Mutations

What are mutations? -They are mistakes made in our genetic code, which may or maynot result in the wrong protein being made which may or may not result in a trait being altered.

Mutagens: Are any chemical or radiation that causes a change in our genetic code. Examples: X-rays, UV sunrays, asbestos and coal dust.

Carcinogens: -Are mutagens that cause a mistake in the genetic code that leads to uncontrollable cell division. - This results in CANCER. -Examples include: Mercury, UV rays and cigarettes

Two categories of mutations: Germ mutation: -mutations which occur in the sperm or the egg. If fertilized this mistake would be passed on to the child. Example: Sickle cell anemia

Somatic mutations: -mutations which occur in a body cell. These cells are not passed on to the offspring. -Example: Skin cancer

Normal Somatic mutation Seeds in both only carry the genes for being all red. However the one on the right has a somatic mutation that only affects its skin and not its seeds.

Types of mutations (either germ or somatic): 1. Chromosomal mutations: -entire chromosomes is affected therefore many genes are involved resulting in the most severe forms of mutations. A baby can be born with a wrong number of chromosomes. -Example: monosomy trisomy insertion deletion translocation

Monosomy mutation Mono means one A monosomy mutation is when a person is born missing a chromosome so instead of having two of each chromosome, one from mom and one from dad, it only has one. Turners Syndrome: Instead of XX this person is missing one sex chromosome so they are only X__. Since they only have the X and no Y it is a girl.

Turners Syndrome

Trisomy Tri means three A trisomy mutation is when a person is born with an extra chromosome so instead of having two of each chromosome, one from mom and one from dad, it three. Down Syndrome is known as Trisomy 21. These babies are born with three 21st chromosomes instead of the normal 2.

Trisomy 21~Down Syndrome

Trisomy 18~ Edwards Syndrome

Insertion mutation One part of a chromosome breaks off in the sperm or egg and reattaches on to another totally different chromosome. Part of chromosome 4 below broke off and attached itself to chromosome 20

Deletion mutation Part of a chromosomes breaks off and those genes are lost or deleted.

Translocation Part of one chromosome breaks off, part of another chromosome breaks off and the two parts switch places. No DNA is lost but just located in a different place. Below, part of chromosome 4 and part of chromosome 20 break off and switch locations.

Section is inverted/translocated

-One single change in a DNA nucleotide is made therefore only affecting one single gene. 2. Gene mutation: (point mutation) Example: Albinism:

Types of gene mutations: 1. Silent or Neutral Mutation Types of gene mutations: 1. Silent or Neutral Mutation -a change in one base does not alter the amino acid sequence.

2. Missense Mutation: -one DNA nucleotide is changed causing it to code for a different amino acid. This mistake still codes for an amino acid BUT just the wrong amino acid.

Sickle Cell Anemia

3. Nonsense Mutations: -one DNA nucleotide is changed forming a stop codon in the middle of a gene resulting in a shortened amino acid sequence that codes for NO protein.

4. Frameshift mutation: -one or two nucleotides gets added to a gene resulting in the entire sequence to get shifted down and throwing off the entire amino acid sequence. The fat cat sat The fat cat sat = hef atc ats at

Mutations are the number one reason organisms evolve……