DNA Replication and Mutation

Review the copying mechanism of DNA and consider the result of mistakes during DNA replication on the organism and at evolutionary levels.

  • Credit: Tim Mitchell

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 videos

  • See how DNA is copied
  • Understand that during DNA replication, each single strand of the original double-stranded DNA helix goes into the two new DNA molecules – semi-conservative replication
  • Review the importance of base-pairing in replication
  • Consider the effect of minute changes to a message amplified over many generations
  • Explain how the length and complexity of a message and the number of generations it is passed down, influences how accurately it is copied

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

Curriculum links

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

Clip 1 - DNA Replication

Every time a cell divides, the DNA has to make a complete copy of itself. Watson and Crick noted this when they published the structure of DNA. They said, “It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material". After reading from the 1953 paper that announced the structure of DNA, Alison Woollard explores this copying mechanism with the help of acrobats from Infinity Elite. Each member wears a coloured t-shirt according to the nucleotide base they represent, and the team starts by assembling a double stranded molecule of DNA, three base pairs tall. On Alison’s command, replication begins: the bonds between the base pairs break, the molecule splits and turns to bond with a newly formed strand, once again obeying the laws of base pairing.

Running Time: 3 min 28 secs

Summary questions

  • What letter does G pair with? What about A? (G pairs with C, A with T, 2:04)
  • DNA is a double stranded helix. What happens to each strand during replication? (Each strand acts as a template to form another strand – the new double helixes contain one of the original strands each)
  • G is red, C is yellow, T is blue, A is green. Can you use the colour t-shirts and the letters they represent to read the DNA sequence in each chain? (from bottom to top in each chain, left to right across the screen at 2:49: CTG, GAC, CTG, GAC)

Background questions

  • Where does DNA replication take place within the cell? (In the nucleus)
  • Before which cell process does DNA replication take place? (Cell division, mitosis or meiosis)
  • What is the name given to this method of replication? (Semi-conservative)

Clip 2 - Mutation

In this clip Alison looks at mutations, and what their effect is on cells, organisms, and evolution. A message is passed along a line of eight volunteers in a game of Chinese whispers. The message represents a gene or a protein and the demonstration illustrates how mistakes can creep into that gene in each division, each time one volunteer passes a message to the next. The final message resembles the initial message but is drastically changed – it is mutated. Once a mistake creeps in it is passed on to all subsequent daughter cells potentially drastically changing the characteristic of the cells.

Running Time: 3 min 32 secs

Summary questions

  • What was the initial message? (“The lab pea was the key”, 2:02)
  • What was the final message? (“A loud thing is a key”, 1:31)
  • What happens to the message? (It changes/is mutated)
  • How long does it take for the message to be changed? (Between the second and third whisperers, 2:07)

Questions for wider discussion and suggested activity

  • Why does the message get changed?
  • How might a mutation in a person be passed on to their descendents? Which cell or organ system would this mutation have to occur in? (The gametes)
  • Play a game of Chinese whispers in the classroom. Try different sentence lengths and complexities. Which sentence is less likely to be mutated? Are mistakes more likely to happen over many generations (more pupils in the chain) or fewer? What does this tell us about mistakes and cell division in our bodies?

Curriculum links

KS4

The resource illustrates a level of DNA replication that goes beyond most KS4 requirements. However it may serve as a useful primer for higher students and those considering A-level. DNA replication and the importance of base pairing are illustrated in an acrobatic display representing two DNA strands which may be used for the illustration of cell cycle and cell division in OCR GCSE Biology A J243/Additional Science A J242 Unit A162 Module B5 ‘How does an organism produce new cells?’ B5.2.

The role of mutation in evolution is considered in a Chinese whisper style game. Mutations in the context of cell division and evolution correspond to the requirements in AQA GCSE Biology 4401/ Science 4405 Unit 1: Biology 1 B1.8.1 ‘Evolution’; Edexcel GCSE Biology 2BI01/Additional Science 2SA01 Unit B2 Topic 1 ‘The building blocks of cells’ 1.25; and OCR GCSE Biology A J243/Science A J241 Unit A161 Module B3 ‘How has life on Earth evolved?’ B3.2.

AS/A2

The resource examines DNA replication and the importance of the laws of base pairing. Semi-conservative replication is illustrated in the clip and the consequences of mutation in DNA replication and evolution are discussed later. This conforms to AQA GCE Biology AS 1411 Unit 2 BIOL2 ‘The variety of living organisms’ sections 3.2.2 and 3.2.5; and OCR GCE Biology AS Unit F212 Module 1 ‘Biological molecules’ 2.1.2 and Unit F215 Module 1 ‘Cellular Control and Variation’ section 5.1.1. 

Related content

Use these resources on TED-Ed

TED-Ed: DNA replication

TED-Ed: Mutation

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).