GENETICS

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GENETICS
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Background Info

• Gregor Mendel
• Austrian Monk (1822-1884)
• Father of Genetics
• Genetics study of heredity
• Heredity passing of characteristics from parent
  to offspring.

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Background Info

• Gregor Mendel
• Identified that all traits are controlled by a
  factor
• This factor is a gene
• GENE section of a chromosome/DNA that codes for
  a trait.
• TRAIT characteristic passed from parent to
  offspring

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Genome

• ALL of an organisms genetic material

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Background Info

• Gregor Mendel
• Studied Pea Plants to show how traits are passed
  from one generation to the next
• He applied math to his observations
• Studied pea plants because they came in 2
  distinct forms

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Why did he choose the Pea Plant?

• 1. The Structure of the Pea Flower
• 2. The seven distinct traits (2 distinct forms)
• 3. Rapid reproduction (Most pea plants reproduce
  in 90 days)

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Pea Plant Traits (Each trait only has 2 distinct
forms)
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Genes Alleles

• Genes chemical factors that determine traits
  (Flower color)
• Alleles different forms of genes that code for
  traits (Purple flowers or White flowers)

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Mendel found Dominant and Recessive Traits

• An Allele is a distinct form of a gene
• A dominant allele is the form that is visibly
  seen.
• A recessive allele is the form that is there but
  not seen (unless there are 2 recessive alleles
  together).

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Symbols

• Dominant Alleles
• Capital Letters

• Recessive Alleles
• Lower Case Letters

A
a
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Genotypes

• Genotype
• Genetic makeup represented by symbols
• AA, Aa, aa, TT, Bb, dd

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Phenotypes

• Phenotype
• Physical appearance expressed in words
• Brown hair, Green eyes, Freckles

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Heterozygous

• Heterozygous (different)
• Gene pairs that carry one dominant and one
  recessive allele
• Aa, Bb, Cc, Dd

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Homozygous

• Homozygous (same)
• Gene pairs that carry 2 dominant OR 2 recessive
  alleles
• AA, aa, BB, bb

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Probability

• Determining the likelihood of an event to occur
• Can be shown in 3 ways
• Fraction 1/2
• Percent 50
• Ratio 12

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Hybrids Purebreds

• Hybrids receive different alleles from each
  parent (Hh, Bb, Zz)
• Purebreds receive the same alleles from each
  parent (HH, bb, ZZ)

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Laws of Genetics

• Law of Dominance Dominant traits will always
  show over recessive traits
• Law of Segregation Alleles separate during
  meiosis
• Law of Independent Assortment gene pairs
  separate randomly and independently of each other

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Mendels Crosses

• He started with 2 groups of purebred plants,
  called the P1 generation.
• He crossed the purebreds by hand.
• The P1s offspring was called the F1 generation.
  The F1s then self-fertilized.
• The F1s offspring was known as the F2
  generation.

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Monohybrid CrossesA genetic cross that looks at
1 trait

• Cross a homozygous tongue roller with a
  non-tongue roller
• Genotype of parents
• TT x tt
• Phenotypes of parents
• Tongue roller, non-tongue roller
• Possible Outcomes
• Genotypic ratio
• 100Tt
• Phenotypic ratio
• 4 Tongue rollers0 non-tongue rollers

T T
t
t
Tt
Tt
Tt
Tt
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Monohybrid Crosses

• Cross 2 Heterozygous tongue rollers
• Genotype of parents
• Tt x Tt
• Phenotypes of parents
• Tongue roller, Tongue roller
• Possible Outcomes
• Genotypic ratio
• 1TT2Tt1tt
• Phenotypic ratio
• 3 tongue rollers 1 non-tongue roller

T t
T
t
Tt
TT
Tt
tt
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Monohybrid Crosses

• Cross a heterozygous Tongue roller with a
  Non-Tongue roller
• Genotype of parents
• Tt x tt
• Phenotypes of parents
• Tongue roller, non-tongue roller
• Possible Outcomes
• Genotypic ratio
• 2Tt2tt
• Phenotypic ratio
• 2 tongue rollers2 non-tongue rollers

T t
t
t
tt
Tt
Tt
tt
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Dihybrid Crosses

• A genetic cross that looks at 2 traits
• Cross 2 heterozygous green, round peas GgRr x
  GgRr
• Genotypic Ratio
• 121242121
• Phenotypic Ratio
• 9331

G green R Round g yellow r wrinkled
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Dihybrid Crosses
GR Gr gR gr
GR
Gr
gR
gr
Gg RR
GG Rr
GGRR
Gg Rr
Gg Rr
GG rr
GG Rr
Gg rr
Gg Rr
Gg RR
gg Rr
gg RR
Gg rr
gg rr
Gg Rr
gg Rr