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Mutations

Mutations. From Gene to Protein Honors Biology Ms. Kim. Mutations. Mutations Are changes in the genetic material (DNA) of a cell 2 TYPES 1. Point mutations can affect protein structure and function Are changes in just one base pair of a gene. POINT MUTATIONS.

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Mutations

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  1. Mutations From Gene to Protein Honors Biology Ms.Kim

  2. Mutations • Mutations • Are changes in the genetic material (DNA) of a cell 2 TYPES • 1. Point mutations can affect protein structureandfunction • Are changes in just one base pair of a gene

  3. POINT MUTATIONS • The change of a single nucleotide in the DNA’s template strand • Can lead to the production of • an abnormal protein or… • the same protein

  4. Point Mutations • Point mutations within a gene are called • Base-pair substitutions • Can result in a mutation (change) that is • harmful • neutral (not harmful or helpful) • beneficial

  5. Substitutions • 2 TYPES • missense (wrong amino acid) • ONLY 1 wrong aa is added to polypeptide…all the other aa’s are the same • nonsense (prematurely STOP) • The change in DNA leads to an early STOP codon polypeptide is SHORTEN!!

  6. POINT MUTATION ANALOGY… • TEMPLATE: THE CAT ATE THE RAT • POINT MUTATION: THE CAT ATE THE RAT • THE CAT ATE THE BAT  What kind of point mutation is this? • MISSENSE • THE CAT ATE THE XAT  What kind of point mutation is this? • NONSENSE

  7. What is the “wobble” effect? • The last base (nucleotide) in a codon is said to be in the WOBBLE position. • codon mutation may encode the same amino acid • Leads to NEUTRAL or SILENT mutations • Not harmful or helpful • SILENT MUTATIONS • Mutation does not change “end result”…change in DNA still makes the SAME amino acid • NO noticeable change occurs • a change from AUU to AUC will still encode leucine

  8. What is a neutral mutation? • May or may not affect the resulting protein. • For example, if the codon AAA is mutated to AGA, arginine would be used in the resulting protein instead of lysine • These amino acids are chemically similar and may not have a large effect in the protein or its function • IF this change causes the protein to not function (and be LETHAL to the organism) then it is not a neutral mutation but rather a missense mutation

  9. 2. Frameshift Mutations • Insertions and deletions • Are additions or losses of nucleotide pairs in a gene • produce frameshift mutations • 2 TYPES • Insertions • Deletions

  10. FRAMESHIFT MUTATION ANALOGY… • TEMPLATE: THE CAT ATE THE RAT • ADDITION of “B” MUTATION: THE CAT ATE THE RAT • THE CAT BAT ETH ERA T  What kind of frameshift mutation is this? • INSERTION • SUBTRACTION of “A” MUTATION: THE CAT ATE THE RAT • THE CAT TET HER AT  What kind of frameshift mutation is this? • DELETION • http://highered.mcgraw-hill.com/sites/0072552980/student_view0/chapter9/animation_quiz_5.html

  11. Which is more harmful? • Typically, frameshift mutations are more harmful BUT some point mutations can be LETHAL • Ex: Tay Sachs and Cystic Fibrosis

  12. Other Types of Mutations • Inversions • “Flip Flops” • Nucleotides trade places on each strand • Deletions (2+ nucleotides) • Many nucleotides are deleted at once

  13. Causes of Mutations • Inherited mutations • From mom and dad • Spontaneous mutations • occurs during DNA replication • Environmental mutations (Mutagens) • physical or chemical agents that can cause mutations • Ex: Sun, viruses, chemicals

  14. Belgian Blue Cattle (so beefy….) The Belgian Blue has a natural mutation in myostatin gene, which codes for protein that inhibits muscle development and fat deposition (creates very lean meat).

  15. Piedmontese cattle (still so beefy…)

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