BIO-121 Topic 13

Question 1

Dihybrid Cross

Answer 1

Cross that involves the inheritance of 2 traits

Question 2

How many possible gametes for a test cross?

Answer 2

4

Question 3

What is the phenotypic ratio of the offspring of a dihybrid cross beginning with heterozygotes?

Answer 3

9:3:3:1

Question 4

9 =

Answer 4

Offspring have both dominant traits

Question 5

3 =

Answer 5

Offspring have one of dominant traits and one of the recessive traits

Question 6

1 =

Answer 6

Offspring has both recessive traits

Question 7

Principle of Independent Assortment

Answer 7

Alleles of a gene will assort independently of alleles of other genes

Question 8

What phase of Meiosis does Independent Assortment refer to?

Answer 8

Metaphase I and II

Question 9

Testcross

Answer 9

A cross used to determine the genotype of an individual with a dominant trait

Question 10

What would be the possible genotypes of an individual in a test cross?

Answer 10

Homozygous dominant or heterozygous

Question 11

What happens in a testcross?

Answer 11

The individual with the dominant trait is crossed with the individual with the recessive trait

Question 12

What are the 2 possible outcomes of a testcross?

Answer 12

100% heterozygous or 50-50% heterozygous-homozygous recessive

Question 13

If the individual with the dominant trait is homozygous dominant, what % of the offspring will show the dominant trait?

Answer 13

100%

Question 14

If the individual with the dominant trait is heterozygous, what % of the offspring will show the dominant trait?

Answer 14

50%

Question 15

If human skin color was inherited by complete dominance, how many skin colors would there be?

Answer 15

Only 2

Question 16

Does the environment effect the expression of genes?

Answer 16

Yes

Question 17

Phenotype =

Answer 17

Genotype and effect on environment

Question 18

What does tyrosinase do in Siamese cats?

Answer 18

Catalyzes the first step in the production of melanin

Question 19

How do warm temperatures effect tyrosinase in the cat?

Answer 19

Enzyme is inactive

Question 20

What color is the cats fur if the enzyme is inactive?

Answer 20

White

Question 21

How do cold temperature effect tyrosinase in the cat?

Answer 21

Enzyme is active

Question 22

What color is the cats fur if the enzyme is active?

Answer 22

Black

Question 23

Continuous Variation =

Answer 23

Polygenic Inheritance

Question 24

Continuous Variation

Answer 24

One trait can be determined by the interactions of many genes

Question 25

What is an example of continuous variation?

Answer 25

Skin color

Question 26

What is the opposite of continuous variation?

Answer 26

Pleiotropy

Question 27

Pleiotropy

Answer 27

One gene effects many traits

Question 28

Why does pleiotropy occur?

Answer 28

Living organisms rely on biochemical pathways and organ systems are interdependent

Question 29

What exhibits many pleiotropic effects?

Answer 29

Human genetic disorders

Question 30

What is an example of pleiotropy?

Answer 30

Cystic fibrosis

Question 31

Do some genes have more than 2 alleles?

Answer 31

Yes

Question 32

What is an example of multiple alleles?

Answer 32

ABO blood type in humans

Question 33

3 alleles in blood type?

Answer 33

IA, IB, i

Question 34

IA

Answer 34

Codes for an enzyme that adds galactosamine to the surface of RBCs; dominant

Question 35

IB

Answer 35

Codes for an enzyme that adds galactose to the surface of RBC's; dominant

Question 36

i

Answer 36

Codes for the enzyme that does not add a sugar; recessive

Question 37

What does the immune system recognize the sugars in RBC's as?

Answer 37

Identity markers

Question 38

How many total blood type genotypes?

Answer 38

6

Question 39

Incomplete Dominance

Answer 39

Phenotype of a heterozygote is the blend of the phenotypes of the 2 homozygous parents

Question 40

What is an example of incomplete dominance?

Answer 40

Red, white, and pink flowers

Question 41

Codominance

Answer 41

Genes are expressed equally; one allele is not dominant over another

Question 42

What is an example of codominance?

Answer 42

Human blood type AB

Question 43

Epistasis

Answer 43

One gene cancels the effects of another gene

Question 44

What is an example of epistasis?

Answer 44

The coat color of labs

Question 45

Melanin

Answer 45

Only pigment produced by mammals

Question 46

Eumelanin

Answer 46

True melanin; brown or black

Question 47

Pheomelanin

Answer 47

Yellow or red

Question 48

When is pheomelanin expressed?

Answer 48

Only when eumelanin isn't functioning

Question 49

As long as eumelanin is being produced, can you see pheomelanin?

Answer 49

No, even though it is being produced

Question 50

Phenotypic ratios due to epistasis?

Answer 50

9:3:4

Question 51

Genotypes of A blood?

Answer 51

IAIA or IAi

Question 52

Genotypes of B blood?

Answer 52

IBIB or IBi

Question 53

Genotypes of AB blood type?

Answer 53

IAIB

Question 54

Genotypes of O blood type?

Answer 54

ii

Question 55

Antigen in A blood?

Answer 55

Galactosamine

Question 56

Antigen in B blood?

Answer 56

Galactose

Question 57

Antigen in AB blood?

Answer 57

Galactosamine and galactose

Question 58

Antigen in O blood?

Answer 58

None

Question 59

Antibodies in A blood?

Answer 59

Anti-B

Question 60

Antibodies in B blood?

Answer 60

Anti-A

Question 61

Antibodies in AB blood?

Answer 61

None

Question 62

Antibodies in O blood?

Answer 62

Anti-A and Anti B

Question 63

O =

Answer 63

Universal donor

Question 64

AB =

Answer 64

Universal recipient

Question 65

Blood Plasma

Answer 65

Liquid part of the blood

Question 66

Rh

Answer 66

Another antigen on the surface of the RBC; either have it (+) or don't (-)

Question 67

RHOgam

Answer 67

Vaccine that prevents mom's body from making antibodies against Rh

Question 68

Linked Genes

Answer 68

Genes on the same chromosome that are typically inherited together

Question 69

Chromosomal Theory of Inheritance

Answer 69

Chromosomes containing genes are inherited by offspring from their parents

Question 70

Autosomes

Answer 70

44 chromosomes other than the 2 sex ones

Question 71

Sex Chromosomes

Answer 71

XX and XY

Question 72

XX

Answer 72

Female

Question 73

XY

Answer 73

Male

Question 74

Why do females develop 2nd?

Answer 74

Due to their inability to respond to testosterone and the lack of the y chromosome

Question 75

Which sex chromosome is larger?

Answer 75

X

Question 76

Which sex chromosome has more genes?

Answer 76

X

Question 77

Are sex-linked disorders more common in males or females?

Answer 77

Males

Question 78

Why are genes on a males X expressed regardless if they're dominant or recessive?

Answer 78

There is no counterpart on the Y chromosome

Question 79

Hemziygous

Answer 79

Genotype that is not similar; X and Y chromosomes

Question 80

How many genes on the X chromosome?

Answer 80

1805

Question 81

How many mutant alleles on the X chromosome?

Answer 81

821

Question 82

X-linked =

Answer 82

Sex-linked

Question 83

Carrier =

Answer 83

Heterozygous

Question 84

What type of disorder is hemophilia?

Answer 84

X-linked recessive

Question 85

How many recessive alleles does a female have to inherit to have hemophilia?

Answer 85

2

Question 86

How many recessive alleles does a male have to inherit to have hemophilia?

Answer 86

1

Question 87

What happens to a person with hemophilia?

Answer 87

Can't clot blood/prevent bleeding because of defective proteins

Question 88

Does a female produce twice as much protein encoded by the genes on the X chromosome?

Answer 88

No

Question 89

What happens to one of the X chromosomes of a female early in embryonic development?

Answer 89

One of the X chromosomes in each cell is randomly inactviated

Question 90

Barr Body

Answer 90

Inactivated X chromosome

Question 91

What is the Barr Body attached to?

Answer 91

The inside of the nuclear membrane

Question 92

Why is a female considered a genetic mosaic?

Answer 92

Different cells express different X-linked alleles depending on the Barr Body

Question 93

What is the color of a Calico cat's fur the result of?

Answer 93

The formation of Barr Bodies and epistasis

Question 94

What is the only part of the sperm that enters into the egg?

Answer 94

The nucleus

Question 95

From which parent do you inherit your cell organelles?

Answer 95

Mom; dad only gives 23 chromosomes, nothing else

Question 96

What is the inheritance of mitochondria called?

Answer 96

Maternal Inheritance

Question 97

If a female has defective genes in her mitochondria DNA, which of her children will inherit these genes?

Answer 97

All of them

Question 98

What type of disorders do mitochondrial DNA cause?

Answer 98

Rare disorders with no cures