Integrated Science Ch. 7

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Integrated ScienceCh. 7

• Tracking Traits
• An Introduction
• to Genetics

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Mendel The Founder of Genetics

• Heredity
• - the passing of traits from parent to
  offspring
• I. Genetics
• -the study of heredity

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Early Idea about Genetics
Homunculus
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A. Gregor Mendel

• - father of genetics
• - proposed the Principles of Heredity
  (1880's)
• - Austrian monk, taught "high school biology"

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B. Experimented with peas

• - several crops per year
• - don't take up much space
• - developed "purebreds"

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- easy to control pollinate
Pistil(female)produceseggs
Stamens(male)producepollen
Pea Flower
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- seven distinct, inherited traits
Seed shape
Seed color
Pod shape
Pod color
Flower color
Flower location
Plant size
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P
F1
9
F1
F2
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II. Principles of Heredity

• A. Concept of Unit Characters
• - traits are controlled by "factors" (genes)
  which occur in pairs
• - one from each parent

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B. Principle of Dominance and Recessiveness

• - some alleles are dominant, or mask, the effect
  of other alleles
• - Allele one of the "versions" of a gene

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C. Law of Segregation

• - during meiosis (production of gametes), each
  pair of genes separate

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Cross Fertilization of Parents
Pollen
Cross-Fertilize
pp
PP
Pollen
Pp
All Purple-flowered (Heterozygous) Offspring
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Self-fertilization of F2
Pp
F1
Self-Fertilize
75 Purple25 White
PP
Pp
Pp
pp
F2
F2
F2
F2
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1. Gametes

• - specialized, reproductive cells (sperm, egg)
• - have 1/2 a set of chromosomes

Human Egg and Sperm Cells
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1. Gametes
- specialized, reproductive cells (sperm, egg) -
have 1/2 a set of chromosomes

• 2. Genotype
• - genetic make-up of an organism
• 3. Phenotype
• - physical appearance of an organism

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4. Homozygous

• - alleles in a gene pair that are identical
• - TT or tt

5. Heterozygous - alleles in a gene pair
that are different - Tt
TT
Tt
tt
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The End