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DNA Mutations. Chapter 12.4. Mutation. Mutation : Any change in a gene is a mutation. Substances that cause a mutation are called mutagens. Mutations can also happen spontaneously. Point Mutation. A change in one nucleotide

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Dna mutations
DNA Mutations

Chapter 12.4


Mutation
Mutation

  • Mutation: Any change in a gene is a mutation.

  • Substances that cause a mutation are called mutagens.

  • Mutations can also happen spontaneously.


Point mutation
Point Mutation

  • A change in one nucleotide

  • Original: The fat cat ate the wee rat. Point Mutation: The fat hat ate the wee rat.


Point mutation1
Point Mutation

  • Base Substitution - One nucleotide is replaced with another nucleotide.

    ACC CUA GGC AUC AU ACC UUA GGC AUC AU

    “C” is substituted with “U”


Redundant systems
Redundant Systems

  • Sometimes these mutations have no effect!! Ex. The codons of UCU, UCC, UCA, & UCG all code for the amino acid Serine. Any substitution in the third base of the codon has no effect.



Frameshift mutations
Frameshift Mutations the codon, changes the code for the amino acid.

  • Either the insertion or a deletion of a nucleotide which results in a shift in the code and mistakes from the point of mutation on.

  • Original The fat cat ate the wee rat.

  • Frame ShiftThe fat caa tet hew eer at.


Somatic cell mutations
Somatic Cell mutations the codon, changes the code for the amino acid.

  • Mutations happen in all organisms, if it happens in a somatic cell then only the individual is affected.


Meiosis mutations
Meiosis Mutations the codon, changes the code for the amino acid.

  • If it happens in a gamete then the mutation is passed on to the offspring.


Meiosis mutations1
Meiosis Mutations the codon, changes the code for the amino acid.

  • Mistakes during meiosis: Mistakes during meiosis, such as non-disjunction, can result in three chromosomes instead of a pair (trisomy) or more than three (polyploidy).


Down s syndrome
Down’s Syndrome the codon, changes the code for the amino acid.

  • Trisomy in humans can result in birth defects such as trisomy 21, or Down’s syndrome.


Quick review
Quick Review the codon, changes the code for the amino acid.

  • Point mutations occur as a result of a change in one nucleotide.

  • The 2 basic types of point mutations are base substitutions and frame shift.


Quick review1
Quick Review the codon, changes the code for the amino acid.

  • Substitution mutations are the result of one nucleotide being replaced by another. This results in one amino acid being incorrectly coded.


Quick review2
Quick Review the codon, changes the code for the amino acid.

  • Frame shift mutations are the result of either a deletion or an insertion of a nucleotide. This results in a mistake in all the triplet codes from the mutation on.


Gene mutations
Gene Mutations the codon, changes the code for the amino acid.

  • Gene Mutations occur as a result of changes in chromosomal fragments. There are four basic types:

  • 1. Translocation

  • 2. Inversion

  • 3. Insertion

  • 4. Deletion


Gene mutations1
Gene Mutations the codon, changes the code for the amino acid.

1.Translocations - When part of one chromosome breaks off and is added to a different chromosome.


Gene mutations2
Gene Mutations the codon, changes the code for the amino acid.

2. Inversion – When part of a chromosome breaks out and is reinserted backwards.


Gene mutations3
Gene Mutations the codon, changes the code for the amino acid.

3. Insertion When part of a chromatid breaks off and attaches to its sister chromatid. The result is a duplication of genes on the same chromosome.


Gene mutations4
Gene Mutations the codon, changes the code for the amino acid.

4. Deletion

When part of a chromosome is left out.


Mutations evolution
Mutations & Evolution the codon, changes the code for the amino acid.

  • Mutations that have a negative effect usually result in the loss of that mutation due to the law of the survival of the fittest.


Mutation evolution
Mutation & Evolution the codon, changes the code for the amino acid.

  • However, there are times that the mutations are beneficial and result in the evolution of the species and increased variation in the population.

  • We’ll learn much more about this next unit!!!


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