CHAPTER 6 (Matters of Sex) Flashcards
(226 cards)
1
Q
It is dictated by genes but it is also layered with psychological and sociological components.
A
Gender
2
Q
It is determined at conception
A
Maleness or femaleness
3
Q
Another level of sexual identity comes from the control that _____ exert over the development of reproductive structures.
A
hormones
4
Q
Both ________ and ________ influence sexual feelings, including the strong sense of whether we are male or female.
A
biological factors and social cues
5
Q
Gender differences do not become apparent until the ______ of prenatal development.
A
ninth week
6
Q
During the fifth week, all embryos develop two unspecialized _____
A
gonads
7
Q
Each such “indifferent” gonad forms near two sets of ____ that offer two developmental options.
A
ducts
8
Q
If one set of tubes, called the ___________, continues to develop, they eventually form the sexual structures characteristic of a female.
A
Müllerian ducts
9
Q
If the other set, the _______, persist, male sexual structures form.
A
Wolffian ducts
10
Q
The choice to follow a male or female developmental pathway occurs during the ____ week, depending upon the sex chromosome constitution and actions of certain genes.
A
sixth
11
Q
If a gene on the Y chromosome called __________ is activated, hormones steer development along a male route.
A
SRY (sex-determining region of the Y)
12
Q
In the absence of ______ activation, a female develops
A
SRY
13
Q
It was considered a “default” option in human development, defined as the absence of maleness
A
Femaleness
14
Q
__________ is more accurately described as a fate imposed on ambiguous precursor structures
A
Sex determination
15
Q
Several ____ besides SRY guide early development of reproductive structures.
A
genes
16
Q
A mutation in a gene called ____, causes a female to have high levels of male sex hormones and lack a vaginal canal and uterus.
A
Wnt4
17
Q
This gene is essential for development and maturation as a female.
A
Wnt4
18
Q
Males and females have equal numbers of ?
A
Autosomes
19
Q
What chromosomes does a male have?
A
one X and one Y chromosomes
20
Q
What chromosomes does a female have?
A
two X chromosomes
21
Q
_____________ is sex with two different sex chromosomes (males)
A
Heterogametic sex
22
Q
_________ has two of the same sex chromosomes (females)
A
Homogametic sex
23
Q
The ___ chromosomes differ both in size and in gene content.
A
sex
24
Q
The X chromosome has more than ______ genes and is much larger than the Y chromosome
A
1,500
25
Y chromosome has ____ protein-encoding genes.
231
26
In meiosis in a ___, the X and Y chromosomes act as if they are a pair of homologs.
male
27
Identifying genes on the human __ chromosome has been difficult.
Y
28
Before the human genome sequence became available, researchers inferred the functions and locations of _______ by determining how men missing parts of the chromosome differ from normal.
Y-linked genes
29
It was not possible to create ____ for the Y because the Y does not cross over along all of its length.
linkage maps
30
The analysis of the _____ revealed that Y chromosome has a very unusual organization that’s why mapping it was so hard.
genome sequence
31
In the 95% of the chromosome that harbors male-specific genes, many DNA segments are ______
palindromes.
32
In written languages, ________ are sequences of letters that read the same in both directions (ex: “Madam, I’m Adam”)
palindromes
33
This symmetry in a DNA sequence, described by researchers as ______ destabilizes DNA replication.
“a hall of mirrors,”
34
During _____, sections of a Y chromosome attract each other
meiosis
35
this __________ organization may also provide a way for the chromosome to recombine with itself, essentially sustaining its structure
“hall of mirrors”
36
She predicts that the Y chromosomes will “self-destruct” within the next 10 million years and her comparison of Y chromosomes in a wide variety of mammals indicates that, important genes are being transferred to other chromosomes
Jennifer Marshall-Graves
37
It is unique in the human genome
It is small, gene-poor, prone to deletion and loss, variable among species, and useless
You can lack it and not be dead, just female
Y chromosome
38
This is a decent sort of chromosome
X chromosome
39
Three models of human Y:
Dominant Y
Selfish Y
Wimp Y
40
This model of a macho Y reflects the fact that the Y contains the male-determining SRY gene.
Dominant Y
41
This model predicts that the Y kidnapped genes from elsewhere.
Selfish Y
42
This model says that the Y is just a relic of the once glorious X chromosome.
Wimp Y
43
Wimp Y model was first proposed by biologist _________in 1967 in the theory that the X and Y originated as a pair of autosomes.
Susumo Ohno
44
the Y acquired the male-determining locus, and other genes that are required for ___________ gathered nearby.
spermatogenesis
45
The Y is degrading fast, losing genes at the rate of __ per million years.
5
46
The males in the audience can take comfort from the __________
mole vole Ellobius lutescens.
47
It has no Y, and SRY but it does have males and females.
Both sexes are XO
mole vole Ellobius lutescens.
48
According to him, Back 300 million years ago, when we were reptiles, we had no sex chromosomes, only ordinary autosomes.
David Page
49
After our ancestors parted company with the ancestors of birds, a mutation arose on one member of a pair of ordinary autosomes to give rise to ____
SRY
50
Once a piece of the Y was no longer able to recombine with the X, its genes began to ___
rot
51
The purpose of ___ (recombination in meiosis) is not just to generate new gene combinations, but to allow genes to rid themselves of mildly deleterious mutations that accumulate.
sex
52
Genes decayed, except for ____ and _____
SRY and the tips
53
Segments on the Y are effectively functioning as ________—30% have a perfect match elsewhere on the chromosome.
alleles
54
A section of the Y chromosome that David Page studies, called _____________, consists of DNA sequences that read the same in either direction, an organization that can lead to instability as well as provide a mechanism to generate new alleles.
AZFc (azoospermia factor c)
55
The ___ chromosome has a distinctive overall structure with a short arm and a long arm.
Y
56
oAt both tips of the Y chromosome are ________ termed _____ and ________
pseudoautosomal regions, termed PAR1 and PAR2.
57
The Y comprise only __ of the chromosome and include ___ pseudoautosomal genes.
5%, 63
58
It means that the DNA sequences have counterparts on the X chromosome and can cross over with them.
Pseudoautosomal
59
It encode a variety of proteins that function in both sexes, participating in or controlling bone growth, cell division, immunity, signal transduction, the synthesis of hormones and receptors, fertility, and energy metabolism.
Pseudoautosomal genes
60
Most of the Y chromosome is the __________, that lies between the two pseudoautosomal regions.
male-specific region, or MSY
61
It consists of three classes of DNA sequences.
male-specific region, or MSY
62
About 10 to 15 percent of the ___ is X-transposed sequences that are 99% identical to counterparts on the X chromosome.
MSY
63
It is scarce in MSY
Protein-encoding genes
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20% of the MSY consists of __________ sequences, which are somewhat similar to X chromosome sequences and may be remnants of an ancient autosome that long ago gave rise to the X chromosome.
X-degenerate DNA
65
The remainder of the MSY includes palindrome-ridden regions, called _______
amplicons.
66
The genes in the MSY include many _________ and ______ that combine in different ways, which is one reason why counting the number of protein-encoding genes on the Y chromosome has been difficult.
repeats and specify protein segments
67
Many of the genes in the MSY are essential to _______, including MSY
Fertility
68
_________ was first seen under a light microscope in 1923, and researchers soon recognized its association with maleness
Y chromosome
69
Men who have two X chromosomes
XX male syndrome
70
Women who have one X and one Y chromosome
XY female syndrome
71
XX males actually had a small piece of a __ chromosome
Y
72
XY females lacked a small part of the __ chromosome
Y
73
The SRY gene encodes a very important type of protein called a ____________, which controls the expression of other genes.
transcription factor
74
_________ stimulates male development by sending signals to the indifferent gonads.
SRY transcription factor
75
___________ in the developing testis secrete anti-Müllerian hormone
Sustentacular (Sertoli) cells
76
This destroys potential female structures
anti-Müllerian hormone
77
_________ in the testis secrete testosterone
Interstitial (Leydig) cells
78
This stimulates the development of male structures
testosterone
79
Some testosterone is also converted to ___________, which directs the development of the urethra, prostate gland, penis, and scrotum
dihydrotestosterone (DHT)
80
Because ________ is a multistep process, genetic abnormalities can intervene at several different points
prenatal sexual development
81
The result may be an XY individual with a block in the gene- and hormone-controlled elaboration of male structures so that the phenotype is _____
female
82
In ____________, caused by a mutation in a gene on the X chromosome, the absence of receptors for androgens stops cells in early reproductive structures from receiving the signal to develop as male. The person looks female, but is XY.
androgen insensitivity syndrome
83
the male sex hormones testosterone and DHT
Androgens
84
It is a term for an individual with both male and female sexual structures.
Hermaphroditism
85
It refers to individuals whose internal structures are inconsistent with external structures, or whose genitalia are ambiguous.
Intersex
86
This refers to the presence of both types of structures but at different stages of life.
Pseudohermaphroditism
87
5-alpha reductase deficiency is autosomal ________
recessive
88
In _________ Affected individuals have a normal Y chromosome, a wild type SRY gene, and testes
5-alpha reductase deficiency
89
When __________, which normally catalyzes the reaction of testosterone to form DHT, is deficient, lack of DHT causes the fetus to develop externally as female— that is, without DHT, a penis cannot form.
5-alpha reductase
90
- Changes begin to be noticed at puberty, when the adrenal glands, which sit atop the kidneys, start to produce ________.
- This now leads to masculinization.
testosterone
91
XX individuals with 5-alpha reductase deficiency look _____
female
92
- In the Dominican Republic in the 1970s, 22 young girls reached the age of puberty and began to transform into boys.
- They had a form of 5-alpha reductase deficiency that was fairly common due to ______.
consanguinity
93
Gender name that means "penis at age 12"
guevedoces
94
In ________, a person’s phenotype and genotype are consistent, and physical attraction is toward members of the same sex.
homosexuality
95
It has been observed for thousands of years and has been documented in more than 500 animal species.
Homosexuality
96
They are more likely to both be homosexual
Identical twins
97
Experiments in the 1990s identified genetic markers on the _________ that tended to be identical among pairs of homosexual brothers, but not other pairs.
X chromosome
98
This finding led to the idea that a _____ gene, or a _____ genes, dictates sexual preference. These results could not be confirmed.
single, few
99
Study done on all of the adult twins in Sweden found that in males, genetics contributes about ____ to homosexuality, whereas among females the genetic contribution is about _____.
35%, 18%
100
Undifferentiated structure begins to develop as testis or ovary (6 weeks after fertilization)
Gonadal sex
101
Development of external and internal reproductive structures continues as male or female in response to hormones (8 weeks after fertilization, puberty)
Phenotypic sex
102
Strong feelings of being male or female develop from childhood, possibly earlier
Gender identity
103
Attraction to same or opposite sex (from childhood)
Sexual orientation
104
Mendel’s law of ________ predicts that populations should have approximately equal numbers of male and female newborns.
segregation
105
____ meiosis should yield equal numbers of X-bearing and Y-bearing sperm.
Male
106
it is the proportion of males to females in a human population
sex ratio
107
it is calculated as the number of males divided by the number of females multiplied by 1,000, for people of a particular age. (Some organizations describe sex ratio based on 1.0.)
sex ratio
108
A sex ratio of equal numbers of males and females would be designated _______
1,000
109
The sex ratio at conception is called the _______
primary sex ratio
110
Sex ratio at birth is termed _______
secondary
111
sex ration at maturity is called?
tertiary
112
It can change markedly with age, reflecting medical conditions that affect the sexes differently, as well as environmental factors, such as engaging in dangerous behaviors.
sex ratio
113
The Chinese government is now promoting a _______ program, which awards housing subsidies and scholarships to families that have girls.
“Care for Girls”
114
Families were using ___________ to detect female pregnancies and were terminating about a fourth of them.
prenatal diagnosis
115
Genes carried on the Y chromosome are said to be ______ and those on the X chromosome are _________
Y-linked, X-linked
116
__________ traits are rare because the chromosome has few genes, and many have counterparts on the X chromosome.
These traits are passed from male to male
Y-linked
117
_______ on the X chromosome have different patterns of expression in females and males, because a female has two X chromosomes and a male just one.
Genes
118
In females, ________ traits are passed just like autosomal traits—that is, two copies are required for expression of a recessive allele, and one copy for a dominant allele.
X-linked
119
In ______, a single copy of an X-linked allele causes expression of the trait or illness because there is no copy of the gene on a second X chromosome to mask the effect.
males
120
A man inherits an X-linked trait only from his _____
mother
121
A man is considered ______ for X-linked traits, because he has only one set of X-linked genes.
hemizygous
122
If a mother is _________ for a particular X-linked gene, her son or daughter has a 50% chance of inheriting either allele from her.
heterozygous
123
There is no male-to-male transmission of _______
X-linked traits
124
An X-linked recessive trait is expressed in ____ if the causative allele is present in two copies.
females
125
An X-linked trait passes from an unaffected ______ mother to an affected son.
heterozygous
126
In the condition, called _______, an enzyme deficiency blocks removal of cholesterol from skin cells. The upper skin layer cannot peel off as it normally does, appearing brown and scaly.
ichthyosis
127
__________ is another X-linked recessive trait
Colorblindness
128
Dalton asked his personal physician, ________, to dissect his eyes after he died
Joseph Ransome
129
Ransome snipped off the back of one eye, removing the ____, where the cone cells that provide color vision are nestled among the more abundant rod cells that impart black-and-white vision.
retina
130
Dalton’s remaining retina lacked one of the three types of _______ that enable cone cells to capture certain wavelengths of light.
photopigments
131
__________ are of three types, defined by the presence of any of three types of photopigments.
cone cells
132
o Each photopigment has a vitamin A-derived portion called _____ and a protein portion called an _____
retinal, opsin
133
Mutations in ____ genes cause three different types of colorblindness.
opsin
134
A gene on chromosome __ encodes shortwave opsins, and mutations in it produce the rare autosomal “blue” form of colorblindness
7
135
Dalton had _______ (green colorblindness), which means his eyes lacked the middle-wavelength opsin.
deuteranopia
136
In the third type, ____ (red colorblindness), long-wavelength opsin is absent.
protanopia
137
Deuteranopia and protanopia are __-linked.
X-linked
138
_________ of Johns Hopkins University is another researcher who has personally contributed to our understanding of color vision.
Jeremy Nathans
139
he used a cow version of a protein called _______ that provides black-and-white vision to identify the human counterpart of the rhodopsin gene.
rhodopsin
140
Although Nathans can see colors, his ____ genes are not entirely normal.
opsin
141
An oocyte lacking either a red or a green opsin gene would, when fertilized by a Y-bearing sperm, give rise to a colorblind ____
male
142
It is an X-linked recessive trait, blood-clotting disorder
Hemophilia A
143
The transmission pattern of ________ is consistent with the criteria for an X-linked recessive trait
hemophilia A
144
_______ X-linked conditions and traits are rare.
Dominant
145
A ______ who inherits a dominant X-linked allele has the associated trait or illness
female
146
a ______ who inherits the allele is usually more severely affected because he has no other allele to mask its effect.
male
147
o An example of an X-linked dominant condition
o In affected females, swirls of skin pigment arise when melanin penetrates the deeper skin layers.
o A newborn girl with this has yellow, pus-filled vesicles on her limbs that come and go over the first few weeks.
o Males with the condition are so severely affected that they do not survive to be born.
incontinentia pigmenti (IP)
148
The gene that causes IP, called ____, activates genes that carry out the immune response and apoptosis in tissues that derive from ectoderm, such as skin, hair, nails, eyes, and the brain.
NEMO
149
Another X-linked dominant condition, __________, produces many extra hair follicles, and hence denser and more abundant upper body hair
congenital generalized hypertrichosis
150
Mendel’s first law _____ applies to genes on the X chromosome.
(segregation)
151
It is an X-linked recessive condition that causes very poor or absent sense of smell and small testes or ovaries.
Kallmann syndrome
152
An __-linked recessive trait generally is more prevalent in males than females.
X
153
A _______ affects a structure or function of the body that is present in only males or only females.
Such a gene may be X-linked or autosomal.
sex-limited trait
154
Understanding _______ is important in animal breeding.
sex-limited inheritance
155
A New Zealand cow named ________, who has a mutation that makes her milk very low in saturated fat, is founding a commercial herd.
Marge
156
An inherited medical condition that arises during pregnancy is obviously sex-limited, but the male genome contributes to the development of supportive structures, such as the _______
placenta
157
a sudden rise in blood pressure late in pregnancy.
preeclampsia
158
In a __________, an allele is dominant in one sex but recessive in the other.
sex-influenced trait
159
A ________ affects body parts or functions present in only one gender.
sex-limited trait
160
It is dominant in one sex but recessive in the other.
sex-influenced allele
161
o Females have two alleles for every gene on the X chromosomes, whereas males have only one.
o In mammals, a mechanism called _________ balances this apparent inequality in the expression of genes on the X chromosome.
X inactivation
162
By the time a female embryo consists of __ cells, about ____ of the genes on one X chromosome in each cell are inactivated, and the remaining ___ are expressed to different degrees in different women.
8, 75%, 25%
163
Which X chromosome is mostly turned off in each cell—the one inherited from the mother or the one from the father—is usually _____
random.
164
o A female mammal expresses the X chromosome genes inherited from her father in some cells and those from her mother in others.
o She is, therefore, a ____ for expression of most genes on the X chromosome
mosaic
165
By studying rare human females who have lost a small part of one X chromosome, researchers identified a specific region, the _________, that shuts off much of the chromosome
X inactivation center
166
Genes in the ______ and some other genes escape inactivation.
PARs
167
A gene called _____ controls X inactivation.
XIST
168
It encodes an RNA that binds to a specific site on the same (inactivated) X chromosome.
XIST
169
___________ can alter the phenotype (gene expression), but not the genotype. It is not permanent, and is reversed in germline cells destined to become oocytes.
X inactivation
170
A fertilized ovum does not have an ___________
X chromosome.
171
X inactivation is an example of an ______ change— one that is passed from one cell generation to the next but that does not alter the DNA base sequence
epigenic
172
This differential staining occurs because inactivated DNA has chemical _________ that prevent it from being transcribed into RNA and also enable it to absorb stain.
methyl groups
173
This can be used to check the sex of an individual.
X inactivation
174
The nucleus of a cell of a female, during interphase, has one dark-staining X chromosome called a _________
Barr body
175
A cell from a male has no ________ because his one X chromosome remains active.
Barr body
176
In 1961, English geneticist _________ proposed that the Barr body is the inactivated X chromosome and that it is turned off in early development.
Mary Lyon
177
For ________ X-linked genotypes, X inactivation has no effect.
homozygous
178
For _________, X inactivation leads to expression of one allele or the other.
heterozygotes
179
The swirls of skin color in __________ patients reflect patterns of X inactivation in skin cells
incontinentia pigmenti (IP)
180
Where the normal allele for melanin pigment is shut off, ____ swirls develop.
pale
181
Where pigment is produced, ______ swirls result.
brown
182
A carrier of an X-linked trait who expresses the phenotype is called a __________
manifesting heterozygote
183
Consider______________, which are deficiencies of specific enzymes that normally dismantle cellular debris in lysosomes.
two lysosomal storage disorders
184
In _____________ , cells that make the enzyme readily send it to neighboring cells that do not, essentially correcting the defect in cells that can’t make the enzyme.
Hunter syndrome (mucopolysaccharidosis II)
185
In _________, the enzyme is not easily released from cells, so a female who is a heterozygote may have cells in the affected organs that lack the enzyme.
Fabry disease (alpha-galactosidase A deficiency)
186
White patches may form due to _______ by an autosomal gene that shuts off pigment synthesis
epistasis
187
A cat with colored patches against such a white background is a _______
calico
188
an affected boy has cerebral palsy, bites his fingers, shoulders, and lips to the point of mutilation, is mentally retarded, and passes painful urinary stones.
Lesch Nyhan syndrome
189
In lesch nyhan syndrome, mutation results in defective or absent ______, an enzyme.
HGPRT
190
It is a neurological condition that affects nearly always females.
Rett Syndrome
191
a gene behind the disorder rett syndrome
MECP2 (methyl-CpG-binding protein 2),
192
Rett syndrome is __________, causing symptoms in several organ systems, because the gene adds methyl groups to other genes, silencing them. It is dominant
pleiotropic
193
this evens out the sexes for expression of X-linked genes.
X inactivation
194
In actuality, a female may not be equivalent, in gene expression, to a male because she has two _____, whereas a male has only one.
cell populations
195
A situation in which being a heterozygote for an X-linked gene is harmful is ___________
craniofrontonasal syndrome
196
For certain genes in mammals, ______ does influence the phenotype.
parental origin
197
In _______, methyl groups cover a gene or several linked genes and prevent them from being accessed to synthesize protein
genomic imprinting
198
For a particular _________, the copy inherited from either the father or the mother is always covered with methyl’s, even in different individuals.
imprinted gene
199
It is an epigenetic alteration. It is a layer of meaning stamped upon a gene without changing its DNA sequence.
Imprinting
200
The ______ pattern is passed from cell to cell in mitosis, but not from individual to individual through meiosis.
imprinting
201
When silenced DNA is replicated during ____, the pattern of blocked genes is exactly placed, or imprinted, on the new DNA, covering the same genes as in the parental DNA.
mitosis
202
The “imprint” of ______ is perpetuated, as if each such gene “remembers” which parent it came from.
inactivation
203
In ______, imprints are removed and reset.
meiosis
204
As oocyte and sperm form, the _____ groups shielding their imprinted genes are stripped away, and new patterns are set down, depending upon whether the fertilized ovum chromosomally is male (XY) or female (XX).
CH3
205
women can have sons and men can have daughters without passing on their sex-specific _____
parental imprints
206
Some genes lose their imprints after birth supports the idea of ___________
early importance.
207
Imprinted genes are in clusters along a chromosome, and are controlled by other regions of DNA called _______
imprinting centers.
208
_________ suggests that for mammals, two opposite-sex parents are necessary to produce a healthy embryo and placenta.
Genomic imprinting
209
When two sperm fertilize an oocyte and the female pronucleus degenerates, an abnormal growth of placenta-like tissue called a ___________ forms
hydatidiform mole
210
If a fertilized ovum contains only two female genomes but no male genome, a mass of random differentiated tissue, called a ______ grows
teratoma
211
A _________, which means “monster cancer,” may consist of a variety of tissues in a bizarre mix.
teratoma
212
With either a hydatidiform mole or a teratoma, no embryo results, although a pregnancy test may be positive, because the pregnancy hormone _____ may be produced.
(hCG)
213
________ can explain incomplete penetrance, in which an individual is known to have inherited a genotype associated with a particular phenotype, but has no signs of the trait
Genomic imprinting
214
The predicted _____ is present, but the associated _____ is not expressed.
genotype, phenotype
215
Imprinting may be an important concern in assisted reproductive technologies that manipulate gametes to treat ______
infertility
216
The very rare _______ and ______ are more prevalent among the offspring of people who used in vitro fertilization and intracytoplasmic sperm injection to become pregnant
Angelman syndrome and Beckwith-Wiedemann syndrome
217
The effects of __________are revealed only when an individual has one copy of a normally imprinted allele and the other, active allele is inactivated or deleted.
genomic imprinting
218
The effects of genomic imprinting gone awry can be dramatic, such as two different syndromes that arise from small deletions in the same region of _______
chromosome 15
219
A child with _______ is small at birth and in infancy has difficulty gaining weight.
Between ages 1 and 3, the child develops an obsession with eating.
Prader-Willi syndrome
220
_________ causes autism and mental retardation, an extended tongue, large jaw, poor muscle coordination, and convulsions that make the arms flap.
Angelman syndrome
221
In many cases of _________, only the mother’s chromosome 15 region is expressed; the father’s chromosome is deleted in that region.
Prader-Willi syndrome
222
In _________, the father’s gene is expressed, and the mother’s chromosome has the deletion.
Angelman syndrome
223
Symptoms of ______ arise because several paternal genes that are not normally imprinted (that is, that are normally active) are missing.
Prader-Willi
224
In _______, a normally active single maternal gene is deleted.
Angelman syndrome
225
Clues that indicate a condition is associated with genomic imprinting include increased severity depending on whether it is inherited from the father or mother and also a phenomenon called ________
uniparental disomy
226
o This term literally means “two bodies from one parent,” and refers to an offspring who inherits both copies of a gene from one parent and none from the other.
uniparental disomy
