Genetics
Heredity
 Inheritance
of traits
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall
biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall.
Genetics
Gregor Mendel
 Suggested
that paired factors,
or genes, carry inherited traits.
 Predicted how traits were
inherited by studying pea plants
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall
biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall.
Simple Dominant Traits
 Traits
that are controlled by one
pair of genes
 One dominant allele is all that the
organism needs to show the
dominant trait
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall
biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall.
Recessive attached ear lobes
Dominant Free Ear Lobes
Tongue Roll
Dominant trait
Hitch hiker’s
thumb
Dominant
Regular thumb
Recessive
Seed Seed
shape color
Flower
color
Flower
position
Pod
color
Pod
shape
purple
axial
(side)
green
inflated
white
terminal
(tips)
yellow
Plant
height
Dominant
trait
round
yellow
tall
Recessive
trait
wrinkled
green
constricted
short
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall
biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall.
Alleles
 Different
forms of a gene type
 Organisms have two genes (alleles) for
each trait.
 One gene (allele) from female gamete
(egg).
 One gene (allele) from male gamete
(sperm).
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall
biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall.
Dominant gene (allele)
 Stronger
of two genes
 Represented with capital letters
 Written first
 Example: T for tall plant height
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall
biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall.
Recessive gene (allele)
 Weaker
of two genes
 Can be hidden by dominant
genes.
 Represented with lower case
letters
 Example: t for short plant height
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall
biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall.
Pure (Homozygous)
 Two
of the same genes (alleles) for a
trait
 Example: TT (homozygous dominant)
or tt (homozygous recessive)
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
Hybrid (Heterozygous)
 Two
different alleles for a trait
 Example: Tt
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
Genotype
 Combination
of alleles or genes for a
certain trait
 Example: Tt, TT, tt
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
Phenotype
 Visible
traits (how it looks)
 Determined by looking at organism
 Example: tall, short
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
Genotype or Phenotype?
Tt
 Round
 Black
 BB
 Smooth
 rr
 Tall

Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
In pea plants, green pods are
completely dominant over yellow.
What are the genotypes?
 Homozygous
yellow gg
 Heterozygous green Gg
 Pure dominant GG
 Hybrid Gg
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
In pea plants, green pods are
completely dominant over yellow.
Pure yellow gg
 Homozygous recessive gg
 Pure green GG
 Heterozygous Gg
 Yellow gg

Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
In guinea pigs, short hair is
dominant over long hair

What letter should be used for the gene
for hair length?

What hair length will be represented by a
capital S?

What hair length will be represented by a
lower case s?
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
What phenotypes would result
from the following genotypes?
 SS
 ss
 Ss
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
What are the phenotypes of the
parent plants?
If both parents are pure, what
are their genotypes?
Which gene or allele can each
parent pass on to the
offspring?
What is the phenotype of the
offspring?
What is the genotype of the
offspring?
Short plant
Tall plant
t
T T
t
t
T
All tall plants
T t
In pea plants, round pea pod texture is
dominant over wrinkled texture.
What is the genotype of the following?
 homozygous
round
 heterozygous
 wrinkled
 pure dominant
 hybrid round
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
In pea plants, round pea pod texture is
dominant over wrinkled texture. What
is the genotype of the following?
 pure
recessive
 heterozygous round
 pure wrinkled
 hybrid
 pure round
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
Punnett Squares

Punnett squares –
used to predict and
compare the genetic
differences that will
result from a cross.
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
Monohybrid crosses
Heterozygous
tall parent
T
t
T
T
t
T
t
TT
Tt
Tt
tt
t
Heterozygous
tall parent
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
Generations of Inheritance
tt
Start by
crossing
homozygous
parents
TT
P1
Short pea plant
Tall pea plant
Results in
heterozygous
offspring
Tt
F1
All tall pea plants
TT
Tt
F2
3 tall: 1 short
Tt
tt
Crossing
heterozygous
offspring from F1
generation
results in three
tall and 1 short
Incomplete dominance
 Alleles
BLEND (mix)
 Neither gene is dominant
 A third or new phenotype can
be seen
 Think about colors of paint 
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
Red
X White
PINK
 If
a red impatient is crossed with a
white impatient, the resulting flowers
are pink.
 Red and white blend like paint colors
to produce pink (new phenotype).
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
Incomplete
Dominance
R
R
W RW
RW
RW
RW
W
www.nerdscience.com
11-3
Codominance
 Both
alleles are dominant
 Both alleles are seen
(expressed) TOGETHER
 There is NO “blending”
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
Codominance
Both alleles or genes are expressed
Red
X White
Red & White
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.

Red cow crossed with white cow
results in roan cattle. Roan cattle
have both red and white hairs.
Codominance
Codominance
Example:
 White chicken x
black chicken =
black and white
checkered chicken

Incomplete or Codominance?
A white cow and a red cow produce a
roan cow, one that has both white and
red hairs.
 A red flower and a white flower produce
pink flowers.
 A black cat and a tan cat produce tabby
cats, cats where black and tan fur is seen
together.

Incomplete or Codominance?
A blue blahblah bird and a white
blahblah bird produce offspring that are
silver.
 A certain species of mouse with black fur
is crossed with a mouse with white fur
and all of the offspring have grey fur.
 A woman with blood type A and a man
with blood type B have a child with blood
type AB.

Blood Types (codominant)
Blood type is
codominant
 4 different blood
types

Phenotype
Genotype
(Blood type) (Alleles or
genes for
blood type)
A
IAIA, IAi
B
IBIB, IBi
AB
IAIB
O
ii
Charles Drew
 Charles
Drew
impacted blood
donation and blood
banks
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
Three Basic Principles of
Genetics
The Principle of Dominance
 One
gene for a trait may hide the
other gene and keep it from
being seen (expressed) in the
organism
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
When Mendel crossed a
tall pea plant with a short
pea plant, all the offspring
plants were tall.
In such crosses when
only one trait was
observed, Mendel called
the observed trait
dominant.
Tall plant
t
T T
t
t
T
F1
All tall plants
T
t
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
The Principle of Segregation
 The
two genes for a trait separate,
or segregate, during the formation of
gametes (meiosis).
 This happens when pairs of
chromosomes separate during
meiosis
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
The Principle of
Independent Assortment
 Genes
for different traits separate
independently during the
formation of gametes.
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
Sex Chromosomes
X
and Y chromosomes
 Determine the sex of the offspring
 Females have two large XX
chromosomes
 Males have an X and a smaller Y
chromosome (XY).
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262285). Upper Saddle River, N.J.: Prentice Hall.
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365).
Upper Saddle River, N.J.: Prentice Hall.
Sex Chromosomes
 All
other chromosomes are
autosomes.
 Human sperm contain 22 autosomes
and an X or Y chromosome
 Human eggs contain 22 autosomes
and an X chromosome
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262285). Upper Saddle River, N.J.: Prentice Hall.
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365).
Upper Saddle River, N.J.: Prentice Hall.
Sex-linked Traits
Most are carried on the X chromosome
 Also called X-linked traits
 Hemophilia and color blindness are
recessive sex-linked traits carried on the
X-chromosome
 Males show recessive traits more than
females

Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262285). Upper Saddle River, N.J.: Prentice Hall.
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365).
Upper Saddle River, N.J.: Prentice Hall.
Sex-linked Traits
 Males
get only one allele for a sexlinked trait carried on the X
chromosome (nothing on Y)
 Females have a second X
chromosome that carries another
allele that can hide recessive traits
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262285). Upper Saddle River, N.J.: Prentice Hall.
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365).
Upper Saddle River, N.J.: Prentice Hall.
Sex-linked Traits
 Females
who have recessive alleles
but show the dominant trait are
called carriers
 A woman can have normal vision
but carry the recessive allele for
colorblindness
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262285). Upper Saddle River, N.J.: Prentice Hall.
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365).
Upper Saddle River, N.J.: Prentice Hall.
Test Cross
 Done
to determine the genotypes of
organisms that show dominant traits
 Unknown genotype organism is
crossed with a homozygous recessive
(Example: tt)
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262285). Upper Saddle River, N.J.: Prentice Hall.
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365).
Upper Saddle River, N.J.: Prentice Hall.
Test Cross
 If
all offspring have the dominant
trait then the genotype is probably
pure (TT x tt)
 If some of the offspring show the
recessive trait, then the genotype is
heterozygous.(Tt x tt)
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262285). Upper Saddle River, N.J.: Prentice Hall.
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365).
Upper Saddle River, N.J.: Prentice Hall.
Pedigree Study
 Method
of determining the genotype
of individuals by looking at
inheritance patterns
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall
biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall.
Human Genetics
 23
pairs of chromosomes (46 total)
 Pedigrees are used to trace genetic
traits
Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice
Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice
Hall.
Male
Parents
Female
Siblings
Affected
male
Affected
female
Mating
Known
heterozygotes
for recessive
allele
Pedigrees
illustrate
inheritance
Death
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall
biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall.
I
Female
Pedigrees
illustrate
inheritance
Male
1
2
II
2
1
3
4
5
III
?
1
2
4
3

In a pedigree, a
circle represents
a female; a
square
represents a
male.
IV
1
2
3
4
5
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall
biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall.
Pedigrees
illustrate
inheritance
I
1
2
II
3
2
1
4
5
III
?
1
2
4
3

Highlighted circles
and squares
represent
individuals showing
the trait being
studied.
IV
1
2
3
4
5
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall
biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall.
Pedigrees
illustrate
inheritance
I
1
2
II
2
1
3
4
5
III
?
1
2
4
3

Circles and
squares that are
not highlighted
represent
individuals that do
not show trait.
IV
1
2
3
4
5
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall
biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall.
Pedigrees illustrate inheritance

A half-shaded
circle or square
represents a
carrier, a
heterozygous
individual.
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall
biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall.
Pedigrees illustrate inheritance

I
1
2
II
2
1
III
?
IV
1
2
1
3
4
4
3
2
5
3
4
A horizontal line
connecting a circle
and a square
indicates that the
individuals are
parents, and a
vertical line connects
parents with their
offspring.
5
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall
biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall.
Pedigrees illustrate inheritance

I
1
2
II
1
III
1
?
IV
2
1
3
2
4
4
3
2
5
3
4
Each horizontal
row of circles and
squares in a
pedigree
designates a
generation, with
the most recent
generation shown
at the bottom.
5
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall
biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall.
Pedigrees illustrate inheritance

I
1
2
II
1
3
2
4
5
III
?
1
2
The generations
are identified in
sequence by
Roman numerals,
and each
individual is given
an Arabic number.
4
3
IV
1
2
3
4
5
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall
biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall.
Pedigree
Chart
Simple
Pedigree
Nondisjunction
 Chromosome
pairs do not separate
correctly
 One gamete has too many the other
too few
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall
biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall.
Nondisjunction
Examples:
 Trisomy 21 - Down Syndrome (extra
chromosome 21)
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall
biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall.
Down Syndrome

XXY syndrome (Klinefelter
Syndrome)
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall
biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall.
Genetic Disorders
Most caused by recessive alleles
 Cystic fibrosis
 Sickle-cell anemia
 Phenylketonuria (PKU)
 Tay-Sachs disease

Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall
biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall.
Karyotype
 Chart
of chromosome pairs
 Shows unusual number of chromosomes
 Can detect trisomy 21 (Down syndrome)
 Identifies male or female
Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall
biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall.
Karyotype
Normal Female
Karyotype
Female with Down Syndrome
Autosomal Disorders in
Humans
www.nerdscience.com
14-1
Dihybrid Cross
RrYy x RrYy
RY
Ry
rY
ry
RY
RRYY
RRYy
RrYY
RrYy
Ry
RRYy
RRyy
RrYy
Rryy
rY
RrYY
RrYy
rrYY
rrYy
ry
RrYy
Rryy
rrYy
rryy
www.nerdscience.com
11-3
Extra Studying

While all of these chapters where not used in
this Power Point, you may find it useful to go
and read, or re-read, the following chapters in
your text book.
 Chapter 11: Introduction to Genetics
 Chapter 12: DNA and RNA
 Chapter 13: Genetic Engineering
 Chapter 14: The Human Genome
 Chapter 16: Evolution of Populations
Underlined Chapters are covered in Power Point.
Bibliography

Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to
Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285).
Upper Saddle River, N.J.: Prentice Hall.

Miller, K. R., & Levine, J. S. (2005). Chapter 12: DNA and RNA.
Prentice Hall biology (North Carolina ed., pp. 286- 317). Upper
Saddle River, N.J.: Prentice Hall.

Miller, K. R., & Levine, J. S. (2005). Chapter 13: Genetic
Engineering. Prentice Hall biology (North Carolina ed., pp. 318339). Upper Saddle River, N.J.: Prentice Hall.

Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human
Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365).
Upper Saddle River, N.J.: Prentice Hall.

Miller, K. R., & Levine, J. S. (2005). Chapter 16: Evolution of
Populations. Prentice Hall biology (North Carolina ed., pp. 392415). Upper Saddle River, N.J.: Prentice Hall.