DNA Gene Mutations What is a gene mutation

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DNA (Gene) Mutations

DNA (Gene) Mutations

What is a gene mutation? ©Parts of DNA will have a base (or more)

What is a gene mutation? ©Parts of DNA will have a base (or more) missing, added, or incorrect ©A mistake in the genetic code ©Wrong instructions wrong building materials wrong structure.

How common are mutations? ©Mutations occurs at a frequency of about 1 in every

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

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: ©Substitution ©Point mutations ©Frame shift mutations

The most common types of gene mutations are: ©Substitution ©Point mutations ©Frame shift mutations (2 kinds) ©Insertion ©Deletion

DNA (Gene) Mutation Normal DNA: CGA – TGC – ATC Mutated DNA: CGA –

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

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 --

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

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 –

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: Amino acids: Mutated DNA: Amino acids: CGA – TGC – ATC

Insertion Normal DNA: Amino acids: Mutated DNA: Amino acids: CGA – TGC – ATC Ala -- Thr -- stop CGA – TAG – CAT – C 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

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 –

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?

Deletion Normal DNA: CGA – TGC – ATC Amino acids: Ala -- Thr --

Deletion Normal DNA: CGA – TGC – ATC Amino acids: Ala -- Thr -- Stop Mutated DNA: CGA – TCA- TC Amino acids: Ala -- Ser --……. What will happen to the amino acids? How many will be affected?

 • What causes mutations? © Replication errors © Transcription errors © Cell division

• What causes mutations? © Replication errors © Transcription errors © Cell division errors © Spontaneous changes © Mutagens • 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

©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 have the least effect on an organism? • On

• Which mutation would have the least effect on an organism? • On intron sections of DNA • On unexpressed recessive traits. • Point mutations/substitutions • Only affects 1 amino acid.

 • Which mutation would have the most effect on an organism? • Frame-shift

• Which mutation would have the most effect on an organism? • Frame-shift mutations: • Deletions and insertions affect all amino acids after the mutation.

 • When would a mutation have the most effect on an organism? •

• When would a mutation have the most effect on an organism? • 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

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.