Phenomena Mutations

Let’s start with a little test… Create this in your notebook: A- B- C- D- E- F- G- H- I-

Now SILENTLY write what you see on each slide

Now SILENTLY write what you see on each slide B-

Now SILENTLY write what you see on each slide

Now SILENTLY write what you see on each slide

Now SILENTLY write what you see on each slide

Now SILENTLY write what you see on each slide F-

Now SILENTLY write what you see on each slide G-

Now SILENTLY write what you see on each slide

Now SILENTLY write what you see on each slide

What were your answers? A- B- C- D- E- F- G- H- I-

How many people did not see what I saw?

This could be caused by a mutation on your X chromosome. Sometimes we call this “colorblindness” but people who cannot distinguish between the colors red and green just have a gene that codes for a different protein than my X chromosome codes for.

This “different protein” coding was probably the result of a mutation in the DNA many generations ago. This “mutation” is passed from parent to offspring just like any other gene. Since the mutation is on the X chromosome, this phenotype (being colorblind) is much more likely to show up in males than in females. This is because males only have one X chromosome, not two X chromosomes like females. If that one X chromosome has the colorblind allele, there is no “backup protein” on the second chromosome.

A pedigree chart model

So how do these “mutations” of a gene happen? https://www.youtube.com/watch?v=GieZ3pk9YVo Make sure to pay attention and take some notes. There is a quiz after…

Let’s see how much of that video you remembered… Quick Quiz Number from 1-5

1- True or False Most mutations to an organism’s DNA are helpful, and are a step in adapting to the environment.

2- What word goes in the blank? _________

3- True or False Mutations in genes can be at the DNA level or even at the chromosome level.

4- Fill in the missing word Mutations are ______________, meaning that an organism can’t force a mutation to happen when it wants a new trait.

5- True or False Not all genes are “turned on” or activated at the same time.

Make this chart in your notes: Outcome of Mutation Example Beneficial Neutral Harmful

Mutations may be beneficial Double Muscling is a mutation in the gene that controls reproducing muscle cells, so they don’t receive the “stop” message as often. Since strength is good for a bull to have, this is beneficial. Nylonase is an example of beneficial mutation in bacteria. The nylonase bacteria can eat short molecules of nylon, not just sugar, like regular bacteria. Nylonase can be used by humans in wastewater treatment plants.

Mutations may be beneficial Ability to digest milk is a mutation that occurred thousands of years ago. Anciently, almonds had a chemical that turned to cyanide inside human bodies. A mutation deleted this chemical, so now humans grow the “safe” form of almond trees.

Mutations may be harmful When a mutation makes extra structures, or structures where they shouldn’t be, this usually makes it harder for the organism to get food, survive, and/or reproduce. These are harmful mutations, and they are usually eliminated from the gene pool.

Mutations may be harmful Many human diseases are caused by mutations. Rapid aging disease is caused by a single-point mutation in one gene. Marfan Syndrome happens because of a mutation in DNA. People with this disorder have problems with their connective tissue.

Mutations may have no effect Anciently, all humans had brown eyes. A mutation about 6,000 years ago produced a protein that makes blue eyes. This is neither beneficial or harmful. Some plants get a mutation in the gene that controls leaf color. These leaves are colored in the middle and white on the edges. This variegation is neutral. Most mutations are neutral because there is more than one gene sequence to make a protein.

Mutations may have no effect Most mutations are neutral because there is more than one gene sequence to make a protein.