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Introduction to the lesson
In order for the human body to maintain itself, mitosis must occur and during mitosis the DNA code of the mother cell must be perfectly copied for both daughter cells. How does this work? The exact mechanism of DNA replication has been a puzzle for scientists for a long time and it was not until 1953 that two scientists, Watson and Crick, finally proposed, tested and proved the chemical mechanism of DNA replication. In this lesson, we will study the results of their experiment and come to understand how DNA replicates itself.
DNA replication
Read the section “DNA replication” on p.113-116 in your text book.
Learning Activity 1
Answer the following questions in your exercise book.
- Design a chart of your own to explain how DNA is replicated. Make sure you understand DNA replication thoroughly and can explain it.
- Answer Question 6.1 on p.116 of your text book.
Experimental evidence for the semi-conservative replication of DNA
Practical Investigation
- Read the section in the purple box (Box 6.1 Experimental evidence for the semiconservative replication of DNA) on page 117 [Note: you will be expected to know this experiment for the theory and multiple choice exams.]
- Watch the following youtube video by Mrs Cooper.
- Summarize the conservative model of DNA replication.
- Summarize the dispersive model of DNA replication.
- Summarize the semi-conservative model of DNA replication and outline the experimental procedure which proved this model to be correct.
- Answer Questions 6.2 on p.118.
Genes and mutations
Read the section under the heading “Genes and mutations” on p.118 of your text book.
Learning Activity 2
Answer the following questions in your text book.
- What are the consequences of a mutation? Can you think of any common disorders and diseases which are a result of genetic mutations?
- Do some research on Turner Syndrome. What causes it? What are the effects? (Think about these effects. Does it make sense that this cause would produce these effects?)
Definitions and review
Definitions
- Semi-conservative replication
- Gene
- Mutation
- Allele
Mindmap
Add this section to your chapter six mindmap.