Genetic Diseases Flashcards
(159 cards)
1
Q
What is a gene?
A
GENE IS THE BASIC UNIT OF INHERITANCE
2
Q
…….. is a discrete locus of heritable, genomic sequence which affects an organism’s trait by being expressed as a functional product or by regulation of gene expression?
A
Gene
3
Q
Gene is a discrete locus of ……….. which affects an organism’s trait by being expressed as a functional product or by regulation of gene expression?
A
heritable genomic sequence
4
Q
Gene is a discrete locus of heritable, genomic sequence which affects an organism’s trait by being expressed as a ……… or by ……..??
A
functional product
regulation of gene expression
5
Q
…….. is the complete set of genes or genetic material in the cell of an Organ
A
Genome
5
Q
What is a genome?
A
Genome is the complete set of genes or genetic material in the cell of an Organ
5
Q
The human genome contains roughly…..?
A
3.2 BILLION DNA BASE PAIRS
6
Q
…….% of the human genome does not encode proteins?
A
98.5
7
Q
98.5% of the human genome does not …..,,?
A
encode proteins
8
Q
Only …..% (20,000 genes) of the genome encode proteins
A
1.5
9
Q
Only 1.5% (20,000 genes) of the genome ……?
A
encode proteins
10
Q
Encoded Proteins Variously
function as?
A
- Enzymes
- Structural components
- signaling molecules
Used to assemble and maintain all the cells in the body
11
Q
Protein-coding genes in higher organisms are separated by ………?
A
long stretches of DNA that do not code for any protein
12
Q
….% of the noncoding regions of the genome provide the critical “architectural planning”
A
80
13
Q
80% of the noncoding regions of the genome provide the critical “………..”?
A
architectural planning
14
Q
80% of the ……… of the genome provide the critical “architectural planning”
A
noncoding regions
15
Q
……… provide the building blocks and the machinery required for assembling cells, tissues and organisms?
A
Protein encoding genes
16
Q
Protein encoding genes provide the …… and ……… required for assembling cells, tissues and organisms?
A
building blocks and the machinery
17
Q
Protein encoding genes provide the building blocks and the machinery required for assembling …….?
A
cells, tissues and organisms?
18
Q
The difference between worms and humans apparently lies more in the ………. than in the construction materials
A
genomic “blueprints”
19
Q
The major classes of functional non-protein-coding sequences found in the human genome are?
A
- Promoter and enhancer regions
- Noncoding regulatory RNAs
- Jumping genes
- Special structural regions of DNA, in particular telomeres (chromosome ends) and centromeres (chromosome “tethers”)
20
Q
………… provide binding sites for transcription factor?
A
Promoter and enhancer regions
21
Q
About noncoding regulatory RNAs, more than ….% of the genome is transcribed into ……. that are never translated into ……., but regulate expression through a variety of mechanisms?
A
60
RNAs
protein
22
Q
The two best-studied varieties of noncoding regulatory RNAs are?
A
(1). MICRO-RNAS (miRNA’S)
(2). LONG NONCODING RNAS (lncRNA’S)
23
Jumping genes are also called ……. e.g. include …..
Mobile genetic elements
Transposons
24
The two best-studied varieties of noncoding regulatory RNAs are?
(1). MICRO-RNAS (miRNA’S)
(2). LONG NONCODING RNAS (lncRNA’S)
25
About jumping genes, more than …….. of the human genome is composed of these elements?
1/3
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About jumping genes, they can move around the genome from one point to another, true or false?
True
27
About jumping genes, they are implicated in ….. and …..?
gene regulation and chromatin organization
28
Define epigenetics?
Epigenetics is defined as the study of heritable chemical modification of DNA or chromatin that does not alter the DNA sequence itself.
29
Different cell types are distinguished by ……… of gene expression
lineage-specific programs
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DNA in cells are not ……?
uniformly or compactly wound
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………… consists of DNA segments 147 base pairs long that are wrapped around a central core structure of highly conserved low molecular weight proteins called histones?
Nucleosomes
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Nucleosomes consists of DNA segments ……… long that are wrapped around a central core structure of highly conserved low molecular weight proteins called histones?
147 base pairs
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Nucleosomes consists of DNA segments 147 base pairs long that are wrapped around a central core structure of ……….. called histones?
highly conserved low molecular weight proteins
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Nucleosomes consists of DNA segments 147 base pairs long that are wrapped around a central core structure of highly conserved low molecular weight proteins called …….?
histones
35
About nucleosomes, The resulting DNA-histone complex resembles a series of beads joined by ………. and is generically called ……?
short DNA linkers
chromatin
36
Human genetic disorders can be broadly classified into three categories, list them
1. Chromosomal disorders
2. Disorders related to mutations in single genes with large effects
3. Complex multigenic disorders
37
At the light microscopic level, nuclear chromatin exists in two basic forms?
(1) Cytochemically dense and transcriptionally inactive heterochromatin
(2) Cytochemically dispersed
Transcriptionally Active euchromatin
38
Define mutation?
Mutation is defined as a permanent
change in DNA
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Mutations that affect ………… are transmitted to the progeny and can give rise to inherited diseases?
germ cells
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Mutations that arise in somatic cells understandably do cause cancers and some congenital malformations, true or false?
True
41
Chromosomal disorders are also known as?
Cytogenic disorders
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About chromosomal disorders, they may take the form of an abnormal number of chromosomes or an alteration in the structure of one or more chromosomes. True or false?
True
43
The normal human chromosome complement is expressed as?
46,XY for males and 46,XX for females
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Any exact multiple of the haploid number of chromosomes (23) is called?
Euploid
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What is an euploid?
Any exact multiple of the haploid number of chromosomes (23)
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…….. occurs if during meiosis or mitosis a cell acquires a chromosome complement that is not an exact multiple of 23?
Aneuploidy
47
Aneuploidy occurs if during meiosis or mitosis a cell acquires a chromosome complement that is not …….?
an exact multiple of 23
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What is Aneuploidy
It occurs if during meiosis or mitosis a cell acquires a chromosome complement that is not an exact multiple of 23.
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The usual causes for aneuploidy are
Nondisjunction and anaphase lag
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The usual causes for ………. are Nondisjunction and anaphase lag
aneuploidy
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When nondisjunction occurs during gametogenesis, the gametes formed have either …… or …….?
an extra chromosome (N+1) or one less chromosome (N-1)
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When …….. occurs during gametogenesis, the gametes formed have either an extra chromosome (N+1) or one less chromosome (N-1)
nondisjunction
53
Is Monosomy or trisomy involving the sex chromosomes, or even more bizarre aberrations compatible with life?
It is
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are autosomal trisomies compatible with life?
Several autosomal trisomies do permit survival
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Is monosomy involving an autosome compatible with life?
Monosomy involving an autosome generally causes loss of too much genetic information to permit live birth or even embryogenesis
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With the exception of …….., all yield severely handicapped infants who almost invariably die at an early age?
trisomy 21
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What is mosaicism?
Mitotic errors in early development give arise to two or more populations of cells with different chromosomal complement in the same individual
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Mosaicism are ………. in early development give arise to two or more populations of cells with different ……….?
Mitotic errors
chromosomal complement in the same individual
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Mosaicism affecting the …….. is relatively common?
Sex chromosomes
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Example of chromosomal disorders involving autosomes include?
Downs syndrome (trisomy 21)
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Down syndrome is the most common chromosomal disorder and is a major cause of ………..?
mental retardation
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About Down syndrome, …..% of affected individuals have trisomy 21
95
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About Down syndrome, 95% of affected individuals have …….?
trisomy 21
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About Down syndrome, Most others have normal chromosome number, but the extra chromosomal material is present as a ………..?
Translocation
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The most common cause of trisomy and therefore of Down syndrome is?
MEIOTIC NONDISJUNCTION
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In meiotic disjunction, the parents of such children have a ………. and are normal in all aspects?
normal karyotype
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About down syndrome, ………. Has a strong influence on its incidence.
Maternal age
67
In about …..% of cases of Down syndrome, extra chromosomal material derived from the presence of a ……….. of the ………. to another ……….. (e.g. 22 or 14)
4
robertsonian translocation
long arm of chromosome 21
acrocentric chromosome
68
Approximately …..% of Down syndrome patients are mosaics, having a mixture of cells with 46 or 47 chromosomes
1
69
The mosaicism in down syndrome results from mitotic nondisjunction of chromosome 21 during an early stage of ……..?
embryogenesis
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Symptoms in cases of mitotic nondisjunction of chromosome 21 during the early stages of embryogenesis are ……………?
variable and milder, depending on the proportion of abnormal cells
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Clearly, in cases of translocation or mosaic Down syndrome, ………. is of no importance?
maternal age
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……. Is the leading cause of severe mental retardation?
Down syndrome
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Approximately ….% of those afflicted have an IQ of …. to ….?
80
25
50
74
Trisomy 18 is called
Edward syndrome
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Trisomy 13 is called
Patau
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Imbalances (excesses or loss) of sex chromosomes are much better tolerated than are similar imbalances of autosomes, true or false?
True
77
Sex chromosomes disorders cause subtle, chronic problems relating to …….?
sexual development and fertility
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Sec chromosome disorders are often difficult to diagnose at birth, true or false?
True
79
About sex chromosome disorders, many are first recognized at the time of puberty, true or false?
True
80
The greater the number of X chromosomes, in both males and females, the greater the likelihood of ……..?
mental retardation
81
Regardless of the number of X chromosomes, the presence of a single Y determines ?
the male sex
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Chromosomal disorders involving sex chromosome are?
1. Klinefelter syndrome
2. Turner syndrome
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Define Klinefelter syndrome?
Best defined as male hypogonadism that occurs when there are two or more X chromosomes and one or more Y chromosome
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…….. is defined as male hypogonadism that occurs when there are two or more X chromosomes and one or more Y chromosome
Klinefelter syndrome
85
The incidence of Klinefelter syndrome is?
Approximately 1 in 600 live male births
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About Klinefelter syndrome, they have …….. body habitus with abnormally ……….?
Eunuchoid
Long legs
87
About Klinefelter syndrome, they have small atrophic ………, often associated with small …….?
Testes
Penis
88
About Klinefelter syndrome, they lack ………. such as ……., …….. and ……….?
secondary male characteristics
deep voice, beard and male distribution of pubic hair
89
About Klinefelter syndrome, The classic pattern of Klinefelter syndrome is associated with a ………?
47, XXY karyotype (90% of cases)
90
About Klinefelter syndrome, ……% of patients with Klinefelter syndrome have a variety of mosaic patterns, most of them being ………?
15
46,XY/47,XXY
91
About Klinefelter syndrome, other patterns are ………?
47,XXY/48,XXXY
92
About Klinefelter syndrome, gynaecomastia may be present. True or false?
True
93
About Klinefelter syndrome, the mean IQ is somewhat lower than normal, but ……. is uncommon?
mental retardation
94
About Klinefelter syndrome, it is an important genetic cause of reduced …….. and ………?
spermatogenesis
male infertility
95
About turner syndrome, turner syndrome results from …………. and is characterized by ……………. in ………….?
complete or partial monosomy of the X chromosome
hypogonadism
phenotypic females
96
About turner syndrome, it is the most common sex chromosome abnormality in ………?
females
97
About turner syndrome, is the single most important cause of primary ……..?
amenorrhea
98
About turner syndrome, in turner syndrome, fetal ovaries develop normally ………?
early in embryogenesis
99
About turner syndrome, The ………. leads to an accelerated loss of oocytes which is complete by age of 2 years?
absence of the second X chromosome
100
About turner syndrome, The absence of the second X chromosome leads to an ……… which is complete by age of 2 years?
accelerated loss of oocytes
101
About turner syndrome, The absence of the second X chromosome leads to an accelerated loss of oocytes which is complete by age of …….?
2 years
102
About turner syndrome, …….. occurs before menarche
menopause
103
About turner syndrome, menopause occurs before ……..
menarche
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About turner syndrome, The ovaries are reduced to ……….
atrophic fibrous strands, devoid of ova and follicles (streak ovaries)
105
What are Mendelian disorders?
These are mutations in single genes with large effects?
106
About mendelian disorders, It is estimated that every individual is a carrier of ………..?
five to eight deleterious genes
107
About mendelian disorders, It is estimated that every individual is a carrier of ………..?
five to eight deleterious genes
108
About mendelian disorders, About …. to ….% of these mutations are familial?
80 to 85
109
About mendelian disorders, The remainder represents new mutations acquired ……. by an affected individual?
De novo
110
About mendelian disorders, Mendelian disorders are also known as?
Single gene disorders
And they follow Mendelian pattern of inheritance
111
What is Mendel’s first law?
Law of segregation
States that “the two alleles for a heritable character segregate during gamete formation and end up in different gametes”
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What is Mendels second law of inheritance?
Law of independent assortment also known as “law of inheritance”
States that “separate genes for separate traits are passed independently of one another from parents to offspring
113
State Mendels third law?
Law of dominance
States that “recessive alleles will always be masked by dominant alleles”
114
Exceptions to Mendel’s law include?
1. Codominance
2. Heterogeneity
3. Linked
115
Transmission patterns of Mendelian disorders are?
1. AUTOSOMAL DOMINANT
2. AUTOSOMAL RECESSIVE
3. SEX-LINKED (RECESSIVE), INVOLVING “X” CHROMOSOME
4. NONCLASSIC PATTERNS OF INHERITANCe
116
Autosomal dominant disorders are manifested in the ………?
Heterozygous state
117
In autosomal dominant disorders, ………….. is usually affected by?
one parent of an index case
118
Both males and females are affected in autosomal dominant disorders. True or false?
True
119
Both parents can transmit the condition in autosomal dominant disorders. True or false?
True
120
About autosomal dominant disorders, When an affected person marries an unaffected one, every child has ……….?
one chance in two of having the disease
121
Both parents can transmit the condition in autosomal dominant disorders. True or false?
True
122
About autosomal dominant disorders, with every autosomal dominant disorder, some proportion of patients do not have ………..?
affected parents
123
About autosomal dominant disorders, Some individuals may inherit the mutant gene but are …….?
phenotypically normal
This is referred to as incomplete penetrance
124
If a trait is seen in all individuals carrying the mutant gene but is expressed differently among individuals the phenomenon is called ……..?
variable expressivity
125
Autosomal recessive traits make up the largest category of ………?
Mendelian disorders
126
Autosomal recessive disorders occur when ………….?
both alleles at a given gene locus are mutated
127
Autosomal recessive disorders, the trait does not usually affect the parents of the affected individual, but siblings may show the disease. True or false?
True
128
Autosomal recessive disorders, siblings have ……… of having the trait (i.e. the recurrence risk is 25% for each birth)
one chance in four
129
Autosomal recessive disorders, if the mutant gene occurs with a low frequency in the population, there is a strong likelihood that the affected individual (proband) is the product of a ………..
cosanguineous marriage
130
Autosomal recessive disorders, the expression of the defect tends to be more uniform than in autosomal dominant disorders. True or false?
True
131
Autosomal recessive disorders, complete penetrance is common. True or false?
True
132
Autosomal recessive disorders, onset is frequently early in life. True or false
True
133
Autosomal recessive disorders, in ………., equal amounts of normal and defective enzyme are synthesized?
heterozygotes
134
Autosomal recessive disorders,
include almost all ………?
inborn errors metabolism
135
Most sex linked disorders are …….?
Recessive
136
Genes located in the “male-specific region of Y” are all related to …….?
Spermatogenesis
137
Genes located in the “………..” are all related to spermatogenesis
male-specific region of Y
138
Males with mutations affecting the Y-linked genes are usually infertile and hence there is no Y-linked inheritance, true or false?
True
139
About X-linked recessive disorders, thus, the male is said to be …………., so these disorders are expressed in the male?
hemizygous for X-linked mutant genes
140
About X-linked recessive disorders, an affected male does not transmit the disorder to his sons, but ………?
all his daughters are carriers
141
About X-linked recessive disorders, sons of heterozygous women have …….. of receiving the mutant gene?
one chance in two
142
About X-linked recessive disorders,
The heterozygous female usually does not express the ………. because of the paired normal allele
full phenotypic change
143
About X-linked recessive disorders, The heterozygous female usually does not express the full phenotypic change because of the …….?
paired normal allele
144
About X-linked recessive disorders, examples include?
1. DUCHENNE MUSCULAR DYSTROPHY
2. HAEMOPHILIA A AND B
3. CHRONIC GRANULOMATOUS DISEASE
4. GLUCOSE-6-PHOSPHATE DEHYDROGENASE DEFICIENCY
6. BRUTON'S AGAMMAGLOBULINEMIA
7. WISKOTT - ALDRICH SYNDROME
8. DIABETES INSIPIDUS
9. LESCH - NYHAN SYNDROME
10. EHLERS - DANLOS SYNDROME (TYPE 9)
11. Color BLINDNESS
12. HUNTER SYNDROM
145
X-linked dominant conditions include?
Vitamin-D resistant rickets
146
Each variant of an allele is referred to as ……?
polymorphism
147
Single-gene disorders with nonclassic inheritance include?
1. Diseases caused by trinucleotide-repeat mutations
2. Disorders caused by mutations mitochondrial genes
3. Disorders associated with genomic imprinting
4. Disorders associated with gonadal mosaicism
148
In the fragile X syndrome, expansions occur during ……..?
OoGenesis
149
In the Huntington syndrome, expansions occur during ……..?
Spermatogenesis
150
About trinucleotide repeat mutation, Loss of function of the affected gene, typically by ……….., as in fragile X syndrome
transcription silencing
151
About trinucleotide repeat mutation, Loss of function of the affected gene, typically by transcription silencing as in ……….?
fragile X syndrome
152
About trinucleotide repeat mutation, toxic gain of function by
alterations of protein structure as
in ………. and ……….?
Huntington disease and spinocerebellar ataxias
153
About trinucleotide-repeat mutation, a toxic gain of function mediated by mRNA as seen in ………….?
fragile X tremor-ataxia syndrome
154
FRAGILE X Syndrome is the second most common genetic cause of ……….. after ……..?
mental retardation
Down syndrome
155
Fragile-X syndrome is caused by a trinucleotide mutation in the ……..?
FAMILIAL MENTAL RETARDATION-1 (FMR1) GENE
156
About trinucleotide-repeat mutation, 20% of males are …….?
clinically and cytogenetically normal (normal transmitting males)
