How are traits passed down from one

generation to the next?

How are traits passed down from one

generation to the next?

LAB: Analyzing Inheritance in Fast Plants

LAB: Analyzing Inheritance in Fast Plants

Why do these plants grow faster than other plants?

Why do these plants grow faster than other plants?

What will our seeds look like when they grow?

What will our seeds look like when they grow?

Fast Plant Development Time Lapse

How did the parent-plants create the next

generation?

How did the parent-plants create the next

generation?

Pollinating and Harvesting Fast Plants

Wisconsin Fast PlantsWisconsin Fast Plants

Non-Purple Stem

Non-Purple Stem Purple StemPurple Stem

Second Generation F2

First Generation F1

Parent Generation (P2)

PURPLE

Parent Generation (P1)

NON-PURPLE

Parent 1 Seeds (P1)

Parent 2 Seeds (P2)

The seeds from the pollinated F1 Plants are

used to grow the F2

Generation

The seeds from the pollinated Non-

Purple Plants are used to grow the F1

Generation

Seeds Grow into F1

Seeds Grow into F2

POLLINATION

X

Fast Plant Generations

POLLINATION

PLANTING PROCEDURESPLANTING PROCEDURES

① Measure 2 cm from the bottom of each filter paper and draw a line.

① Measure 2 cm from the bottom of each filter paper and draw a line.

2 cm

Table NameClass Name

Generation Name② Write the name of the

generation (P1 , P2 , F1 , F2) and the names of your table/class.

PLANTING PROCEDURESPLANTING PROCEDURES③ Put the filter paper inside the petri

dishes.③ Put the filter paper inside the petri

dishes.

2 cm

Table NameClass Name

Generation Name

④ Fill the pipet with water; slowly moisten the filter paper with drops of H2O.

⑤ Send 1 person to Ms. B collect the seeds for each generation.

PLANTING PROCEDURESPLANTING PROCEDURES⑥ Evenly spread out the seeds on the

filter paper. Place them ABOVE the line.

⑥ Evenly spread out the seeds on the filter paper. Place them ABOVE the line.

2 cm

Table NameClass Name

Generation Name

⑦ Wait for 1 minute then cover the petri dishes.

⑧ Bring the petri dishes to Ms. B to place under the lamp.

Results: P GenerationResults: P Generation

Results: F1 GenerationResults: F1 Generation

Results: F2 GenerationResults: F2 Generation

The A, B, Peas…

of Life!!

The A, B, Peas…

of Life!!

How the study of pea plants changed the way we think about

life.(Genetics Week 1)

How the study of pea plants changed the way we think about

life.(Genetics Week 1)

I Can #10I Can #10

I CAN describe the results of Mendel's crosses and explain the significance of Mendel's findings for modern genetics.

Have you ever wondered why some family members look very similar while others look very different?

Have you ever wondered why some family members look very similar while others look very different?

These are pictures of Peter, Lois, and Chris from Family Guy.

Which character traits does Chris have in common with his Dad or his Mom?

DAD: Peter

MOM: Lois

SON (offspring): Chris

Heredity and TraitsHeredity and Traits

• Traits are different forms of a characteristic.

• Heredity is the passing of traits from parent to offspring (children).

• Traits are different forms of a characteristic.

• Heredity is the passing of traits from parent to offspring (children).

Detached Earlobe

Attached Earlobe

More on Heredity…More on Heredity…• Only certain traits can be passed from parent

to offspring…• For example, you might inherit your Dad’s hair

color but you wouldn’t inherit the scar on his chin leftover from a painful football practice…

• Only certain traits can be passed from parent to offspring…

• For example, you might inherit your Dad’s hair color but you wouldn’t inherit the scar on his chin leftover from a painful football practice…

PurebredPurebred

• A true-breeding or a purebred organism is the offspring of many generations that have the same characteristics.

• For example, purebred purple pea plants always come from purple parent plants.

• A true-breeding or a purebred organism is the offspring of many generations that have the same characteristics.

• For example, purebred purple pea plants always come from purple parent plants.

Gregor Mendel and Genetics

Gregor Mendel and Genetics

• Gregor Mendel (a 19th century monk), was the first person to study genetics (the scientific study of heredity).

• Gregor Mendel (a 19th century monk), was the first person to study genetics (the scientific study of heredity).

Mendel’s QuestionMendel’s Question

• Why are pea plant’s traits sometimes similar to their parents and sometimes very different?

• Why are pea plant’s traits sometimes similar to their parents and sometimes very different?

Mendel’s HypothesisMendel’s Hypothesis

• Mendel hypothesized that something was being passed from parent to offspring to control the passing of traits--but how? And was there a pattern?

• Mendel hypothesized that something was being passed from parent to offspring to control the passing of traits--but how? And was there a pattern?

Hmmm…the passing of traits

must be controlled by something…

right?

Mendel’s ExperimentMendel’s Experiment

• Mendel decided to “cross” two plants with different traits to see what traits the offspring would have.

• In his first experiment he “crossed” a tall plant with a short plant.

• Mendel decided to “cross” two plants with different traits to see what traits the offspring would have.

• In his first experiment he “crossed” a tall plant with a short plant.

Mendel’s ExperimentMendel’s Experiment• Mendel called this first

generation of parent plants the parental generation or P generation

• The tall and short pea plants he used were both purebred.

• Mendel used a paint brush to “cross-pollinate” the two plants.

• Mendel called this first generation of parent plants the parental generation or P generation

• The tall and short pea plants he used were both purebred.

• Mendel used a paint brush to “cross-pollinate” the two plants. ?

Mendel’s DataMendel’s Data

• In the second generation of pea plants, Mendel saw that all of the offspring were tall.

• He decided to cross this second generation (called F1 Generation) with each other to see what would happen.

• In the second generation of pea plants, Mendel saw that all of the offspring were tall.

• He decided to cross this second generation (called F1 Generation) with each other to see what would happen.

?

Mendel’s DataMendel’s Data

• But the next generation (F2 Generation) was more surprising!

• He had all tall plants except for one small plant!

• But the next generation (F2 Generation) was more surprising!

• He had all tall plants except for one small plant!

WAIT! So 2 tall plants

produced a SHORT plant?!

WAIT! So 2 tall plants

produced a SHORT plant?!

Mendel Experiments Again (and again….)

Mendel Experiments Again (and again….)

• Mendel was so confused by the sudden re-appearance of the “short” trait, that he decided to do more experiments like this one but with different traits.

• Mendel was so confused by the sudden re-appearance of the “short” trait, that he decided to do more experiments like this one but with different traits.

Mendel’s Next ExperimentMendel’s Next Experiment

Violet vs.

White

Violet vs.

White

Mendel’s DataMendel’s Data

• In all of Mendel’s crosses, only one form of the trait showed in the F1 Generation.

• However, in the F2 Generation, the “lost” form of the trait always appeared in 1/4 of the plants.

• In all of Mendel’s crosses, only one form of the trait showed in the F1 Generation.

• However, in the F2 Generation, the “lost” form of the trait always appeared in 1/4 of the plants.

Mendel’s ConclusionsMendel’s Conclusions

• The “factors” that control each trait exist in pairs. The female parent contributes one factor, while the male parent contributes another factor.

• One factor in a pair can “hide” the other factor. (The “tall factor” hides the “short factor”.

• The “factors” that control each trait exist in pairs. The female parent contributes one factor, while the male parent contributes another factor.

• One factor in a pair can “hide” the other factor. (The “tall factor” hides the “short factor”.

Summarizing Mendel’s Experiments

Summarizing Mendel’s Experiments

Mendel wanted to know how it was possible for a trait like white pea plant color to disappear in one generation and then reappear in the next.

His conclusion: the trait is always there--its just hidden by another trait!!

Mendel wanted to know how it was possible for a trait like white pea plant color to disappear in one generation and then reappear in the next.

His conclusion: the trait is always there--its just hidden by another trait!!

Dominant and Recessive Alleles

Dominant and Recessive Alleles

Mendel came up with the terms DOMINANT and RECESSIVE alleles to describe how some traits could be “hidden” or “masked” by other traits.

Mendel came up with the terms DOMINANT and RECESSIVE alleles to describe how some traits could be “hidden” or “masked” by other traits.