BIOLOGY 2

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BIOLOGY 2

• GENETICS CONTINUED
• MENDELIAN GENETICS

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BACKGROUND INFO

• SEXUAL REPRODUCTION combining of sperm egg
  from two individuals
• OFFSPRING WILL HAVE CHARACTERISTICS OF BOTH
  PARENTS

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• ORGANISMS THAT ARE PRODUCED BY CROSSING
  INDIVIDUALS WITH DIFFERENT TRAITS ARE CALLED
  HYBRIDS
• HYBRID VIGOR -- hybrid organisms are more
  successful than those that are produced by a very
  small gene pool

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• GENE POOL all the genes that can be shared by
  reproduction within a population
• INBREEDING AND THE UNDESIRABLE TRAITS THAT
  ACCOMPANY IT ARE THE RESULT OF A LIMITED GENE POOL

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THE FATHER OF GENETICS

• GREGOR MENDEL NOTICED DIFFERENCES IN THE PEA
  PLANTS HE GREW IN HIS GARDEN

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• APPLIED THE SCIENTIFIC METHOD TO DETERMINE THE
  CAUSE OF THESE DIFFERENCES

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IMPORTANT GENETIC TERMS

• GENOTYPE -- the genetic make up of an organism
• PHENOTYPE -- the external appearance of an
  organism
• HOMOZYGOUS TRAIT -- genes for the trait that are
  the same ( RR or rr)

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• HETEROZYGOUS TRAIT -- genes for a trait that are
  not the same (Rr or Bb)
• MONOHYBRID CROSS -- a cross between individuals
  with one pair of contrasting genes
• ALLELE -- alternate forms of a gene usually
  represented by capital and lower case letters

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• DIHYBRID CROSS -- a cross between two individuals
  with two pairs of contrasting genes
• F1 GENERATION -- the offspring from the parents
• F2 GENERATION -- the offspring produced by
  crossing two F1 individuals

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• TEST CROSS -- mate a homozygous recessive
  individual with an unknown genotype for that
  characteristic
• PUNNETT SQUARE -- a chart used to solve genetic
  problems

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Mendels Laws

• LAW OF UNIT CHARACTERS
• there are units in the cell that are responsible
  for traits
• these units come in pairs
• offspring receive one unit from each parent

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• LAW OF SEGREGATION
• during sex cell formationgene pairs separate
• this separation occurs in meiosis
• this allows for the normal number of chromosomes
  to occur in the offspring

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• LAW OF INDEPENDENT ASSORTMENT
• fertilizationthe chromosomes with the traits are
  RANDOMLY sorted and passed on to the offspring
• LAW OF DOMINANCE
• dominant traits prevent the expression of the
  recessive traits

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GENETICS AND PROBABILITIES

• THE PASSING OF TRAITS IS A RANDOM EVENT
• THE PROBABILITY OF A PARTICULAR EVENT OCCURING IS
  THE FRACTION OF OUTCOMES IN WHICH THAT EVENT
  OCCURS

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WORKING WITH PROBABILITIES

• WHAT IS THE PROBABILITY THAT A 5 WILL COME UP
  WHEN A DICE IS ROLLED?

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• Possible outcomes are 1,2,3,4,5,6
• six possible outcomes - - -one of those being the
  number 5
• probability of a 5 coming up is 1/6 or 16.6667

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• WHAT IS THE PROBABILITY OF ROLLING AN EVEN NUMBER
  WITH A DICE?

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• The even numbers are 2,4,6
• each has a 1/6 chance of coming up
• the probability is 3/6 or 50

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• WHAT ARE THE CHANCES OF GETTING AN ACE WHEN
  CUTTING A SHUFFLED DECK OF PLAYING CARDS?
• 4 aces in 52 cards or 1 in 13
• 7.6923