Sex Linked Flashcards
1
Q
XRXR
what is the phenotype
A
Red-eyed female
2
Q
A
3
Q
XRXr
what phenotype
A
Red-eyed female
4
Q
XrXr
A
White-eyed female
5
Q
XRY
what phenotype
A
Red-eyed male
6
Q
XrY
what phenotype
A
white-eyed male
7
Q
are used to
predict the outcome of sexlinked inheritance.
A
punnett square
8
Q
A “__-” is a female who is
heterozygous for the trait
A
carrier
9
Q
This gene has its ___ on the X-chromosome, it is said to be ___
A
LOCUS
SEX-LINKED
10
Q
In sex linked characteristics the ___crosses
do not give the same results
A
reciprocal
11
Q
For X-linked genes fathers do not pass the mutant
allele onto their ___
A
sons
12
Q
For X-linked genes fathers pass the mutant allele
onto their daughters who are ___
A
carriers
13
Q
Carrier mothers may pass the allele onto their sons with a chance of ___
A
50%
14
Q
- Females showing the trait for an X-linked mutant
allele can exist but they are ___
A
rare
15
Q
Female carriers may show patches of cells with
either trait due to ___
A
X chromosome inactivation
16
Q
example of sex-linked traits and disorders
A
Male pattern baldness, red-green colour
blindness, myopia, night blindness,
hemophilia
17
Q
Color blindness is found mostly in
A
males
18
Q
- complete color blindness, seeing
only shades of gray
A
achromatopsia
19
Q
difficulty telling the difference
between red/purple and green/purple
A
deuteranopia
20
Q
– Deuteranopia - difficulty telling the difference
between
A
red/purple and green/purple
21
Q
A
21
Q
difficulty telling the difference
between blue/green and red/green
A
protanopia
22
Q
– Protanopia - difficulty telling the difference
between
A
blue/green
red/green
23
Q
difficulty telling the difference
between yellow/green and blue/green)
A
tritanopia
24
Tritanopia - difficulty telling the difference
between
yellow/green
blue/green
25
= Red-Green
Colourblindness
daltonism
26
daltonism is ___colorblindness
red/green
27
two types of photoreceptor
cones
rods
28
photoreceptor with a max sensitivity of 505nm
rods
29
photoreceptor that has red, green, and blue sensitive
cones
30
cone
___ sensitive 560nm
red
31
cone
___ sensitive 530nm
green
32
cone
___ sensitive 420nm
blue
33
rod
max sensitivity ____
505nm
34
its distribution is Concentrated in the fovea
color photoreception
35
is a small pit in the retina that provides sharp, central vision.
fovea
36
Widely spread over whole
retina, absent from fovea
monochrome photoreception
37
3 proteins controlled by 3 genes
color photoreception
38
which pigments in color photoreception are sex linked
red
green
39
which pigment in photoreception is autosomal
blue
40
pigment for monochrome photoreception
rhodopsion
41
rhodopsin is composed of (2)
retinol (vit a)
opsin (protein)
42
rhodopsin is also called
visual purple
43
43
bleaching of color photoreception is
slow
44
44
bleaching of monochrome photoreceptioin is
fast (very sensitive)
45
regeneration of color photoreception
slow (after images in bright light, complementary colors)
46
regeneration of monochrome photoreception
fast
47
use of color photoreception
Daylight vision
Light adaptation 5 min
48
use of monochrome photoreception
Night vision
Dark adaptation 20 min or
wear red goggles!
49
Hemophilia is a recessive X-linked
trait. What is the probability of a
couple having a hemophiliac child if
the man does not have hemophilia
and the woman is a carrier?
Hemophilia is indeed a recessive X-linked trait, meaning the gene responsible for hemophilia is located on the X chromosome. Men have one X and one Y chromosome (XY), while women have two X chromosomes (XX).
In this scenario:
The man does not have hemophilia (XᵐY), where Xᵐ is a normal X chromosome.
The woman is a carrier (XʰXᵐ), where Xʰ carries the hemophilia gene.
Let's consider the possible combinations for their children:
The possible combinations for daughters are:
XʰXᵐ (carrier, like the mother)
XᵐXᵐ (normal, not a carrier)
The possible combinations for sons are:
XʰY (affected by hemophilia)
XᵐY (normal, like the father)
Since each child inherits one X chromosome from the mother and one sex chromosome from the father (either X or Y), the probabilities are as follows:
50% of their daughters will be carriers (XʰXᵐ).
50% of their daughters will be normal (XᵐXᵐ).
50% of their sons will have hemophilia (XʰY).
50% of their sons will be normal (XᵐY).
Given these combinations, the overall probability of the couple having a child with hemophilia is 25%. This is because 50% of their sons have a 50% chance of having hemophilia, and sons make up half of their potential offspring.
50
hese exposed fibers activate a series of proteins in the blood called
clotting factors
51
One of these clotting factors eventually converts a protein called prothrombin into its active form
thrombin
52
Thrombin then converts another protein, fibrinogen, into
fibrin
53
This involves a deficiency in Factor VIII
what type of hemophilia
hemophilia A
54
This involves a deficiency in Factor IX (antihemophilic factor B)
hemophilia B
55
The blood clotting reaction is an ___ involving Factors XII, XI, IX, X and II
enzyme cascade
56
The blood clotting reaction is an enzyme
cascade involving Factors
XII
XI
IX
X
II
57
Other factors including proteins like Factor __
are essential as coenzymes.
VIII
58
* About 85% of hemophiliacs suffer from ___
classic hemophilia
59
They cannot produce factor VIII
classic hemophilia
60
The rest show ___disease where they
cannot make factor IX
christmas
61
The rest show Christmas disease where they
cannot make factor __
IX
62
Hemophiliacs do clot their blood slowly because
there is an alternative pathway via
thromboplastin
63
is a genetic
family tree that shows
how prevalent a trait is
in a family unit from
generation to
generation.
pedigree
64
They are often used to
track the expression of
genetic conditions and
disorders
pedigree
65
___ represent males
and ___females
squares
circles
66
A ___in shape
means that person has the
trait in question
coloured
67
67
A ____ in shape
means that they are
carrying an allele for a
recessive trait.
half coloured
68
Refers to those situations in which a single
copy of an allele is sufficient to cause
expression of a trait
autosomal dominant inheritance
68
means not on the sex
chromosomes
autosomal
69
1. Every affected person should have at least one
affected parent.
* 2. Males and females should be equally often
affected.
* 3. An affected person has at least a 50% chance
of transmitting the dominant allele to each
offspring.
autosomal dominant inheritance
70
(caused by a mutation) in which the
person ages very rapidly. They die before they can
reproduce.
progeria
71
Autosomal Dominant Inheritance
Examples
progeria
huntington's disease
72
e in which the central nervous
system starts to break down around the age of 30.
huntinton's disease
73
Refers to those situations where two
recessive alleles result in a trait being
expressed.
autosomal recessive inheritance
74
75
1. An affected person may not have affected parents. Parents
would be carriers.
* 2. Affects both sexes equally. Can appear to skip generations.
* 3. Two affected parents will have affected children 100% of the time.
autosomal recessive inheritance
76
Autosomal Recessive
Examples
albinism
tay sachs
77
is a genetic condition which is the loss
of pigment in hair, skin and eyes
albinism
78
is a genetic disorder which is a build
up of fatty deposits in the brain, eventually
proving to be fatal.
Tay Sachs
79
* Refers to those situations where a recessive
allele on the X chromosome can lead to a
trait/condition or disorder
x-linked recessive inheritance
80
Males are affected more often than females. Ratio of ___ in x-linked recessive inheritance
8:1
81
Affected males will transmit the allele to all
___, but not to sons.
x-linked recessive inheritance
daughters
82
82
can arise only from
matings in which the father is affected and the
mother is affected or a carrier.
homozygous recessive females
83
which
causes progressive and degenerative
muscle weakness
duchenne muscular dystrophy
84
x-linked recessive disorders include
hemophilia
duchenne muscular dystrophy
85
given that the gametes are
XC
Xc
Y
where
Xc = colorblind gene
give the GR and PR
GR: 1XCXc:1XCY
PR: 1 normal female (but carrier): 1 normal male
86
Refers to situations where a single dominant
allele on the X chromosome can lead to a
trait/condition
x-linked dominant inheritance
87
1. Twice as many females are affected as males.
* 2. Usually half the children of an affected female will be
affected, regardless of sex.
* 3. All the daughters of an affected male will be affected but
none of the sons.
x-linked dominant inheritance
88
example of x-linked dominant
vitamin D resistant rickets
89
which can
lead to bone deformities, particularly in
the lower limbs (bowed legs)
vitamin D resistant rickets
90
XDXD - female with defective teeth enamel
XDXd - female with defective teeth enamel
XdXd - female with normal teeth
XD -- male with defective teeth enamel
XdY - male with normal teeth
defective teeth x normal teeth
XDXD x XdY
give GR and PR
1 XDxd
1 XDY
PR: 1 daughter with defective teeth
1 son with defective teeth
91
Chart showing genetic relationships between members
of a family
pedigrees
92
produces bone disorders such as rickets that cannot be cured with vitamin D
hypophosphatemia
93
hypophosphatemia is an example of X-linked ___
dominant
94
characterized by browning of teeth
defective teeth enamel
95
defective teeth enamel is an example of X-linked ___
dominant
96
atrophy of adrenal glans, mental deterioration, death 1-5 years after onset
adrenuloeukodystrophy
97
adrenoleukodystrophy is an example of X-linked ___
recessive
98
insensitive to green light; 60-75 percent of color blindness
deutan colorblindness
99
deutan colorblindness is an example of X-linked ___
recessive
100
insensitivity to red light; 25-40 percent of colorblindness
protan colorblindness
101
protan colorblindess is an example of X-linked ___
recessive
102
metabolic disease caused by lack of enzyme a-galactosidase A; progressive cardiac, renal problems, early death
farby's death
103
farby's death is an example of X-linked ___
recessive
104
benign condition that can produce severe even fatal anemia in presence of certain foods and drugs
glucose-6-phosphate dehydrogenase deficiency
105
105
g6p dehydrogenase deficiency is an example of X-linked ___
recessive
105
inability to form blood clots; caused by a lack of clotting factor VIII
hemophilia A
105
christmas disease clotting defect caused by lack of factor IX
hemophilia B
105
hemophilia is an example of X-linked ___
recessive
106
skin disorder causing large, dark scales on extremities, trunk
Icthyosis
107
icthyosis is an example of X-linked ___
recessive
108
metabolic defect caused by lack of enzyme hypoxanthine guanine phosphoribosyl transferase (HGPRT); causes mental, self mutilation, early death
Lesch-Nyhan Syndrome
109
Lesch-Nyhan Snydrome is is an example of X-linked ___
recessive
110
duchenne-type, progressive; fatal condition accompanied by muscle wasting
muscular dystrophy
111
muscular dystrophy
112
insensitivity to testosteron in XY individual resulting in female sexual phenotyp
testicular feminization
113
114
115
whole body except palms, soles, head, and face is covered with rough bristly scales and cylindrical bristle-like outhrowths nearly an inch long
porcupine man
116
characterized by a web like connection between second and third toes
webbed toes
117
a conspicuous growth of hair on the outer rim of the ears
hypertrichosis of the ears
118
A carrier female (XCXc) marries a
normal male (XCY). What would be the
chance of colorblindness appearing in
their progenies?
Probability:
25% Normal female
25% Carrier female
25% Normal male
25% Colorblind male
So, there's a 25% chance that any male child will be colorblind, while no female child will exhibit colorblindness due to this genetic combination
