Independent Research Big picture goal you will be

Independent Research! Big picture goal… you will be able to conduct your own research after high school! Today we will be learning about how traits can be predicted using punnet squares. Take notes to be able to answer the following questions: “Independent Research: Punnet Squares” 1. 2. 3. 4. Who is Gregor Mendel? TIP: Use index to start! What is a DOMINANT trait? What is a RECESSIVE trait? Describe at least 3 traits were found to be either dominant or recessive in pea plants.

How do we know about traits ? ! It’s all because of Gregor Mendel! Video clip

Gregor Mendel • Gregor Mendel was a priest who liked to garden • He grew pea plants and found a way to crosspollinate them cross-pollinate = to combine pollen and eggs from two different flowers

Mendel’s Contributions 1. What is a gene? Genes = pieces of DNA that pass on traits 2. What is an allele? different forms of a gene are called alleles 3. Where do alleles come from? One allele for each gene is passed on from each parent

Mendel’s Law of Dominance For every gene, there is 1 dominant allele 5. What is the difference between dominant and recessive alleles? • Dominant alleles = capital letters (B) • Recessive alleles = lowercase letters (b) * If a dominant allele is present, it will always be shown!

Naming Traits 6. What is homozygous? If both alleles are the same (both capital or both lowercase) Purebred 7. What is heterozygous? If the two alleles are different (one capital and one lowercase) Hybrid → RR or rr Homozygous “Same zygote” → Rr Heterozygous “Different zygote”

Predicting Traits 8. What is a punnet square? We can predict the results of a genetic cross using a Punnett Square! Parent #2 alleles Draw this square in your notes Parent #1 alleles Multiply traits to get 4 possible offspring results

Punnett Squares!

Punnett Squares! B b b b

Punnett Squares! B b B b

Punnett Squares! B b b B b

Punnett Squares! B b b Bb bb b B b

Punnett Squares! B b b Bb bb

Punnett Squares! B b b Bb bb

9. How do punnet squares show fertilization? Sperm or Egg Cell + B b b Bb bb Egg Cell +

9. How do punnet squares show fertilization? B b 4 possible zygotes! b Bb bb

Predicting Traits Let’s look at the trait of rolling your tongue: 1. First assign the trait a letter: Let’s choose “r”. 2. Then assign alleles: • Tongue rollers = R (dominant) • Non-tongue rollers = r (recessive) If your genes are RR or Rr you can roll your tongue If your genes are rr you cannot roll your tongue.

Predicting Traits What would happen if a tongue roller had children with a non-tongue roller? RR x rr = ? Parent #1 trait Parent #2 trait R R r Rr Rr There is a 100% chance (4 / 4) that all of their children will be tongue- rollers!

Homozygous or Heterozygous? What would happen if a tongue roller had children with a non-tongue roller? RR x r r Homozygous rr = ? Homozygous R R Rr Rr All offspring will be heterozygous!

But how will the genes be expressed? 10. What is Genotype? = genetic make-up (alleles) RR, Rr, rr 11. What is Phenotype = physical characteristics (expression) Tongue rollers vs. non-tongue rollers

But how will the genes be expressed? What is genotype? Genotype = genetic make-up (alleles) RR, Rr, rr What is phenotype? Phenotype = physical characteristics (expression) Tongue rollers vs. non-tongue rollers

Practice Problems If a homozygous dominant parent with dimples had children with a heterozygous parent with dimples, what phenotypes could the children have? D= has dimples, d= no dimples D D d D

Practice Problems If a homozygous dominant parent with dimples had children with a heterozygous parent with dimples, what phenotypes could the children have? D= has dimples, d= no dimples D DD DD d Dd Dd All offspring will have dimples!

Practice Problems If two heterozygous parents with dimples had children, what phenotypes could the children have? D d DD Dd Dd dd 75% chance offspring will have dimples! 25% chance offspring will NOT have dimples!

Practice Problems If two heterozygous parents with dimples had children, what phenotypes could the children have? D D d d

Let’s Review: • What is a GENOTYPE? • If a girl is heterozygous for eye color, and the alleles for eye color are brown (B) and blue (b), what would be her GENOTYPE? • If a boy has blue eyes and is homozygous for eye color, what would be his GENOTYPE? • Now…what if these two individuals have a baby?

DOMINANT AND RECESSIVE TRAITS LAB

“Dominant and Recessive Traits Lab” Copy and use this chart to survey people in the class: YES Roll Your Tongue Attached Earlobes Dimples Widow’s Peak Longer Second Toe Bent Little Finger Hitchhiker’s Thumb NO % with trait

Dominant VS Recessive Longer Second Toe Shorter Second Toe Bent Little Finger Straight Little Finger Normal Thumb Hitchhiker’s Thumb

Dominant VS Recessive Tongue Roller Can’t Roll Tongue Unattached Earlobes Attached Earlobes Dimples No Dimples Widow’s Peak No Widow’s Peak

Extra Slides Below. Advanced & Additional material

But how will the genes be expressed? Genotype Phenotype RR Rr tongue rollers rr non-tongue rollers *Remember: If a dominant trait is present, it will always be exhibited.

Mendel’s Law #2: Law of Segregation Segregate = to separate • Alleles segregate during meiosis T t T Meiosis = Copy DNA once, Divide twice T t t 4 cells with different alleles

Mendel’s Law #3: Law of Independent Assortment Genes for different traits can independently separate from each other For example: seed color does not have to depend on seed shape or vice versa • Yellow wrinkled seeds and green wrinkled seeds • Yellow smooth seeds and green smooth seeds

Mendel’s Contributions The second offspring plants = F 2 generation • The ‘ 2’ tells you that they are the offspring of the F 1 generation P generation 1 tall, 1 short F 1 generation 4 tall, no short F 2 generation 3 tall, 1 short

Why Pea Plants? • They were easy to grow and they grew quickly! • They had 7 different traits (seed shape, seed color, pod shape, pod color, height, etc. ) • For each trait, they had 2 distinct forms (yellow vs. green, short vs. tall) • They could self-pollinate OR cross-pollinate

Mendel’s Contributions The original pair of plants = P generation • P for parental The first offspring plants = F 1 generation • F for filia (Latin for “daughter”) P generation 1 tall, 1 short F 1 generation 4 tall, no short

Now it’s time for … Odd but TRUE!

Burmese Neck Stretching The Padaung tribe of Burma considered a long neck beautiful. At age 5, girls were introduced to the first neck ring. As they grew, rings were added. Their shoulders were pushed down, making the neck look longer. A fully stretched neck was between 1015" long. A woman could not drink from a cup, because tipping her head back would make her fall- she could only drink from a straw. If a woman offended her tribe, her rings were cut off and she would choke to death.

True… but is it a trait? Families passed the tradition down. A long neck was a way to attract good husbands. Is it possible for a woman to pass on the trait of a long neck to her children? Why or why not? Write down your thoughts!

Chinese Foot Binding In the 10 th century in China, legend says a prince began the practice of foot binding because he loved the small feet of his wife. A tiny foot became the mark of a wealthy and well-born woman. Foot binding began as early as age 4. A strip of bandage was wrapped tightly around the foot, and the four small toes were broken and bent under the sole.

Chinese Foot Binding The bandage was tightened each day and the foot was put into smaller and smaller shoes. An ideal foot was only 4 inches long. By then, the foot was useless for walking very far. Bound feet would bend, becoming so concave they were sometimes described as "lotus hooks".

True… but is it a trait? Could a mother whose feet were bound pass on the trait of small feet to her children? Why or why not? What are your thoughts? !