MutationsMutations

How will a change in the DNA sequence affect the overall properties

of the protein?

How will a change in the DNA sequence affect the overall properties

of the protein?

Where mutations occur?Where mutations occur?

Somatic (body) cells: mutations are NOT passes to offspring.

Gametes (sex) cells: mutations CAN BE passes to offspring through fertilization.

Somatic (body) cells: mutations are NOT passes to offspring.

Gametes (sex) cells: mutations CAN BE passes to offspring through fertilization.

Two types of mutationsTwo types of mutations

1. Gene mutations: change in single nucleotides

2. Chromosomal mutations: occur when a section of chromosome relocate.

1. Gene mutations: change in single nucleotides

2. Chromosomal mutations: occur when a section of chromosome relocate.

Gene MutationsGene Mutations1. Point Mutations: occur when a single nucleotide

is substituted for another nucleotide.

Ex: THE DOG BIT THE CAT THE DOG BIT THE CAR

1. Point Mutations: occur when a single nucleotide is substituted for another nucleotide.

Ex: THE DOG BIT THE CAT THE DOG BIT THE CAR

Gene Mutations 2. Frameshift Mutations: occur when a

single base pair is added (inserted) or subtracted (deleted) to “shift” the original nucleotides.

Ex: THE DOG BIT THE CAT

THE DOB ITT HEC AT

(deleting the G, “shifted” the nucleotide to the left one place, thus coding for new amino acids)

Gene Mutations 2. Frameshift Mutations: occur when a

single base pair is added (inserted) or subtracted (deleted) to “shift” the original nucleotides.

Ex: THE DOG BIT THE CAT

THE DOB ITT HEC AT

(deleting the G, “shifted” the nucleotide to the left one place, thus coding for new amino acids)

Results of gene mutationsResults of gene mutations

The mutation can be:

a. Silent: codes for same amino acid

b. Mis-sense: codes for another amino acid,

changing the protein

c. Nonsense: codes for a stop codon in an inappropriate place.

The mutation can be:

a. Silent: codes for same amino acid

b. Mis-sense: codes for another amino acid,

changing the protein

c. Nonsense: codes for a stop codon in an inappropriate place.

Chromosomal MutationsChromosomal Mutations1. Deletions: a segment of nucleotides are

removed.ABCDEFGABFG

2. Inversions: detach and reattachment in reversing order of a segment of nucleotides:

ABCDEFGABEDCFG

1. Deletions: a segment of nucleotides are removed.

ABCDEFGABFG

2. Inversions: detach and reattachment in reversing order of a segment of nucleotides:

ABCDEFGABEDCFG

Chromosomal MutationsChromosomal Mutations

3. Translocations: a segment of one chromosome detaches and reattaches to another chromosome.

Ex. ABCDEF GHIJKLABC DEFGHIJKL

4. Non-disjunction: unequal separation of chromosomes during meiosis.

Ex. Trisomy: extra 21st X chromosome causing Down’s Syndrome.Ex. Monosomy: Turner’s Syndrome (sex chromosome) and Cri du Chat (chromosome 5)

3. Translocations: a segment of one chromosome detaches and reattaches to another chromosome.

Ex. ABCDEF GHIJKLABC DEFGHIJKL

4. Non-disjunction: unequal separation of chromosomes during meiosis.

Ex. Trisomy: extra 21st X chromosome causing Down’s Syndrome.Ex. Monosomy: Turner’s Syndrome (sex chromosome) and Cri du Chat (chromosome 5)

What causes mutations?What causes mutations?

Mutagens: any agent that causes a change in DNA High energy radiation: X-ray, Cosmic Rays,

UV rays, and nuclear radiation Chemicals: Dioxins, asbestos, Benzene,

Cyanide and formaldehyde High Temperatures

Science is the coolest!! We’re almost done!

Mutagens: any agent that causes a change in DNA High energy radiation: X-ray, Cosmic Rays,

UV rays, and nuclear radiation Chemicals: Dioxins, asbestos, Benzene,

Cyanide and formaldehyde High Temperatures

Science is the coolest!! We’re almost done!

DNA RepairDNA Repair Cells naturally identify and repair damage.

However, too much damage may be irreparable. Depends on: cell type, age of cell, and the extra

cellular environment. A cell that has accumulated a large amount of

DNA damage, or one that no longer effectively repairs damage incurred to its DNA, can enter one of three possible states:

1. Permanent dormancy (senescence)

2. cell suicide (apoptosis) 3. unregulated cell division (cancerous)

Cells naturally identify and repair damage. However, too much damage may be irreparable.

Depends on: cell type, age of cell, and the extra cellular environment.

A cell that has accumulated a large amount of DNA damage, or one that no longer effectively repairs damage incurred to its DNA, can enter one of three possible states:

1. Permanent dormancy (senescence)

2. cell suicide (apoptosis) 3. unregulated cell division (cancerous)

Are mutations good or bad?Are mutations good or bad?

Good? New traits

Bad? Mutation causing a new protein

Using the information you just learned explain how a mutation could occur that wouldn’t cause negative effect for a human.

Good? New traits

Bad? Mutation causing a new protein

Using the information you just learned explain how a mutation could occur that wouldn’t cause negative effect for a human.