Genes and Alleles

Genes and Alleles

Open Ended

‘Natural selection relies on descent with modification’. What does ‘modification’ mean in this sentence?

'Modification'

... means that the offspring will be slightly different from the parents, even though there are many similarities.

In this lesson we will review some of the ideas we have learned about genes and understand how modification occurs.

First, a few review questions:

Multiple Choice

Chromosomes are found in what part of every cell?

• the cytoplasm

• the chloroplasts

• the nucleus

• the genes

Multiple Choice

On each chromosome there are hundreds of ................... that provide instructions to make proteins

• chromosomes

• genes

• DNA

• mitochondria

How does a cell 'read' instructions from genes?

Multiple Choice

The cell is able to ‘read’ the instructions from a gene to make proteins using:

• mitochondria

• eyes

• ribosomes

• chloroplasts

What is a gene exactly?

see 5 minute video from Stated Clearly here

https://youtu.be/5MQdXjRPHmQ

BIG-LONG8-5556-rough-pink-32444-type45

BIG-LONG4-5556-rough-pink-32441-type45

We have two copies of each chromosome, one copy from dad, and one copy from mum.

Some of the genes will be the same, but some will be slightly different.

Can you see the two differences above?

Different versions of the same gene are called ALLELES

BIG-LONG8-5556-rough-pink-32444-type45

BIG-LONG4-5556-rough-pink-32441-type45

In the example above, there are two alleles of the LONG* gene and two of the 3244* gene. There may be others in the population, but an individual can have two at the most, because they only have two parents!

Alleles

watch (3 mins)

https://youtu.be/FsaYSGWuRmo

TRAITS

There may be different alleles (versions) of genes that control size, colour, number, effectiveness etc of something.

These features are called genetic ‘TRAITS’.

How can we tell what traits an individual has based on their alleles?

more about this next lesson

Multiple Choice

Which of these statements is NOT correct?

• A gene contains many small sections called chromosomes

• Chromosomes are made of DNA

• All DNA is found in the nucleus

• Different versions of the same gene are called alleles

Multiple Choice

Alleles are:

• the same thing as traits

• made of chromosomes

• not found in plants

• versions of a gene