Download File

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
Agenda
1/30
• 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 lefthanded 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)
Lefthanded
Righthanded
Baby is
Righthanded
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)
Lefthanded
Righthanded
Baby is
Righthanded
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
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
Righthanded
Righthanded
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
Lefthanded
Righthanded
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
Allele for
Brown eyes
Allele for
Brown eyes
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
Brown
eyes
<-OR->
Lefthanded
Lefthanded
Mendel’s Laws
2. LAW OF INDEPENDENT ASSORTMENT: As
gametes form, alleles on different chromosomes
sort independently from each other.
Brown
eyes
Brown
eyes
<-OR->
Lefthanded
Lefthanded
Practice Time!
• Work alone or with a partner
• If it’s not done, it’s due tomorrow