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MutationsChapter 12-4

+What are mutations?Any change to the genetic codeCauses:

Usually error when DNA is being replicated during mitosis

environmental factors: UV rays, X-rays, drugs

Gene mutations: A change in a single gene

+What are mutations?point mutation : Change of 1 or a few nucleotide bases, possibly changing the amino acid coded for

Example: Substitutions: one nitrogen base substituted for another

+ Effects of substitutionsSome substitutions result in coding for same amino acid

Some change amino acid but doesn’t affect overall protein

Some change 1 amino acid and changes structure of entire protein

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+ Sickle Cell Anemia

Normal hemoglobin

Sickle CellHemoglobin

sickle cell video

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+ Frameshift mutation: Shift in the reading frame that causes every amino acid after the mutation to be different.(Caused by Insertions or deletions)

Insertion

Deletion

+ Effects of Frameshift mutationsGood:

disables CCR5 HIV receptor which allows HIV virus to attack Immune cells

Mutations that allow evolution of species

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+Negative Examples:Causes disorders:Tay SachsChron’s diseaseCystic FibrosisCancer

+ Cystic FibrosisA mutation in the CFTR gene

The CFTR gene makes a protein that controls the movement of salt and water in and out of your body's cells.

In people who have CF, the gene makes a protein that doesn't work well.

70% of cases caused by this mutationA T C A T C T T T G G T G T T T C C lle lle Phe Gly Val SerA T C A T T G G T G T T T C C lle lle Gly Val Ser

+ Results of Cystic Fibrosis

Thick mucus is produced by the bodyMucus fills lungs causing lung infections

Mucus blocks pancreas which causes digestive problems

Mucus can block bile ducts in liver causing liver failure.

+ Cancer results from a series of mutations

within a single cell Often, a faulty, damaged, or

missing p53 gene is to blame The p53 gene makes a protein

that stops cells from dividing Without this protein, cells divide

unchecked and become tumors.

+ Tay SachsThe HEXA gene makes part of an enzyme called

beta-hexosaminidase A enzyme helps break down a fatty substance called

GM2 ganglioside in nerve cells of brainMutations in the HEXA gene disrupt the activity of

beta-hexosaminidase A, preventing the breakdown of the fatty substances.

As a result, the fatty substances accumulate to deadly levels in the brain and spinal cord.

The buildup of GM2 ganglioside causes progressive damage to the nerve cells

+What are mutations?Chromosomal mutations: may change the location of genes and number of genes

4 Types: 1) Deletion: Loss of part/all of chromosome

2) Duplication: Segment is repeated

+ 3. Inversion- part of chromosome becomes orientated in opposite direction

4. Translocation- part of one chromosome breaks off and attaches to another

+ Intro to Cancer Biology video