January 27, 2015
Materials:
• Pen/pencil
• Notebook
• Packet
• Cells Heredity book
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Agenda
AGENDA
Daily question
Gregor Mendel notes
Reading activity
Brain pop
DQ: What traits
did you obtain
from your
parents, list 2?
Chapter 4 Vocabulary
GREGOR MENDEL
“The Father of Genetics”
•Austrian monk from the 1800’s.
•Studied over 30,000 specimens of pea plants during an
8 year period.
•He studied 7 characteristics of pea plants:
1. Plant height (dwarf vs. tall)
2. Flower & pod position (on side or top of stem)
3. Seed shape (round or wrinkled)
4. Seed color (green or yellow)
5. Pod shape (inflated or constricted)
6. Pod color (green or yellow)
7. Flower color (white or purple)
•True-breeder: Will always produce offspring w/ a
particular trait when allowed to breed naturally. “Pure
bred.”
•Non-true-breeder: Will produce offspring that are not
necessarily identical to itself.
•Mendel’s 1st experiment crossed a true-breeding plant
of regular height w/ a true-breeding plant of short height.
•All of the plants were of regular height. → 1st
Generation.
•The short trait seemed to have disappeared.
•Next, Mendel let the 1st generation self-pollinate w/
each other → 2nd Generation.
•75% of the plants were regular height, 25% were short.
•He repeated this experiment for multiple traits – flower
color, pod color, etc.
•He found that similar results were obtained in each
experiment.
He realized that…
1. Organisms must have 2 “factors” for each possible
trait, one from each parent.
2. Some traits can be masked by others.
Heredity Video
HEREDITY AND GENETICS
NOTES
PARENTS AND OFFSPRING ARE SIMILAR
 Inherited Traits
 Examples: Dimples, Freckles, Eye Color, Hair Color, Height, Body Type
GENES ARE ON CHROMOSOME PAIRS
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Individuals inherit genes from PARENTS
Genes are located on CHROMOSOMES
Each parent contributes ONE gene for each trait
Genes code for TRAITS
Humans have 46 chromosomes, 23 from each parent
Dif ferent forms of the same gene are ALLELES
 EX: Alleles for the eye color gene: blue, green, brown, hazel, etc.
GREGOR MENDEL’S DISCOVERIES ABOUT
HEREDIT Y
 He studied…
 How traits were inherited in pea plants!
 Mendel’s Conclusions
 Traits inherited in patterns
 Some traits were stronger than others
ALLELES INTERACT TO PRODUCE TRAITS
 An allele is a dif ferent form of a gene
 Phenotype
 Physical or observable traits
 Ex: blue eyes, black hair, etc
 Phenotype is determined by
GENOT YPE
 Genotype
 Gene pairs, or gene combo
 Represented by 2 letters
(one for each allele)
 EX: Bb, TT, rr
 2 alleles make a GENOT YPE
 Dominant
 Stronger trait, hides recessive trait
 Represented by A CAPITAL LETTER
 EX: B, T, R
 Recessive
 Weaker trait, sometimes hidden
 Represented by a lower case letter
 EX: b, t, r