Transcript 74 Punnett Squares

Bellwork Monday 1/23
*Come to tutorial if you have missing work or want to retake the test
*Quiz friday
1. What is the difference between
alleles, traits, and genes?
Agenda
1. Pass a few things back (don’t
let me forget)
2. Discuss Punnett Squares
3. Practice with Punnett Squares
4. Short video if time
Dad’s
chromosomes
Mom’s
Chromosomes
Trait
Dominant
Recessive
Hair Length
Long (L)
Short (l)
Hair Textrure
Wiry (W)
Silky (w)
Hair Curliness
Curly ( C)
Straight ( c)
Coat Pattern
Spotted (S)
Solid (s)
For Hair length, what gametes can dad give to the puppy?
For hair length, what gametes can mom give to the puppy?
Punnett Square
Notes
Trait
Dominant
Recessive
Hair Length
Long (L)
Short (l)
Hair Textrure
Wiry (W)
Silky (w)
Hair Curliness
Curly ( C)
Straight ( c)
Coat Pattern
Spotted (S)
Solid (s)
1. Find the letters that represents the alleles for the trait
Hair Length the letters will be_________
L and l
Ex: For the trait = ____________,
2. Write out the genotypes of the parents to show the cross
Ll
ll
Ex: Cross a heterozygous parent with a homozygous recessive parent _____
x ______
3. Draw a Punnett Square and put the possible gametes of each parent
on the top and side. (Remember to make uppercase and lowercase different)
l
l
L
l
Ll
ll
Ll
ll
4. Complete the Punnett Square by filling in
The genotypes of the possible offspring of
The cross
5. Determine the ratio of genotypes: 1 Ll : 1 ll
And the ratio of phenotypes:
1 Long : 1 short
Trait
Dominant
Recessive
Hair Length
Long (L)
Short (l)
Hair Textrure
Wiry (W)
Silky (w)
Hair Curliness
Curly ( C)
Straight ( c)
Coat Pattern
Spotted (S)
Solid (s)
1. Ex: Cross two heterozygous curly parents. Find the
genotype and phenotype ratios
Cc x Cc
C
C
c
CC
Cc
c
Cc
cc
Genotype ratio:
Phenotype ratio:
1 CC : 2 Cc : 1 cc
3 Curly : 1 straight
Finally, the good stuff
What advice did the geneticist give to the
football kicker?
“Punt-it Square”
Trait
Dominant
Recessive
Hair Length
Long (L)
Short (l)
Hair Textrure
Wiry (W)
Silky (w)
Hair Curliness Curly ( C)
Coat Pattern
Straight ( c)
Spotted (S) Solid (s)
Genetics video
• http://www.youtube.com/watch?v=bVk0t
wJYL6Y
Graphing
Parents: 2 Curly Hair, 0 Straight Hair
1 Spotted Coat, 1 Solid Coat
Puppies: 12 Straight hair, 4 Curly hair
6 Spotted coat, 6 Solid Coat
Trait
Dominant
Recessive
Hair Length
Long (L)
Short (l)
Hair Textrure
Wiry (W)
Silky (w)
Hair Curliness
Curly ( C)
Straight ( c)
Coat Pattern
Spotted (S)
Solid (s)