, and C pairs with G.

Emphasise that the nucleotides are inverted on one of the DNA strands and that each nucleotide is a monomer/subunit which is why DNA is a polymer. Can model the structure of DNA using paper with the 4 different bases cut out and then matched together.
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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Starter quiz

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6 Questions

Q1.
This image shows a model of ...
An image in a quiz
a bacterial cell.
Correct answer: DNA
a mitochondrion.
an enzyme.
Q2.
Which of the following is the definition of a polymer?
A single subunit that makes up a long repeating chain.
Correct answer: A long chain of repeating subunits called monomers.
A type of cell division that produces genetically identical cells.
Individual subunits that make up DNA.
Q3.
Match each structure to its correct definition.
Correct Answer:Nucleus,Contains DNA and controls cell activities.

Contains DNA and controls cell activities.

Correct Answer:Chromosome,Made from coiled DNA; humans have 23 pairs in their nuclei.

Made from coiled DNA; humans have 23 pairs in their nuclei.

Correct Answer:DNA,A polymer with a double helix structure; carries the genetic material.

A polymer with a double helix structure; carries the genetic material.

Q4.
What happens during interphase in the cell cycle?
The cell membrane and cytoplasm divide.
The chromatids are pulled to either end of the cell.
Correct answer: The DNA and sub-cellular structures are copied.
Q5.
Which type of cell division creates two genetically identical cells?
meiosis
Correct answer: mitosis
Q6.
Which term describes a cell with a membrane bound nucleus?
Correct Answer: eukaryotic, eukaryote, eukaryotic cell, eukaryotes

Exit quiz

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6 Questions

Q1.
Which words describe the structure of DNA?
monomer
Correct answer: polymer
Correct answer: double helix
single strand
Q2.
DNA is made from single repeating subunits called ...
bases.
nuclei.
Correct answer: nucleotides.
phosphates.
Q3.
Which of these statements about DNA are true?
The base A always pairs with G.
Correct answer: Nucleotides are inverted on one strand of DNA.
Correct answer: The base C always pairs with G.
The sugar phosphate backbone includes the base of a nucleotide.
Q4.
What is complementary base pairing?
DNA is made from repeating bases.
DNA has a double helix structure.
DNA unwinds during interphase.
Correct answer: Bases only pair in a certain way; A-T and C-G.
Q5.
Which of the following statements about copying DNA are true?
DNA is copied during mitosis.
Correct answer: The double helix DNA unwinds before copying.
Correct answer: Each single strand acts as a template.
Four copies of the same double helix DNA are created.
Q6.
Use the diagram to match the letter to the correct part of the nucleotide.
An image in a quiz
Correct Answer:A,phosphate

phosphate

Correct Answer:B,base

base

Correct Answer:C,sugar

sugar