1. W m up
ar
Match the items on the left with one item on
the right
1. HH
A. heterozygous
2. Curly hair
B. homozygous
3. Hh
C. phenotype
4. Genotype
D. tt
2. Hel pf ul
Bozeman Biology
Crash Course Biology
Hank Green
Paul Anderson
5. The father of genetics
Gregor Mendel is
considered the Father of
Genetics
Born in 1822
Studied math & physics
at an Austrian university
He was the first person to
study how traits are
passed along from one
generation to the next.
He did his work with the
pea plant
Who’s your
daddy?
7. Mendel’s Garden
Eight years & 20
volumes of data
and analysis on 7
distinctive traits
Published in 1865
8. Why peas?
The garden pea was a good choice for a
variety of reasons. The garden pea:
is easy to raise
produces large numbers of offspring
reproduces quickly
has flowers which are self fertilizing but can be
easily crossed to other varieties
12. Allele for purple flowers
Locus for flower-color gene
Allele for white flowers
Homologous
pair of
chromosomes
13. Mendel's
Theory of Segregation
Diploid organisms inherit two genes
per trait
Each gene segregates from the other
during meiosis so that each gamete
will receive only one gene per trait
14. How can the Chances of an Offspring’s Traits
be Determined?
The chance of an offspring showing a certain trait can
be determined by using the Punnett square.
The table contains spaces for the parent’s gametes
and the possible offspring from that mating.
The alleles are represented by their letters.
Genes come in pairs and must be separated during
gamete formation.
These gametes (letter) of each pair are placed in each
of the outside spaces.
They are then combined to form the possible
offspring.
16. Monohybrid Crosses
Mendel's first
experiments
One trait
Monohybrid crosses
have two parents that
are true-breeding for
contrasting forms of a
trait.
17. All the offspring from the
first cross showed only 1
form of the trait
This trait seemed
“stronger” so he called it
DOMINANT
When he crossed the
offspring from the first
cross, the other form of
the trait reappeared, but
only 1/4 of the time
This trait seemed
“weaker” so he called it
recessive
18. Predicting the Outcome
Why does one form of the trait disappear
in the
first generation (F1 ),
only to show up in the
second generation (F2 )??
19. Prevailing Theories
Artificial selection: populations could evolve (i.e.
change) if members show variation in heritable traits
Variations that improved survival chances in the wild
would be more common in each generation
This idea is known as natural selection
20. Mendel’s Experiments
Natural selection did not fit with prevailing view
of inheritance-blending
Blending would produce uniform populations;
such populations could not evolve
21. Mendel’s Experiments
Many observations did not fit blending
A white horse and a black horse did not
produce only gray horses
22. Test (Back) Crosses
To support his concept of segregation,
Mendel crossed F1 plants (Pp) BACK with
homozygous recessives (pp)
What ratio would
Mendel have gotten?
He didn’t know the letter
combination of the F1
plants. The test (back)
cross allowed him to
figure it out
23. His back
crossed
supported
his idea of 2
“factors” for
each
individual,
and the idea
that those
“factors” are
segregated
Dominant phenotype,
unknown genotype:
PP or Pp?
Recessive phenotype,
known genotype:
pp
If Pp,
then 2 offspring purple
and 1 2 offspring white:
If PP,
then all offspring
purple:
p
1
p
P
p
p
Pp
Pp
pp
pp
P
Pp
Pp
P
P
Pp
Pp
25. Predicting the Outcome
What is the predicted PHENOTYPIC
ratio
and the predicted
GENOTYPIC ratio
that Mendel saw?
26. Predicting the Outcome
The F2 results showed 9/16
were tall and purpleflowered and 1/16 were
dwarf and whiteflowered-as were the
original parents;
however, there were 3/16
each of two new
combinations: dwarf
purple-flowered and tall
white-flowered.
28. Theory of Independent Assortment
Each gene of a pair tends to assort into
gametes independently of other gene pairs
on non-homologous chromosomes
29. Theory in
Modern Form
Genes located
on nonhomologous
chromosomes
segregate
independently
of each other
30. Mendel’s Work
The work that Mendel did
helped explain patterns of
inheritance in eukaryotes.
But Mendel worked with
traits that had a clear
dominant/recessive
pattern.
Also, the traits he worked
with were all controlled by
a single gene.
31. Different Patterns of Inheritance
As we now know,
many traits do not
follow Mendelian
Inheritance patterns.
32. Co-dominance
When both
alleles are
expressed
equally in the
heterozygous
individual.
A and B blood type alleles are
co-dominant, because a person
with AB genotype will have
both A and B blood proteins.
Black and orange color in cats
are co-dominant, because a
heterozygous female will have
both orange and black hair.
33. Incomplete Dominance
Both alleles are blended
together in the
heterozygous individual.
Dominant allele cannot
completely mask the
expression of another
34. Practice with your neighbor
For the following questions
Work with your neighbor to answer
the question.
Answer the multiple choice question
then,
Use your notes to determine which one
of Mendel’s principles it demonstrates
35. 1. A father carries 2 alleles for the gene
for widow’s peak. He carries one
dominant allele and one recessive
allele. His gametes will
a.
b.
c.
d.
All contain the dominant allele
All contain the recessive allele
½ will get the dominant allele and ½ will get the
recessive allele
Each gamete will get both the dominant and the
recessive allele
36. Which principle does question
number one best demonstrate?
Principle of Segregation
The dominant allele goes to one gamete and
the recessive allele goes to another
gamete
37. 2. A mother that is homozygous dominant
for bushy eyebrows (BB) and
heterozygous for round ears (Rr). The
gametes she can make will
a. All have a B and a R in them
b. ½ will have a B and ½ will have a R or a r in
them
c. ½ will have a B and a R and ½ will have b and
r
d. ½ will have B and R and ½ will have B and r
38. What principle does number 2
demonstrate?
The Principle of Independent Assortment
All gametes will have a B, since mom only has B.
The big B can be with the big R or the big B can
be with the little r.
39. 3. In meiosis, a diploid cell divides
twice to form 4 haploid gametes.
Each gamete contains:
a. A complete set of DNA identical to the parents
b. A ½ set of DNA, with just one copy of each
chromosome
c. Homologous pairs of chromosomes
d. Multiple copies of chromosomes, depending on
which ones moved during meiosis
40. Which one of Mendel’s Principles
does number 3 demonstrate?
Principle of Segregation
All the homologous pairs of chromosomes
separate so that there is just one of each
pair in each gamete.
41. 4. When Mendel crossed a true
breeding green pea plant (GG) with a
true breeding yellow pea plant (gg),
the offspring plants were
a.
b.
c.
d.
All green
All yellow
½ green and ½ yellow
Green and yellow mixed
42. Which one of Mendel’s principles
does number 4 demonstrate?
Principle of Complete Dominance
All offspring were Gg, and the dominant
allele (G) masked the recessive allele (g)
43. 5. Mendel wanted to know if the color for
pea seeds was linked to the shape of the
pea seeds. He crossed a green, wrinkled
seed plant (Ggrr) with a yellow, smooth
seed (ggRr) plant. The offspring produced
were:
a.
b.
c.
d.
e.
All green and wrinkled
All yellow and wrinkled
All green and smooth
All yellow and smooth
Some of each of the above
44. Which one of Mendel’s Principles
does number 5 demonstrate?
Principle of Independent Assortment
The green trait can go with the smooth or
the wrinkled trait
The yellow trait can go with the smooth or
the wrinkled trait
45. Multiple Alleles
traits controlled by more
that one gene (2 alleles)
and so they have many
different possible
phenotypes.
These alleles can show
dominant/recessive
patterns or codominant
patterns.
46. Bl ood Types
Genotype of Phenotype of
offspring
offspring
iAiA
A
iAi
i i
AB
A
iBiB
iBi
ii
AB
B
B
o
47. Rh f act or
Rh factor
Rh+
Rh-
Possible genotypes
+/+ or +/-
-/-
48. X-linked traits
genes found on the X chromosome.
show different inheritance patterns in men
than in women.
X-linked traits may show dominant/recessive
or codominant patterns.
49. X-linked traits
Women have 2 Xchromosomes, men have an X
and a Y.
For women to express a
recessive phenotype, they
must inherit 2 Xchromosomes, both with the
recessive allele.
For men to express the
recessive phenotype, they
need only 1 recessive X
50. Multifactorial Inheritance
traits controlled by
multiple alleles and the
phenotypes can also be
affected by the
environment.
The environment can
include exposure to
sunlight, chemicals,
hormones from the
mother during
pregnancy, etc.
51. DNA in organelles
DNA is also found in
mitochondria and
chloroplasts.
Mitochondrial DNA is only
passed from Mother to
child.
