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There may be more than one correct answer per question.

CHAPTER 2: The Cellular and Molecular Basis of Inheritance

1 Base substitutions:

a May result in nonsense mutations
b Can affect splicing
c Are always pathogenic
d Can affect gene expression
e Result in frameshift mutations

2 Transcription:

a Describes the production of polypeptides from the mRNA template
b Occurs in the nucleus
c Produces single-stranded mRNA using the antisense DNA strand as a template
d Is regulated by transcription factors that bind to the 3′ UTR
e Precedes 5′ capping and polyadenylation

3 The following are directly involved in DNA repair:

a Glycosylases
b DNA polymerases
c Ligases
d Splicing
e Ribosomes

4 During DNA replication:

a DNA helicase separates the double-stranded DNA
b DNA is synthesized in one direction
c Okazaki fragments are synthesized
d DNA is synthesized in a conservative manner
e Uracil is inserted to pair with adenine

CHAPTER 3: Chromosomes and Cell Division

1 Meiosis differs from mitosis in the following ways:

a Daughter cells are haploid, not diploid
b Meiosis is restricted to the gametes and mitosis occurs only in somatic cells
c In mitosis, there is only one division
d Meiosis generates genetic diversity
e The prophase stage of mitosis is one step; in meiosis I, there are four stages

2 Chromosome abnormalities reliably detected by light microscopy include:

a Trisomy
b Monosomy
c Reciprocal translocation
d Interstitial deletion
e Robertsonian translocation

3 Fluorescent in situ hybridization using whole-chromosome (painting) or specific locus probes enables routine detection of:

a Gene amplification
b Subtelomeric deletion
c Trisomy
d Supernumerary marker chromosomes
e Reciprocal translocation

4 Chemicals used in the preparation of metaphase chromosomes for analysis by light microscopy include:

a Colchicine
b Phytohemagglutinin
c Giemsa
d Quinacrine
e Hypotonic saline

CHAPTER 4: DNA Technology and Applications

1 The following statements apply to restriction enzymes:

a They can generate DNA fragments with ‘sticky’ ends
b They are viral in origin
c They are used to detect point mutations
d They are used in Southern blotting
e They are also called restriction exonucleases

2 The following describe the polymerase chain reaction (PCR):

a A type of cell-free cloning
b A process that uses a heat-labile DNA polymerase
c A very sensitive method of amplifying DNA that can be prone to contamination
d A technique that can routinely amplify up to 100 kb of DNA
e A method of amplifying genes that requires no prior sequence knowledge

3 Types of nucleic acid hybridization include:

a Southern blotting
b Microarray
c Western blotting
d Northern blotting
e DNA fingerprinting

4 The following techniques can be used to screen genes for unknown mutations:

a Sequencing
b Single-stranded conformational polymorphism (SSCP)
c Denaturing high-performance liquid chromatography (DHPLC)
d Oligonucleotide ligation assay (OLA)
e Real-time PCR

CHAPTER 5: Mapping and Identifying Genes for Monogenic Disorders

1 Positional cloning uses:

a Genetic databases
b Knowledge of orthologous genes
c Patients with chromosomal abnormalities
d Candidate genes selected by biological knowledge
e Microsatellite markers

2 A candidate gene is likely to be a disease-associated gene if:

a A loss-of-function mutation causes the phenotype
b An animal model with a mutation in the orthologous gene has the same phenotype
c Multiple different mutations cause the phenotype
d The pattern of expression of the gene is consistent with the phenotype
e It is a pseudogene

3 Achievements of the Human Genome Project include:

a Draft sequence published in 2000
b Sequencing completed in 2003
c Development of bioinformatics tools
d Identification of all disease-causing genes
e Studies of ethical, legal, and social issues

CHAPTER 6: Developmental Genetics

1 In development, HOX genes:

a Function as transcription factors
b When mutated have been shown to be associated with many malformation syndromes
c Show very divergent structures across different species
d Are functionally redundant in postnatal life
e Individually can be important in the normal development of widely different body systems

2 In the embryo and fetus:

a Gastrulation is the process leading to the formation of the 16-cell early embryo 3 days after fertilization
b Organogenesis takes place at between 8 and 12 weeks’ gestation
c The notch signaling and sonic hedgehog pathways are important for ensuring normal development in diverse organs and tissues
d Somites form in a caudo-rostral direction from the presomitic mesoderm
e TBX genes appear to be crucial to normal limb development

3 Concerning developmental pathways and processes:

a In mammalian development, the jaw is formed from the second pharyngeal arch
b Pharyngeal arch arteries ultimately become the great vessels around the heart
c TBX1 is a key gene in the defects associated with DiGeorge syndrome
d Achondroplasia can be caused by a wide variety of mutations in the FGFR3 gene
e Loss-of-function mutations and gain-of-function mutations usually cause similar defects

4 Regarding the X-chromosome:

a In most males with a karyotype of 46,XX, the SRY gene is present and found on one of the X chromosomes
b In lyonization, or X-chromosome inactivation, all the genes of one X chromosome are switched off
c As a result of lyonization, all females are X-chromosome mosaics
d Male fetal development is solely dependent on the SRY gene having normal functioning
e X-chromosome inactivation may be linked in some way to the monozygotic twinning process

5 Transcription factors:

a Are RNA sequences that interfere with translation in the ribosomes
b Their only function is to switch off genes in development
c When mutated in Drosophila body segments may be completely reorganized
d Are not involved in defects of laterality
e Include genes that have a zinc finger motif

CHAPTER 7: Patterns of Inheritance

1 Concerning autosomal recessive inheritance:

a Females are more likely to be affected than males
b If both parents are carriers, the risk at conception that any child might be a carrier is image
c Diseases following this pattern of inheritance are more common in societies where cousin marriage is normal
d Usually only a single generation has affected individuals
e Angelman syndrome follows this pattern

2 Concerning X-linked inheritance:

a The condition cannot be passed from an affected father to his son
b When recessive, an affected man will not see the condition in his children but it may appear in his grandchildren
c When dominant, females are usually as severely affected as males
d When dominant, there are usually more affected females than affected males in a family
e The risk of germline mosaicism does not need to be considered

3 In mitochondrial genetics:

a Heteroplasmy refers to the presence of more than one mutation in mitochondria
b Mitochondrial genes mutate less often than nuclear genes
c Mitochondrial conditions affect only muscle and nerve tissue
d The risk of passing on a mitochondrial condition to the next generation may be as high as 100%
e Mitochondrial diseases have nothing to do with nuclear genes

4 Concerning terminology:

a Locus heterogeneity means that the same disease can be caused by genes on different chromosomes
b Pseudo-dominance refers to the risk to the offspring when both parents have the same dominantly inherited condition
c If a condition demonstrates reduced penetrance it may skip generations
d Variable expression characterizes diseases that demonstrate anticipation
e Pleiotropy is simply a more striking form of variable expression

5 In inheritance:

a An autosomal recessive condition can occasionally arise through uniparental disomy
b Imprinted genes can be unmasked through uniparental disomy
c Digenic inheritance is simply another way of referring to uniparental disomy
d Hormonal factors may account for conditions demonstrating sex influence
e Most of the human genome is subject to imprinting

CHAPTER 8: Mathematical and Population Genetics

1 In applying the Hardy-Weinberg equilibrium, the following assumptions are made:

a The population is small
b There is no consanguinity
c New mutations do not occur
d No babies are born by donor insemination
e There is no significant movement of population

2 If the population incidence of a recessive disease is 1 in 10,000, the carrier frequency in the population is:

a 1 in 100
b 1 in 200
c 1 in 25
d 1 in 50
e 1 in 500

3 Heterozygote advantage:

a May lead to an increased incidence of autosomal dominant disorders
b Does not mean that biological fitness is increased in the homozygous state
c May explain the worldwide distribution of sickle cell disease and malaria
d May lead to distortion of the Hardy-Weinberg equilibrium
e Is very unlikely to be traced to a founder effect

4 Polymorphic loci:

a Are defined as those loci at which there are at least two alleles, each with frequencies greater than 10%
b Have been crucial to gene discoveries
c Can be helpful in determining someone’s genetic status in a family
d Have nothing to do with calculating LOD scores
e By themselves have no consequence for genetically determined disease

5 In population genetics:

a To calculate the mutation rate for a disorder, it is necessary only to know the biological fitness for the condition
b If medical treatment can improve biological fitness, the frequency of an autosomal dominant condition will increase far more rapidly than that of an autosomal recessive condition
c Even when a large number of families is studied, the calculated segregation ratio for a disorder might not yield the expected figures for a given pattern of inheritance
d For X-linked disorders, the frequency of affected males equals the frequency of the mutated allele
e Autozygosity mapping is a useful strategy to look for the gene in any autosomal recessive condition

CHAPTER 9: Polygenic and Multifactorial Inheritance

1 Concerning autism:

a It is best classified as an inborn error of metabolism
b The concordance rate in dizygotic twins is approximately 50%
c Fragile X syndrome is a major cause
d The risk to the siblings of an affected person is approximately 5%
e Girls are more frequently affected than boys

2 Linkage analysis is more difficult in multifactorial conditions than in single-gene disorders because:

a Variants in more than one gene are likely to contribute to the disorder
b The number of affected persons within in a family is likely to be fewer than for a single-gene disorder
c The mode of inheritance is usually uncertain
d Some multifactorial disorders are likely to have more than one etiology
e Many multifactorial conditions have a late age of onset

3 Association studies:

a Can give false-positive results because of population stratification
b Include the transmission disequilibrium test (TDT)
c Positive association studies should be replicated
d Are used to map genes in multifactorial disorders
e Require closely matched control and patient groups

4 Variants in genes that confer susceptibility to type 2 diabetes (T2DM) have been found:

a By linkage analysis using affected sibling pairs
b Using animal models
c By candidate gene studies from monogenic subtypes of diabetes
d Through the study of biological candidates
e In isolated populations

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