block day- april 25, 2012 homework: none make an entry- entry 41:heredity and genetics2- 4/25/12 see...
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Block Day- April 25, 2012Homework: none
Make an entry-
Entry 41:Heredity and Genetics2- 4/25/12
See attached entry
Symbols used for alleles• The traditional symbols used for alleles
are big and small letters• The letter chosen usually refers to the
dominant allele
Example: R = Red allele
r = Blue allele
The combination of alleles determines the observed characteristics
REDalleleChromosome
combination
Allelecombination
Observedcharacteristic
RED allele
REDallele
BLUE allele
BLUEallele
BLUE allele
red, red red, blue(or blue, red)
blue, blue
RED RED BLUE
The combination of alleles determines the observed characteristics
RChromosomecombination
Allelecombination
Observedcharacteristic
RR Rr rr
RED RED BLUE
R R r r r
The combination of alleles determines the observed characteristics
RChromosomecombination
GENOTYPE
PHENOTYPE
RR Rr rr
RED RED BLUE
R R r r r
Homozygous – the two alleles are the same
• RR and rr are homozygous genotypes
Heterozygous – the two alleles are different
• Rr is a heterozygous genotype
Draw the enzymes and pigment molecules present in the cells of each type of flower below.
GENOTYPE for flower type 2:
Allele of chromosome 2A= Y1 (functional enzyme)
PHENOTYPEof flower type 2:
nucleus
Y1
Y2
Yes or no, is any functional enzyme Y in the cell?
Allele of chromosome 2B= Y2 (non-functional enzyme) 2A 2B
1B
1A
YES RED
WHAT DOES Rr ACTUALLY MEAN?
Rr
Possible combinations of inherited chromosomes/genes
R rR r
Dad Mom
R
r
Parents
PossibleOffspring r
r
R
R
r
R
X
Order doesn’t matter, these two are the same (Rr)
What are all possible genotypes produced from the parents?
RR, Rr, rr
1 out of 4 possibilities is rr = What is probability of Rr?• How many out of 4 are red? • What is the probability of red? • What is the probability of blue?
R r
R RR Rr
r Rr rrGenotypic ratio = 1RR: 2Rr:1rr
25 %
50 %
3/475 %
25 %
R= red flower alleler= blue flower allele
Phenotypic ratio = 3 Red:1 blue
Your turn:• What are all possible genotypes and
phenotypes produced by crossing Rr with rr?
Complete the Punnett Square
r r
R Rr Rr
r rr rr
Punnett squares predict ratios of all genotypes and phenotypes produced
Genotypic ratio = 2 Rr:2 rr or 1Rr : 1 rr
Phenotypic ratio =
2 Red:2 Blue or 1 Red : 1 Blue
r r
R Rr Rr
r rr rr
R= red flower alleler= blue flower allele
Punnett square practiceCalculate the predicted genotypic and phenotypic ratios
1) Hh X HH
H(hairy) is dominant over h(not hairy)
2a) Gg X gg
G(green sepals) is dominant over g(yellow sepals)
2b) What would the cells of the green and yellow plants look like? (functional vs non-functional)
Genotypic ratio = 2 HH:2 Hh or 1HH : 1Hh
Phenotypic ratio = 4 Hairy: 0 Non-hairy
H H
H HH HH
h Hh Hh
Genotypic ratio = 2 Gg:2 gg or 1Gg : 1gg
Phenotypic ratio = 2 Green: 2 Yellow or
1 Green : 1 Yellow
g g
G Gg Gg
g gg gg
GENOTYPE for Green Flower (Gg) :
Allele of chromosome A= C1 (functional enzyme)
PHENOTYPEof flower type 2:
nucleus
Yes or no, is any functional enzyme C in the cell?
Allele of chromosome B= C2 (non-functional enzyme)
Y1
Y2
A
B
1B1A
GENOTYPE for yellow flower (gg):
Allele of chromosome A= C2 (non-functional enzyme)
PHENOTYPEof flower type 3:
nucleus
Y2
Y2
Yes or no, is any functional enzyme Y in the cell?
Allele of chromosome B= C2 (non-functional enzyme)
A
B1B
1A
YES
Green
NO
Yellow
• #1 In rabbits, black fur is dominant over white fur. Show the cross of a heterozygous black male with a homozygous white female.
• Parents: Bb x bb b b
• Genotypic Ratio: B
1 Bb : 1bb
• Phenotypic Ratio: b
1 black: 1 white
Bb Bb
bb bb
• #2 Tall is dominant over short in pea plants. Show the cross of a homozygous short plant is crossed with a homozygous tall plant.
• Parents: tt x TT
• Genotypic Ratio:
4 Tt (or 100% Tt)
• Phenotypic Ratio:
All or 100% Tall
Tt Tt
Tt Tt
T T
t
t
• # 3 In humans, free-ear lobes are dominant to attached ear lobes. Two parents that are both heterozygous free are expecting a child. What are the chances that the child will have free ear lobes of attached?
• Parents: Ff x Ff
F f • Genotypic Ratio: F
1 FF:2Ff: 1ff
• Phenotypic Ratio: f
3 Free: 1 attached
FF Ff
Ff ff
#4
S=smooth
s= wrinkled
Parents: ss x Ss
Genotypic ratio: 2 Ss:2 ss
Phenotypic ratio: 2 smooth: 2 wrinkled
#5
S=smooth
s= wrinkled
Parents: Ss x Ss
Genotypic ratio: 1 SS: 2Ss: 1ss
Phenotypic ratio: 3 smooth: 1 wrinkled
#6
B=blue eyes
b=red eyes
Parents: Bb x bb
Genotypic ratio: 2 Bb: 2 bb
Phenotypic ratio: 2 blue eyes: 2 red eyes
#7
R= red eyes
r= white eyes
Parents: rr x rr
Genotypic Ratio: 4 rr or all rr
Phenotypic: 4 white eyes or all white eyes
• #8 A homozygous dominant brown mouse is crossed with a heterozygous brown mouse (tan is the recessive color).
• Parents: BB x Bb B b
• Genotypic Ratio: B
1 BB : 1Bb
• Phenotypic Ratio: B
All Brown or
4 Brown: 0 Tan
BB Bb
BB Bb
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