The document discusses heredity and genetics, including Gregor Mendel's pioneering experiments with pea plants in which he found that traits are passed from parents to offspring. Mendel conducted controlled breeding experiments and found that traits behave according to dominant and recessive patterns, with a 3:1 ratio of dominant to recessive traits appearing in the second filial generation. His work established the basic principles of heredity and laid the foundation for the modern science of genetics.

1. Genetics 101 Part 1

2. Tim & Moby: Genetics

3. Heredity
Heredity = The study of
characteristics that are passed
from parents to offspring

4. Think About It…….
Examples: Hair color, hair shape,
eye color, shape of mouth, height,
skin color
Name one characteristic that is inherited but that may
also be influenced by behavior or environment.
List five characteristics that are passed on in families.
Examples: Skin color, weight, height

5. What characteristics are inherited in
plants?
Shape of
the
leaves
Height of
plant
Color of
flowers

6. What characteristics are inherited in
animals?
Height of
animal
Shape of
body
Color of
fur/feathe
rs

7. Heredity Vocabulary
Character = inherited physical feature
Trait = different possible forms of a
character
Example
Characters:
Flower Color
Plant Height
Example Traits for
Flower Color:
purple or white
Self-Pollinating = The plant fertilizes itself
Cross-Pollinating = One plant fertilizes another
Dominant = A trait that will always be seen when present
Recessive = A trait that will only be seen if there is no
dominant trait present

8. Character Trait
Hair Color Blonde
Red
Brown
Black
White
Eye Color Brown
Blue
Green
Hair Shape Straight
Curly
Skin Color White
Brown
Black
Character vs. Trait

9. Who was Gregor Mendel?
 Gregor Mendel was a monk (in the 1800´s) who did
many scientific experiments with pea plants

10. Mendel´s Breeding
Experiments
 Mendel mixed many different characters of pea plants
and recorded his results
 After making thousands of experiments, Mendel was
able to predict patterns of heredity in pea plants (he
could determine the probability of how an offspring
would look)
Example Prediction:
Green Pea Pod + Yellow
Pea Pod

all green pea pod offspring

11. Why Pea Plants?
Mendel chose pea plants for three reasons:
1. Grows easily
2. Usually self-pollinates (offspring are exact copies
of parent)
3. Has many contrasting traits (two very different
traits for each character)

12. Mendel´s Experiment
 Mendel controlled which male and female parts
came in contact for fertilization
*Sometimes
Mendel Cross-
Pollinated the
plants
*Sometimes
Mendel allowed
the plants to Self-
Pollinate

13. Mendel´s First Experiments
STEP 1= Allow plant to self-pollinate for many
generations so each offspring produced is always the
same (True Breeding)
 This generation is called P (parental)
STEP 2 = Cross two P generations with contrasting traits
(example: purple flowers vs. white flowers)
 Offspring of P generation = F1 (first generation)
STEP 3 = F1 generation allowed to self-pollinate and
produce new plants
 Offspring of F1 generation = F2 (second generation)

14. Mendel´s First Experiments

15. Ratios of Mendel´s
Results
Ratios
3:1

16. Mendel´s Results
 F1 generations only showed one trait (this trait is
dominant)
 F2 generations showed both dominant and recessive
traits
 Each of the 7 characters had similar ratios in the F2
generation : 3:1
For every 4
offspring: 3 showed
the dominant trait
and 1 showed the
recessive trait

17. • Draw Mendel’s first experiment
using a character other than flower
color
• Draw the process and results in your
copybook (include labels)