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Genetic Changes

Genetic Changes. Gene and Chromosomal Mutations. Mutations. Mutations are a result in a change in DNA sequence A protein with a different AA sequence could be produced. Germ Cell - If mutations occur in sex cells they may be passed on to the next generation.

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Genetic Changes

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  1. Genetic Changes Gene and Chromosomal Mutations

  2. Mutations • Mutations are a result in a change in DNA sequence • A protein with a different AA sequence could be produced. • Germ Cell - If mutations occur in sex cells they may be passed on to the next generation. • Somatic- A mutation occurring only in body cells may be a problem for the individual but will not be passed on to the offspring. • Mutations may be classified as chromosomal alterations or gene mutations • Chromosomal alterations are generally more severe because many genes are usually involved.

  3. Significance of Mutations • Most are neutral • Eye color • Birth marks • Some are harmful • Cystic Fibrosis • Down Syndrome • Some are beneficial • Sickle Cell Anemia to Malaria • Immunity to HIV

  4. What Causes Mutations? • There are two ways in which DNA can become mutated: • Mutations can be inherited. • Parent to child • Mutations can be acquired. • Environmental damage • Mistakes when DNA is copied

  5. Types of Gene Mutations • Silent mutation • any mutation that is not expressed because it does not cause a change in amino acid chain. • Point mutation • base-pair substitution • 1base is replaced by a different base

  6. Point mutation • Only one nucleotide changes, but it makes a different protein

  7. Gene Mutations • Point Mutations – changes in one or a few nucleotides • Substitution • THE FAT CAT ATE THE RAT • THE FAT HAT ATE THE RAT • Insertion • THE FAT CAT ATE THE RAT • THE FAT CAT XLW ATE THE RAT • Deletion • THE FAT CAT ATE THE RAT • THE FAT ATE THE RAT

  8. Frameshift • Causes every codon in the DNA sequence to be changed after the mutation: • Insertion- one or more bases are added • Deletion- one or more bases are removed A

  9. Chromosomal Alterations • Deletion - part of chromosome is left out. • Duplication - part of chromatid breaks off add attaches to the sister chromatid creating a duplication of genes on the same chromosome. • Deletion and duplication mutations are errors that occur during crossing over in Meiosis I. • Translocation- when part of one chromosome breaks off and is added to a different chromosome. • Inversion- when part of a chromosome breaks off and is reinserted backwards.

  10. Structural Errors

  11. Chromosome Mutations • Changes in number and structure of entire chromosomes • Original Chromosome ABC * DEF • Deletion AC * DEF • Duplication ABBC * DEF • Transposition ACB * DEF • Inversion AED * CBF • Translocation ABC * JKL GHI * DEF

  12. Chromosomal Deletion A dinky Y chromosome and the hairy ear gene on the Y chromosome

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