Mutations are changes in the genetic material Mutations may be genetic mutations or chromosomal mutations Genetic Mutations occur in the code on DNA or mRNA Mistakes in copying the DNA ID: 473344
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Slide1
Mutations (p. 307)
Mutations are changes in the genetic material.
Mutations may be genetic mutations or chromosomal mutations.Slide2
Genetic Mutations occur in the “code” on DNA or mRNA
Mistakes in
copying the DNA :
Inserting the wrong nucleotide
Skipping or adding a base when a new strand is assembled.Slide3
There are 2 general types of genetic mutations.
Point Mutations
Involve
only one or a few nucleotides.
Occur at a single point on the sequence.
Are substitutions.
Substitution:
THE FAT CAT ATE THE RAT
THE TAT CAT ATE THE RATSlide4
2. Frameshift Mutations
Involve the insertion or deletion of a nucleotide
The resulting shift causes every grouping of three bases after the mutation to be different. Slide5
Deletion:
THE FAT CAT ATE THE RAT
THE ATC ATA TET HER AT
Insertion:
THE FAT CAT ATE THE RAT
THE FFA TCA TAT ETH ETA TSlide6
Are these
a) point mutations or frameshift mutations?
b) substitutions, deletions or insertions?
1. THE FAT CTA TER AT
2. THE FAT CAA ATE THE RAT
3. THE EFA TCA TAT ETH ERA T Slide7
Gene Mutations
So, gene mutations result from changes in a single gene.
They may be point mutation (substitution) or
frameshift
mutations (insertions or deletions).Slide8
They may be passed on to the next cellular generation. HOW?
Depending on which gene they effect they may cause no obvious problem or they may be devastating.
(What would happen if there was a
frameshift
mutation in the gene that codes for the production of DNA polymerase?)Slide9
Chromosomal mutations (p. 308)
Chromosomal mutations involve changes in the number or structure of chromosomes.
Such mutations may change the locations of genes on a chromosome and may even change the number of copies of some genes available to the organism. Slide10
Four types (p. 308):
Deletions
The loss of all or part of a chromosome
Duplications
Extra copies of the chromosome
Inversions
Reversal of the direction of part of the chromosome
Translocations
Part of one chromosome breaks off and attaches to another (
ie
. 13 to 14) Slide11
Chromosomal mutations
http://www.youtube.com/watch?v=XAGxp9j5rtcSlide12
Chromosomal Disorders
Non-disjunction
: when this occurs, abnormal numbers of chromosomes may find their way into gametes, and a disorder of chromosome numbers may result. Slide13
Homologous chromosomes fail to separate
Meiosis I:
Nondisjunction
Meiosis II
Section 14-2
Nondisjunction
Go to Section:Slide14
Examples of
Non-Disjunction
Disorders
Down’s Syndrome
XXY
Klinefelter’s
Turner’s SyndromeSlide15
Gene regulation
For Monday, read pages 309 to 312 in your text.