DNA - the Stuff of Life

Explore the structure of DNA and how it is organised into chromosomes.

  • Credit: Paul Wilkinson

Introduction

We have developed a series of clips to explore the Life Fantastic with your students. The pages are intended for use as a prompt to help you prepare when exploring these topics in lessons. Teachers have told us that the videos and questions best suit being used as a topic introduction.

On this page you will find an overview of the topic covered by the clips, a brief summary of each clip, related questions and how the topic links to the curriculum. This is one of eight available resources on developmental biology. For more topics see the teaching resources list.

Overview

Topics in the video

  • Understand that cells contain chromosomes within the nucleus.
  • Understand that chromosomes are made of DNA and hold the genes
  • Describe the structure of DNA as a double helix
  • Understand that DNA contains a sequence of nucleotide bases
  • Explain the rules of base pairing and explain how this results in a reliable copying method
  • Evaluate the importance of the discovery of the structure of DNA in the evidence for evolution

The material in this resource is supported by video clips from the CHRISTMAS LECTURES 2013.

Curriculum links:

This resource is suitable for Key Stages 3 and 4 and AS/A2 level. Full curriculum links are given at the bottom of the page.

Clip 1 - The stuff of life

In this clip from the Royal Institution’s Chromosome series, Aoife McLysaght gives an overview of the chromosomes within our cells. Dr McLysaght explains that though every living thing has DNA, different organisms have slightly different versions of the DNA molecule. DNA contains genes; in the case of humans, 22,000 genes, and these genes are organised onto chromosomes. Aoife illustrates this using plasticine models of the chromosomes and shows how genes, such as amylase, are arranged along the chromosome. The chromosomes themselves are packaged so that they fit within the nucleus, and this contributes a great deal to gene expression. Aoife shows that one advantage of DNA being packaged into chromosomes is during cell division; whether in mitosis or meiosis, the partitioning of DNA into daughter cells is aided by it being arranged in chromosomes.

Running Time: 4 min 20 secs

Summary questions

  • What can DNA do that no other molecule can? (Make copies of itself, 0:27)
  • How many genes do humans have? (22,000, 1:09)
  • How are these genes organised? (Onto chromosomes, 1:11)
  • How many chromosome pairs do humans have? (23 pairs, 1:19)

Background questions

  • Where is DNA found in human cells?
  • What are long molecules of DNA called?
  • What is a locus?
  • Can you name some examples of genes?
  • What are the two mechanisms of cell division called?

Clip 2 - The structure of DNA

Alison Woollard demonstrates the structure of DNA with this 2 metre-tall model in a clip from the first CHRISTMAS LECTURE, Where Do I Come From?. Alison describes the double-helix structure, including the sugar-phosphate backbone and nucleotide base pairs.

Running Time: 2 min 17 secs

Summary questions:

  • What is the shape of DNA? (Double helix, 0:44)
  • How many different bases are there in DNA? (Four, 1:02)
  • Can you name the nucleotide bases of DNA? (Adenine - A, guanine - G, cytosine - C, thymine - T, 1:02)
  • What is the rule of base pairing? (A with T, C with G, 1:17)

Questions for wider discussion

  • What is the difference between DNA shown in the clip and RNA?
  • How did the discovery of DNA and its structure affect scientific thinking, especially in relation to evolution?
  • What is a gene?

Curriculum links

KS3

Conforming to ‘Genetics and Evolution: Inheritance, chromosomes, DNA and genes’, this resource expands on knowledge of chromosomes, genes and DNA. The clips look in detail at the structure of the DNA molecule which may be of interest for advanced level students.

KS4

The resource aligns with the discussion of chromosomes and DNA structure requirements in:

  • AQA GCSE Biology 4401/Additional Science 4408 Unit 2: Biology 2 B2.7.1 ‘Cell division’ and B2.7.2 ‘Genetic variation’;
  • Edexcel GCSE Biology 2BI01/ Science 2SC01 Unit B1 Topic 1  ‘Classification, variation and inheritance’ 1.20 and Biology 2BI01/Additional Science 2SA01 Unit B2 Topic 1 ‘The building blocks of cells’ 1.6-8;
  • OCR GCSE Biology A J243/Science A J241 Unit A161 Module B1 ‘What are genes and how do they affect the way organisms develop?’ B1.1; OCR GCSE Biology A J243/Additional Science A J242 Unit A162 Module B5 ‘How do genes control growth and development within the cell?’ B5.3; 
  • AQA GCSE Science B 4450 Unit 2: My Family and Home 3.4.1.3 ‘Human Inheritance and genetic disorders ’in the discussion of chromosomes.

AS/A2

The clips provide solid base for the discussion of the structure and genetic storage role of DNA found in:

  • AQA GCE Biology AS 1411 Unit 2 BIOL2 ‘The variety of living organisms’ section 3.2.2; and OCR GCE Biology AS Unit F212 Module 1 ‘Biological molecules’ section 2.1.2.

The resource and clips consider DNA in the context of evolution, and so provide a useful framework for the discussion of the use of DNA in elucidating evolutionary relationships and as evidence for evolution discussed in:

  • AQA A-level Biology Unit 2 BIOL2 ‘The variety of living organisms’ section 3.2.9;
  • OCR GCE Biology AS Unit F212 Module 3 ‘Biodiversity and Evolution’ section 2.3.3.

It also provides a background for discussing the triplet genetic code and amino acid sequence, found in the Royal Institution resource, Genes and the genetic code.

Related content

Use these resources on TED-Ed

TED-Ed: The stuff of life

TED-Ed: DNA structure

Watch the full lectures

View the full CHRISTMAS LECTURES, Life Fantastic, along with behind the scenes footage, and related content, at the Ri Channel (www.richannel.org).