LO – Explain how alleles cause differences in inherited characteristics

• All – explain what inherited variation is• Most – describe the structure of the nucleus

of a cell to include chromosomes and genes• Some - use the key word allele to show how

genes can give rise to different inherited characteristics

So what is inheritance?1. What kind of things can be inherited?

2. How does this cause variation?

3. What is continuous variation? Give an example

4. What is discontinuous variation? Give an example

5. What is the difference between environmental and genetic variation? Can you give examples?

So what is inheritance?1. What kind of things can be inherited?

Eye colour, skin colour etc2. How does this cause variation?

We get half our genes from each of our parents3. What is continuous variation? Give an example

things like height – continuous scale4. What is discontinuous variation? Give an example

things like eye colour – categories (brown/blue)5. What is the difference between environmental and

genetic variation? Can you give examples?Environmental – things you’re not born with

Genetic – things you are born with

How many people got 5 out of 5?• How does this lead to inheritance? We inherit

traits from our parents as we get our genes from them

The structure of the nucleus• Nucleus –

• Chromosome – • Gene –

• DNA

• Cell –

• Mitochondria -

The structure of the nucleus

• Nucleus – membrane enclosed part of the cell which contains the genetic material

• Chromosome – a coiled piece of DNA which stores the genes

• Gene – a section of DNA which codes for a specific feature

• DNA – contains all the genes for an organism – like blueprints

• Cell – building blocks of life • Mitochondria – organelles of a cell which provide

energy for the cell

This looks like…

What’s an allele?

• Genes come in alternative forms • This means that there is not just one ‘type’ of

gene for something• For example there are many genes for height• So you don’t get a ‘tall’ or ‘short’ gene but lots of

different ones together to help control how tall you will be

• Or the genes for eye colour can be different causing variation in the eye colour trait inherited

Lets use an analogy

• A car factory

Have we met the success criteria?

• All – explain what inherited variation is• Most – describe the structure of the nucleus

of a cell to include chromosomes and genes• Some - use the key word allele to show how

genes can give rise to different inherited characteristics