Beyond Mendel's Law (Chapter 5) Flashcards
(282 cards)
1
Q
In _________ single mutation causes several symptoms.
A
alkaptonuria
2
Q
In alkaptonuria, the inability to break down _____ causes buildup of an acid that reacts to produce a black pigment that is deposited in urine, nails, skin, and cartilage.
A
tyrosine
3
Q
When urine is exposed to _____, it turns black.
A
oxygen
4
Q
______ rarely completely control a phenotype in the way that Mendel’s experiments suggested.
A
Single genes
5
Q
____ interact with each other, and with environmental influences, in intricate and myriad ways
A
Genes
6
Q
When transmission patterns of a visible trait do not fit autosomal recessive or autosomal dominant modes of inheritance, Mendel’s laws are still operating, and the underlying ______ ratios persist, but other factors help to mold _______
A
genotypic, phenotypes
7
Q
“Outside-the-gene” influences includes:
A
*protein-encoding genes.
*DNA sequences
*RNA sequences
*epigenetic alterations of DNA
*environmental stimuli
8
Q
______ classes are not in the proportions that Punnett squares or probabilities predict
A
offspring
9
Q
transmission patterns of a ______ are not consistent with autosomal recessive or autosomal dominant inheritance.
A
visible trait
10
Q
either the nature of the phenotype or influences from other genes or the environment alter _________
A
phenotypic ratios
11
Q
A genotype (allele combination) that causes death is, by definition, ______
A
lethal
12
Q
______ disease is lethal by age 3 or 4;
A
Tay-Sachs
13
Q
___________ may not be lethal until late middle age
A
Huntington disease
14
Q
A _____ genotype causes death before the individual can reproduce, which prevents passage of genes to the next generation.
A
lethal
15
Q
In organisms, such as fruit flies, pea plants, or mice, __________ remove an expected progeny class following a specific cross
A
lethal allele combinations
16
Q
In a cross of heterozygous flies, _________ progeny dies as embryos, leaving only heterozygous and homozygous dominant adult fly offspring.
A
homozygous recessive
17
Q
In humans, early-acting _______ cause spontaneous abortion.
A
lethal alleles
18
Q
When both a man and a woman carry a _________ lethal allele for the same gene, each pregnancy has a 25% chance of spontaneously aborting—this is the homozygous recessive class.
A
recessive
19
Q
___ copies of a dominant allele may be lethal, as is the case for Mexican hairless dogs.
A
Two
20
Q
Inheriting one _______ allele confers the coveted hairlessness trait, but inheriting two _____ alleles is lethal to the unlucky embryo.
A
dominant
21
Q
Breeders cross hairless to hairy (“powderpuff”) dogs, rather than hairless to hairless, to avoid losing the __________
A
lethal homozygous dominant class
22
Q
A mutation in a gene called ______ causes the condition in which the dogs have missing or abnormally shaped teeth.
A
forkhead box I3 (FOXI3)
23
Q
the condition ________, dogs have missing or abnormally shaped teeth.
A
canine ectodermal dysplasia
24
Q
Humans also have the ____ gene, but it has not been associated with a phenotype.
A
FOXI3
25
An example of a lethal genotype in humans is __________ which has a very distinct phenotype of a long trunk, very short limbs, and a large head with a flat face.
achondroplastic dwarfism
26
It is inherited as an autosomal dominant trait, but is most often the result of a spontaneous (new) mutation.
achondroplastic dwarfism
27
Observations of other species that have this mutation suggest that the _______ would be unable to breathe because the lungs do not have room to inflate.
homozygote
28
The mutation is in the gene that encodes a receptor for a ____ factor.
growth
29
An individual has two alleles for any ________—one allele on each homolog.
autosomal gene
30
A _____ can exist in more than two allelic forms in a population because it can mutate in many ways.
gene
31
The sequence of hundreds of ____ bases that makes up a gene can be altered in many ways.
DNA
32
Different allele combinations can produce variations in the _____
phenotype.
33
The more _____, the more variations of the phenotype are possible.
allele
34
Predicting the course of an illness is difficult because other genes and environmental effects can modify a _______
phenotype
35
Two disorders for which allele identification can predict severity and types of symptoms are ________
phenylketonuria (PKU) and cystic fibrosis
36
In PKU, too little or lack of an enzyme causes the amino acid _______to build up in brain cells.
phenylalanine
37
Hundreds of mutant alleles pair to cause four basic phenotypes:
*classic PKU with profound mental retardation
*moderate PKU
*mild PKU
*asymptomatic PKU, with excretion of excess phenylalanine in urine
38
Eating a special diet extremely low in _______ allows normal brain development.
phenylalanine
39
When the CF gene was discovered in 1989, researchers identified one mutant allele, _____, that causes about 70% of cases in many populations.
ΔF508
40
People homozygous for ____ have frequent, severe respiratory infections, very congested lungs, and poor weight gain.
ΔF508
41
Genetic tests probe panels of ___ mutations that are the most common in a patient’s ethnic group, maximizing the likelihood of detecting carriers and avoiding the cost of testing for 1,500+ alleles.
CF
42
In ______, one allele is expressed, while the other isn’t.
complete dominance
43
In _________, the heterozygous phenotype is intermediate between that of either homozygote.
incomplete dominance
44
_____ deficiencies illustrate both complete and incomplete dominance—depending upon how one evaluates the phenotype.
Enzyme
45
______ displays complete dominance because the heterozygote (carrier) is as healthy as a homozygous dominant individual
Tay-Sachs disease
46
If phenotype is based on ______, then the heterozygote is intermediate between the homozygous dominant (full enzyme level) and homozygous recessive (no enzyme).
enzyme level
47
Half the normal amount of enzyme is sufficient for health, which is why, the ________ allele is completely dominant.
wild type
48
Even heterozygotes whose phenotypes are the same as those of homozygotes are distinctive at the __________
biochemical level
49
___________ is an example of incomplete dominance in humans that can be observed on both the molecular and whole-body levels
Familial hypercholesterolemia (FH)
50
A person with two disease-causing alleles lacks receptors on liver cells that take up the _______ form of cholesterol from the bloodstream.
low-density lipoprotein (LDL)
51
A person with ___________ allele has half the normal number of receptors.
one disease-causing allele
52
Someone with _______ type alleles has the normal number of receptors.
two wild type
53
The _______ parallel the number of receptors
phenotypes
54
those with ___ mutant alleles die as children of heart attacks
two
55
those with ___ mutant allele may suffer heart attacks in young adulthood
one
56
those with _____ alleles do not develop this inherited form of heart disease.
two wild type
57
Different alleles that are both expressed in a heterozygote are _______
codominant.
58
The ______ is based on the expression of codominant alleles.
ABO blood group
59
______ are determined by the patterns of molecules on the surfaces of red blood cells.
Blood types
60
Most of these molecules are ____ embedded in the plasma membrane with attached sugars that extend from the cell surface.
proteins
61
The sugar is the ______, which is the molecule that the immune system recognizes.
antigen
62
People who belong to blood group ____ have an allele that encodes an enzyme that adds a final piece to a certain sugar to produce antigen A.
A
63
In people with blood type ___, the allele and its encoded enzyme are slightly different, which causes a different piece to attach to the sugar, producing antigen B.
B
64
People in blood group __ have both antigen types.
AB
65
Blood group __ reflects yet a third allele of this gene.
O
66
Blood group O is missing one _____, but this drastically changes the encoded enzyme in a way that robs the sugar chain of its final piece.
DNA nucleotide
67
Type __ red blood cells lack both A and B antigens.
O
68
The A and B alleles are _____
codominant
69
The A and B alleles are both _____ to O.
completely dominant
70
In the past, ABO blood types have been described as variants of a gene called ___ although MIM now abbreviates the designations.
“I”
71
Older I system is easier to understand. (“I” stands for ____.)
isoagglutinin
72
three alleles are?
I^A, I^B, and i.
73
People with blood type A have antigen A on the surfaces of their red blood cells, and may be of genotype _______
IAIA or IAi.
74
People with blood type B have antigen B on their red blood cell surfaces, and may be of genotype ____
IBIB or IBi.
75
People with the rare blood type AB have both antigens A and B on their cell surfaces, and are genotype ____
IAIB
76
People with blood type O have neither antigen, and are genotype ___
ii
77
A person with type A or B blood can be _______
heterozygous
78
A person who is genotype IAi and a person who is IBi can jointly produce offspring of any ____ genotype or phenotype
ABO
79
______ can appear not to operate when one gene masks or otherwise affects the phenotype of another.
Mendel’s laws
80
it refers to interaction between different genes, not between the alleles of the same gene.
Epistasis
81
It is a gene that affects expression of another
Modifier gene
82
In _____, the blocked gene is expressed normally, but the product of the modifier gene inactivates it, removes a structure needed for it to contribute to the phenotype, or otherwise counteracts its effects.
epistasis
83
hairless genes in dogs is example of?
epistasis
84
An epistatic interaction seen in many species is ____ in which one gene blocks the action of genes whose products confer color.
albinism
85
A more complex example of epistasis is a blood type called the _______
Bombay phenotype.
86
Bombay phenotype results from an interaction between a gene called __ and the __ gene that confers ABO blood type.
H, I
87
The __ gene controls the placement of a molecule to which antigens A and B attach on red blood cell surfaces.
H
88
In a person of genotype __, that molecule isn’t made, so the A and B antigens have no way to attach to the red blood cell surface.
hh
89
_____ antigens fall off—and the person tests as type O blood, although any ABO genotype is possible.
A and B
90
______ can explain why siblings who inherit the same disorder can suffer to differing degrees
Epistasis
91
One study examined siblings who both inherited _______, in which nerves cannot signal muscles.
- The muscles weaken and atrophy, usually proving fatal in early childhood.
spinal muscular atrophy 1
92
In __________ the mutation encodes an abnormal protein that shortens axons, which are the extensions on nerve cells that send messages.
spinal muscular atrophy 1
93
Siblings who inherited the SMA mutation never developed symptoms because of the gene, _____ which increases production of the cytoskeletal protein actin that extends axons
- Because these children inherited the ability to make extra-long axons, the axon-shortening effects of SMA are not harmful.
plastin 3
94
The same allele combination can produce different degrees of a ____ because a gene does not act alone.
phenotype
95
The terms _______ and ______ describe degrees of expression of a single gene.
penetrance and expressivity
96
_______ refers to the all-or-none expression of a genotype
Penetrance
97
it refers to severity or extent
Expressivity
98
An allele combination that produces a phenotype in everyone who inherits it is completely _____—this is very rare.
penetrant
99
______ is nearly completely penetrant—almost all people who inherit the mutant allele will develop symptoms if they live long enough.
Huntington disease
100
o A genotype is _________ if it doesn’t express the phenotype (have no symptoms).
incompletely penetrant
101
_____ is incompletely penetrant and variably expressive
Polydactyly
102
it is described numerically.
penetrance
103
A phenotype is _______ if symptoms vary in intensity among different people.
variably expressive
104
For ________, variable expressivity reflects greater influence of other genes that regulate lipid levels in the blood and the environment.
familial hypercholesterolemia
105
________ develop heart disease due to high serum cholesterol in middle adulthood.
FH heterozygotes
106
it is a single-gene disorder with many symptoms, or a gene that controls several functions or has more than one effect
Pleiotropic
107
In _______, such conditions can be difficult to trace through families because people with different subsets of symptoms may appear to have different disorders.
pleiotropy
108
A classic case of pleiotropy is _______, an autosomal dominant disease that affected several members of the royal families of Europe
porphyria variegata
109
_________ ruled England during the American Revolution
King George III
110
Finally, an attack in 1811 placed George in a prolonged stupor, and the Prince of ____ dethroned him.
Wales
111
20th century researchers found that _________ caused George’s red urine.
porphyria variegata
112
It is one of several types of porphyria, which result from deficiency of any of several enzymes required to manufacture _____
heme.
113
The king’s disorder arises from lack of ________ in the heme pathway
enzyme #7
114
_________ is part of hemoglobin, the molecule that carries oxygen in the blood and imparts the red color
Heme
115
In the disease, a part of heme called a _______ is routed into the urine instead of being broken down and metabolized in cells.
porphyrin ring
116
it also builds up and attacks the nervous system.
Porphyrin
117
Today, _________ remains rare, and is often misdiagnosed as a seizure disorder.
porphyria variegata
118
Medical records and hair analysis indicate that a medicine based on the element _________ was forced upon the king in the madhouse.
antimony
119
Antimony was often contaminated with ____ which inactivates several of the enzymes in the heme biosynthetic pathway
arsenic
120
On a molecular level, _______ occurs when a single protein affects different body parts, participates in more than one biochemical reaction, or has different effects in different amounts.
pleiotropy
121
Consider __________ The most common form of this autosomal dominant condition is a defect in an elastic connective tissue protein called _____
Marfan syndrome, fibrillin
122
- The symptoms are lens dislocation, long limbs, spindly fingers, and a caved-in chest.
- The most serious symptom is a life-threatening weakening in the aorta, which can suddenly burst.
marfan syndorome
123
If the weakening in the aorta is detected early, a ________ can replace the section of artery wall
synthetic graft
124
Certain proteins that form a structure in the eye called ________ beautifully illustrate pleiotropy.
lens crystallins
125
If in ___ abundance as single molecules, these proteins are metabolic enzymes, functioning in many cell types
low
126
At higher abundance they join and form ________ which aggregate to create a transparent lens whose physical properties enable it to focus incoming light on the retina.
crystallins
127
These multifunctional lens ______ are well-studied in a variety of species, including insects, jellyfish, and vertebrates.
crystalline proteins
128
When different genes produce the same phenotype, a phenomenon called ____________, it may appear that Mendel’s laws are not operating.
genetic heterogeneity
129
In ______, abnormal collagen causes children’s bones to break easily
Osteogenesis imperfecta
130
This gene normally encodes an enzyme that adds a small chemical group to ______, enabling it to function.
collagen
131
it can occur when genes encode enzymes that catalyze the same biochemical pathway, or different proteins that are part of the pathway.
Genetic heterogeneity
132
it is an environmentally caused trait that appears to be inherited
Phenocopy
133
Such a trait can either produce symptoms that resemble those of a known single-gene disorder or mimic inheritance patterns by affecting certain relatives.
Phenocopy
134
Limb birth defect caused by the drug thalidomide is a phenocopy of the inherited illness ________.
phocomelia
135
A birth defect caused by exposure to a _______ was more likely than a sudden increase in incidence of a rare inherited disease.
teratogen
136
An ____ can be a phenocopy.
infection
137
Children who have AIDS may have parents who also have the disease, but these children acquired AIDS by _____, not by inheriting a gene
viral infection
138
A _______ caused by a highly contagious infection can seem to be inherited if it affects more than one family member
phenocopy
139
An ________ who has frequent colds may show some signs of cystic fibrosis, but may instead suffer from malnutrition.
underweight child
140
Phenomena once considered to complicate __________ aren’t rare, and they may be common
single-gene inheritance
141
Consider Marfan syndrome. Most affected individuals have a mutation in the fibrillin gene. However, some people with the syndrome instead have a mutation in the gene that encodes the __________-
transforming growth factor beta receptor (TGFβR).
142
____ and _____ are part of the same biochemical pathway.
Fibrillin and TGFβR
143
Marfan syndrome fit the definition of _________ because mutations in different genes cause identical symptoms.
genetic heterogeneity
144
marfan syndrome is also _____ because a mutation in TGFβR blocks the activity of fibrillin.
epistatic
145
Gene interactions also underlie ___________, once thought to be strictly a characteristic of a particular gene.
penetrance and expressivity
146
____ that do not directly interact, in space or time, can affect each other’s expression.
Genes
147
This is the case for _______, in which cells in a certain part of the brain die, typically beginning in young adulthood.
Huntington disease
148
Siblings who inherit the exact same _____ may differ in the number of cells that they have in the affected brain area, thanks to variants of other genes that affected the division rate of neural stem cells in the brain during embryonic development
HD mutation
149
An individual who inherits HD, but also extra brain cells, might develop symptoms much ______ in life than a brother or sister who does not have such a built-in reserve supply.
later
150
If the delay is long enough that death comes from another cause, HD would then be _______
nonpenetrant
151
_________ that reveal gene expression patterns in different tissues are painting detailed portraits of pleiotropy, showing that inherited disorders may affect more tissues or organs than are obvious as symptoms.
DNA microarrays
152
Gregor Mendel derived the two _________ working with traits conferred by genes located on different chromosomes in the nucleus.
laws of inheritance
153
A ________ genotype does not appear as a progeny class.
lethal
154
In _______ one gene influences expression of another.
epistasis
155
_______ vary in penetrance and expressivity of the phenotype.
Genotypes
156
In __________ different genes cause the same phenotype.
genetic heterogeneity
157
A trait caused by the environment but resembling a known genetic trait or occurring in certain family members is a _________
phenocopy
158
The basis of the ___________, that both parents contribute genes equally to offspring, does not apply for genes in mitochondria.
law of segregation
159
Thousands of mitochondria in each human cell contain several copies of a _________ that carries just __ genes.
“mini-chromosome”, 37
160
________ act in the mitochondrion, but the organelle also requires the activities of certain genes from the nucleus
mtDNA-encoded genes
161
The inheritance patterns and mutation rates for mitochondrial genes differ from those for genes in the ____
nucleus
162
________ are maternally inherited because sperm almost never contribute mitochondria when they fertilize an oocyte
Mitochondrial genes
163
In the rare instances when mitochondria from ____ enter an oocyte, they are usually selectively destroyed early in development.
sperm
164
DNA in the _____ differs functionally from DNA in the nucleus in several ways.
mitochondria
165
______ does not cross over.
Mitochondrial DNA
166
_____ mutates faster than DNA in the nucleus because it has fewer ways to repair DNA, and the mitochondrion is the site of energy reactions that produce oxygen free radicals that damage DNA.
mtDNA
167
Unlike nuclear DNA, mtDNA is not wrapped in _____, nor are genes “interrupted” by DNA sequences that do not encode protein.
proteins
168
A cell has one nucleus but many mitochondria—and each ________ harbors several copies of its chromosome.
mitochondrion
169
_______ with different alleles for the same gene can reside in the same cell.
Mitochondria
170
Mitochondrial genes encode _____ that participate in protein synthesis and energy production.
proteins
171
24 of the 37 genes encode___ molecules (22 transfer RNAs and 2 ribosomal RNAs) that help assemble proteins.
RNA
172
13 mitochondrial genes encode proteins that function in _______, which is the process that uses energy from digested nutrients to synthesize ATP, the biological energy molecule.
cellular respiration
173
Several diseases that result from mutations in mitochondrial genes. are called ________ and have specific names, but news reports often lump them together as _________
mitochondrial myopathies, “mitochondrial disease.”
174
Symptoms arise from ____ whose cells have many mitochondria, such as skeletal muscle.
tissues
175
Skeletal muscle fibers appear ________ when stained and viewed under a light microscope, their abundant abnormal mitochondria visible beneath the plasma membrane.
"red and ragged”
176
A defect in an energy-related gene can produce symptoms other than fatigue. This is the case for ______, which impairs vision.
Leber optic atrophy
177
This disorder was associated in 1988 with a mitochondrial mutation that impairs cellular energy reactions.
Leber optic atrophy
178
A ____ in a mitochondrial gene that encodes a tRNA or rRNA impairs the organelle’s ability to manufacture proteins
mutation
179
a once active and articulate dental hygienist
Lindzy S.
180
MELAS stands for?
“mitochondrial myopathy encephalopathy lactic acidosis syndrome”.
181
About _____ people has a mutation in a mitochondrial gene that could cause disease.
1 in 200
182
Mitochondrial diseases are very rare, apparently because of a __________ process during egg formation.
weeding-out process
183
The fact that a cell contains many mitochondria makes possible a rare condition called _______
heteroplasmy
184
In this state a particular mutation is in some mitochondrial chromosomes, but not others.
heteroplasmy
185
At each cell division, the ____ are distributed at random into daughter cells.
mitochondria
186
Over time, the chromosomes within a mitochondrion tend to be all _____ or ______ for any particular gene.
wild type or all mutant
187
As an _____ matures, the number of mitochondria drops from about 100,000 to 100 or fewer.
oocyte
188
If the woman is ______ for a particular mutation, she can produce an oocyte that has mostly mitochondria that are wild type for that gene, mostly mitochondria that have the mutation, or anything in between.
heteroplasmic
189
_________ has several consequences for the inheritance of mitochondrial phenotypes.
Heteroplasmy
190
_____ may vary widely among siblings, depending upon how many mutation bearing mitochondria were in the oocyte that became each brother or sister.
Expressivity
191
Severity of symptoms reflects which ______ have cells whose mitochondria bear the mutation.
tissues
192
_______ affects the enzyme that directly produces ATP.
Leigh syndrome
193
The most severe mitochondrial illnesses are ________
heteroplasmic
194
This is presumably because _______—when all mitochondria bear the mutant allele—too severely impairs protein synthesis or energy production for embryonic development to complete.
homo plasmy
195
Often, severe __________ mitochondrial disorders do not produce symptoms until adulthood because it takes many cell divisions, and therefore years, for a cell to receive enough mitochondria bearing mutant alleles to cause symptoms.
heteroplasmic
196
_________ usually does not affect vision until adulthood.
Leber optic atrophy
197
_____ provides a powerful forensic tool used to link suspects to crimes, identify war dead, and support or challenge historical records.
mtDNA
198
______ is used in forensics because it is more likely to remain after extensive damage, because cells have many copies of it.
mtDNA
199
__________ encode RNAs or proteins that function in protein synthesis or energy metabolism.
mitochondrial genes
200
In ______, cells contain mitochondria that have different alleles of a gene.
heteroplasmy
201
Most of the traits that Mendel studied in pea plants were conferred by genes on different _______
chromosomes
202
When genes are close to each other on the same chromosome, they usually do not _____ at random during meiosis and therefore do not support Mendel’s predictions.
segregate
203
Genes close on a chromosome are packaged into the same gametes and are said to be _______
“linked”
204
________ refers to the transmission of genes on the same chromosome.
Linkage
205
____ genes do not assort independently and do not produce Mendelian ratios for crosses tracking two or more genes.
Linked
206
___________ and __________ first observed the unexpected ratios indicating linkage in the early 1900s, again in pea plants.
William Bateson and R. C. Punnett
207
The more prevalent parental allele combinations could reflect genes that are transmitted on the same chromosome and that therefore do not separate during _____
meiosis.
208
The two less common offspring classes could also be explained by a meiotic event—_______
crossing over
209
It is an exchange between homologs that mixes up maternal and paternal gene combinations without disturbing the sequence of genes on the chromosome
crossing over
210
Progeny that exhibits this mixing of maternal and paternal alleles on a single chromosome are called ______
recombinant
211
Had the parents in Bateson and Punnett’s crosses been of genotypes ppL_ and P_ll, then P_L_ and ppll would be _________ rather than parental classes.
recombinant
212
Two other terms describe the configurations of linked genes in __________
dihybrids.
213
If the two dominant alleles are on one chromosome and the two recessive alleles on the other, the genes are in _____
cis
214
With one dominant and one recessive allele on each chromosome, the genes are in ____
trans
215
Whether alleles in a dihybrid are in cis or trans is important in distinguishing _____ from parental progeny classes in specific crosses.
recombinant
216
As Bateson and Punnett were discovering linkage in peas, geneticist, ________ and his coworkers at Columbia University were doing the same
Thomas Hunt Morgan
217
Thomas Hunt Morgan and his coworkers at Columbia University were doing the same using the fruit fly ___________
Drosophila melanogaster.
218
The traits fell into ______ groups because their genes are inherited together on the same chromosome.
four
219
The researchers translated the data of linkage in fruit flies into _____ depicting positions of genes on chromosomes.
actual maps
220
Morgan wondered why the ____ of the recombinant classes varied for different genes.
sizes
221
In 1911, Morgan’s undergraduate student, ________, proposed that the farther apart two genes are on a chromosome, the more likely they are to cross over simply because more physical distance separates them
Alfred Sturtevant
222
The correlation between crossover frequency and the distance between genes is used to construct _________
linkage maps
223
________ show the order of genes on chromosomes and the relative distances between them
diagrams
224
The distance is represented using “map units” called ______, where 1 centimorgan equals 1 percent recombination.
centimorgans
225
map units are used today to construct _____
SNP maps
226
________ provide an estimate of genetic distance along a chromosome.
map units
227
The frequency of a crossover between any two linked genes is inferred from the proportion of offspring that are _______
recombinant
228
_________ is based on the percentage of meiotic divisions that break the linkage between—that is, separate—two parental alleles.
Frequency of recombination
229
Genes at opposite ends of the same chromosome cross over often, generating a large ______ class.
recombinant
230
Genes lying very close on the chromosome would only rarely be separated by a _______.
crossover
231
The probability that genes on opposite ends of a chromosome cross over approaches the probability that, if on different chromosomes, they would independently assort— about ___
50%
232
More crossovers, or progeny with recombinant genotypes, are seen when two genes are _____ apart on the same chromosome.
farther
233
Geneticists in Columbia University’s “fly room” mapped several genes on all ____ chromosomes.
four
234
Localizing genes on the __ chromosome was easier than doing so on the autosomes
X
235
_________ follow an inheritance pattern that is distinct from the one followed by all autosomal genes.
X-linked traits
236
In human males, with their single X chromosome, ________ alleles on the X are expressed.
recessive
237
By 1950, geneticists began to think about mapping genes on the ___ human autosomes
22
238
Matching phenotypes to chromosomal variants is a field called
cytogenetics
239
he was observing chromosomes in his own white blood cells when he noticed a dark area consistently located near the centromere of one member of his largest chromosome pair (chromosome 1).
R. P. Donohue
240
In 1968, researchers assigned the first human gene to an _______
autosome.
241
He examined chromosomes from several family members for the dark area, noting also whether each family member had a blood type called _____
Duffy.
242
Donohue found that the _____ blood type was linked to the chromosome variant.
Duffy
243
He could predict a relative’s Duffy blood type by whether or not the chromosome had the telltale ____
dark area
244
As an example of determining the degree of linkage by percent recombination, consider the traits of Rh blood type and a form of anemia called _______
elliptocytosis.
245
it is a rare autosomal dominant trait that causes absent or underdeveloped fingernails and toenails, and painful arthritis in the knee and elbow joints.
Nail patella syndrome
246
The gene is 10 map units from the I gene that determines the ABO blood type, on _________
chromosome 9
247
The Rh blood type and elliptocytosis, and nail-patella syndrome and ABO blood type, are examples of ________.
linked gene pairs
248
A _________ begins to emerge when percent recombination is known between all possible pairs of three or more linked genes
linkage map
249
________ between linked genes is useful in crudely ordering them on genetic maps.
percent recombination
250
Understanding the structure of DNA, and then sequencing the human genome, revealed an unexpected complexity in _______
linkage mapping
251
_________ is nonrandom association between DNA sequences
Linkage disequilibrium (LD)
252
The human genome consists of many _______ where stretches of alleles stick together, interspersed with areas where crossing over is prevalent.
“LD” blocks
253
In the first half of the 20th century, gene maps for nonhuman organisms, such as fruit flies, were constructed based on _________ between pairs of visible traits.
recombination frequencies
254
In 1980, researchers began using DNA sequences near genes of interest as landmarks called __________
genetic markers
255
these ______ need not necessarily encode a protein that causes a phenotype—they might be DNA sequence differences that alter where a DNA cutting enzyme cuts, or differing numbers of short repeated sequences of DNA with no obvious function, or single nucleotide polymorphisms (SNPs).
genetic markers
256
The term __________ is used popularly to mean any DNA sequence that is associated with a particular phenotype, usually one affecting health.
“genetic marker”
257
The sequencing of the human genome has taken DNA mapping to a new level, but built on the old idea of _____
linkage
258
Instead of relying on a few neighbors of protein-encoding genes in families, __________ scan the genomes of thousands of individuals who have a particular phenotype for DNA sequences that they share, but are much rarer in people who do not have the trait
genome-wide association studies
259
The “signposts” are ____ and repeats.
SNPs
260
The underlying assumption is that these shared genome regions will point the way toward genes that control or contribute to the _____
phenotype
261
The great value of the new types of markers is that they can shed light on the biological bases of common, ________ disorders
multifactorial
262
traits appears with unusual chromosome
chromosomal
263
dna cutting site
RFLPs
264
Repeats
STRs. SNPs
265
single-base differences
SNPs
266
copy number variants
CNVs
267
_______ tally how often genes and their markers are inherited together.
Computers
268
The “tightness” of linkage between a marker and a gene of interest is represented as a ________
LOD score (logarithm of the odds)
269
A _____ indicates the likelihood that particular crossover frequency data indicate linkage, rather than the inheritance of two alleles by chance
LOD score
270
A LOD score of 3 or greater signifies ________
linkage
271
Before sequencing of the human genome, ___________were used to predict which individuals in some families were most likely to have inherited a particular disorder, before symptoms began.
genetic markers
272
_________ are still used to distinguish parts of chromosomes.
genetic markers
273
In _______, marker designations are sometimes placed beneath the traditional symbols to further describe chromosomes.
pedigrees
274
Such a panel of linked markers, a _______, is a set of DNA sequences inherited together on the same chromosome due to linkage disequilibrium.
haplotype
275
Genes on the same chromosome are _______ They are inherited in different patterns
linked
276
________ translate crossover frequency into relative distances between genes on a chromosome.
linkage maps
277
___________ revealed the first linkage associations.
Cytogenetic abnormalities
278
it is a linkage combination that is stronger than that predicted by gene frequencies in a population.
Linkage disequilibrium
279
______ were used in early linkage mapping and today in genome-wide association studies.
Genetic markers
280
this reflect the percent recombination between linked genes
Linkage maps
281
this describe the tightness of linkage
LOD scores
282
this indicate linked DNA sequences, and reflect a variety of marker types.
Haplotypes
