Transcript Punnett Square Genetics

Punnett Square Genetics Intro.
• Trait: genetically determined feature of an
organism
• Gene: a section of a chromosome that
codes for a trait; you have 2 alleles for
every gene
• Allele: alternate forms of a gene that are
shown with letters; you received one
allele from each parent
Punnett Square Genetics Intro.
• Dominant: the allele that will be
expressed even if a recessive one is
present
• Recessive: these alleles are hidden when
dominant ones are present; the only way
recessives will be expressed is if there are
two of them for the gene
Punnett Square Genetics Intro.
• Genotype: the allele combination
possessed; it is written out in letters
• Phenotype: the features determined by
the genes; it is written out in words
Part 1 – Simple Crosses #1
R
r
R
RR
Rr
R
RR
Rr
Genotype ratio
2/4 RR : 2/4 Rr
Phenotype ratio
4/4 Round
Part 1 – Simple Crosses #2
G
g
G
GG
Gg
G
GG
Gg
Genotype ratio
2/4 GG : 2/4 Gg
Phenotype ratio
4/4 Green
Part 1 – Simple Crosses #3
T
t
T
TT
Tt
t
Tt
tt
Genotype ratio
1/4 TT : 2/4 Tt : 1/4 tt
Phenotype ratio
3/4 tall : 1/4 short
Part 1 – Simple Crosses #4
r
r
R
Rr
Rr
r
rr
rr
Genotype ratio
2/4 Rr : 2/4 rr
Phenotype ratio
2/4 Round : 2/4
wrinkled
Part 1 – Simple Crosses #5
G
g
G
GG
Gg
g
Gg
gg
Genotype ratio
1/4 GG : 2/4 Gg : 1/4 gg
Phenotype ratio
3/4 green : 1/4
yellow
Part 1 – Simple Crosses #6
G
G
g
Gg
Gg
g
Gg
Gg
Genotype ratio
4/4 Gg
Phenotype ratio
4/4 Green
Part 1 – Simple Crosses #7
T
T
t
Tt
Tt
t
Tt
Tt
Genotype ratio
4/4 Tt
Phenotype ratio
4/4 tall
Part 1 – Simple Crosses #8
b
b
B
Bb
Bb
b
bb
bb
Genotype ratio
2/4 Bb : 2/4 bb
Phenotype ratio
2/4 brown : 2/4
white
Part 2 - Pedigree Charts #1
• Does the trait show up more often in males or females or does it affect
males and females [somewhat] equally? Males
• Are there carriers? Yes
• Therefore it is: Sex-linked recessive
Part 2 - Pedigree Charts #2
• Does the trait show up more often in males or females or does it affect
males and females [somewhat] equally? Equal
• Are there carriers? No
• Therefore it is: Autosomal dominant
Part 2 - Pedigree Charts #3
• Does the trait show up more often in males or females or does it affect
males and females [somewhat] equally? Females
• Are there carriers? No
• Therefore it is: Sex-linked dominant
Part 2 - Pedigree Charts #4
• Does the trait show up more often in males or females or does it affect
males and females [somewhat] equally? Equal
• Are there carriers? Yes
• Therefore it is: Autosomal recessive
Part 3 – Special Punnett Squares #1
i
IA
IB
IA
IAIA
IAIB
IAi
IB
IAIB
I BI B
IBi
i
IAi
IBi
ii
IAIA
IBIB
ii
IAi
IBi
IAIB
= 1/9
= 1/9
= 1/9
= 2/9
= 2/9
= 2/9
Type A
Type B
Type AB
= 3/9
= 3/9
= 2/9 “Universal
Recipient”
= 1/9 “Universal
Donor”
Type O
Part 3 – Special Punnett Squares #2
R
R
r
Rr
Rr
r
Rr
Rr
Genotype ratio
4/4 Rr
Phenotype ratio
4/4 pink
Part 3 – Special Punnett Squares #3
R
r
R
RR
Rr
r
Rr
rr
Genotype ratio
1/4 RR : 2/4 Rr :
1/4 rr
Phenotype ratio
1/4 red : 2/4 pink :
1/4 white
Part 3 – Special Punnett Squares #4
r
r
R
Rr
Rr
r
rr
rr
Genotype ratio
2/4 Rr : 2/4 rr
Phenotype ratio
2/4 pink : 2/4 white
Part 3 – Special Punnett Squares #5
XH
Xh
Y
XHXh
XHY
H = normal; h = hemophilia
1/4 XHXh = carrier female
1/4 XhXh = hemophiliac female
Xh
XhXh
XhY
1/4 XHY = normal male
1/4 XhY = hemophiliac male
Part 3 – Special Punnett Squares #6
XC
Xc
Y
XCXc
XCY
C = normal; c = color-blind
2/4 XCXc = carrier female
2/4 XCY = normal male
XC
XCXc
XCY
Enrichment Sample Problem #1
Step 1 Determine the
genotypes of the parents.
Step 2 Determine the
gamete genotypes
produced by each parent.
Step 3 Set up a Punnett
square using the gamete
genotypes.
Step 4 Combine the
gamete genotypes from
one parent with those
from the other parent to
show all possible
offspring genotypes.
Step 5 State the genotype
ratio and the phenotype
ratio.
RT
RT
RT
RT
RT
RRTT
RRTT
RRTT
RRTT
RT
RRTT
RRTT
RRTT
RRTT
RT
RRTT
RRTT
RRTT
RRTT
RT
RRTT
RRTT
RRTT
RRTT
Enrichment Sample Problem #2
Step 1 Determine the
genotypes of the parents.
Step 2 Determine the
gamete genotypes
produced by each parent.
Step 3 Set up a Punnett
square using the gamete
genotypes.
Step 4 Combine the
gamete genotypes from
one parent with those
from the other parent to
show all possible
offspring genotypes.
Step 5 State the genotype
ratio and the phenotype
ratio.
RT
RT
rT
Rt
RRTt
RRTt
RrTt
RrTt
Rt
RRTt
RRTt
RrTt
RrTt
Rt
RRTt
RRTt
RrTt
RrTt
Rt
RRTt
RrTt
RrTt
RRTt
rT
Enrichment Sample Problem #3
Step 1 Determine the
genotypes of the parents.
Step 2 Determine the
gamete genotypes
produced by each parent.
Step 3 Set up a Punnett
square using the gamete
genotypes.
Step 4 Combine the
gamete genotypes from
one parent with those
from the other parent to
show all possible
offspring genotypes.
Step 5 State the genotype
ratio and the phenotype
ratio.
GT
Gt
gT
gt
GT
GGTT
GGTt
GgTT
GgTt
Gt
GGTt
GGtt
GgTt
Ggtt
gT
GgTT
GgTt
ggTT
ggTt
gt
GgTt
ggTt
ggtt
Ggtt
Enrichment Practice #1
RB
A. RrBb x RRBB
C. 16/16 running,
black mice
Rb
rB
rb
RB
RRBB RRBb
RrBB
RrBb
RB
RRBB
RRBb
RrBB
RrBb
RB
RRBB
RRBb
RrBB
RrBb
RB
RRBB RRBb
RrBB
RrBb
Enrichment Practice #2
A. RRBB x Rrbb
C. 16/16 running,
black mice
RB
RB
RB
RB
Rb
RRBb
RRBb
RRBb
RRBb
Rb
RRBb
RRBb
RRBb
RRBb
rb
RrBb
RrBb
RrBb
RrBb
rb
RrBb
RrBb
RrBb
RrBb
Enrichment Practice #3
A. rrbb x rrbb
C. 16/16 waltzing,
brown mice
rb
rb
rb
rb
rb
rrbb
rrbb
rrbb
rrbb
rb
rrbb
rrbb
rrbb
rrbb
rb
rrbb
rrbb
rrbb
rrbb
rb
rrbb
rrbb
rrbb
rrbb
Enrichment Practice #4
A. RRBb x rrbb
C. 8/16 running,
black mice : 8/16
running, brown
mice
RB
Rb
RB
rb
RrBb
Rrbb
RrBb
Rrbb
rb
RrBb
Rrbb
RrBb
Rrbb
rb
RrBb
Rrbb
RrBb
Rrbb
rb
RrBb
RrBb
Rrbb
Rrbb
Rb
Heterozygous blue, homozygous tail
B = blue
b = yellow
X
Yellow, heterozygous tail
T = tail
t = no tail
What are the parent genotypes?
BbTT X bbTt
What are the possible gamete genotypes?
BT, BT, bT, bT, bT, bt, bT, bt
BT
BT
bT
bT
bT
BbTT
BbTT
bbTT
bbTT
bt
BbTt
BbTt
bbTt
bbTt
bT
BbTT
BbTT
bbTT
bbTT
bt
BbTt
BbTt
bbTt
bbTt