Genetics Test 3

Front 1

Genetics
The study of..?

Back 1

Not the study of genes. NOT molecular. Its INHERITANCE PATTERNS!

Front 2

Genes

Back 2

Biological factos that induce particular traits.

Front 3

Alleles

Back 3

Alternate forms of a given gene, inherited from different parents. (1 copy on each homolog)

Front 4

Locus

Back 4

The location on a chromosome, often used to refer to the gene at that site.
(Refers to the site on a chromosome of a particular gene.)

Front 5

Dominant

Back 5

An allele which always determines the phenotype.

Front 6

Recessive

Back 6

An allele which only determines phenotype in the absence of a dominant allele.

Front 7

Mutant

Back 7

A mutant allele, or individual with a mutated allele.

Front 8

Wild Type

Back 8

An allele that is not mutated, alleles that occur normally in nature. Usually these are dominant alleles. Wild type can also be used to refer to an individual who does not carry a mutated allele.

Front 9

Genotype

Back 9

The combination of alleles in an individual. (ex- the genotype for someone with a Brown eye allele and a Blue eye allele is Bb.)

Front 10

Phenotype

Back 10

Observable characteristics. The physical manifestation of the genotype. (ex- the phenotype of a Bb person is Brown eyes.)

Front 11

Homozygous

Back 11

To carry both copies of the same allele (Both dominant, BB, or both recessive, bb.)

Front 12

Heterozygous

Back 12

To have different alleles. (One dominant and one recessive, ex- Bb.)

Front 13

Homozygote

Back 13

A homozygous individual.

Front 14

Heterozygote

Back 14

A heterozygous individual.

Front 15

Monohybrid Cross

Back 15

A cross where one gene locus is tracked. (ex- Aa x Aa)

Front 16

Dihybrid Cross

Back 16

A cross where two loci are tracked. (ex- AaBb x AaBb)

Front 17

Trihybrid Cross

Back 17

A cross where three loci are tracked. (ex- AaBbCc x AaBbCc)

Front 18

F1

Back 18

Filial One
The first generation produced in a series of crosses.

Front 19

F2

Back 19

Filial Two
The second generation produced ina series of crosses.

Front 20

Independent Assortment

Back 20

Inheritance of alleles at one locus does not influence inheritance at other loci.

Front 21

This is a product of crossing over.

Back 21

Independent Assortment.

Front 22

Sex Chromosome

Back 22

Sex determining chromosome, X or Y.

Front 23

Autosome

Back 23

Any chromosome except X or Y.

Front 24

X Linked

Back 24

(Sex Linked)
A gene located on the X chromosome.

Front 25

Autosomal

Back 25

Any genen not located on X, or characteristic not associated with X.

Front 26

blu=?
blu+=?

Back 26

blu= blue eye color
blu+= brown eye color

Front 27

eds=?
+=?

Back 27

eds= Ehlers Danlos Syndrome
+=wild type

Front 28

Parent (In Monohybrid Cross)

Back 28

a typical monohybrid cross begins with two homozygous parents, one dominant and one recessive.

Front 29

Gametes (In Monohybrid Cross)

Back 29

The dominant parent can only produce dominant gametes, the other only recessive.

Front 30

F1 (In Monohybrid Cross)

Back 30

The first parent must contribute a dominant allele while the other must give a recessive allele, so all first generation progeny must be heterozygous.

Front 31

F1 Gametes (In Monohybrid Cross)

Back 31

Each gamete from each parent has an equal chance of inheriting iether allele, so half will carry the dominant form, half recessive.

Front 32

F2 (In Monohybrid Cross)
How many ways to produce homozygous dominant progeny?
Heterozygous progeny?
Homozygous recessive progeny?

Back 32

There is only one way to produce a homozygous dominant progeny.
There are two ways to produce heterozygous progeny (dominant from the father, recessive from the mother; recessive from the father, dominant from the mother)
There is only one way to produce homozygous recessive progeny.

Front 33

What is the ratio of the F2 generation in a Monohybrid Cross?

Back 33

1:2:1
Homozygous Dominant: Heterozygous: Homozygous Recessive

Front 34

What is the phenotypic ratio of a Monohybrid Cross?

Back 34

Because homozygous dominant and heterozygous progeny have the same appearance, the phenotypic ratio is 3:1.

Front 35

Monohybrid Cross

Back 35

A cross where one gene locus is tracked.
(ex- AA x aa)

Front 36

Dihybrid Cross

Back 36

A cross where two gene loci are tracked.
(ex- BBEE x bbee)

Front 37

What is the F2 genotypic ratio for a dihybrid cross?

Back 37

1:2:1:2:4:2:1:2:1

Front 38

What is the F2 phenotypic ratio for a dihybrid cross?

Back 38

9:3:3:1

Front 39

F1 generation in a Dihybrid Cross?

Back 39

As with the monohybrid cross, all first generation progeny must be heterozygous.

Front 40

Where does independent assortment occur in a Dihybrid Cross?

Back 40

In the F1 Gametes

Front 41

Inheritance at one allele is ____ of another.

Back 41

Independent

Front 42

Why is inheritance at one locus independent of another in the F1 gametes of a Dihybrid Cross?

Back 42

Because meiosis segregation of one pair of homologs is independent of another, and because crossing over shuffles alleles between homologs.

Front 43

For a heterozygous, dihybrid cross, there are ___ possible combinations of the alleles in the gametes.

Back 43

Four

Front 44

F2 Generation in a Dihybrid Cross:
The ___ different types of gametes fromt eh two different parents can combine in ___ different ways.

Back 44

four
16

Front 45

How can you distinguish an individual's genotype from their phenotype?

Back 45

Heterozygotes look the same as homozygous dominant. A test cross is a simple procedure for making this determination.

Front 46

What is the procedure for distinguishing an individual's genotype from their phenotype?

Back 46

Cross the unknown subject with a homozygous recessive mate. (ex- B? x bb)

If ? is B, all F1 have brown eyes.
If ? is b, f1 ia half brown, half blue eyes.

Front 47

What is the rational behind a test cross?

Back 47

Because the test subject is dominant phenotype, they must have at least one dominant allele. The unknown is their second allele. With a test cross this unknown allele must pair with a recessive allele from the mate. That is all the mate has to contribute. Thus, if the unknown allele is recessive, half the F1 will be homozygous recessive. If the test subject is homozygous dominant, all the F1 will be heterozygous with dominant phenotype.

Front 48

This serves to reveal recessive alleles by guaranteeing that they pair with other recessive alleles.

Back 48

Test Cross

Front 49

In a test cross, if the F1 are all dominant phenotype, then the test subject was _____?

Back 49

Homozygous Dominant

Front 50

In a test cross, if the F1 are half dominant phenotype, half recessive, then the test subject was _________?

Back 50

Heterozygous

Front 51

What is the ratio produced whenever you cross a homozygous recessive with a heterozygote?

Back 51

1:1

Front 52

This is a method for determining genotypic or phenotypic ratios by writing every possible combination in a matrix.

Back 52

Punnett Squares

Front 53

Test Cross
Genotypic Ratio?
Phenotypic Ratio?

Back 53

1:1 (Bb x bb)
1:1 (B x b)

Front 54

Monohybrid Cross
Genotypic Ratio?
Phenotypic Ratio?

Back 54

1:2:1 (BB: Bb: bb)
3:1 (B: b)

Front 55

Dihybrid Cross
Genotypic Ratio?
Phenotypic Ratio?

Back 55

1:2:1:2:4:2:1:2:1
9:3:3:1

Front 56

What kind of test would you do to answer this question-
Are two mutants with the same phenotype (ex- EDS) priduced by different mutations of the same gene OR by defects in separate genes where either mutation results in the same phenotype?

Back 56

Complementation Test

Front 57

What is the procedure in a complementation test?

Back 57

Cross two homozygous mutants with each other.

Front 58

What is the rational behind the procedure of a complementation test?

Back 58

Procedure- Cross two homozygous mutants with each other.
Rationale- If the mutations are in the same gene, then the F1 will inherit two mutated alleles for the locus and they will have the condition.

Front 59

In a complementation test, if the mutated alleles are in separate genes-?

Back 59

The F1 will all be heterozygous for both loci and they will be healthy. The wild type allele at each locus corrects the defect, and the genes are said to compliment each other.

Front 60

Complimentary genes are ____ genes.

Back 60

Separate
(If two mutations compliment each other, they are in different genes.)

Front 61

Non-Mendelian Inheritance

Back 61

There are genetic interactions other than the autosomal recessive pattern characterized by Mendel. These are known as non-Mendelian inheritance.

Front 62

What are seven types of Non-Mendelian Inheritance?

Back 62

1) Semidominance
2) Codominance
3) Polygenic Inheritance
4) Epistasis
5) X linkage
6) Sex Influenced Inheritance
7) Linkage

Front 63

Semidominance

Back 63

Partial or incomplete dominance.
Different alleles for a particular gene have equal effects, so that heterozygotes have intermediate phenotypes.

Front 64

This is an example of what?
In snapdragon flowers, one allele mkes the flower red when homozygous. Another allele makes them white. However, heterozygotes are pink, intermediate between red and white.

Back 64

Semidominance

Front 65

What are the phenotypic ratios in semidominance?

Back 65

The phenotypic ratios are the same as genotypic ratios. (1 red:2 pink:1 white)

Front 66

Codominance

Back 66

Different alleles for a gene that impart independent effects on phenotype.

Front 67

What is a classical example of Codominance?

Back 67

A and B blood types.
Homozygotes for the Ia allele are blood type A, which means their RBCs express the A antigen, so they do not produce anti-A antibodies, and they do not react against A type blood. They do reacts against B type transfusions, because B antigens are recognized as foreign.

Front 68

Homozygotes for the Ib allele react against ___ type blood.

Back 68

A

Front 69

Polymorphism

Back 69

more than two alleles for a given gene
(ex- eye color)

Front 70

Polygenic Inheritance

Back 70

To have multiple genes influencing the same trait.

Front 71

Epistasis

Back 71

For a gene to mask the phenotype of another gene, at another locus.

Front 72

This is not a dominant allele masking a recessive allele, this is a gene suppressing the phenotype of a totally separate gene.

Back 72

Epistasis

Front 73

In epistasis, the gene that masks the phenotype is called a ___?

Back 73

Suppressor

Front 74

The gene that masks the phenotype is said to be ___ to the gene it suppresses.

Back 74

Epistatic

Front 75

The suppressed gene is sometimes described as ___?

Back 75

Hypostatic

Front 76

Epistasis Analysis

Back 76

This is another type of diagnostic cross. It uses suppressors to determine the order of different genes ina regulatory pathway.

Front 77

This analysis determines whether a gene acts upstream or downstream of another gene.

Back 77

Epistasis Analysis

Front 78

In this type of analysis, we would begin by performing a series of crosses to generate progeny that are homozygous for two loci (ex- bbpp). We would then score these double homozygotes to determine which phenotype is suppressed.

Back 78

Epistasis Analysis

Front 79

One gene suppressing another. Used to determine the order of genes in a pathway.

Back 79

Epistasis Analysis

Front 80

X Linkage

Back 80

Genes carried on the X Chromosome

Front 81

Sex Chromosomes

Back 81

Sex determining chromsomes, X and Y.

Front 82

Autosomes

Back 82

All chromsomes besides X and Y.

Front 83

X Linked

Back 83

gene located on X chromosome

Front 84

Autosomal

Back 84

A gene not located on X or Y

Front 85

Hemizygotes

Back 85

Males have half as many X linked alleles as females. They carry alleles on their X with no corresponding alleles on their Y. This is because Y only carries a few genes.

Front 86

Sex Influenced Inheritance

Back 86

Autosomal gnees, not carried by the X or Y chromosomes, but which are differentially expressed in males and females.

Front 87

These are usually involved with secondary sexual characterisitics such as body hair, fat distribution and aggression.

Back 87

Sex Influenced Inheritance

Front 88

Characteristics of X Linkage

Back 88

The distinguishing characteristic of X linked recessive alleles is they are passed from affected grandfathers, through unaffected mothers, to affected grandsomes.

Front 89

These are expressed in males more often than females.

Back 89

X Linked Genes

Front 90

What is the key pattern in a Sex Linkage?

Back 90

Affected Grandfather
Carrier Mother
Affected Son

Front 91

If a homozygous wild type mother is crossed witha color blind father, what is the F1 generation?

Back 91

This generations progeny are all wild phenotype, but the daughters are heterozygous carriers, not hte sones. The hemizygous boys have wild type X chromosomes while their Y chromosomes carry no alleles for this locus.

Front 92

F2 generation if a homozygous wild type mother is crossed with a color blind father.

Back 92

Because the F1 daughters are heterozygous, they give wild type alleles to half the F2 progeny, and mutated alleles to the other half.

Front 93

What is the genotype and phenotype of F2 granddaughters iwth a homozygous wild type mother crossed with a color blind father?

Back 93

The F2 granddaughters are either heterozygous or homozygous wild type. They all have wild phenotypes.

Front 94

What is the genotype and phenotype of F2 grandsones froma homozygous wild type mother crossed with a color blind father?

Back 94

The hemizygous grandsons lack an allele on their Y chromosomes so they are either wild phenotype or color blind.

Front 95

Homozygous wild type mother crossed with a color blind father.
All the F1 children and F2 granddaughters are ____ type, but half the grandsons are ___ and half are ___.

Back 95

Wild type
Wild type
Color blind

Front 96

The X linked allele is passed from the father, through his daughters to half his ___.

Back 96

Grandsons.

Front 97

What is the rational behind dosage compensation?

Back 97

The X chromosome carries numerous genes while the Y chromosomes carries very few. Most Y linked genes are involved with sex determination. Therefore females, who have two X chromosomes possess twice as many X linked genes as males, who only have one X. To avoid genetic imbalance there must be a mechanism to adjust expression of X linked genes.

Front 98

X Inactivation

Back 98

In mammals, the adjustment for dosage compensation is achieved by inactivation one X chromosome in each blastomere. These inactivated X chromosomes become condensed (heterochromatic).

Front 99

Inactivated, condensed, heterochromatic X chromosomes are known as___?

Back 99

Barr bodies

Front 100

When does X chromosome inactivation offur?

Back 100

Early in embryogenesis, around the 64 cell stage.

Front 101

How does X chromosome inactivation work?

Back 101

It is random. One or the other X may be inactivated in each blastomere. This results in body regions where all the cells have the same inactivated X.

Front 102

Genetic Mosaics

Back 102

Female mammals, in which certain body regions all have the same inactivated X chromosome.

Front 103

Anhidrotic Ectodermal Dysplasia
What is it?
What does it demonstrate?

Back 103

The absence of sweat glands.
Results from genetic mosaics due to inactivation of X chromosomes in the blastomeres.

Front 104

Why are all calico cats female?

Back 104

Result of genetic mosaics where cells of a certain area all share the same inactivated X chromosome. Dosage compensation.

Front 105

Linkage

Back 105

When two genes are so close they usually segregate together during inheritance.

Front 106

This is a violation of the principle of independent assortment.

Back 106

Linkage

Front 107

If two alleles are on the same homolog, they are ___ to each other. If they are on different homologs, they are in the ___ conformation.

Back 107

Cis
Trans

Front 108

Consider two heterozygous loci that are cis to each other. If these loci are far apart there is a great chance of a cross over occurring between them. Whenever this occurs recombinant ___ progeny are produced.

Back 108

Trans

Front 109

The closer two genes are, the less ____ you see between them.

Back 109

Recombination (Crossing Over)

Front 110

Linkage Mapping

Back 110

Estimating distances between loci by determining recombination frequencies.

Front 111

Recombination frequency between genes is proportional to the ___?

Back 111

Distance between the loci

Front 112

Map Unit

Back 112

Percent recombination between two loci.
(1 MU = 1%)

Front 113

How do you determine which are the parental types and which are the recombinant types in linkage mapping?

Back 113

The parental types have a higher number.

Front 114

What is the formula for Linkage Mapping?

Back 114

100 x (Recombinant)/ (Total)

Front 115

What is the greatest number of map units you can have?

Back 115

50
This is because if the distance is greater than 50 MU, there is an equal chance of having an equal or odd number of crossover between the lci, so there is the same chance of producing recombinant or parental genotypes.

Front 116

What is the criteria for linkage?

Back 116

Genes that are 50 MU apart or greater are not linked, while if they are less than 50 MU apart, they are linked.

Front 117

Multifactorial Traits

Back 117

Characteristics controlled by multiple factors, both genetic and environmental.

Front 118

What is an example of something that is purely genetic? (Not multifactorial.)

Back 118

Finger prints

Front 119

Any trait controlled by multiple genes AND environmental factors. NOT just genetics!

Back 119

Multifactorial trait

Front 120

Polygenic Inheritance

Back 120

For a trait to be controlled by multiple genes

Front 121

This is the genetic component of a multifactorial trait.

Back 121

Polygenic Inheritance

Front 122

Pleiotropy

Back 122

For a single gene to control multiple traits.

Front 123

What is an example of Pleiotrophy?

Back 123

Cystic Fibrosis
Knock out 1 gene leads to multiple effects.

Front 124

Polymorphism

Back 124

Multiple alleles in a population for a gene.

Front 125

For a given locus, there are multiple alleles in the population.

Back 125

Polymorphism

Front 126

Heritability

Back 126

Estimate of how much genetics (as opposed to environment) contributes to a given trait.

Front 127

Estimate of how much of a trait is controlled by the polygenic component.

Back 127

Heritability

Front 128

Quantitative Multifactorial Traits

Back 128

Can be assigned a numerical value. (ex- BP, height, weight)

Front 129

Qualitative Multifactorial Traits

Back 129

Either occur or dont. These are all or none phenomenon. (ex- heart attacks, nerual tube defects)

Front 130

A multifactorial trait is influenced by numerous factors. These factors are ___ as well as ___.

Back 130

Genetic
Environmental

Front 131

Polygenic traits are by definition ___.

Back 131

Multifactorial

Front 132

This is controlled by an interaction between many different factors, both the multitude of genes that influence the trait, and any environmental conditions that the individual is exposed to.

Back 132

Multifactorial Traits

Front 133

Normal Distribution of Multifactorial Traits

Back 133

Most multifactorial traits fall into a normal distribution (bell shaped curve).

Front 134

Hardy Weinberg Equilibrium

Back 134

This is a model explaining how genes and alleles are distributed throughout a population. The model assumes that the distribution, or frequency of each allele, is at steady state.

Front 135

What is the formular for the Hardy Weinberg Equilibrium?

Back 135

p2 + 2pq + q2 = 1
p + q = 1

Front 136

In the Hardy Weinberg Equilibrium,
p=?
q=?

Back 136

p = frequency of most abundant allele in the population
q = less abundant allelic frequency (usually the recessive)

Front 137

Frequency refers to the ___. This is why p and q add up to one.

Back 137

The fracion of all the alleles in the population.

Front 138

Carrier frequency

Back 138

Aa
2pq

Front 139

Affected frequency

Back 139

q2
usually homozygous recessive (aa)

Front 140

allelic frequencies

Back 140

p and q

Front 141

genotypic frequencies
(Hardy Weinber Equilibrium)

Back 141

p2, 2pq, q2

Front 142

p2 = ?
2pq = ?
q2 = ?

Back 142

p2 = unaffected frequency
2pq = carrier frequency
q2 = incidence (frequency of disease or trait)

Front 143

What is the primary assumption of the Hardy Weinberg model?

Back 143

That the population is at equilibrium, which is to say gene frequencies are constant.

Front 144

What is the true definition of evolution?
With this in mind, what is another way to state the primary assumption of the Hardy Weinberg Model?

Back 144

Evolution is any change in gene frequency.
The population is not evolving.

Front 145

What are the secondary assumptions of the Hardy Weinberg Model?

Back 145

Four mechanisms for changing gene frequencies. Must be met for the primary assumption to be valid.
1) Mutation
2) Genetic Drift
3) Migration
4) Selection

Front 146

Mutation

Back 146

A change in gene sequence, usually resulting from an error in DNA replication. Any giben mutation only adds one allele to the population. This represents a minute change in allelic requency, so mutation is considered a minor force driving evolution.

Front 147

Genetic Drift

Back 147

Fora generation/s to randomly inherit a disproportionately high or low frequency of a particular allele. A random change.

Front 148

In small populations such as isolated villages, this can have a much more substantial affect.

Back 148

Genetic Drift

Front 149

Migration

Back 149

Emigration of a new population, with gene frequencies different from the native population, resulting in a combined population with frequencies different from either of the original populations.

Front 150

This is a major factor in modern human populations, where advances in transportation are resulting in intermixing of races around the world.

Back 150

Migration

Front 151

What is the most important of the secondary assumtions in the Hardy Weinberg Equilibrium?

Back 151

Selection

Front 152

Selection

Back 152

Forces that influence the chance that an allele will be passed onto future generations. Related to fitness.

Front 153

Fitness

Back 153

The ability to pass genes onto the next generation.

Front 154

Pedigree

Back 154

diagrammatic representation of a family history

Front 155

Proband

Back 155

Index case.
The first family member identified with the inherited trait of interest.

Front 156

Inbreeding

Back 156

For consanguineous individuals to produce offsprings.

Front 157

Consanguineous

Back 157

Any two individuals who are descended from a common ancestor. This term usually refers to two individuals with a common ancestor in their recent family history, so that they are closely related.

Front 158

What is the symbol for an X-linked recessive carrier?

Back 158

A circle with a darkened circle in the middle.

Front 159

What is the symbol for a Proband?

Back 159

A darkened circle or square with an arrow pointing to it.

Front 160

What are the characteristics for identifying an autosomal recessive inheritance pattern?

Back 160

1) Tends to skip generations.
2) On the average, 25% of the offspring of carriers will be affected, 2/3 of the unaffected offspring will be carriers.
3) Both parents must be carriers.
4) Common for multiple siblings to be affected (horizontal transmission).
5) Affected offspring will be more common with consanguinity.

Front 161

What are the characterisitics for identifying an autosomal dominant inheritance pattern?

Back 161

1) There are usually several generations of affected offspring (vertical transmission).
2) All carriers are affected.
3) On the average, half of a carrier's offspring will be affected.
4) One one parent need be a carrier.
5) Homozygotes are usually rare. Most carriers are heterozygotes.
6) Sporadic cases caused by new mutations may be observable.

Front 162

What are the characteristics for identifying a Sex Linked inheritance pattern?

Back 162

1) More males will be affected than females.
2) Transmission will usually be from affected fathers, through carrier daughters, to affected grandsons.
3) No father to son transmission.
4) All daughters of affected males will be carriers.
5) Half the offspring of the female carriers will receive the mutated allele. The sons will be affected, the daughetrs carriers.
6) Sporadic cases caused by new mutations in hemizygous males may be observable.

Front 163

What are the characterisitics for indentifying a Multifactorial inheritance pattern?

Back 163

1) Distinguishing characteristic of polygenic traits is familial recurrence without any distinctive inheritance pattern.
2) The more closely related a subject is to an affected relative, the greater the subject's risk of manifesting the trait.
3) The occurrence tends to decline in a family from generation to generation.
4) Risk increases with greater numbers of affected family members.
5) Risk increases with more severe symptoms in family members.
6) If occurrence is frequent in a sex, risk increases for family members of that sex.

Front 164

Coefficient of Relationship (R)

Back 164

The fraction of identical genes shared by two relatives.

Front 165

The number of matings (n) in a line is counted, and 1/2 is multiplied for each mating.

Back 165

Coefficient of Relationship

Front 166

Coefficient of Inbreeding (F)

Back 166

The fraction of homozygous loci resulting from a consanguineous mating.

Front 167

This can also be thought of as the chance that any given loci will be homozygous due to inbreeding.

Back 167

Coefficient of Inbreeding (F)