Genes to Traits

Genes Gene- a piece of DNA that makes a certain protein – Example: Gene for tongue-rolling Allele- different forms of a gene – Example: One allele is for tongue-rolling, the other allele is for not tongue-rolling

Gregor Mendel Austrian monk in 1800s. Bred pea plants together for experiments. Experiment: X X

Where did the White Flower come from? Dominant allele- the allele that is shown when the two alleles are different or they are both the strong allele – Example: Purple color in Mendel’s peas Recessive allele- the allele that is only shown if you have two copies of it – Example: White color in Mendel’s peas

Take a guess! What do you have? Which allele is dominant? Freckles? Dimples? Nearsightedness? 5 fingers? Dwarfism? Roll tongue? First toe longest? Attached ear lobe? Widow’s Peaks? Cleft Chin? Hitchhiker’s Thumb?

Take a guess! What do you have? Which allele is dominant? Freckles? Dimples? Nearsightedness? 5 fingers? Dwarfism? Roll tongue? First toe longest? Attached ear lobe? Widow’s Peaks? Cleft Chin? Hitchhiker’s Thumb? Thumb crossing, L or R? Dominant Traits are NOT necessarily more common nor are they “stronger” or “better”!

If you have freckles… Having freckles is dominant (F) – No freckles is recessive (f) What could your two alleles be if you HAVE freckles? What if you don’t have freckles?

More Vocabulary Genotype- The two alleles a person has – Example: RR or Rr or rr Phenotype- The trait that you see – Example: Rolls tongue, can’t roll your tongue

Tongue-rolling is dominant (R) to not tongue- rolling (r). What are the three possible genotypes and their corresponding phenotypes? Genotype possibilitiesPhenotype they show

Tongue-rolling is dominant (R) to not tongue- rolling (r). What are the three possible genotypes and their corresponding phenotypes? Genotype possibilitiesPhenotype they show RRTongue-rolling RrTongue-rolling rrNot tongue-rolling

More Vocab Homozygous- two of the SAME alleles – Example: Heterozygous- two different alleles – Example:

What trait will you see? 6 fingers per hand (F) is dominant to 5 fingers (f) If a person is homozygous recessive, what trait will he show? If a person is heterozygous, what trait will he show? If a person is homozygous dominant, what trait will he show?

What trait will you see? Genotype (letters)Phenotype (trait shown) Homozygous recessive Heterozygous Homozygous dominant

What if… A man who can roll his tongue (RR) has a baby with a woman who cannot roll her tongue (rr). What chance does the baby have of rolling his/her tongue?

What if… A person with freckles (Ff) has babies with his partner who also has freckles (Ff). What is the chance that their baby will have freckles?

The B allele is for brown eyes. The b allele is for blue eyes. B is dominant allele. b is the recessive allele. Geraldo has the genotype BB. What will his phenotype be? Vanessa has the genotype bb. What will her phenotype be? If Geraldo and Vanessa have a baby, what eye color do you think the baby will most likely have? Why? Do you think that Geraldo and Vanessa can possibly have a child with blue eyes? Why or why not?

Sex-linked Traits These traits are located on the sex chromosomes. Autosomal traits: located on chromosomes other than sex chromosomes (1-22)

Sex-linked traits Colorblindness is a recessive trait on the X- chromosome. If a heterozygous female (____) has kids with a normal male (____), what chance do their male/female kids have of being colorblind?

Statistics on X-linked diseases Colorblindness – 8% of males – 0.5% of females Hemophilia – 1/5,000 births in males – 1/20,000 births in females Duchenne muscular dystrophy – 1/3500 males – ~0 females?