mendel and his peas. why don’t you look like a rhinoceros? heredity – passing of traits from...

Mendel and his Peas

Why Don’t You Look Like a Rhinoceros?

Heredity – passing of traits from parent to offspring

Who was Gregor Mendel?• Born in 1822• Austrian monk • Studied how traits are passed from

parent to offspring in the monastery garden

http://science.discovery.com/videos/100-greatest-discoveries-shorts-genetics.html

Unraveling the MysteryMendel studied pea plants WHY?• Easy to grow• Have many traits• Pea plants can self-pollinate

– this means the plant has both MALE and FEMALE reproductive

parts

Self PollinatingDuring pollination, pollen from the

anthers (male) is transferred to the stigma (female)

Peas Be My PonderMendel chose to study only one

characteristic at a time such as - height OR pea color Tall/Short Green/Yellow

And he chose plants that had two forms for each of the characteristics studied

How many different “forms” of eye color exist?

Pea Plant TraitsCharacteristics:Use Figure 4 (pg 110) in your textbook to list

the 7 characteristics of pea plants and their two forms – think, pair, share!

Pea

Trai

ts

True Breeding Plants

• A true bred parent will ALWAYS produce offspring with the same trait

• Examples …– A true bred purple flower will produce ? flowers– A true bred yellow seed will produce ? seeds

MENDEL’s 1st ExperimentMendel crossed two true bred plants

with different forms of the same trait

Wrinkled seed plant X Round seed plant

MEDEL’S 1ST EXPERIMENT

When Mendel crossed round seed plants X wrinkled seed plants, the new plant had ALL ROUND seeds

The offspring from this cross are knownas the First generation or F1

MENDEL’S 1ST EXPERIMENT

For each cross, one trait always appeared and the other seemed to vanish in F1

Dominant – trait that appears/strongerRecessive – trait that vanishes/hidden

What is the dominant trait?What is the recessive trait?

MENDEL’S 2nd EXPERIMENTMendel allowed first generation (F1)

from each cross to self-pollinate Round seeds X Round seeds

When the F1 generation self-pollinated, the wrinkled (recessive) reappeared in the Second generation (F2)!

MENDEL’S RESULTSMENDEL’S RESULTS: In the 2ndgeneration, the

RECESSIVE trait showed up again but NOT as often as the DOMINANT

Can you determine the ratio of D to R? __:__

MENDEL’S EXPERIMENTSUse Figure 6 (p. 109) to explain Mendel’s First

and Second Experiments:

MENDEL’S EXPERIMENTS

http://www.videosurf.com/video/gregor-mendel-rap-54017176