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Chapter 16 (Mutations # (Somatic mutation (may matter in extensive…

- - - - chemicals
        
        mostly man made
        
        increasing drastically in environments
      - x-rays
      - UV light
      - Radiation
    - - caused in several ways
        
        self-complementary sequence
        
        DNA unwinds ahead of DNA polymerase
        
        self-complementary sequence may form loop
        
        DNA polymerase pass through loop
        
        DNA molecule gets shorter than it should
      - transposable elements
    - - variety of enzymes repair DNA
      - transposable elements
        
        most useful causes of insertion
        
        Pieces of dna
        
        Change position between chromosomes
        
        two basic forms
        
        insertion sequence
        
        few thousand base pairs long
        
        contain genes that code for enzymes
        
        enzymes involved in cutting and splicing
        
        transposons
        
        like insertion sequence except for
        
        may be much longer
        
        carries genes tha code
        
        genes code for proteins
        
        proteins not associated with transposition
        
        insertion mutations caused may vary
        
        element inserted into spacer DNA is ok
        
        insertion in gene causes disruption
        
        may be viruses
        
        plants have mechanisms to fight
        
        but most nuclei contain transposable elements
  - - - If mutations are in spacers, there's no effect
      - insertion/deletion in introns are unimportant
      - in exons small mutations wont matter if amino acid is same
      - some codon mutations can disrupt proteins
      - an insertion can cause improper folding
      - mutations in promoter area can inactivate genes
    - - enzymes are 300-400 amino acids long
      - trillions of proteins can exist
      - Mutations in tRNA and rRNA can be less useful
  - - - in blackberries, alder, and prickly pear cactus
      - if it affects rise in vegetative offshoot
      - mutation could affect a flowers sex cells
  - - - loops
      - base mismatches
      - other problems
    - - may make an error 1 in 1million nucleotides
      - genomes can be several billion base pairs long
      - this means numerous errors
- - - - needs exact same genotype
      - results in 3 types of F1's
  - - - they may carry recessive trait
      - only way to know is to show it
    - - all gametes produced carry recessive
      - unable to mask homologous alle
      - if question plats is homo dominant, all show dominant trait
      - if hetero, show half and half
    - - dominant homo, selfed is always dom homo
      - useful in expirements
- - - - genes on different chromosomes
      - alleles of 1 gene move independently
- - - - 2 sets of chromosomes
      - even ploidy levels are fertile
      - odd are sterile
    - - how change in chromosome # comes about
      - per nucleus, in plants
    - - deleterious mutations are not eliminated quickly
      - extra copy of genes become nonfunctional
      - genes still recognized as duplicates of wildtype
    - - made of multiple copies
      - extra paralogs of a gene needed