Because stuff happens
Download
1 / 23

Mutations - PowerPoint PPT Presentation


  • 151 Views
  • Uploaded on

Because Stuff Happens. Mutations. A. Mutation Overview. Any change or random error in the nucleotide sequence (either DNA or mRNA) is called a mutation Can occur in any cell in body Gamete : cell that determines sex; sperm or egg cell Mutation passed down to offspring

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Mutations' - kalb


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

A mutation overview
A. Mutation Overview

  • Any change or random error in the nucleotide sequence (either DNA or mRNA) is called a mutation

  • Can occur in any cell in body

    • Gamete: cell that determines sex; sperm or egg cell

      • Mutation passed down to offspring

    • Somatic cell: all other cells

      • Mutation stays with cell; may be copied in cell replication



  • Two types of mutations:

    • Point mutation: one base is mutated into another (one amino acid change)

    • Frameshift mutation: one base is added or deleted (all amino acids changed)

  • Affects may be neutral (no change in expression), positive, or negative (disease or death)


A mutation in the thumb joint changed it to an opposable thumb = positive mutation!


Introns exons
Introns & Exons

  • Entire DNA strand is 3 billion (3,000,000,000) base pairs

    • In eukaryotes, divided into two types:

      • Introns: no coding information (nonsense)

      • Exons: code for proteins


mutation

INTRON

EXON

INTRON



Point mutation
Point Mutation (making proteins from mRNA) -

  • Single nucleotide (base, PO4, sugar) changes

    • Original : The fat cat ate the wee rat.

    • Mutation: The fat hat ate the wee rat.

  • Many diseases are result of single point mutation in gene


  • Sickle cell anemia (making proteins from mRNA) -

    • Point mutation: aa glutamine mutated into valine

    • Result: red blood cell changed from round shape to sickle (crescent) shape

      • Gets stuck on walls of blood vessels & can cause clog


  • Cystic fibrosis (making proteins from mRNA) -

    • Point mutation: aa glutamine becomes STOP codon

    • Result: should be 1480 aa in protein, now only 493

      • Mucosal cells produce excess mucus which blocks ducts (tubes linking organs) which causes infections


Frameshift
Frameshift (making proteins from mRNA) -

  • Any mutation which causes shift of codon sequences or incorrect amino acid number

  • Caused by two scenarios:

    • Deletion of nucleotide (base)

      • Original: The fat cat ate the wee rat.

      • Mutation: The fat atatet hew eer at.

    • Insertion of extra nucleotide(s) (base)

      • Original: The fat cat ate the wee rat.

      • Mutation: The fat caa tat eth ewe era t.

  • Many diseases caused by frame-shift mutations


Frameshift1
Frameshift (making proteins from mRNA) -


  • Huntington’s Disease (making proteins from mRNA) -

    • Mutation: additional CAG in protein

    • Result: early cell death in brain

Huntington’s Disease

Normal


  • Fragile X Syndrome (making proteins from mRNA) -

    • Mutation: extra GGG codons inserted on X chromosome

    • Result: mental retardation in males

normal


  • Muscular dystrophy (making proteins from mRNA) -

    • Mutation: extra CTG or CCTG in muscle protein

    • Result: deteriorating (weakening) muscles


  • Tay (making proteins from mRNA) - -Sachs Disease

    • Mutation: insertion of TACT in exon 11

    • Result: enzyme that breaks down fat in central nervous system (brain & spinal cord) defective

      • Fat accumulates on brain & spinal cord, permanently damaging cells & killing child before age 5


Point vs frameshift
Point vs. (making proteins from mRNA) - Frameshift


Classwork
Classwork (making proteins from mRNA) -

  • Mutations worksheet

    • Use mRNA codes to look up amino acids in proteins

    • Do the same thing for the mutated mRNAs.

    • a. Where is the mutation? Either circle it or explain (G is now C or G got deleted/inserted)

    • b. What is the result? Describe the change to the amino acid(s) .


Homework
Homework (making proteins from mRNA) -

  • Do p. 220 #3-5

  • Do p. 222 #1-3, 8, 10-12

  • Study for a quiz tomorrow just on central dogma (25 points)

    • Transcription – DNA to RNA

    • Translation – RNA to protein

    • Know the process of transcription and translation (how it happens, where it happens, what happens)


ad