dna (gene) mutations. what is a gene mutation? parts of dna will have a base (or more) missing,...
TRANSCRIPT
DNA (Gene) Mutations
What is a gene mutation?
Parts of DNA will have a base (or more) missing, added, or incorrectA mistake in the genetic codeWrong instructions wrong building materials
wrong structure.
How common are mutations?
Mutations occurs at a frequency of about 1 in every 1 billion base pairs
Everybody has about 6 mutations in each cell in their body!
If I have that many mutations, why don’t I look weird?
Mutations are not always seen. Every part of your DNA doesn’t make a protein or trait.Remember introns and exons?
Some genes are recessive and are therefore hidden, they can be passed to your kids but you don’t notice them.
The most common types of gene mutations are:
SubstitutionPoint mutations
Frame shift mutations (2 kinds)InsertionDeletion
DNA (Gene) Mutation
Normal DNA: CGA – TGC – ATC
Mutated DNA: CGA – TGC - TTC
What happened?
DNA (Gene) Mutation #1
Normal DNA: CGA – TGC – ATC
Mutated DNA: CGA – TGC - TTC
*Adenine was accidentally replaced with thymine
*What is this mutation called?
Substitution (point mutation)
Normal DNA: CGA – TGC – ATC
Amino acids: Ala -- Thr -- stop
Mutated DNA: CGA – TGC – TTC
Amino acids: Ala -- Thr -- Lys
What will happen to the amino acids? How many will be affected?
DNA (Gene) Mutation #2
Normal DNA: CGA – TGC – ATC
Mutated DNA: CGA – TAG – CAT - C
What happened?
DNA (Gene) Mutations
Normal DNA: CGA – TGC – ATC
Mutated DNA: CGA – TAG – CAT - C
*Adenine was inserted,causing the remaining DNA to shift to the right
*What is this mutation called?
Insertion
Normal DNA: CGA – TGC – ATC
Amino acids: Ala -- Thr -- stop
Mutated DNA: CGA – TAG – CAT – C
Amino acids: Ala -- Tyr -- Val -- …..
What will happen to the amino acids? How many will be affected?
DNA (Gene) Mutation #3
Normal DNA: CGA – TGC – ATC
Mutated DNA: CGA – TCA- TC
What happened?
DNA (Gene) Mutation
Normal DNA: CGA – TGC – ATC
Mutated DNA: CGA – TCA- TC
*Guanine was removed, causing the remaining DNA to shift to the left
*What is this mutation called?
Normal DNA: CGA – TGC – ATC
Amino acids: Ala -- Thr -- Stop
Mutated DNA: CGA – TCA- TC
Amino acids: Ala -- Ser --…….
Deletion
What will happen to the amino acids? How many will be affected?
• What causes mutations?Replication errorsTranscription errorsCell division errorsSpontaneous changesMutagens
•Mutagen? What’s that?•“Stuff” that causes mutations when a cell is exposed.
•Examples: UV light, Xrays, chemicals, etc.
What happens to someone with a mutation?That all depends…..
What kind of mutation it is.How many proteins are affected.Where in the polypeptide chain is the mutation.How many cells does it affect.
Mutations can be fatal, harmful, beneficial or nuetral.
• Which mutation would
organism?
have the least effect on an
•On intron sections of DNA•On unexpressed recessive traits.•Point mutations/substitutions
•Only affects 1 amino acid.
• Which mutation would
organism?
have the most effect on an
•Frame-shift mutations: •Deletions and insertions affect all amino acids after the mutation.
• When would a mutation
an organism?
have the most effect on
•During Meiosis•If gametes are produced with mutations, those mutations will be passed onto the offspring…….•Every cell of organism will contain mutation.
Repairing DNA
Enzymes proofread the DNA and replace incorrect nucleotides with correct nucleotides.
The greater the exposure to a mutagen such as UV light, the greater the chance that a mistake will not be corrected.