DNA, Mutations, Chromosomes, and Reproduction Review

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DNA, Mutations, Chromosomes, and Reproduction
Review
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DNA The Genetic Code

• Genes
• main function is to control the production of
  proteins in an organisms cells.
• Proteins help to determine the size, shape,
  color, and many other traits of an organism

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DNA Structure

• DNA structure
• 4 Nitrogen bases Adenine (A), Thymine (T),
  Guanine (G), and Cytosine (C).
• Form the rungs of the DNA ladder
• Adenine always binds with Thymine
• Guanine always Binds Cytosine
• RNA
• Thymine is replaced by Uracil
• So Adenine binds with Uracil

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Genes

• A section of DNA
• Contains the information to code for one specific
  protein
• Made up of a series of bases in a row

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Making Proteins

• During protein synthesis, the cell uses
  information from a gene on a chromosome to
  produce a specific protein

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Mutations

• Any change in a gene or chromosome
• Can cause a cell to produce an incorrect protein
  during protein synthesis
• The trait or phenotype may be different
• Body cell mutations will not be passed on to
  offspring
• If the mutation is in a sex cell, the mutation
  can be passed on to an offspring and affect the
  offsprings phenotype

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Question

• If a cat gets hit by a car and loses a leg, does
  this mean it will have kittens that are also
  missing a leg?

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Effects of Mutations

• Introduce changes in an organism
• Can be a source of genetic variety
• Some are harmful, some are helpful, others are
  neither helpful nor harmful
• A mutation is harmful if it reduces the
  organisms chance for survival and reproduction

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Chromosome Theory of Inheritance

• Sutton discovered that sex cells contain half the
  number of chromosomes as body cells.
• One set of alleles comes from the male parent
  the second set comes from the female parent
• Chromosome theory of inheritance
• Genes are carried from parents to their offspring
  on chromosomes

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Mitosis

• Mitosis (asexual reproduction)
• No change in genetic variability
• No genetic loss from meiosis or recombination
• Good in stable environmentsones that are NOT
  always changing
• Occurs in body cells
• Results in 2 cells
• Results in cells with the same of chromosomes
  as the original parent cell

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Meiosis

• Sexual Reproduction
• Rearranging the genome creates variability
• Almost 50 of genetic material is lost during
  recombination
• Good in variable environmentsones that are
  always changing
• Occurs only in sex cells
• Results in 4 cells
• Results in cells with half the chromosome as
  the parent cell

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