Reproduction and Genes

YOU ARE LEARNING:

Genetic Variants

Variations in coding sections of DNA, known as genes, can affect the amino acids produced. This in turn may alter the protein produced, and possibly the phenotype of an organism.

What is the term for a coding region of DNA?

Mutations can cause changes in the DNA base sequence, which causes a genetic variant to form. What is the definition of a genetic variant?

So a genetic variant is a different form of a gene within an organism.

Genetic variation is what makes up the trait differences in a population. For example, you could say there is genetic variation in eye colour.

Different forms of a gene are called alleles.

If you have a scar on your body, do you think this is a form of genetic variation?

Some forms of genetic variation are also influenced by variation in the environment, which affects their presence in the phenotype. Which of these do you think that applies to?

You can select multiple answers

Mutations in coding regions of DNA (genes) can introduce new genetic variant. However, it is rare for a mutation in DNA to go on to produce a genetic variant that is actually visible in the phenotype.

Now, if a mutation in DNA did actually go on to become visible in the phenotype, which of these would be a new genetic variant to humans?

So a new genetic variant is one that isn't already present in the population. A genetic variant is called an allele. Which of these do you think are alleles of each other? Pick all the options you think are correct.

You can select multiple answers

Humans have thousands of genes and a lot of alleles (variation) for a lot of genes. Many alleles, like eye colour, evolved long ago. Let's see how genetic variants can be produced.

Look at this image of a gene, and it's genetic variant. What mutation do you think has occurred here?

A) Extraction B) Deletion C) Subtraction

When DNA is being read for protein synthesis, it is unzipped by DNA helicase, and one strand is read to make mRNA. In the genetic variant above, 6 bases on one strand were deleted. How many codons would that make?

If two codons were taken out of the original DNA strand, how many fewer amino acids would be in the peptide chain and the protein?

How might two fewer amino acids affect the final protein produced?

A genetic mutation in a coding section of DNA (a gene) can cause amino acid change that can lead to a protein change.

If proteins change, this could affect the phenotype. It could for example change hair colour, hair thickness, rate of hair growth, and many other things, depending on which gene the mutation occurred.

A genetic variant may form when a mutation in a coding section of DNA ...