1. Gregor Mendel “Father of Genetics” His work wasn’t discovered
Wrote “Experiments in
Plant Hybridization” in 1865
His work wasn’t discovered
until the next century

2. Painting of Mendel

3. Mendel

4. Table 14.1 The Results of Mendel’s F1 Crosses for Seven Characters in Pea Plants

6. Sweet Pea Flowers

7. Alleles, Alternative Versions of a Gene

8. Homozygous means
having only one form
of gene or allele
Ex: WW or ww

9. Heterozygous means a
trait represented by at least two different alleles, or forms of a gene
Ex: Ww

10. In the formation of a zygote, or fertilized egg, each parent of an
organism contributes one form of a
gene or allele, for each trait in most cases.

11. In Mendelian Genetics,
dominant traits are
represented by capital
letters; recessive ones
by lower case letters

12. Dominant traits (genes) are always expressed if the gene is present; recessive traits
are expressed only if the
dominant genes are absent

13. For example, widow’s peak (W) is a dominant trait in humans.
If the gene for widow’s
peak is present, W, the
person will have widow’s
Peak. (WW, Ww)

14. Homologous Chromosomes
Paternal
Maternal
eye color locus
B = brown eyes
eye color locus
b = blue eyes
This person would have brown eyes (Bb)

15. Meiosis - eye color B B Bb b b sperm haploid (n) diploid (2n)
meiosis II B b
meiosis I Bb
diploid (2n)

16. The physical appearance
of an organism is known as
the phenotype; the genetic
makeup (the letters) are
known as the genotype
Ex: Widow’s peak is the pheno-
type; Ww is the genotype

18. The way to show the pos-
sible pairings of genes
between two organisms is
called a Punnett Square.

19. Punnett Square
A Punnett square is used to show the possible combinations of gametes.

20. Breed the P generation
tall (TT) vs. dwarf (tt) pea plants T t

21. tall (TT) vs. dwarf (tt) pea plants
All Tt = tall
(heterozygous tall)
produces the
F1 generation Tt

22. Breed the F1 generation
Heterozygous Tall (Tt) pea plants
T t T t

23. Cross a purebred black
guinea pig and a
purebred brown guinea pig. Black is dominant
over brown.

24. B B (black) Bb Bb b Bb Bb b (Brown)
All offspringare black and heterozygous. Bb Bb b
(Brown)

25. If bushy eyebrows (B) are
dominant over fine eyebrows, (b), show the cross between one parent heterozygous for the trait and one who is
homozygous recessive.

26. What are the phenotypes
and genotypes of the
offspring?
Answer: Bushy (Bb) 50%
and fine (bb) 50%

27. Monohybrid Cross
A breeding experiment that tracks the inheritance of a single trait.
Dihybrid Cross
A breeding experiment that tracks
the inheritance of two traits.

28. Mendel’s “principle of segregation”
a. pairs of genes on homologous chromosomes separate
during gamete formation (meiosis)
and end up in different gametes.
b. the fusion of gametes at
fertilization pairs genes once again.
Ex: The alleles for height in Mendel’s
pea plants end up in separate gametes. Tt X Tt could yield four
the offspring: TT, Tt, Tt, tt.

29. Meiosis - eye color B B Bb b b sperm haploid (n) diploid (2n)
meiosis II B b
meiosis I Bb
diploid (2n)

30. Mendel’s Law of Segregation

31. Mendel’s “principle of independent assortment” (2 different genes)
a. each pair of alleles on nonhomologous chromosomes segregates independently of other pairs during gamete formation
Ex: When Mendel crossed F1 plants that were heterozygous for
round yellow peas, some F2 plants
did not resemble the parent plants.

32. Independent Assortment
How many different gametes can be produced for the following allele arrangements?
Remember: 2n (n = # of heterozygotes)
1. RrYy
2. AaBbCCDd
3. MmNnOoPPQQRrssTtUu

33. Answers: 1. RrYy: 2n = 22 = 4 gametes RY Ry rY ry
2. AaBbCCDd: 2n = 23 = 8 gametes
ABCD ABCd AbCD AbCd
aBCD aBCd abCD abCD
3. MmNnOoPPQQRrssTtUu: 2n = 26 = 64 gametes

34. Autosomal Inherited Traits are inherited via
the autosomes (non-sex)
chromosomes. How many
autosomes are in each
of your somatic cells?

35. That’s right! There are 44
autosomes and 2 sex chro-
mosomes in each of your
somatic (non-sex) cells.

36. Figure 13.x5 Human male karyotype shown by bright field G-banding of chromosomes

37. Autosomal Inherited
Genetic Disorders
include:
Cystic Fibrosis
Tay-Sachs Disease
Sickle Cell Anemia
Huntington Disease (this
one is dominant!)

38. Testing a Fetus for Genetic Disorders

40. Cystic Fibrosis
Most common inherited fatal disorder in the U.S.
Median age of death–37
One in every 29 Americans has the gene
Mucus builds up in the lungs

41. Francis Collins, current director of the National Human Genome Research Institute (NHGRI) helped pioneer the discovery of the CF gene in 1989.

42. Francis
Collins,
discoverer
of the Cystic
Fibrosis
Gene

43. Former NFL Quarterback, Boomer Esiason and his
son, Gunnar, who has CF.

45. Diagnosis: Treatment:

47. If a man who does not have Cystic Fibrosis has a sister who died of CF
If a man who does not have Cystic Fibrosis has a sister who died of CF. He marries a woman who does not have the disease or any history of it in her family, what is the probability that they will have kids with the disease?

48. Tay Sachs Disease a lipid-digesting enzyme is defective in lysosomes

49. If two parents are each
carriers of the gene for
Tay-Sachs Disease, what
is the probability of them
having a child with the
disease?

50. That’s right! They have a 25% chance!
Homozygous
Dominant
Heterozygous tt Tt t
Homozygous
Recessive

51. Sickle Cell Anemia

52. The molecular basis of sickle-cell disease: a point mutation

54. A degenerative disorder
Huntington Disease
A degenerative disorder
of the nervous system
Most people don’t realize that they have the disease until after age 30
and may have passed on the gene

55. Lake Maracaibo, Venezuela

57. Nancy Wexler’s Pedigree of 10,000 people in Lake Maracaibo

59. Huntington Disease (chorea)

60. Caused by a stuttering
gene - CAG repeat
Also called Huntington’s
Chorea
This is a dominant gene

61. Some human traits are
sex-linked; that is they
are carried on the X and
Y Chromosomes

62. For Example:
Hemophilia, Duchenne
Muscular Dystrophy, and
Colorblindness are all traits
carried on the X chromo-
some

63. Hemophilia

64. Colorblindness

68. Duchenne Muscular Dystrophy

69. If a female who is carrier
for Duchenne Muscular
Dystrophy (D), what is the probability of she
and her“normal”husband having a child with MD?

70. D d X X D D d D D X X X X X D d Y X Y X Y Normal Male with Disease
Carrier Female D d Y
X Y
X Y
Male with Disease

71. A pedigree shows the genetic relationship between organisms or
people.

72. Bloodtypes are also
inherited:
A = has antigen A
B = has antigen B
O =neither
AB =has both antigens
A and B

73. A = AA or AO (codominance)
Genotypes
O = OO
AB = AB
A = AA or AO (codominance)
B = BB or BO
(codominance)

74. Alleles and Genes Interact to Produce Phenotypes
Codominance—two alleles of a gene produce phenotypes that are both present in the heterozygote.
Example: ABO blood group system has three alleles of the gene: IA, IB, and IO.
See Chapter 31

75. ABO Blood Reactions Are Important in Transfusions75

76. O is the universal
donor (can donate
blood to anyone)
AB is the universal
recipient ( can receive blood from anyone)

77. Patient Donor
A A or O
B B or O
AB anyone
O O
a person who is Rh negative for any blood type must take only Rh negative blood

78. The Rh Factor is also inherited.
Approximately 85% of Americans are positive for the Rh Factor.
For example, if you have type A blood and are positive for the Rh Factor then your bloodtype is A positive.

79. So technically there are
8 blood groups:
A positive AB positive
A negative AB negative
B positive O positive
B negative O negative

80. In terms of a couple having kids, positive blood dominates
negative blood.
For example, a father with A positive blood and his wife
with A negative blood would have kids with A positive
blood.

81. RhoGAM
A woman who is pregnant and is Rh negative and has an Rh positive child must take RhoGAM in order to not reject the child.

82. If a woman who is
type O and a man
who is type A have
kids, what are their possible bloodtypes?

83. WOMAN
O O AO AO A
MAN AO AO A

84. A O O AO OO AO O OO

85. 1) If a brown eyed man marries a brown eyed woman and they have a blue eyed child, what are the genotypes of the parents?

86. 2) In rabbits, the allele for black coat
color (B) is dominant over the allele
for brown coat color (b). Predict
the results of a cross between a
rabbit homozygous for black coat
color (BB) and a rabbit homozygous
for brown coat color (bb)

87. 3) If two sisters in a family have free
earlobes (F) and their two brothers
have attached earlobes (f), what
genotypes are the parents most
likely to have if neither parent has
attached earlobes?

88. 4) What is the probability of a couple
who are both heterozygous for widow’s peak (W) and free earlobes (F) having a child with neither trait?

89. 5) In pea plants, smooth seed texture
is dominant over wrinkled seed
texture. A gardener has a pea
plant that produces smooth seeds. How can the gardener determine
whether the plant is homozygous
or heterozygous for the allele that
determines seed texture?

90. 6) In pea plants, if purple flowers
are dominant over white, and
smooth seeds are dominant
over wrinkled, predict the out-
come of the crossing of a pea
plant heterozygous for color
and homozygous recessive for
seed coat texture with one
heterozygous for both traits.

91. 7) In fruit flies, L = long wings and
l = short wings. When a
long-winged fly is crossed with a
short-winged fly, the offspring
exhibit a 1:1 ratio.
What is the genotype of the
parent flies?

92. 8) In squash an allele for white color
(W) is dominant over yellow (w). Give the phenotypic ratios for the results of each of the following crosses:
a) W/W x w/w
b) W/w x w/w
c) W/w x W/w

93. 9) In humans, pointed eyebrows
(B) are dominant over smooth
eyebrows (b). Mary’s father has pointed eyebrows, but she and
her mother have smooth. What
is the genotype of the father?

94. 10) In tomatoes, red fruit (R) is
dominantover yellow fruit (r), and
tallness (T) is dominant over
shortness (t). A plant that is RrTT
is crossed with aplant that is rrTt.
What are the chances of an offspring
beingheterozygous for both traits?

95. 11) In fruit flies, gray wings (G) are
dominant to black wings and normal
wing length (N) is dominant to vestigial (short) wing length. What is the probability of a gray fly with normal
wings heterozygous for both traits and a black fly with normal wings, but homozygous for wing length having offspring which are
gray and have normal wing lengths?

96. 12) Free ear lobes (F) and widow’s peak
(W) are dominant traits in humans. What is the probability of a woman who has attached earlobes and no widow’s peak and a man who is heterozygous
for both traits having kids who have
attached ear lobes and no widow’s
peak?

97. Genes A and B are 6 map units apart, and A and C are 4 map units apart
Genes A and B are 6 map units apart, and A and C are 4 map units apart. Which gene is in the middle if B and C are 10 map units apart? Which is in the middle if B and C are 2 map units apart?

98. In the cross RrTt X rrtt,
all of the offspring will be tall with red fruit
b. 75% will be tall with red fruit
c. 50% will be tall with red fruit
d. 25% will be tall with red fruit

99. In terms of evolution, why is
the incidence of sickle
cell anemia higher among the
African-American population
in the United States?

100. If one parent has type O blood
and one of the kids is type A,
what are the possible blood types of the other parent?
If one parent has type AB blood and the other has A, what are the possible blood types of the kids?

101. For most human traits, how many alleles does each parent contribute to the zygote or fertilized egg?
What is the term used to describe traits that are inherited
by a number of genes of each
parent?

102. show a Punnett square with the inheritance pattern
If you have good notes from yesterday
on Cystic Fibrosis you should be able to:
describe at least two organs affected
show a Punnett square with the
inheritance pattern
3) list one organization which raises
awareness of CF
4) name and describe the specific protein affected by CF
5) significance of discovery of the CF gene

103. When RhoGAM is given to a
pregnant mother,
what is the Rh status of the
mother, father, and baby?