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