1. 12–4 Mutations
12-4 Mutations
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2. 12-4 Mutations Mutations are changes in the genetic material.
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3. Kinds of Mutations Kinds of Mutations
Mutations that produce changes in a single gene are known as gene mutations.
Mutations that produce changes in whole chromosomes are known as chromosomal mutations.
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4. Kinds of Mutations
Gene mutations involving a change in one or a few nucleotides are known as point mutations.
Point mutations:
Substitutions
insertions
deletions.
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5. Substitutions usually affect no more than a single amino acid.
Gene mutations result from changes in a single gene. In a substitution, one base replaces another.
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6. The effects of insertions or deletions are more dramatic.
The addition or deletion of a nucleotide causes a shift in the grouping of codons.
Changes like these are called frameshift mutations.
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7. Frameshift mutations may change every amino acid that follows the point of the mutation.
Frameshift mutations can alter a protein so much that it is unable to perform its normal functions.
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8. In an insertion, an extra base is inserted into a base sequence.
Gene mutations result from changes in a single gene. In an insertion, an extra base is inserted into a base sequence.
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9. In a deletion, the loss of a single base is deleted and the reading frame is shifted.
Gene mutations result from changes in a single gene. The loss of a single letter in a sentence models the effects of the deletion of one base in a DNA sequence.
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11. Chromosomal mutations involve changes in the # or structure of chromosomes.
Chromosomal mutations include deletions, duplications, inversions, and translocations.
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12. Deletions involve the loss of all or part of a chromosome.
Chromosomal mutations involve changes in whole chromosomes.

13. Duplications produce extra copies of parts of a chromosome.
Chromosomal mutations involve changes in whole chromosomes.
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14. Inversions reverse the direction of parts of chromosomes.
Chromosomal mutations involve changes in whole chromosomes.
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15. Translocations occurs when part of one chromosome breaks off and attaches to another.
Chromosomal mutations involve changes in whole chromosomes.
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16. Significance of Mutations
Many mutations have little or no effect on gene expression.
Some mutations are the cause of genetic disorders.
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17. Beneficial mutations may produce proteins with new or altered activities that can be useful.
Polyploidy is the condition in which an organism has extra sets of chromosomes.
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18. http://goat. wakavision
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