Topic: Genetics
Aim: How do we use pedigree charts to
follow a trait through generations of a
family?
Do Now: Take out your punnett square
notes sheet.
HW: Reproduction Exam Review Sheet
Castle Learning due TUESDAY!
Example #3:
Red is dominant in flowers & white
is recessive. Cross a
heterozygous flower with a
homozygous dominant flower.
• R = red r = white
• Rr x RR
Rr x RR
R
R RR
r
Rr
R R R Rr
Genotype =
50% homozygous
dominant
50% heterozygous
Phenotype=
100% red
One dog carries the
heterozygous, black fur trait and
the other carries homozygous
recessive white traits. What are
the chances of having a puppy
with black fur?
B = black, b = white
Bb x bb
Bb x bb
B
b Bb
b
bb
b B b bb
Answer: 50%
chance of having a
puppy with black
fur
Humans have 46
chromosomes in EVERY
somatic cell in the body.
Out the 46 chromosomes,
2 of them are
sex chromosomes that
determine gender.
The other 44
chromosomes are called
autosomes.
Sex
chromosomes
• XY - male
• XX - female
Female chromosomes
Male chromosomes
How is the sex of an individual
determined?
• Eggs = X
• Sperm = X or Y
The X chromosome
carries a couple of
thousand genes but
few, if any, of these
have anything to do
directly with sex
determination. The X
chromosome likely
contains genes that
provide instructions for
making proteins. These
proteins perform a
variety of different roles
in the body.
The Y chromosome likely
contains genes that provide
instructions for making
proteins. The genes on this
chromosome tend to be
involved in male sex
determination and
development. Sex is
determined by the SRY
gene, which is responsible
for the development of a
fetus into a male. Other
genes on the Y chromosome
are important for male
fertility.
1. What • To follow a trait through
are
generations of a family
pedigree
charts
used
for?
Male without the trait.
Male with the trait.
Female without the trait.
Female with the trait.
Female and male carriers
Diagonal line = dead from inherited
condition
Marriage line connects people
Offspring line going down
Offspring (oldest to the left)
Topic: Genetics
Aim: How do we use pedigree charts to
follow a trait through generations of a
family?
Do Now: Take out your pedigree chart
notes and your punnett square notes
sheet.
HW: Castle Learning!!!!
One dog carries the heterozygous,
black fur trait and the other carries
homozygous recessive white traits.
What are the chances of having a
puppy with black fur?
B = black, b = white
Bb x bb
Bb x bb
B
b Bb
b
bb
b B b bb
Answer: 50%
chance of having a
puppy with black
fur
3. What does the pedigree
chart below show?
How the British Queen
Victoria’s family was
affected by a disease
called hemophilia.
4. Describe hemophilia.
A disease that causes
the body to make too
little of a certain protein
that stops bleeding from
damaged blood vessels.
The shape of earlobes is inherited. The letter “E” stands for the gene (allele) for
unattached or “free” earlobes. The letter “e” stands for the gene (allele) for
attached earlobes.
6. Identify the allele represented by “E.” Free earlobes
7. Identify the allele represented by “e.” Attached
earlobes
The shape of earlobes is inherited. The letter “E” stands for the gene (allele) for
unattached or “free” earlobes. The letter “e” stands for the gene (allele) for
attached earlobes.
8. James and Yolanda are a married couple.
a. Identify the kind of earlobes James has.
Attached earlobes
b. Identify the kind of earlobes Yolanda has.
Free earlobes
The shape of earlobes is inherited. The letter “E” stands for the gene (allele) for
unattached or “free” earlobes. The letter “e” stands for the gene (allele) for
attached earlobes.
c. How many children do James and Yolanda have?
What are their names? TWO Tony and Jasmine
d. Identify Tony’s children and the types of earlobes
each child has. Andrew - unattached
Maria - unattached
The shape of earlobes is inherited. The letter “E” stands for the gene (allele) for
unattached or “free” earlobes. The letter “e” stands for the gene (allele) for
attached earlobes.
e. Identify Jasmine’s children and the types of earlobes
each child has. T.J. - unattached
Caroline - attached
The shape of earlobes is inherited. The letter “E” stands for the gene (allele) for
unattached or “free” earlobes. The letter “e” stands for the gene (allele) for
attached earlobes.
f. Identify Caroline’s genotype. ee
g. Why does Caroline have attached earlobes?
Her parents must be heterozygous for the train.
(Ee x Ee)
9. Person # 1 is:
a carrier for the trait.
10. Identify the difference
between #7 and #9.
#7 is a carrier and #9 is
not.
11. What is the relationship
between individuals #1 and #2?
#1 and #2 are married.
12. Which statement about
individual #3 is true?
#3 is married to #4
13. What is the meaning of the
line through #4?
The person dies from the
inherited trait.
14. What is the relationship
between #4 and #5?
#4 is the sister of #5
15. How is it possible for #9, #10
and #11 to not have the trait?
The trait is recessive.
1
3
5
4
14
2
15
6
16
17
7
18
19
8
9
10
22
20
21
1. Identify the genotypes of 1 and 2.
Heterozygous
2. How many offspring did 1 and 2 have?
Six
3. Identify the genotype of 5.
Homozygous recessive
11
12
13
25
23
24
1. Identify the genotype of
the father.
heterozygous
2. Identify the genotype of
the mother.
Homozygous
recessive
3. How many children did
the first generation have?
4
4. How many children have
the trait? 2
1. How many offspring did the
first generation have?
4
2. How many offspring from
the first generation were born
with the trait?
None
3. How many females did the
first generation have?
TWO
4. How many males did the
first generation have?
TWO
1. How many offspring did
the 1st generation have?
3
2. How many offspring
from the 1st generation
were born with the trait?
1
3. Individual 3 had
children with individual 4.
a. How many children did 3
and 4 have? 2
b. Which child was born
with the trait?
male
c. What were the
genotypes of individuals 3
and 4? heterozygous
T = tall t = short
Cross two heterozygous plants.
Tt x Tt
T
t
T T T Tt
t Tt
tt
T
t
T T T Tt
t Tt
tt
Phenotype %:
75% tall
25% short
Genotype %:
25% homozygous
dominant
50% heterozygous
25% homozygous
recessive
G = green
g = yellow
Cross a pure green plant with a
hybrid plant.
GG X Gg
G
G
G GG GG
g Gg Gg
G
G
G GG GG
g Gg Gg
Phenotype
percentages:
100% green
Genotype percentages:
50% heterozygous
50% homozygous
dominant