Mutations

On the test expect questions about: - Analyzing the frameshift - A case study (Mutaions like Albinos) - Identifying the change in the mRNA

Definition of Genetic Mutation:

Definition of Genetic Mutation:

A change in gene structure that can cause a change in an organism.

Gene:

Sequence of DNA bases that codes for a protein.

Mutation Flow:

DNA → mRNA → Protein → Human trait controlled by protein.

Mutagen:

Internal or external factor causing mutation.

Chemical Mutagens:

dioxins, benzene, asbestos, DDT, and cigarette smoke.

Radioactive Mutagens:

UV rays, X-rays.

Other Mutagens:

Trauma, disease.

Frameshift Mutations:

Change the order of DNA nucleotides.

Insertion:

• Original: THE BIG DOG BIT TED

• Insertion: THE BIG DOG BBI TTE D.

Deletion:

• Original: THE BIG DOG BIT TED

• Deletion: THE /GD OGB ITT ED

Substitution:

• Original: THE BIG DOG BIT TED

• Substitution: THE BIG JOG BIT TED.

Sense Mutations:

Change in DNA → Change in mRNA → Change in amino acids.

Silent Mutation:

DNA=ACA→ACG, mRNA=UGU→UGC, AA=Cys → Cys (*amino acid unchanged).

Missense Mutation:

DNA=ACA-ACC, mRNA=UGU→UGG, AA= Cys→ Trp (*different amino acid coded for).

Nonsense Mutation:

DNA=ACA→ACT, mRNA=UGU→UGA, AA=Cys → STOP (*translation stops prematurely).

Sickle Cell Anemia (Missense Mutation):

• Valine replaces glutamate in the amino acid chain of hemoglobin.

• Normal blood cells replaced by sickle-shaped cells, causing blockages in blood

Translocation:

Switch order of genes between chromosomes.

Inversion:

Genes within one chromosome change order.

Duplication:

Copy genes or even entire chromosomes.

Deletion:

Remove genes or even entire chromosomes.

Down's Syndrome (Duplication):

• Extra chromosome #21.

• Facial features change, and mental processing is slowed.

Turner's Syndrome (Deletion):

• No second chromosome (X or Y).

• EX) Single X results in a short, infertile female.

Kleinfelter's Syndrome (Duplication):

• 3 sex chromosomes - XXY.

• EX) Tall male with long limbs, significantly lower IQ, and may be infertile with low sperm count.