6. Inheritable &
Non-Inheritable Variation

Success Criteria

Your learning has been successful if you can do the following:

I can give examples of inheritable and non-inheritable variation.
I can explain the consequences of mutations that occur in gametes and somatic cells.
I can explain the importance of mutations in forming new alleles.

Vocabulary

Learn these so you can communicate this concept well.

Gametes: Sex cells (sperm, egg, pollen)
Genetic variation: Differences in DNA / genes / alleles.
Inheritable variation: Type of variation that can be passed onto offspring, via gametes.
Mutation: Change in the base sequence of DNA / a gene, which may result in a new allele.
Non-inheritable variation: Type of variation due to the environment or changes in DNA of somatic cells only.
Variation: Differences in traits of individuals in a population.
Harmful mutation: Type of mutation that codes for a protein that does not function properly.
Beneficial mutation: Type of mutation that codes for a protein that functions better than the original.
Neutral mutation: Type of mutation that has no effect on the protein produced.

Hei Mahi (Do Now)

Do Now: In your OneNote/Notebook, write the correct answer and justify why.

Hei Mahi (Do Now)

Do Now: In your OneNote/Notebook, write the correct answer and justify why.

Exit Task

In your Learning Journal:

Re-write this interpreting question so it is asking about Non-Inheritable Variation:

Why do you think it is like that?

Then, write an answer for it.

Exit Task

In your Learning Journal:

Re-write this interpreting question so it is asking about Harmful, Beneficial & Neutral Mutations:

How is it different?

Then, write an answer for it.

Variation

Variation is the differences in traits of individuals in a population. Variations can come from mutations, sexual reproduction and the environment. But only genetic characteristics can be inherited. Not those acquired as a result of the environment!

Can scars be passed down from parent to offspring?

A change in the DNA is passed on from parents to offspring through the gametes. Scars affect areas of the body, but not the DNA or te gametes, so cannot be passed onto offspring.

Can infections be passed down to offspring?

Reproductive cells (gametes) can only pass on genetic characteristics. Things like infections will not pass to offspring.

Inheritable (genetic) variation

Some variation is genetic due to the different alleles carried by particular individuals. GENETIC VARIATION are differences in DNA / genes / alleles.

For example in plants: Wrinkled pea shape allele
For example in animals: White coat allele

INHERITABLE VARIATION can be passed on to offspring and involves a change / mutation / information in the DNA of GAMETES.

Non-inheritable variation

Some variation is acquired due to environmental effects and/or the effects of an indvidual's actions.

For example in plants: Stunted growth from lack of nutrients.
For example in animals: Overfed (obese) domestic rabbit.

NON-INHERITABLE VARIATION may be due to the environment (or only occurs in body cells) and so affects only that organism, not its offspring.

Mutations

What is a mutation?

A MUTATION is a change in the order of DNA bases This results in a change in how the genetic information is read and can create a new allele / different protein, and so changes in the phenotype.

Mutations are the only source of new alleles.

Some mutations are HARMFUL as they code for modified proteins that don't function properly.
Occasionally, a mutation is BENEFICIAL, as it codes for a modified protein that functions better than the original.

Mutations are the ultimate source of genetic variation because they can result in new beneficial alleles within a population.

However, most mutations are NEUTRAL, and has no effect on the protein produced - they are neither harmful nor beneficial.

What causes mutations?

Mutations can be caused by exposure to mutagens (e.g. certain chemicals or radiation) or by an error in the replication of DNA just before a cell divides.