Title: Mendelian Genetics Date: 11-18-15 Find your booklet from yesterday, then set up today’s page in your journal… Page: 43 Title: Mendelian Genetics Date: 11-18-15 Essential Question: How can I predict outcomes of genetic combinations?

Standard: predict possible outcomes of various genetic combinations such as monohybrid crosses (B.6F)

For today’s notes… As we discuss words that are in yesterday’s booklet, check your definition. Add or adjust information as needed. If you were not here yesterday, be sure to copy all definitions. Be sure to copy any ADDITIONAL notes as well.

How would you describe the person next to you without using their name?

TRAIT: a characteristic that varies from one individual to another For example…

Inheritance is determined by biological factors that are passed from one generation to the next. In other words, which traits you can pass on to your children depends on what genes you got from your parents. Remember… genes are small sections of your DNA that carry the code for certain traits. ALLELES: different forms of a gene (blue eye allele, green eye allele, hazel eye allele, etc.)

PRINCIPLE OF DOMINANCE: some alleles are dominant and others are recessive DOMINANT: allele will always be expressed when it is present a capital letter is used to represent a dominant allele Y = Dominant

RECESSIVE: allele will only be expressed when the dominant is not present a lowercase letter is used to represent a recessive allele y = Recessive Which color do you think is the DOMINANT trait?

PHENOTYPE: what it looks like GENOTYPE: the combination of alleles (genes) *Two organisms can have the same phenotype but different genotypes* Dimples vs no dimples DD Dd dd

BB Bb bb HOMOZYGOUS = same allele for a trait (purebred) HETEROZYGOUS = different alleles for a trait (hybrid) BB Bb bb

Remember… the way alleles separate during meiosis is completely random! **This is why you cannot predict what a baby will look like before it’s born!**

So what CAN we predict?

PROBABILITY: the chances of a particular event occurring We can predict possible genetic outcomes using Punnett squares.

The letters in a Punnett square represent alleles passed on from parent to child. Punnett squares are used to predict which traits can be passed to the offspring.

How to complete a Punnett Square 1st Step = Identify the trait & what letter will represent it What would be the possible outcomes for the offspring of a cross between pink flower (PP) and a white flower (pp)? Trait = color (pink or white) Letter = P or p

How to complete a Punnett Square 2nd Step = Assign the dominant/recessive trait for your letters What would be the possible outcomes for the offspring of a cross between pink flower (PP) and a white flower (pp)? P = pink (dominant) p = white (recessive)

How to complete a Punnett Square 3rd Step = Match the letters to the correct parent (if no parent is specified, assume the FIRST one is dad) What would be the possible outcomes for the offspring of a cross between pink flower (PP) and a white flower (pp)? = PP = pp DAD MOM

How to complete a Punnett Square 4th Step = Write the parent alleles on the outside of your Punnett square What would be the possible outcomes for the offspring of a cross between pink flower (PP) and a white flower (pp)? P P p p

Let’s sum it up….. 1st = Identify the trait and what letter will represent it 2nd = Assign the dominant/recessive trait for your letters 3rd = Match the letters to the correct parent 4th = Write the parent alleles Now fill in your Punnett square!!

P P P = Pink p = White DAD = PP MOM = pp Pp p Pp p Pp Pp Punnett Square practice… 1. What would be the possible outcomes for the offspring of a cross between pink flower (PP) and a white flower (pp)? P P P = Pink p = White DAD = PP MOM = pp Pp p Pp p Pp Pp **When using the letters like “P and p” OR “C and c”, draw the lowercase letter in cursive or just make sure you make them look different. Otherwise, you might confuse the dominant for the recessive **

All PINK! (all offspring would have a DOMINANT allele) Possible Outcomes? All PINK! (all offspring would have a DOMINANT allele)

F = Long f = Short DAD = Ff MOM = ff F f Ff ff f f Ff ff 2. Long fingers are dominant (F) to short fingers (f). Complete the Punnett square for a homozygous recessive mom and a heterozygous dad. F = Long f = Short DAD = Ff MOM = ff F f Ff ff f f Ff ff

L L L = Long L = Short DAD = LL MOM = ll l Ll Ll l Ll Ll 3. In a plant, long stems are dominant (L) to short stems (l). If a homozygous dominant flower and a homozygous recessive plant are crossed, what would be the phenotypic ratio of their offspring? L L L = Long L = Short DAD = LL MOM = ll l Ll Ll l Ll Ll

Phenotypic Ratio? # long : # short 4

C c C = Straight c = Curly DAD = Cc MOM = Cc C CC Cc c Cc cc 4. Straight hair (C) is dominant to curly hair (c). What would be the probability that a child would have curly hair if both parents are heterozygous? C c C = Straight c = Curly DAD = Cc MOM = Cc C CC Cc c Cc cc

Probability of curly hair? # out of 4 ___ % 1 25

T t T = Hitchhiker t = Straight DAD = Tt MOM = tt Tt tt t t Tt tt 5. Having a hitchhiker's thumb is a dominant trait (T). If a woman with a straight thumb has a child with a man who is heterozygous for the trait, what are the chances their child will have a hitchhiker's thumb? T t T = Hitchhiker t = Straight DAD = Tt MOM = tt Tt tt t t Tt tt

Probability of hitchhiker’s thumb? # out of 4 ___ % 2 50

P= Purple p= White DAD = Pp MOM = Pp P p P PP Pp Pp pp p 6. What would the phenotypic and genotypic ratios be for two purple (Pp) flowers that were bred together? P= Purple p= White DAD = Pp MOM = Pp P p P PP Pp Pp pp p

3 1 # purple: # white 1 2 1 # PP : # Pp : # pp Phenotypic Ratio? Genotypic Ratio? 1 2 1 # PP : # Pp : # pp

Can you identify your own genotypes and phenotypes? Hairline: Widow’s peak is dominant to straight hairline Eye Shape: Almond eyes is dominant to round eyes

Eyelash Length: Long eyelashes is dominant to short eyelashes Tongue Rolling: CAN roll the tongue is dominant to cannot

Hitchhiker’s Thumb: Hitchhiker’s thumb is dominant to straight thumb Lip Thickness: Thick lips are dominant to thin lips