Genetics Chapter 8

Front 1

refers to the differences between members of the same species or those of different species?

Back 1

genetic variation

Front 2

are due to mutations in particular genes?

Back 2

allelic varations

Front 3

changes in chromosomes structure?

Back 3

chromosomal aberrations

Front 4

chromosomal aberrations typically affect more than one _____?

Back 4

gene

Front 5

chromosomal aberrations are also called?

Back 5

chromosomal mutations

Front 6

a change in chromosome number?

Back 6

genome mutation

Front 7

genome mutations are the result of changes in the number of

Back 7

sets or individual chromosomes in a set

Front 8

variations in chromosome structure is important for 3 reasons?

Back 8

can affect phenotype of the organism; can affect the phenotype of the offspring; can be important force in evolution of species

Front 9

field of genetics that involves the microscopic examination of chromosomes?

Back 9

cytogenetics

Front 10

A _______ typically examines the chromosomal composition of a particular cell or organism?

Back 10

cytogenicist

Front 11

what does this examination provide?

Back 11

means of determining species and abnormal chromosome structure/ number

Front 12

what are the three different features to identify and classify chromosomes?

Back 12

Size; Location of centromere; Banding patterns;

Front 13

these features are all seen in a ________?

Back 13

karyotype

Front 14

what is G-banding?

Back 14

karyotype using the dye Giemsa

Front 15

in humans ____ G-bands are seen in metaphase?

Back 15

300

Front 16

in humans ___ G-bands are seen in prophase?

Back 16

2000

Front 17

there are two primary ways in which the structure of a chromosome can be altered?

Back 17

the amount of info can change (deletions/duplications) or the amount of material remains the same but is rearrangesd (inversion/translocation)

Front 18

the loss of a chromosomal segment?

Back 18

deficiency or deletion

Front 19

the repitition of chromosomal segment compared to the normal parent chromosome?

Back 19

duplication

Front 20

a change in the direction of the genetic material along a single chromosome?

Back 20

inversion

Front 21

a segment of one chromosome becomes attached to a different chromosome?

Back 21

translocation

Front 22

two types of translocations?

Back 22

simple translocations/ recipricol translocations

Front 23

phenotypic consequences of deletions depends on ?

Back 23

Size of the deletion; the material deleted

Front 24

when deletions have phenotypic effects they ussually are detrimental; give an example in which part of chromosome 5 is deleted?

Back 24

cri-du-crat syndrome in humans (page 191)

Front 25

cri-du-crat syndrom is caused by deletion in the ?

Back 25

short arm of chromosome number 5

Front 26

ways of detecting deletions?

Back 26

cytological (microscope); molecular; genetic

Front 27

what is a good indication that a mutation is due to a deletion?

Back 27

if a mutant population cannot revert back to the wildtype

Front 28

deletions can also reveal a phenomenom known as a ________?

Back 28

pseudodominance

Front 29

what is pseudodominance?

Back 29

when one copy of the gene is deleted so the recessive allele is now expressed

Front 30

ussually caused by an abnormal event during recombination such as a "misaligned crossover"?

Back 30

duplications

Front 31

true or false; duplications tend to have less harmful effects than deletions of comparable size?

Back 31

true

Front 32

investigated the Bar-eye phenotype in Drosophila?

Back 32

Bridges experiment

Front 33

is a trait in which flies have a reduced number of facets?

Back 33

Bar eyes

Front 34

is a trait in which flies have even fewer facets than the Bar homozygote?

Back 34

ultra-bar (or double bar)

Front 35

both of these traits are _____ and show incomplete dominance?

Back 35

X linked

Front 36

bridges used the cells of salivary gland of drosophila because they have gigantic chromosomes; this is called?

Back 36

polytene chromosomes

Front 37

what was bridges hypothesis?

Back 37

information about the bar and ultrabar phenotypes may be revealed by a cytological examination of polytene chromosomes

Front 38

the mechanism of formation of the bar allele (also the untrabar and wildtype) can be explained by a ______ ______?

Back 38

misaligned crossover

Front 39

the wildtype is also called the bar ______?

Back 39

revertant

Front 40

the bar and ultra bar alleles are also associated with the phenomenom of ______ ____?

Back 40

position effect

Front 41

what is the positioning effect?

Back 41

positioning the three copies of the allele next to each other increases the severity of the effect (slide 8-26)

Front 42

a female that is homozygous for the bar allele has 4 copies and ____ facets?

Back 42

70

Front 43

a female that is heterozygous for ultra bar and wildtype has 4 copies as well but only ___ facets?

Back 43

45

Front 44

the majority of small chromosonal duplications have no phenotypical effect; however they are vitals because provide raw material for additional genes. this can lead to the formation of _____ _____?

Back 44

gene families

Front 45

consist of two are more genes that are similar to each other?

Back 45

gene families

Front 46

what is an examlpe of gene families?

Back 46

the globin gene

Front 47

in the globin gene family; the accumulation of different mutations in the members of the gene family created?

Back 47

globin genes expressed during different stages of human development; globin proteins that are more specialized for their function (slide 8-30)

Front 48

when a segment is flipped to the opposite orientation?

Back 48

inversion

Front 49

inversion in which the centromere lies within the inverted region?

Back 49

pericentric inversion

Front 50

" " lies outside the inverted region?

Back 50

paracentric inversion

Front 51

in an inversion the total number of genetic information _______?

Back 51

stays the same

Front 52

why does the great majority of inversions have no phenotypical effects?

Back 52

because the amount of genetic material is the same

Front 53

in rare cases, inversion can alter the phenotype of an individual?

Back 53

break point effect; position effect

Front 54

the breaks to the inversion occur in a vital gene?

Back 54

break point effect

Front 55

a gene is repositioned in a way that alters gene expression?

Back 55

position effect

Front 56

about __ of the human population carry inversions that are detectable by light microscope?

Back 56

2 %

Front 57

individuals with one copy of a normal chromosome and one copy of an inverted chromosome?

Back 57

inversion heterozygote

Front 58

are inversion heterozygotes phenotypically normal?

Back 58

they may be but they have a high probability of producing abnormal gametes

Front 59

what causes the abnomormal gametes?

Back 59

crossing over in the inverted segment

Front 60

for the normal and inversion chromosome to synapes properly an ______ ____ must form?

Back 60

inversion loop (slide 8-34)

Front 61

occurs when the segment of one chromosome becomes attached to another?

Back 61

translocations

Front 62

in ______ ______ two non-homologous chromosomes exchange genetic material?

Back 62

recipricol translocation

Front 63

recipricol translocations arise from two different mechanisms?

Back 63

chromosomal breakage and abnormal crossover

Front 64

recipricol translocations lead to..?

Back 64

rearrangement of genetic material not change in amount

Front 65

thus, they are called?

Back 65

balanced translocations

Front 66

like inversion, recipricol translocations do not lead to phenotypic problems.

Back 66

note

Front 67

in ______ translocations the transfer of genetic material occurs in only one direction ?

Back 67

simple

Front 68

thus these are called ?

Back 68

unbalanced translocation

Front 69

unbalanced translocations are associated with ...?

Back 69

phenotypic abnormalities and lethality

Front 70

examlpe of simple translocation?

Back 70

familial down syndrome

Front 71

in familial down syndrome, the majority of chromosome 21 is attached to chromosome ?

Back 71

14

Front 72

familial down syndrome is an examlpe of ______ _____ ?

Back 72

robersonian translocation (most common type in humans)

Front 73

individuals carrying balanced translocations have a greater chance of producing gametes with _______ combinations of chromosomes?

Back 73

unbalanced

Front 74

this depends on the segregation pattern during ?

Back 74

meiosis I

Front 75

during ______, homologous chromosomes synapse with each other?

Back 75

meiosis I

Front 76

for the translocated chromosomes to synapse properly and _____ ____ must form?

Back 76

translocation cross

Front 77

meiotic segregation can occur in one of 3 ways?

Back 77

alternate segregation; adjacent-1 segregation; adjacent-2 segregation

Front 78

eukaryotic cells have evolved ____ which tend to prevent translocation from occuring?

Back 78

telomeres

Front 79

specialized repeated sequences of DNA-are formed at the ends of normal chromosomes?

Back 79

telomeres

Front 80

if cell are exposed to agents tah cause chromosomes to break, the borken ends lack telomeres and are said to be _____?

Back 80

reactive

Front 81

when two different chromsomes break, the broken ends are recognized by DNA repair enzymes, which attempt tp reatach broken ends.

Back 81

note

Front 82

if two different chromosomes are broken at the same time, the incorrect ends may become attached to each other.

Back 82

note

Front 83

a reciprocal translocation can be produced when two ______ chromosomes cross over?

Back 83

non homologous

Front 84

reciprocal translocation result in rearrangment of the genetic material, though not a change in the total amount of genetic material.

Back 84

note

Front 85

reciprocal translocation in which the total amount of genetic material is not altered?

Back 85

balanced translocations

Front 86

the ____ gamete that carries chromosome 21 and the fused chromosome will result in an offspring with familial down syndrome?

Back 86

unbalanced

Front 87

the abnormal chromosome that occurs in familial down syndrome is an example of _____ ______?

Back 87

robertsonian translocation

Front 88

Robersonian translocation arises from breaks near the centromeres of two ______ _____ chromsomes?

Back 88

nonhomologous acrocentric

Front 89

note: individuals with reciprocal translocations may produce abnormal gametes due to the segregation of chromosomes.

Back 89

note

Front 90

individuals who carry balances translocations have a higher risk of producing gametes with unbalanced combinations of chromosomes. whether or not this occurs depends on the segregation pattern during ____?

Back 90

meiosis I

Front 91

when two different chromsomes break, the broken ends are recognized by DNA repair enzymes, which attempt tp reatach broken ends.

Back 91

note

Front 92

if two different chromosomes are broken at the same time, the incorrect ends may become attached to each other.

Back 92

note

Front 93

a reciprocal translocation can be produced when two ______ chromosomes cross over?

Back 93

non homologous

Front 94

reciprocal translocation result in rearrangment of the genetic material, though not a change in the total amount of genetic material.

Back 94

note

Front 95

reciprocal translocation in which the total amount of genetic material is not altered?

Back 95

balanced translocations

Front 96

the ____ gamete that carries chromosome 21 and the fused chromosome will result in an offspring with familial down syndrome?

Back 96

unbalanced

Front 97

the abnormal chromosome that occurs in familial down syndrome is an example of _____ ______?

Back 97

robertsonian translocation

Front 98

Robersonian translocation arises from breaks near the centromeres of two ______ _____ chromsomes?

Back 98

nonhomologous acrocentric

Front 99

note: individuals with reciprocal translocations may produce abnormal gametes due to the segregation of chromosomes.

Back 99

note

Front 100

individuals who carry balances translocations have a higher risk of producing gametes with unbalanced combinations of chromosomes. whether or not this occurs depends on the segregation pattern during ____?

Back 100

meiosis I

Front 101

chromosome number can vary in two main ways?

Back 101

euploidy; and aneuploidy

Front 102

variations in the number of complete sets of chromosomes?

Back 102

euploidy

Front 103

variations in particular chromosomes within a set?

Back 103

aneuploidy

Front 104

occurs occasionally in animal and frequently in plants?

Back 104

euploidy

Front 105

regarded as abnormal conditions?

Back 105

aneuploidy

Front 106

______ organisms have 3 or more sets of chromosomes?

Back 106

polyploidy

Front 107

a trisomic animal is ______?

Back 107

2n+1

Front 108

a monosomic animal is _____?

Back 108

2n-1

Front 109

who was the first to discover the harmful affects of aneuploidy?

Back 109

Albert Blackslee

Front 110

what did they study?

Back 110

the Jimson weed

Front 111

alterations in chromosome number occur frequently in gamete formation.

Back 111

note

Front 112

about ___ to ___ percent of embryos have abnormal chromosome number?

Back 112

5 to 10 percent

Front 113

indeed, ___ percent of spontaneous abortions are due to such abnormalities?

Back 113

50

Front 114

in some cases and abnormality produces and offspring that can survive. what is trisomy 18?

Back 114

edwards syndrome

Front 115

what is trisomy 13?

Back 115

patau's syndrome

Front 116

XXY?

Back 116

klinefelter syndrome

Front 117

XYY?

Back 117

jacobs syndrome

Front 118

XXX?

Back 118

triple X syndrome

Front 119

XO?

Back 119

turners syndrome

Front 120

why are people with autosomal aneuploidies such as trisomy 21, 13, and 18 able to survive?

Back 120

because the chromosomes are relatively small;

Front 121

aneuoploidies involving sex chromosomes are usually less severe than those involving autosomes. why is this so???

Back 121

because of X inactivation

Front 122

_____ parents are more likely to produce abnormal offspring?

Back 122

older

Front 123

is caused by a failure of chromosome 21 to segregate properly (non disjunction)?

Back 123

downs

Front 124

this _______ most commonly occurs during meiosis I of the oocyte?

Back 124

non disjunction

Front 125

human females are born with as many primary oocytes as she will ever have. they however arrest in _____ until time of ovulation?

Back 125

prophase I

Front 126

most species of animal are _____?

Back 126

diploid

Front 127

polyploidy in animals is usually a lethal condition. some euploidy variations are naturally occuring. give an example of this?

Back 127

females bees are diploid; male bees are (drones) are monoploid

Front 128

male bees are drones (monoploid) this means they contains a _______?

Back 128

single set of chromosomes

Front 129

in many animals, certain body tissues display normal variations in the number of sets of chromosomes. diploid animals sometimes produce tissues that are _______?

Back 129

polyploid

Front 130

what is this phenomenom termed?

Back 130

endopolyploidy

Front 131

liver cells for example, can be _____, _______ and even ______?

Back 131

triploid, tetraploid, and even octaploid (8n)

Front 132

______ ______ of insects provide an unusaul example of natural variations in ploidy?

Back 132

polytene chromosomes

Front 133

the occurence of polyploid tissues or cells in organisms that are otherwise diplooid is known as ______?

Back 133

endopolyploidy

Front 134

what is the biological significance of endopolyploidy?

Back 134

the increase in chromosome number in certain cells may enhance their ability tot produce specific gene products that are needed in great abumcance

Front 135

polytene chromosome occur mainly in the ______ ____ of drosophilia and a few other insects?

Back 135

salivary glands

Front 136

in polytene chromosomes , chromosomes undergo repeated rounds of replication without cellular division.

Back 136

note

Front 137

the central point where chromosomes aggregate?

Back 137

chromocenter

Front 138

each of the fout types of chromosome is attached to the chromocenter near its _____?

Back 138

centromere

Front 139

polytene chromosomes are so large they can be even seen in _______?

Back 139

interphase

Front 140

polytene chromosomes exhibit a characteristic banding pattern, each dark band is known as a ______?

Back 140

chromomere

Front 141

why is the chromomere dark?

Back 141

because the DNA is more compacted

Front 142

polytene chromosomes allow for the study of _______?

Back 142

interphase chromosomes

Front 143

plants commonly exhibit polyploidy. in many instances polyploidy strains of plants display outstanding agricultural characteristics.

Back 143

note

Front 144

polyploids having an odd number of chromosomes sets are usually ______?

Back 144

sterile

Front 145

this type of sterility is sometimes desirable and sometimes detrimental. in agriculture it is usefull because it results in ____ fruit?

Back 145

seedless

Front 146

another example...?

Back 146

seedless flowers

Front 147

name the 3 ways to naturally produce variations in chromosome numbers?

Back 147

meiotic nondisjunction; mitotic abnormalities; interspecies crosses

Front 148

can produce haploid cells that have too many or too few chromosomes.

Back 148

meiotic nondisjunction

Front 149

if such a cell gives rise to a gamete that fuses with a normal gamete during fertilization , the resulting offspring will have an ______ chromosome number in all its cells

Back 149

abnormal

Front 150

failure of a chromosome to segregate properly during ANAPHASE?

Back 150

nondisjunction

Front 151

results in abnormal chromosome composition in ALL of its cells?

Back 151

meiotic nondisjunction

Front 152

non disjunction in meiosis I results in ___ abnormal gamets?

Back 152

all 4

Front 153

nondisjunction in meiosis II results in ____ abnormal gametes?

Back 153

50%

Front 154

in rare cases, all the chromosomes can undergo nondisjunction and migrate to one daughter cell. this is called?

Back 154

complete nondisjunction

Front 155

results in a diploid cell and one without chromosomes?

Back 155

complete nondisjunction

Front 156

what happens if the diplioid cells fertilized a normal gamets?

Back 156

produces a triploid cell

Front 157

abnomalities in chromosome number that occurs after fertilization?

Back 157

mitotic abnomalities

Front 158

leads to trisomic or monosomic daughter cells?

Back 158

mitotic abnormalities

Front 159

when one of the sister chromatids fail to migrate to a pole; results in a normal and monosomic individual?

Back 159

chromosome loss

Front 160

mitotic abnormalities result in one ____ cell and one ____ cell?

Back 160

trisomic and monosomic

Front 161

genetic abnormalities that occur after fertilization leads to _______; part of the organism contains cell that are genetically different from the rest of the organism?

Back 161

mosaicism

Front 162

a flie that has a most extreme form of MOSAICISM is termed a ?

Back 162

bilateral gynandromorph

Front 163

a complete nondisjunctin can produce and individual with one or more sets of chromosomes; this person is termed?

Back 163

autopolyploidy

Front 164

alloploidy is the result of _____ ____?

Back 164

interspecies crosses

Front 165

has one set of chromosomes from two different species?

Back 165

allodiploid

Front 166

contains a combination of both autopolyploidy and alloploidy

Back 166

allopolyploid

Front 167

contains two complete sets of chromosomes from two different species?

Back 167

allotetraploid

Front 168

evolutionary related chromosomes from two different species are

Back 168

homeologous chromosomes

Front 169

why is a allodiploid fertile?

Back 169

because homeologous chromosomes can synapse