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DNA Mutations

DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

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Page 1: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

DNA Mutations

Page 2: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

Victims of Chernobyl - Mutations

Page 3: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

What are mutations?Mutations are a change in the

genetic material of a cell (i.e. the genes).

Page 4: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

Key TermsMutation (Germ cell and Somatic)

◦Gene mutation◦Chromosome mutation

Point Mutation◦Substitution

Frameshift mutation◦Insertion◦Deletion

Page 5: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

What can cause mutations?

These mutations can come from the environment (such as radiation = cancer) or they can come from errors in transcription and translation

Page 6: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

2 Types of mutations

Germ cell mutation: These are mutations that occur in the sperm cell or egg cell. ◦ These mutations will be passed down from

parent to child

Somatic mutations: Occur in all other cells in the body◦ E.g. cancer

Page 7: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

Where can mutations occur?

Gene mutations involve large segments of DNA or a single nitrogenous base.

Chromosome mutations occurs when an entire chromosome is lost or the structure of it changes

◦We will look at chromosome mutations later

Page 8: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

2 Types of Gene Mutations

Point mutation- Substitution

Frameshift mutation - Insertion- Deletions

Page 9: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

Point Mutation - Substitution

Substitution occurs when a single nitrogenous base is replaced with a different nitrogenous base

E.g.

Page 10: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

Frameshift Mutations – Insertion/ Deletion

Insertion occurs when one or more nitrogenous base is added

Deletion: Occurs when one or more nitrogenous base is deleted

Page 11: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

5 Possible Results of a Mutation

1. Silent Mutation

2. Substitution

3. Premature Stop

4. Codon Deletion or Insertion

5. Frame Shift

Page 12: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

1. Silent Mutation (Point Mutation)

Occurs when a nitrogenous base is substituted but the change still produces the same amino acid.

E.g. AGA and AGG both produce the amino acid Arginine

Page 13: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

1. Silent Mutation

Page 14: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

2. Substitution (Point Mutation)

When an amino acid is substituted and the new codon makes a different amino acid

E.g. AGA makes Arginine and GGA makes Glycine

Page 15: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

2. Amino Acid Substitution

Page 16: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

3. Premature Stop (Point Mutation)

When a substitution results in the formation of a STOP codon.

This causes the amino acids after the STOP codon from being produced.

E.g. Original RNA AUGAAACAAGUUGCU

Mutated RNA AUGAAAUAAGUUGCU

Page 17: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

4. Codon Deletion or InsertionA whole new amino acid is

added, or one is missing from the mutant DNA

E.g. Original RNA AUGAAACAA

Mutated RNA AUGGUUAAACAA

Page 18: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

5. Frame ShiftWhen a deletion or insertion results in a

the shifting of codons causing a large change in the amino acids being produced

E.g. Original RNA AUGAAACAAGUC

Mutated RNA AUGAUAACAAGUC

Page 19: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

5. Frame Shift

Page 20: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

The Impact of DNA mutations

Silent mutations will not effect us because these mutations still produce the same amino acid

A substituted mutation that makes a s single different amino acid will have a small effect◦This is because only one amino acid

is changed

Page 21: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

The Impact of DNA mutations

A premature STOP mutation will have a large impact because it will stop making the protein

A deletion mutation that removes an amino acid will often lead to a small impact.◦This is because only one amino acid

is affected

Page 22: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

The Impact of DNA mutations

A frameshift mutation can have a severe impact because it can produce an entirely different protein

Page 23: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

Examples

Sickle Cell Anemia (Substitution)

Colour Blindness (Substitution)

Page 24: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

Examples

Thalassemia (Premature STOP codon)

Page 25: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

Williams Syndrome (Deletion)

Page 26: DNA Mutations. Victims of Chernobyl - Mutations What are mutations? Mutations are a change in the genetic material of a cell (i.e. the genes)

Tay-Sachs Disease (Frameshift)

Symptoms in infants include:

Slowing down of development Weakening of muscles Loss of motor skills such as turning

over, sitting, and crawling. 

As the disease progresses, other symptoms may also occur, including:

  Seizures Increased startle reflex to noise Vision loss Hearing loss Inability to swallow Mental retardation Paralysis Dementia