Genetic ChangesChapter 11.3 

Any change in the DNA sequence is called a mutation. 

Genetic changes

• Mutations affect the reproductive cells of an organism by changing the sequence of nucleotides within a gene in a sperm or an egg cell.

If Fertilization occurs

If fertilization occurs, the mutated gene would be duplicated in the new individual.

This mutation could result in several different things:

it could produce a new trait it could produce a defective proteinit could cause structural or functional

problems in cells and organism.it could be so severe that the embryo

does not survive.

All living creatures have genes, made up of DNA. Without DNA mutations, life on Earth could not have evolved. Mutations can affect the way a gene works, which may in turn cause changes in an animal's appearance, or behavior. Sometimes, a new gene variant may mean the animal is better adapted to its surroundings, improving its chances of survival. So this animal is more likely to have offspring, which will inherit the beneficial gene variant. This process is called natural selection.

Positive mutations

Some rare mutations have positive effects like increasing or decreasing the speed of certain reactions in the body.

mutations that benefit a species plays an important role is the evolution of that species.

Tortoises have evolved protective shells to retract into when faced by predators.

Non reproductive cell mutation

If a mutation occurs in a non-reproductive cell, like a body cell, the mutation will not be passed on to the offspring. It will affect or cause damage to the

organism. It may impair the function of the cell.

Some mutations affect cell division, like cancerous cells

They result in rapid cell division.

DNA Muscles

(AP) Somewhere in Germany is an extremely strong toddler: born in Berlin with bulging arm and leg muscles. Not yet 5, he can hold seven-pound weights with arms extended, something many adults cannot do. The boy - whose name is being withheld to protect his privacy - is reported to have muscles twice the size of other kids his age and half their body fat. Medical researches say DNA tests show the reason: he has a genetic mutation that boosts muscle growth.

Types of DNA mutations

There are three major types:

1. Point mutation

2. Frameshift mutation3. Chromosomal mutations

Point mutation

This is a result of an incorrect base being inserted into the DNA sequence.

ex: TACCTC could change to TACCTT resulting in a new amino acid.

point mutation

A point mutation is a simple change in one base of the gene sequence. This is equivalent to changing one letter in a sentence, such as this example, where we change the 'c' in cat to an 'h':

Original The fat cat ate the wee rat.

Point Mutation The fat hat ate the wee rat.

Point mutation 2.

This can cause the wrong amino acid to be produced, resulting in the wrong protein, which could have various affects on the cell or organism.

Point mutation and Sickle Cell

There is a certain genetic disorder known as Sickle Cell Anemia. It causes a warping of the blood cells, so you get cells like the one in the bottom left:

This genetic trait will cause less oxygen to be delivered thought the blood, causing weakness and pain. It differs from a normal blood cell gene by one, single point mutation.

Frameshift mutation

When a base is added or deleted from the DNA sequence:

ex: TACCTC could mutate into TACACTC or TACTC

An example of a frame-shift mutation using our sample sentence is when the 't' from cat is removed, but we keep the original letter spacing:

Original The fat cat ate the wee rat.

Frame Shift The fat caa tet hew eer at.

Frameshift mutation 2.

This will shift the reading of the codons. Therefore, resulting in an incorrect amino acid chain.

Chromosomal mutations

These are mutations in the formation of the chromosome where:

parts of the chromosome may break off and become lost in the cell during mitosis or meiosis

chromosomes may rejoin incorrectly

Chromosomal mutations 2.

These types of mutations are more common in plants.

Few of these mutations are passed on to offspring because more than likely the zygote does not survive.

Causes of Mutations 

Mistakes in base pairing can occur during DNA transcription or replication

Mutations are also caused by environmental factors. A mutagen is any agent that can cause a

change in DNA. They include things such as chemicals,

high energy radiation and high temperatures.

Mutations 2

Mutations in cells are sometimes fixed by the body’s own self-check system. There are proof-reading enzymes inside

the cell that check the DNA after replication or transcription that insert or delete incorrect base pairs.

Mutations 3

Like most living things, it is not a perfect process, but works extremely well… just like a spell check on your computer fixes most things, it still skips over things that seem to make sense, but don’t.

Ex: if you meant to write the word dye, but put die instead… spell check probably won’t catch it. 

 

Aging is said to be a possible genetic mutation