Heredity

We know that traits are inherited, but how?

• What characteristics do you have in common with your parents? Your grandparents?

• If you have siblings, what characteristics do you have in common with them?

Take a look at yourself…

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Dominant or Recessive?

Cheek Dimples

• cheek dimples are dominant

Brown/black eyes?

• brown/black eyes are dominant over blue/green eyes

Attached Earlobes?

• attached earlobes are recessive

Widow’s Peak?

• pointed hairline is dominant over straight hairline

Hitchhiker’s thumb?

• a straight thumb is dominant over a bent thumb

Tongue roller?

• the ability to roll your tongue is dominant

Left thumb on top?

• when you fold your hands, the left thumb on top is dominant over the right thumb on top

6 fingers?

• polydactyly is dominant

How are these traits inherited?

Monks are known for many things…

Gregor Mendel (1822-1884)

• Austrian monk• did experiments with

garden peas that laid the foundation for modern genetics

• “the father of modern genetics”

• http://science.discovery.com/tv-shows/greatest-discoveries/videos/100-greatest-discoveries-shorts-genetics.htm

Mendel’s conclusions

• inherited characteristics are controlled by factors that occur in pairs

• one factor masks the effect of another (the principle of dominance)

• a pair of factors separate during the formation of sex cells

• each sex cell contains only one factor for each characteristic

Punnett square

• chart that organizes the possible combination of “factors” in offspring

• See this website for a simple animation on creating a Punnett square:

• http://www.ctahr.hawaii.edu/dnatoday/genepool/genepool%20think.html

Questions

• Read 4.2 (p.134-137) and answer the following questions: #1,3 (p. 137-138)