Your “Do Now”1/30 1.Complete the weekly Pre-Quiz (up front) 2.Write our next 2 learning targets: – I can describe and explain the differences between dominant and recessive traits – I can explain Mendel’s laws of segregation and independent assortment

Agenda1/30 Exploring different types of traits Ch 11 Notes #3 Traits activity (online)

Exploring different types of traits Work with a partner We’ll discuss results in 7 minutes

Exploration Discussion What was the baby left handed? When was the baby right handed? Can two right-handed people have a left- handed baby?

CH 11 Notes #3 1/30 Traits & Inheritance

Starting on the back of Notes #3

Dominant Trait Description: An allele that hides another allele for the trait – Example in Humans: Being right-handed – Symbol: Capitol letters (R, B, T) Right- handed Left- handed Baby is Right- handed

Recessive Trait Description: An allele that gets hidden when it’s paired with another allele for the trait – Examples in humans: being left-handed – Symbol: lowercase letters (r, b, t) Right- handed Left- handed Baby is Right- handed

Dominant or Recessive? Blue-eyed allele + Brown-eyed allele = Brown-eyed person – Blue-eyed is ___________________ – Brown-eyed is __________________

Front Side of Notes #3

Describing an organism GENOTYPE: The letters coding for a trait (“Bb”) The genes present in the DNA of an organism – Example: bb, Rr, Tt – Represented by 2 letters for a gene: “bb” for blue eyes Blue eyes

Describing an organism PHENOTYPE: The appearance of a trait – Example: Having blue eyes

What’s the difference? An organism can have a gene for a trait without showing it! – Allele for left-handed doesn’t mean person will be left-handed

So what? This means we can’t always tell genotype by observing phenotype! – Example: A right-handed person can carry a gene for being left-handed

Describing genotypes If an organism has two of the same allele for a trait it’s called HOMOZYGOUS – Example: Right-handed allele + Right-handed allele Right- handed

2 types of Homozygous Homozygous dominant – Two dominant alleles. – Example: RR for right-handed Homozygous recessive – Two recessive alleles – Example: rr for left-handed

Heterozygous Rr

Describing genotypes If an organism has two different alleles for a trait it’s called HETEROZYGOUS – Example: Left-handed allele + Right-handed allele – Genotype: Rr Right- handed Left- handed

What would it be? homozygous dom., homozygous rec., or heterozygous? Brown eye allele + Brown eye allele Brown eye allele + Blue eye allele Left-handed allele + Right-handed allele Right-handed allele + Right-handed allele

Gregor Mendel An Austrian monk known as the father of genetics.

Gregor Mendel Experimented with pea plants – Easy to care for – Simple traits to observe

Mendel’s Laws 1. LAW OF SEGREGATION: When gametes are formed, the two alleles responsible for the trait are separated from each other. Allele for Brown eyes

Mendel’s Laws 2. LAW OF INDEPENDENT ASSORTMENT: As gametes form, alleles on different chromosomes sort independently from each other. Brown eyes Left- handed Brown eyes Left- handed

Mendel’s Laws 2. LAW OF INDEPENDENT ASSORTMENT: As gametes form, alleles on different chromosomes sort independently from each other. Brown eyes Left- handed Brown eyes Left- handed

Practice Time! Work alone or with a partner If it’s not done, it’s due tomorrow