Mutations
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Mutations. Mutations . Point mutations single base change base-pair substitution silent mutation no amino acid change redundancy in code missense change amino acid nonsense change to stop codon. When do mutations affect the next generation? . Point mutation leads to Sickle cell anemia.

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Mutations

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Mutations


Mutations

  • Point mutations

    • single base change

    • base-pair substitution

      • silent mutation

        • no amino acid change

        • redundancy in code

      • missense

        • change amino acid

      • nonsense

        • change to stop codon

When do mutationsaffect the nextgeneration?


Point mutation leads to Sickle cell anemia

What kind of mutation?

Missense!


Sickle cell anemia

  • Primarily Africans

    • recessive inheritance pattern

    • strikes 1 out of 400 African Americans

hydrophilicamino acid

hydrophobic amino acid


Mutations

  • Frameshift

    • shift in the reading frame

      • changes everything “downstream”

    • insertions

      • adding base(s)

    • deletions

      • losing base(s)

Where would this mutation cause the most change:beginning or end of gene?


Cystic fibrosis

  • Primarily whites of European descent

    • strikes 1 in 2500 births

      • 1 in 25 whites is a carrier (Aa)

    • normal allele codes for a membrane protein that transports Cl- across cell membrane

      • defective or absent channels limit transport of Cl- (& H2O) across cell membrane

      • thicker & stickier mucus coats around cells

      • mucus build-up in the pancreas, lungs, digestive tract & causes bacterial infections

    • without treatment children die before 5; with treatment can live past their late 20s


Chloride channel

transports chloride through protein channel out of cell

Osmotic effects: H2O follows Cl-

Effect on Lungs

normal lungs

airway

Cl-

Cl- channel

H2O

cells lining lungs

cystic fibrosis

Cl-

H2O

bacteria & mucus build up

thickened mucus hard to secrete

mucus secreting glands


Deletion leads to Cystic fibrosis

delta F508

loss of oneamino acid


What’s the value ofmutations?


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