INHERITED TRAITS

INHERITED TRAITS

Inherited Traits-A characteristic that is passed from parent to offspring. • For example, Corn-Can you thing of inherited traits it passes on? kernel color ear size plant height

Heredity-is the passing of these traits from one generation to the next. (Heredity applies to all organisms, including plants, animals, and even bacteria.) • Genetics-is the study of how heredity works.

Pollination-is the transfer of pollen grains from the male part of a flower to the female part of a flower. • Self-pollination is the pollination of a flower’s female parts by pollen from the male parts of the same flower. • Cross-pollination takes place when pollen from one flower is transported to a different flower.

Purebred-the same form of that trait is shown in all of its offspring for several generations. • Hybrid-is an organism produced by crossing parents that have two different forms of the same trait.

Dominant Traits-the form of the trait that appears in the hybrid generation. • Recessive Traits-the form of the trait hidden, or masked, in the hybrid generation.

Gregor Mendel discovered principles of heredity through gardening.

Gregor Mendel • He grew up on his family’s farm. As he learned how to take care of plants and animals, he became curious about how traits are passed from one generation to the next. • Eventually, he became a science teacher and a monk. He lived in a monastery and was in charge of the gardens there. • He began conducting controlled experiments at the monastery.

Gregor Mendel made huge advances in the area of biology. This is what he did. He crossed pea plants by taking a paintbrush and transferred pollen from one purebred pea flower to another purebred pea flower. This is referred to as cross-pollination.

Mendel’s Experiment • Refer to handout

Traits in Garden Pea Plants Studied by Mendel

Why did he use pea plants? • Pea plants have distinct traits, which are easy to trace from one generation to another. • Since the pea plant flowers are reproductive organs, you can see the male and female parts easily. (Pea plants self-pollinate because male and female parts are in the same flower.) • Pea’s offspring grow and mature quickly. • Easy to gather large amounts of data.

Mendel’s Experiment Concluded Each tall hybrid in the first offspring generation carried both tall and short traits. Dominant traits - the trait in the hybrid generation that was visible (tallness). Recessive traits - the trait in the hybrid generation that was hidden or masked (shortness). In the second offspring, for every three dominant traits there was one recessive, or 3:1.

What is Probability? • Probability means “how likely it is that something will happen. • The probability that something will happen can be calculated using mathematics.

Example of Probability • If you had a penny and tossed it once in the air, what would be the probability of getting heads? • 50% or one out of two

Now You Try This What if you toss a penny 50 times? What would the outcome likely be? 25 heads and 25 tails The greater the number of trials the closer the outcome will be to 50%.

Using Probability to Predict Genetic Outcomes • This is like tossing two coins at once. • There are four possible outcomes Heads-Heads 25% Tails-Tails 25% Heads-Tails 25% Tails-Heads 25%

The possible outcomes of two coins tossed are very similar to those of a genetic cross. • Geneticists use the laws of probability to predict the results of genetic crosses. Why? • There are two possible factors for a trait. Each parent, like a coin, has two factors for a trait. • Like tossing two coins, two parents give one factor each for a trait to the offspring.

In the Punnett Square, letters are used to represent Mendel’s factors for each trait. Dominant Factor Recessive Factor Factor that appears less often Always written with a lowercase (“little”) letter Only way you see a recessive factor is if there are two recessive factors together • Factor that appears most often • Always written with a CAPITAL LETTER • If a dominant and recessive factor are together, you will see the dominant factor

Punnett Square Table is for predicting outcomes of crossing different traits. PARENT ONE PARENT TWO Written along the left side One letter per box • Written across the top • One letter per box

You don’t inherit traits, you inherit factors for traits.

TIME TO PLAY

Traits Bingo • Mark the square marked I cross my right thumb over my left when I clasp my hands if this describes you. • Mark the square marked Shared trait-Left if you have a trait with the person sitting to your left. • Mark the square marked Least common trait if you have a trait that no one else in your group share.

Mark the square Attached earlobes if you have this trait. • Mark the square Blue eyes if you have this trait. • Mark the square or squares naming the relatives from whom you do not inherit traits. • Mark the square marked I have allergies if you have this trait. • Mark the square marked Trait in common-Right if you and your neighbor to the right share a common trait.

Mark the square marked Detached earlobe if you have this trait. • Mark the square marked Straight hairline if you have this trait. • Mark the square marked Can not roll tongue if you have this trait. • Mark the square naming relatives from whom you do inherit traits. • Mark the square marked I have a different trait than the person sitting next to me if this describes you.

Mark the square Curly hair if you have this trait. • Mark the square marked Freckles if you have this trait. • Mark the square marked Dimples if you have this trait. • Mark the square marked Cleft chin if you have this trait. • Mark the square marked I cross my left thumb over my right when I clasp my hands if this describes you.

Mark the square Brown hair if you have this trait.

Have a GREAT day! • I would like to give special thanks to Mrs. Johnson for allowing me to be part of your classroom. • I hope you learned something new and exciting. • Thank you for allowing me to teach you about inherited traits.

INHERITED TRAITS