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Mutations - PowerPoint PPT Presentation

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Mutations. Mutations. Hollywood’s images of mutation. Mutations. Actual Mutations in fruit flies. What is a mutation?. A mutation is any change in a cell’s DNA A mutation can occur in an individual gene - results in a single changed protein

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  • Hollywood’s images of



  • Actual Mutations

    in fruit flies

What is a mutation
What is a mutation?

  • A mutation is any change in a cell’s DNA

  • A mutation can occur in an individual gene

    - results in a single changed protein

    - cystic fibrosis a mutation in the protein that makes a type of ion channels in cell membrane

    - bacterial resistance to antibiotics is an example of a beneficial gene mutation

What is a mutation continued
What is a mutation continued

  • A mutation can occur in a chromosome

    - a chromosome contains many genes

    - chromosomal mutations affect many


    Examples: Down Syndrome

    Edward’s Syndrome


What causes mutations
What Causes Mutations?

  • Can be caused by mutagens- a physical or chemical cause of mutation. Examples: UV light, radiation, drugs, and benzene.

  • Mutagens are often also carcinogens – anything that causes cancer

  • Can be natural, random events.

    - mutations occur in 1/100,000 DNA replications

  • Mutations do not have to be bad (evolution)

Critical thinking
Critical Thinking

  • Will all mutations have a dramatic impact on an individual? How do you know? Which types of mutations do you think will have the greatest impact on an organism?

Kinds of mutations
Kinds of Mutations

  • Substitutions usually affect no more than a single amino acid.

  • Also known as point mutations

Kinds of mutations1
Kinds of Mutations

The effects of insertions or deletions are more dramatic.

The addition or deletion of a nucleotide causes a shift in the grouping of codons.

Changes like these are called frameshift mutations.

Kinds of mutations2
Kinds of Mutations

  • In an insertion, an extra base is inserted into a base sequence.

Kinds of mutations3
Kinds of Mutations

  • In a deletion, the loss of a single base is deleted and the reading frame is shifted.

Knowledge check
Knowledge Check

  • What is a point mutation? Example?

  • What is a frameshift mutation? Example?

Chromosomal mutations
Chromosomal Mutations

  • Chromosomal mutations involve changes in the number or structure of chromosomes.

  • Chromosomal mutations include deletions, duplications, inversions, and translocations.

Chromosomal mutations1
Chromosomal Mutations

  • Deletions involve the loss of all or part of a chromosome.

Chromosomal mutations2
Chromosomal Mutations

  • Duplications produce extra copies of parts of a chromosome.

Chromosomal mutations3
Chromosomal Mutations

  • Inversions reverse the direction of parts of chromosomes.

Chromosomal mutations4
Chromosomal Mutations

  • Translocations occurs when part of one chromosome breaks off and attaches to another.

Critical thinking1
Critical Thinking

  • If Down Syndrome is characterized by having 3 copies of the 21st chromosomes, would it be explained by a gene or chromosomal mutation? Which specific type of gene or chromosomal mutation? Why?

Significance of mutations
Significance of Mutations

  • Many mutations have little or no effect on gene expression.

  • Some mutations are the cause of genetic disorders.

    • Cancer

    • Down Syndrome