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GENETICSLavender

TRUE or FALSE?

Like mixing paints, parents’ traits always blend in their offspring.

If you look more like your mother than your father, then you received more traits from your mother.

New DNA is copied from existing DNA.

What makes you unique?

Earlobes? Thumbs? Interlacing fingers?

Why might some students have types of traits that others do not?

Genetics

The study of how traits are passed from parents to offspring.

Gregor Mendel – the father of genetics An Austrian monk Performed experiments that helped answer questions about

heredity and disprove the idea of blending inheritance Mendel

Heredity & Traits

Heredity: The passing of traits from parents to offspring.

Traits: a distinguishing characteristic or quality, especially of one's personal nature

Mendel’s Experiments

Mendel used PEA PLANTS to study genetics

They reproduce quickly = lots of data They have easily observed traits (flower color, pea

shape) He could control reproduction – which plants result in

which traits

Pollination in Pea Plants

Read this section on page 672. Jot down notes Draw the diagram from figure 1. Answer the following questions.

Would this pea plant be more likely to self-pollinate or to cross-pollinate?

What does the arrow indicate is happening to the pollen?

True Breed vs. Cross Pollination

Mendel began his experiments with true breed pea plants. Ex: When a round pea plant self-pollinates it always

produces round pea plants.

Mendel used true breed pea plants to cross pollinate. Observe figure 2 – he crossed a purple flower with a

white flower to observe the TRAITS that appeared in the offspring.

He did this with flower color, seed color, seed shape

Mendel’s Results

First generation crosses Purple x Purple = Purple White x White = White Purple x White = Purple

WHY? This led to Mendel conducting second-generation crosses…

Second Generation Crosses

Hybrid plants – purple plants (came from purple x white)

He crossed two purple hybrid plants Observe figure 4 (pg 675)

The trait that disappeared in the first generation (white) always reappeared in the second generation.

Observe Mendel’s Data

Page 676 – Table 1 What characteristics did Gregor Mendel study? What do you notice about the ratio?

Mendel’s Conclusion

When organisms reproduce, each reproductive cell (sperm & egg) contributes one factor for each trait.

Dominant – a genetic factor that blocks another genetic factor

Recessive – a genetic factor that is blocked by the presence of a dominant factor (only observed when 2 recessive factors are present)