Heredity Heredity = The study ofcharacteristics that are passed from parents to offspring
Think About It…….List five characteristics that are passed on in families. 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. Examples: Skin color, weight, height
What characteristics are inherited inplants? Shape of the leaves Height of plant Color of flowers
What characteristics are inherited inanimals? Height of animal Shape of body Color of fur/feathe rs
Heredity Vocabulary Example Characters: Flower Color Character = inherited physical feature Plant HeightExample Traits for Trait = different possible forms of a Flower Color: character purple or whiteSelf-Pollinating = The plant fertilizes itselfCross-Pollinating = One plant fertilizes anotherDominant = A trait that will always be seen when presentRecessive = A trait that will only be seen if there is nodominant trait present
Character vs. Trait Character TraitHair Color Blonde Red Brown Black WhiteEye Color Brown Blue GreenHair Shape Straight CurlySkin Color White Brown Black
Who was Gregor Mendel? Gregor Mendel was a monk (in the 1800 s) who did many scientific experiments with pea plants
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
Why Pea Plants?Mendel chose pea plants for three reasons:1. Grows easily2. Usually self-pollinates (offspring are exact copies of parent)3. Has many contrasting traits (two very different traits for each character)
Mendel´s Experiment Mendel controlled which male and female parts came in contact for fertilization*SometimesMendel Cross-Pollinated theplants*SometimesMendel allowedthe plants to Self-Pollinate
Mendel´s First ExperimentsSTEP 1= Allow plant to self-pollinate for manygenerations so each offspring produced is always thesame (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 andproduce new plants Offspring of F1 generation = F2 (second generation)
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 4offspring: 3 showed the dominant trait and 1 showed the recessive trait
• Draw Mendel’s first experiment using a character other than flower color• Draw the process and results in your copybook (include labels)
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