EXAM 1 Flashcards
According to Mendel’s laws, if a homozygous dominant individual (RR) is crossed with a homozygous recessive individual (rr) for a single trait, what will be the genotype of all individuals in the F1 generation?
a) RR
b) rr
c) Rr
d) RR and rr equally
c) Rr
The law of dominance states that in a cross between true-breeding parents with contrasting traits, all offspring will be heterozygous and express only the dominant trait
Which of the following is an example of an autosomal recessive inheritance pattern?
a) Huntington’s disease
b) Achondroplasia
c) Cystic fibrosis
d) Free hanging earlobes
c) Cystic fibrosis
Autosomal recessive inheritance requires two copies of the recessive gene for the trait to be expressed. Huntington’s disease and achondroplasia are autosomal dominant, and free hanging earlobes are a dominant trait
A pedigree analysis shows that a certain trait appears in every generation, and affected individuals all have at least one affected parent. This pattern is most consistent with:
a) Autosomal recessive inheritance
b) X-linked recessive inheritance
c) Autosomal dominant inheritance
d) Mitochondrial inheritance
c) Autosomal dominant inheritance
Dominant traits typically appear in each generation, and affected individuals usually have an affected parent in autosomal dominant inheritance
What is the term for the phenomenon where a heterozygous individual expresses an intermediate phenotype compared to the two homozygous phenotypes?
a) Codominance
b) Complete dominance
c) Incomplete dominance
d) Polygenic inheritance
c) Incomplete dominance
Intermediate expression, also known as incomplete dominance, results in a heterozygous phenotype that is a blend of the two homozygous phenotypes
Blood type AB in humans is an example of:
a) Complete dominance
b) Incomplete dominance
c) Codominance
d) Sex-linked inheritance
c) Codominance
In codominance, both alleles are expressed in the heterozygous individual. In blood type AB, both the IA and IB alleles are expressed
The percentage of individuals with a particular genotype who actually display the expected phenotype is known as:
a) Expressivity
b) Penetrance
c) Pleiotropy
d) Epistasis
b) Penetrance
Penetrance refers to the proportion of individuals with a specific genotype that exhibit the corresponding phenotype
Which of the following describes a reciprocal translocation?
a) Loss of a segment of a chromosome
b) Duplication of a segment within a chromosome
c) Exchange of segments between nonhomologous chromosomes
d) Inversion of a segment within a chromosome
c) Exchange of segments between nonhomologous chromosomes
A reciprocal translocation involves a two-way exchange of segments between two nonhomologous chromosomes
Down syndrome is most commonly the result of which type of chromosomal abnormality?
a) Monosomy
b) Trisomy
c) Deletion
d) Translocation
b) Trisomy
Down syndrome typically results from trisomy 21, meaning there are three copies of chromosome 21 instead of the usual two
What is the karyotype of a female with Turner syndrome?
a) 45, XXY
b) 45, X
c) 45, XXX
d) 45, XY
b) 45, X
Turner syndrome in females is characterized by the presence of only one X chromosome, resulting in a 45, X karyotype
Fluorescence in situ hybridization (FISH) is a molecular cytogenetic technique that uses:
a) Antibodies to detect specific proteins on chromosomes
b) Radioactive isotopes to label DNA sequences
c) Fluorescently labeled DNA probes to target specific DNA or RNA sequences
d) Enzymes to cut DNA at specific restriction sites
c) Fluorescently labeled DNA probes to target specific DNA or RNA sequences
FISH utilizes DNA probes labeled with different colored fluorescent tags to visualize specific regions of the genome
What is the fundamental repeating unit of chromatin in eukaryotes?
a) Histone
b) Nucleosome
c) Solenoid
d) Chromatosome
b) Nucleosome
The nucleosome, consisting of histone proteins and wrapped DNA, is the basic structural and functional unit of chromatin
Which of the following nitrogenous bases is found in RNA but not in DNA?
a) Adenine
b) Guanine
c) Cytosine
d) Uracil
d) Uracil
RNA contains uracil as one of its pyrimidine bases, while DNA contains thymine instead
What type of bond connects the nucleotides in a single strand of DNA?
a) Hydrogen bond
b) Ionic bond
c) Peptide bond
d) Phosphodiester bond
d) Phosphodiester bond
A phosphodiester bond links the 5’ phosphate group of one nucleotide to the 3’ hydroxyl group of the next, forming the DNA backbone
According to Chargaff’s rules, in a double-stranded DNA molecule:
a) [A] = [G] and [C] = [T]
b) [A] = [T] and [C] = [G]
c) [A] = [C] and [T] = [G]
d) [A] + [T] = [G] + [C]
b) [A] = [T] and [C] = [G]
Chargaff observed that the amount of adenine is equal to the amount of thymine, and the amount of cytosine is equal to the amount of guanine in DNA
The semi-conservative model of DNA replication suggests that each new DNA molecule consists of:
a) Two newly synthesized strands
b) Two parental strands
c) One parental strand and one newly synthesized strand
d) Fragments of parental and newly synthesized strands
c) One parental strand and one newly synthesized strand
In semi-conservative replication, each daughter DNA molecule inherits one original parental strand and one newly synthesized complementary strand
Which enzyme is responsible for unwinding the double-stranded DNA at the replication fork in prokaryotes?
a) DNA polymerase
b) DNA ligase
c) Helicase
d) Primase
c) Helicase
Helicase unwinds the DNA double helix at the origin of replication, creating two replication forks
Okazaki fragments are synthesized on the:
a) Leading strand in the 5’ to 3’ direction
b) Leading strand in the 3’ to 5’ direction
c) Lagging strand in the 5’ to 3’ direction
d) Lagging strand in the 3’ to 5’ direction
c) Lagging strand in the 5’ to 3’ direction
Due to the 5’ to 3’ directionality of DNA polymerase, the lagging strand is synthesized discontinuously in short fragments called Okazaki fragments, each synthesized in the 5’ to 3’ direction away from the replication fork
Telomeres are repetitive nucleotide sequences found at the:
a) Centromeres of chromosomes
b) Origins of replication
c) Ends of chromosomes
d) Spindle fibre attachment sites
c) Ends of chromosomes
Telomeres are located at the ends of chromosomes and consist of repetitive DNA sequences
Which DNA repair mechanism directly reverses pyrimidine dimers formed by UV radiation in some organisms?
a) Base excision repair
b) Nucleotide excision repair
c) DNA photolyase
d) Mismatch repair
c) DNA photolyase
DNA photolyase uses light energy to break the covalent bonds in pyrimidine dimers, directly restoring the original bases
The Human Genome Project aimed to:
a) Identify all proteins in the human body
b) Determine the complete DNA sequence of the human genome
c) Develop new gene therapy techniques
d) Understand the function of all human genes
b) Determine the complete DNA sequence of the human genome
A primary goal of the Human Genome Project was to determine the sequence of the approximately 3 billion base pairs that make up human DNA
Which of the following best describes a gene in the context of genomics?
a) The sum total of all an individual organism’s DNA
b) A segment of DNA that codes for a protein only
c) A segment of DNA that contains biological information, including sequences for proteins and functional RNAs
d) A non-coding region of the genome with regulatory functions
c) A segment of DNA that contains biological information, including sequences for proteins and functional RNAs
Genes are parts of the genome that contain biological information, which includes coding sequences for proteins as well as sequences for various functional RNAs
Interspersed repeats and tandem repeats are two main types of:
a) Protein-coding genes
b) Regulatory DNA sequences
c) Repetitive DNA
d) Single nucleotide polymorphisms
c) Repetitive DNA
The human genome contains a significant amount of repetitive DNA, which can be broadly classified into interspersed repeats and tandem repeats
The enzyme reverse transcriptase is crucial for the movement of:
a) DNA transposons
b) SINEs (Short Interspersed Nuclear Elements) like Alu repeats
c) Simple sequence repeats
d) Centromeric DNA
b) SINEs (Short Interspersed Nuclear Elements) like Alu repeats
SINEs are retrotransposons that rely on reverse transcriptase to convert their RNA transcripts back into DNA for insertion into the genome
What is a key difference in gene organization between prokaryotes and eukaryotes?
a) Prokaryotes have linear chromosomes, while eukaryotes have circular chromosomes.
b) Eukaryotic genes often contain introns, which are typically absent in prokaryotic genes.
c) Prokaryotes have their DNA enclosed within a nucleus, while eukaryotes do not.
d) Eukaryotic genes are always organized into operons, unlike prokaryotic genes.
b) Eukaryotic genes often contain introns, which are typically absent in prokaryotic genes.
Eukaryotic genes are frequently interrupted by non-coding regions called introns, which are removed by splicing before translation. Prokaryotic genes generally lack introns
Next Generation Sequencing (NGS) technologies are characterized by:
a) Sequencing of single DNA molecules in real time.
b) High-throughput sequencing of millions of DNA fragments in parallel.
c) Chain-termination chemistry followed by gel electrophoresis.
d) A low error rate and short read lengths.
b) High-throughput sequencing of millions of DNA fragments in parallel.
NGS involves massively parallel sequencing, allowing for the simultaneous sequencing of millions of DNA templates
A true-breeding plant with round seeds (RR) is crossed with a plant with wrinkled seeds (rr). The F1 generation all have round seeds (Rr). If two plants from the F1 generation are crossed, what proportion of the F2 generation would be expected to be heterozygous for this trait?
a) 1/4
b) 1/2
c) 3/4
d) All of them
b) 1/2
The F1 cross is Rr x Rr. The Punnett square for this cross yields genotypes RR, Rr, Rr, and rr in a 1:2:1 ratio. Therefore, 2 out of 4, or 1/2, of the F2 generation is expected to be heterozygous (Rr)
Which of the following scenarios would most likely lead to the manifestation of a recessive autosomal allele?
a) The allele is present in a heterozygous individual.
b) The allele exhibits complete dominance.
c) Both parents are carriers for the allele.
d) The allele is located on a non-autosomal chromosome.
c) Both parents are carriers for the allele
Autosomal recessive inheritance requires two copies of the recessive allele for the trait to be expressed. If both parents are carriers (heterozygous), there is a 25% chance their offspring will inherit two copies of the recessive allele
A genetic condition shows incomplete penetrance. An individual with a known disease-causing genotype for this condition:
a) Will exhibit a more severe form of the phenotype.
b) Will exhibit a milder form of the phenotype.
c) May not exhibit any phenotype associated with the genotype.
d) Will pass on the condition to all of their offspring.
c) May not exhibit any phenotype associated with the genotype
Incomplete penetrance means that not all individuals with a particular genotype will express the expected phenotype
Which of the following best explains the observation that males are more frequently affected by X-linked recessive disorders than females?
a) Males inherit the affected X chromosome from their father.
b) Males have two copies of the X chromosome, increasing their chance of inheriting the recessive allele.
c) Males only have one X chromosome, so if they inherit the recessive allele on that chromosome, they will express the trait.
d) The Y chromosome in males often carries dominant alleles that mask recessive alleles on the X chromosome.
c) Males only have one X chromosome, so if they inherit the recessive allele on that chromosome, they will express the trait
Males have an XY chromosome composition. If their single X chromosome carries a recessive allele for a particular trait, there is no corresponding allele on the Y chromosome to mask its expression
A chromosomal rearrangement in which a segment of a chromosome is reversed end-to-end is known as a(n):
a) Deletion
b) Duplication
c) Inversion
d) Translocation
c) Inversion
An inversion involves a chromosome breaking in two places, and the broken segment being reinserted in the reverse orientation
Non-disjunction during meiosis I results in gametes that have:
a) The correct number of chromosomes.
b) Half the normal number of chromosomes.
c) An extra copy or a missing copy of an entire chromosome.
d) Structural abnormalities within the chromosomes.
c) An extra copy or a missing copy of an entire chromosome
Non-disjunction, the failure of homologous chromosomes to separate properly during meiosis I, leads to some gametes having an extra chromosome (n+1) and others missing a chromosome (n-1)
Which molecular cytogenetic technique is most suitable for detecting microdeletions or microduplications that are too small to be observed by standard karyotyping?
a) G banding
b) Q banding
c) Karyotyping
d) Fluorescence in situ hybridization (FISH)
d) Fluorescence in situ hybridization (FISH)
FISH uses fluorescently labeled DNA probes that can hybridize to specific regions of the genome, allowing the detection of submicroscopic deletions or duplications as small as 100 kb.
The primary chemical difference between deoxyribose and ribose sugars in nucleic acids is the presence of a:
a) Phosphate group at the 5’ carbon.
b) Hydroxyl group at the 2’ carbon in ribose, which is absent in deoxyribose.
c) Nitrogenous base attached to the 1’ carbon.
d) Methyl group in thymine that is absent in uracil.
b) Hydroxyl group at the 2’ carbon in ribose, which is absent in deoxyribose
Ribose has a hydroxyl (-OH) group on the 2’ carbon, while deoxyribose has a hydrogen (-H) atom at this position
Which of the following types of non-covalent interactions plays a crucial role in stabilizing the double helix structure of DNA by forming specific pairings between nitrogenous bases?
a) Phosphodiester bonds
b) Peptide bonds
c) Glycosidic bonds
d) Hydrogen bonds
d) Hydrogen bonds
Hydrogen bonds form between the nitrogenous bases on opposite strands of the DNA double helix (A with T, and C with G), providing stability to the structure
In the context of genomics, the term “annotation” primarily refers to:
a) Determining the order of nucleotides in a DNA molecule.
b) Comparing genome sequences across different species.
c) Attaching biological information to genomic sequences.
d) Identifying repetitive elements within a genome
c) Attaching biological information to genomic sequences
Genome annotation is the process of identifying the locations of genes and other functional elements within the genome and assigning biological meaning to these sequences
Which of the following is a key characteristic distinguishing eukaryotic genomes from prokaryotic genomes?
a) The absence of protein-coding genes.
b) A smaller overall genome size.
c) The presence of a high proportion of non-coding DNA, including introns.
d) The organization of genes into operons.
c) The presence of a high proportion of non-coding DNA, including introns
Eukaryotic genomes are characterized by a large amount of non-coding DNA, including introns within genes and intergenic sequences, which is significantly more than in prokaryotic genomes. Prokaryotic genes are often organized into operons, which is not a common feature of eukaryotic genomes
Plasmids, found in some prokaryotic cells, are best described as:
a) Essential linear DNA molecules required for survival.
b) Small circular DNA molecules that replicate independently of the main chromosome.
c) Non-functional RNA molecules involved in gene regulation.
d) Protein complexes that package and protect the bacterial DNA
b) Small circular DNA molecules that replicate independently of the main chromosome
Plasmids are extrachromosomal, circular DNA molecules capable of independent replication and often carry genes that provide a selective advantage to the bacterium
Retrotransposons, such as Alu repeats in the human genome, move through a mechanism that involves:
a) Direct excision from one genomic location and insertion into another.
b) The creation of an RNA intermediate that is reverse transcribed into DNA for insertion.
c) Replication of the DNA element and insertion of the new copy at a distant site.
d) The activity of transposase enzymes that recognize specific DNA sequences.
b) The creation of an RNA intermediate that is reverse transcribed into DNA for insertion
Retrotransposons are mobile genetic elements that are transcribed into RNA, which is then reverse transcribed back into DNA by reverse transcriptase and inserted into a new location in the genome
The C-value paradox refers to the observation that:
a) The number of genes in an organism directly correlates with the size of its genome.
b) Organisms with similar complexity can have vastly different genome sizes.
c) Coding regions of genes (exons) are significantly larger than non-coding regions (introns).
d) The rate of mutation is inversely proportional to the size of the genome.
b) Organisms with similar complexity can have vastly different genome sizes
The C-value paradox highlights the lack of correlation between the genome size (C-value) of an organism and its perceived complexity
During DNA replication, the enzyme responsible for synthesizing short RNA primers is:
a) DNA polymerase III
b) DNA ligase
c) Helicase
d) Primase
d) Primase
Primase (dnaG) is an RNA polymerase that synthesizes short RNA primers, providing the 3’-OH group necessary for DNA polymerase to initiate DNA synthesis
Which of the following is a key function of single-strand binding (SSB) proteins during DNA replication?
a) To unwind the DNA double helix at the replication fork.
b) To catalyse the formation of phosphodiester bonds between Okazaki fragments.
c) To stabilise the separated DNA strands and prevent their reannealing.
d) To add nucleotides to the growing DNA strand in a 5’ to 3’ direction.
c) To stabilize the separated DNA strands and prevent their reannealing
SSB proteins bind to the single-stranded DNA created by helicase, preventing the strands from rejoining and ensuring that they remain available as templates for DNA synthesis
The proofreading activity of DNA polymerase III relies on its:
a) 5’ to 3’ exonuclease activity.
b) Ability to add nucleotides only in the 5’ to 3’ direction.
c) 3’ to 5’ exonuclease activity.
d) Requirement for an RNA primer to initiate synthesis.
c) 3’ to 5’ exonuclease activity
DNA polymerase III possesses a 3’ to 5’ exonuclease activity that allows it to detect and remove incorrectly incorporated nucleotides at the 3’ end of the growing DNA strand, thus ensuring high fidelity of replication
Telomerase, the enzyme responsible for maintaining telomere length, is a:
a) DNA polymerase that synthesises DNA using a DNA template.
b) RNA-dependent DNA polymerase that uses an RNA molecule as a template to synthesise DNA repeats.
c) DNA ligase that joins telomeric DNA repeats.
d) Nuclease that degrades damaged telomeric DNA.
b) RNA-dependent DNA polymerase that uses an RNA molecule as a template to synthesize DNA repeats
Telomerase is a reverse transcriptase, meaning it uses its own RNA component as a template to synthesize the repetitive DNA sequences that constitute telomeres
Which DNA repair mechanism is primarily responsible for correcting errors that occur during DNA replication and escape the proofreading activity of DNA polymerase?
a) Base excision repair
b) Nucleotide excision repair
c) Mismatch repair
d) Direct repair
c) Mismatch repair
Mismatch repair systems recognise and correct base pair mismatches and small insertions or deletions that occur during DNA replication
The direct repair of pyrimidine dimers in DNA, utilising light energy, is carried out by the enzyme:
a) DNA glycosylase
b) AP endonuclease
c) DNA photolyase
d) Excinuclease
c) DNA photolyase
DNA photolyase is an enzyme that can directly reverse the formation of pyrimidine dimers caused by UV radiation by using light energy to break the covalent bonds linking the adjacent pyrimidines
Next Generation Sequencing (NGS) technologies differ significantly from Sanger sequencing primarily due to their ability to:
a) Sequence longer DNA fragments with higher accuracy.
b) Simultaneously sequence millions of DNA fragments.
c) Eliminate the need for PCR amplification.
d) Directly determine the sequence of RNA molecules.
b) Simultaneously sequence millions of DNA fragments
NGS technologies are characterized by massively parallel sequencing, allowing for the simultaneous analysis of millions to billions of DNA fragments, leading to much higher throughput compared to Sanger sequencing
Long-read Next Generation Sequencing technologies are particularly advantageous for:
a) Identifying single nucleotide polymorphisms with high accuracy.
b) Quantifying gene expression levels.
c) Resolving complex genomic rearrangements such as large insertions, deletions, and inversions.
d) Sequencing highly fragmented DNA samples.
c) Resolving complex genomic rearrangements such as large insertions, deletions, and inversions
The long read lengths produced by third-generation sequencing technologies (e.g., PacBio, Nanopore) are crucial for spanning large repetitive regions and identifying complex structural variants in the genome
The use of dideoxynucleotide triphosphates (ddNTPs) is a key component of:
a) Polymerase chain reaction (PCR).
b) Next Generation Sequencing by synthesis.
c) Sanger sequencing
d) Gel electrophoresis for DNA fragment separation.
c) Sanger sequencing
Sanger sequencing relies on the random incorporation of ddNTPs, which lack a 3’-OH group, causing chain termination at various points along the DNA template. These fragments of different lengths are then separated to determine the DNA sequence
Comparative genomics can provide insights into evolutionary relationships by:
a) Measuring the rate of protein synthesis in different species.
b) Analyzing the differences and similarities in the DNA sequences of different organisms.
c) Studying the expression patterns of specific genes across tissues.
d) Determining the three-dimensional structure of conserved proteins.
b) Analyzing the differences and similarities in the DNA sequences of different organisms
By comparing the genomes of different species, scientists can identify conserved sequences that may indicate shared ancestry and functional importance, as well as unique sequences that contribute to species-specific traits. The degree of difference in genomic sequences is generally proportional to the evolutionary distance between species
Genome-Wide Association Studies (GWAS) are a powerful tool for:
a) Identifying the complete genomic sequence of an individual.
b) Determining the function of all genes in a genome.
c) Finding associations between genetic variations and specific traits or diseases in large populations.
d) Correcting disease-causing mutations in living organisms.
c) Finding associations between genetic variations and specific traits or diseases in large populations.
GWAS involve scanning the genomes of many individuals with and without a particular trait or disease to identify genetic variants (typically SNPs) that are statistically associated with the phenotype
According to Mendel’s work with pea plants, which of the following characteristics was relatively easy to observe, making peas a suitable model organism?
a) The ability to produce multiple offspring over a long lifespan
b) Complex cellular structures requiring high-powered microscopy
c) Easily distinguishable traits such as stem height and seed color
d) A very large and complex genome requiring advanced sequencing techniques
c) Easily distinguishable traits such as stem height and seed color
Mendel chose peas because they had relatively easy to observe characteristics such as stem height, seed color, seed shape, pod color, pod shape, flower color, and flower position
What term describes individuals who have two identical alleles for a particular gene?
a) Heterozygous
b) Homozygous
c) Hemizygous
d) Phenotypic
b) Homozygous
True-breeding individuals, in Mendelian genetics, are described as homozygous, meaning they have two identical alleles for a trait
In a dihybrid cross involving two independently assorting genes, if both parents have the genotype TtPp, what is the expected phenotypic ratio of their offspring?
a) 1:1:1:1
b) 3:1
c) 9:3:3:1
d) 1:2:1
c) 9:3:3:1
A dihybrid cross of two heterozygous individuals (TtPp x TtPp) for two independently assorting genes is expected to yield a 9:3:3:1 phenotypic ratio in the F2 generation
Which of the following genetic disorders is an example of an autosomal dominant inheritance pattern?
a) Albinism
b) Cystic fibrosis
c) Huntington’s disease
d) Sickle cell anaemia
c) Huntington’s disease
Huntington’s disease is listed as an example of a disorder caused by autosomal dominant inheritance. Albinism and cystic fibrosis are autosomal recessive, and sickle cell anaemia, while having complex inheritance aspects, is often considered autosomal recessive in its classic presentation
If an individual has attached earlobes, which is a recessive trait, what is their genotype?
a) EE
b) Ee
c) ee
d) Cannot be determined from the information given
c) ee
The gene for attached earlobes is recessive, and if you have attached earlobes, your genotype is ee
What term describes a family tree that indicates the presence or absence of a trait for each member across generations, used to reveal patterns of inheritance?
a) Punnett square
b) Linkage map
c) Pedigree
d) Karyotype
c) Pedigree
A pedigree is defined as a family tree indicating the presence or absence of a trait for each member of each generation, used to reveal patterns of inheritance
Incomplete dominance is illustrated by the pitch of human male voices, where intermediate range baritones are heterozygous. What does this indicate about the alleles involved?
a) One allele completely masks the other.
b) Both alleles are equally and fully expressed.
c) The heterozygous phenotype is a blend of the two homozygous phenotypes.
d) Multiple genes contribute to the phenotype.
c) The heterozygous phenotype is a blend of the two homozygous phenotypes.
The example of human male voice pitch illustrates intermediate expression, where the heterozygous individuals (baritones) show a phenotype between the two homozygous extremes
Blood type O is caused by the IO allele, which results in no extra sugar residue on the H-antigen. If a homozygous Type B individual (IBIB) has a child with a heterozygous Type A individual (IAIO), what are the possible blood types of their offspring?
a) Type A only
b) Type B only
c) Type AB and Type A
d) Type AB and Type B
d) Type AB and Type B
A Punnett square for IBIB x IAIO shows possible genotypes IAIB and IBIO, resulting in blood types AB and B, respectively
Familial diabetes and obesity are given as examples of traits with less than 100% penetrance. What does this mean?
a) Individuals with the genotype for these traits will always exhibit the phenotype but to varying degrees.
b) Only a certain percentage of individuals with the genotype for these traits will actually develop the condition.
c) These conditions are caused by multiple genes and environmental factors.
d) The dominant allele for these traits is not very common in the population.
b) Only a certain percentage of individuals with the genotype for these traits will actually develop the condition.
Penetrance is the percentage of individuals with a certain genotype who show the expected phenotype. A penetrance of less than 100% means that some individuals with the genotype will not exhibit the trait
What is the term for a single gene being responsible for a variety of seemingly unrelated traits, as seen in albinism affecting pigmentation and vision?
a) Polygenic inheritance
b) Pleiotropy
c) Epistasis
d) Linkage
b) Pleiotropy
Pleiotropy is defined as a single gene being responsible for a variety of traits, and albinism, affecting skin, hair, eye pigmentation, and vision.
Who observed that chromosomes and genes both occur in pairs in diploid cells and that homologous chromosomes separate during meiosis?
a) Gregor Mendel
b) Walter Fleming
c) Walter Sutton
d) Thomas Hunt Morgan
c) Walter Sutton
Walter Sutton, in 1902, observed the parallels between the behavior of chromosomes during meiosis and Mendel’s laws of inheritance, concluding that Mendelian factors (genes) are located on chromosomes
In humans, which parent determines the sex of the offspring?
a) Mother only, as she always contributes an X chromosome.
b) Father only, as he can contribute either an X or a Y chromosome.
c) Both parents equally contribute to the sex of the offspring.
d) It depends on which X chromosome is inactivated.
b) Father only, as he can contribute either an X or a Y chromosome.
The sex of an individual is determined by the sex chromosomes. Females have XX and males have XY. Therefore, the father’s contribution of either an X or a Y chromosome determines the sex of the offspring
Haemophilia is an X-linked recessive disorder. If a carrier female has children with an unaffected male, what is the probability that their sons will have haemophilia?
a) 0%
b) 25%
c) 50%
d) 100%
c) 50%
A carrier female has one normal X chromosome and one X chromosome with the recessive haemophilia allele. Her sons will inherit either the normal X (unaffected) or the affected X (haemophilia), each with a 50% probability
What is a Barr body?
a) A highly condensed region of autosomal chromosomes.
b) An inactive X chromosome found in the nucleus of interphase cells in females.
c) A structure formed during crossing over in meiosis.
d) A region of the Y chromosome responsible for male sex determination.
b) An inactive X chromosome found in the nucleus of interphase cells in females.
A Barr body is the highly condensed, inactive X chromosome in the somatic cells of females, resulting from X inactivation
Genetic distance between two linked genes is expressed in what unit?
a) Base pairs
b) Genes per chromosome
c) Map units
d) Chromosomes per genome
c) Map units
Genetic distance between two genes is expressed in map units, which are equivalent to the percentage of recombination frequency
Down syndrome is most commonly caused by which type of chromosomal abnormality?
a) Monosomy
b) Trisomy
c) Deletion
d) Translocation
b) Trisomy
Down syndrome (trisomy 21) is caused by an extra copy of chromosome 21
Cri du chat syndrome is associated with which type of chromosomal abnormality?
a) Trisomy of chromosome 18
b) Deletion of part of chromosome 5
c) Translocation between chromosome 9 and 22
d) Monosomy of the X chromosome
b) Deletion of part of chromosome 5
Cri du chat syndrome is caused by a deletion of a segment of chromosome 5
Which of the following is a characteristic of Klinefelter syndrome in males?
a) 45, X karyotype
b) Increased fertility
c) Low testosterone levels
d) Below average height
c) Low testosterone levels
Klinefelter syndrome (XXY) in males is often associated with low testosterone levels
What is the term for an individual with two or more genetically different cell lines derived from a single zygote?
a) Chimera
b) Mosaic
c) Hybrid
d) Clone
b) Mosaic
A mosaic organism has two or more genetically different cell lines that originated from a single zygote
Amniocentesis is a prenatal genetic testing procedure that involves obtaining a sample of:
a) Maternal blood
b) Chorionic villi
c) Amniotic fluid
d) Fetal cells sorted from maternal circulation
c) Amniotic fluid
Amniocentesis involves extracting a small sample of amniotic fluid surrounding the fetus, which contains fetal cells for genetic analysis
The study of normal and abnormal chromosomes is known as:
a) Molecular biology
b) Genomics
c) Cytogenetics
d) Proteomics
c) Cytogenetics
Cytogenetics is the branch of genetics that deals with the study of chromosomes, their structure, function, and abnormalities
G banding is a cytogenetic technique that involves staining chromosomes with Giemsa stain. Which regions of DNA does this stain preferentially bind to?
a) Regions rich in GC base pairs
b) Regions rich in AT base pairs
c) Centromeric regions
d) Telomeric regions
b) Regions rich in AT base pairs
G banding uses Giemsa stain to stain areas of DNA that are rich in AT base pairs
Fluorescence in situ hybridization (FISH) uses DNA probes to:
a) Amplify specific DNA sequences.
b) Cut DNA at specific restriction sites.
c) Hybridize to complementary DNA or RNA sequences, allowing visualization.
d) Methylate specific regions of the genome.
c) Hybridize to complementary DNA or RNA sequences, allowing visualization.
FISH involves using fluorescently labeled DNA probes that hybridize to specific complementary sequences on chromosomes, allowing their presence and location to be visualized
Which of the following is a key goal of the Human Genome Project?
a) To develop gene therapies for all known genetic diseases
b) To identify all proteins encoded by the human genome
c) To determine the complete nucleotide sequence of the human genome
d) To understand the function of every gene in the human genome
c) To determine the complete nucleotide sequence of the human genome
A primary goal of the Human Genome Project was to determine the sequences of the 3 billion base pairs that make up human DNA
Next-generation sequencing (NGS) technologies are characterized by:
a) Low throughput and long read lengths.
b) High throughput and massively parallel sequencing.
c) Sequencing of single DNA molecules.
d) Dependence on dideoxy chain termination.
b) High throughput and massively parallel sequencing.
Next Generation Sequencing (NGS) is based on the massive parallel sequencing method, allowing millions of DNA templates to be sequenced in one reaction
The exponential growth in next generation sequence archives since 1990 is partly attributed to a significant decrease in the price to sequence a base, which fell over how many times from 1990 to 2010?
a) 10 times
b) 50 times
c) 100 times
d) 1000 times
c) 100 times
The price to sequence a base has fallen over 100 times from 1990 to 2010
The detection of cancer can be linked to mutations in which specific gene, with a deletion of approximately 2000 bases leading to a 90% predisposition to cancer?
a) BRCA1
b) TP53
c) RAS
d) APC
b) TP53
The detection of cancer is attributed to mutation in the TP53 gene, and a deletion of ~2000 bases in this gene results in a 90% predisposition to cancer
The analysis of mutations in viruses, facilitated by genomic sequencing, has allowed us to observe how a virus affects its hosts. This was particularly important in understanding which recent global health event?
a) The Spanish Flu pandemic
b) The HIV/AIDS epidemic
c) The COVID-19 pandemic
d) The Ebola outbreak
c) The COVID-19 pandemic
The analysis of mutations allowed the detection of viral variants and helped understand how the virus affects its hosts, citing COVID-19 as an example where this analysis was crucial
Gregor Mendel’s work on inheritance initially focused on which organism due to its relatively easy-to-observe characteristics?
a) Fruit flies
b) Mice
c) Peas
d) Yeast
c) Peas
Because their characteristics were relatively easy to observe
Mendel’s experiments involved mating true-breeding flowers, which exhibit only one phenotype for a particular trait. What genetic term describes individuals with two identical alleles for a trait?
a) Heterozygous
b) Homozygous
c) Hemizygous
d) Polygenic
b) Homozygous
True-breeding individuals are defined as homozygous, meaning they have both alleles for a trait as the same
In autosomal dominant inheritance, how many copies of the dominant allele are required for an individual to express the trait?
a) Zero
b) One
c) Two
d) It depends on the specific gene
b) One
Autosomal dominant inheritance occurs when one autosomal allele masks the expression of the other allele, meaning inheriting just one copy of the dominant allele will cause the disorder
Punnett squares are described in the source as standard tools used by which professionals to help determine the risk for genetically inherited diseases?
a) Microbiologists
b) Genetic counselors
c) Epidemiologists
d) Biotechnologists
b) Genetic counselors
Punnett squares are mentioned as standard tools used by genetic counselors
Which term describes the mating between two individuals who are closely related, increasing the chance of their offspring inheriting two copies of the same rare allele?
a) Outcrossing
b) Hybridization
c) Consanguinous matings
d) Test cross
c) Consanguinous matings
Consanguinous matings as increasing the chance of mating between two carriers of the same rare allele
Human stature, skin colour, hair colour, and eye colour are given as examples of traits that are typically determined by the combined effect of more than one pair of genes. What is this pattern of inheritance called?
a) Incomplete dominance
b) Codominance
c) Polygenic inheritance
d) Sex-linked inheritance
c) Polygenic inheritance
Polygenic inheritance is determined by the combined effect of more than one pair of genes and provides the listed traits as examples
In codominance, as exemplified by human blood types, how many alleles are expressed in heterozygous individuals?
a) Only one allele
b) Both alleles
c) Neither allele
d) A blended version of both alleles
b) Both alleles
Codominance is defined as when two alleles are expressed in heterozygous individuals
What term describes the phenomenon where a genotype is present in an individual, but the expected phenotype is absent?
a) Expressivity
b) Incomplete dominance
c) Penetrance less than 100%
d) Pleiotropy
c) Penetrance less than 100%
Penetrance and states that some traits have a penetrance of <100%, meaning the genotype is present, but the phenotype is absent
A single gene being responsible for a variety of traits, such as in albinism which affects pigmentation and vision, is known as:
a) Epistasis
b) Pleiotropy
c) Polygeny
d) Linkage
b) Pleiotropy
Pleiotropy is defined as when a single gene may be responsible for a variety of traits, and albinism is given as an example
In many animals, including humans and fruit flies, females typically have which combination of sex chromosomes?
a) XY
b) XX
c) X0
d) YY
b) XX
In humans and fruit flies, females have two X chromosomes
Haemophilia, colourblindness, and Duchenne muscular dystrophy are listed as examples of traits that follow which pattern of inheritance?
a) Autosomal dominant
b) Autosomal recessive
c) X-linked recessive
d) Y-linked
c) X-linked recessive
The X chromosome contains genes for these conditions and classifies them as X-linked recessive
What is the term for the organized profile of a person’s chromosomes, used to identify genetic causes of diseases or disorders?
a) Genotype
b) Phenotype
c) Karyotype
d) Pedigree
c) Karyotype
A karyotype is an organized profile of a person’s chromosomes that can help identify the genetic cause of a disease/disorder
Down syndrome is cited as an example of which type of chromosomal abnormality, involving an extra copy of a chromosome?
a) Monosomy
b) Trisomy
c) Deletion
d) Translocation
b) Trisomy
Turner syndrome in females is typically associated with which karyotype?
a) 45, XX
b) 45, XY
c) 45, X
d) 45, XXX
c) 45, X
The genotype for Turner syndrome is X0, which corresponds to a karyotype with 45 chromosomes (44 autosomes + one X chromosome)
Klinefelter syndrome in males is associated with which genotype?
a) XY
b) XX
c) XYY
d) XXY
d) XXY
The table of sex chromosome abnormalities lists XXY as the male genotype for Klinefelter syndrome
What term describes individuals who have two or more genetically different cell lines derived from a single zygote, resulting from a change such as a gene mutation or a chromosomal abnormality after fertilisation?
a) Chimeras
b) Mosaics
c) Hybrids
d) Mutants
b) Mosaics
Mosaics having two or more genetically different cell lines derived from a single zygote, with the change occurring after fertilization
Fluorescence in situ hybridization (FISH) is a molecular cytogenetic technique that uses what type of probes to visualize specific regions of the genome?
a) Antibody-based probes
b) Radioactive probes
c) Fluorescently labeled DNA probes
d) Enzyme-linked probes
c) Fluorescently labeled DNA probes
FISH involves the use of DNA probes labeled with different colored fluorescent tags
What is the basic repeating unit of chromatin, consisting of a segment of DNA wound around a histone protein core?
a) Solenoid
b) Chromatosome
c) Nucleosome
d) Scaffold protein
c) Nucleosome
DNA wrapped around a histone core as being protected from nuclease, implying this structure is a fundamental unit
Which of the following nitrogenous bases is a pyrimidine found in DNA?
a) Adenine
b) Guanine
c) Thymine
d) Uracil
c) Thymine
Thymine is listed under the pyrimidines and specifically mentioned as being found in DNA
What type of bond links the 5’ phosphate group of one nucleotide to the 3’ hydroxyl group of the next, forming the sugar-phosphate backbone of DNA?
a) Hydrogen bond
b) Glycosidic bond
c) Peptide bond
d) Phosphodiester bond
d) Phosphodiester bond
The description of nucleotide linkage in DNA implies the formation of a phosphodiester bond
The semi-conservative model of DNA replication, supported by the Messelsohn-Stahl experiment, results in each new DNA molecule consisting of:
a) Two newly synthesized strands
b) Two parental strands
c) One parental strand and one newly synthesized strand
d) A mixture of parental and new segments on both strands
c) One parental strand and one newly synthesized strand
Semi-conservative replication as the separation of two complementary strands, with each individual strand acting as a parent template to create a new daughter strand
In prokaryotic DNA replication, which enzyme is responsible for unwinding the double-stranded DNA at the origin of replication?
a) DNA polymerase I
b) DNA ligase
c) Helicase
d) Primase
c) Helicase
Helicase is described as the enzyme that unwinds double-stranded DNA at the origin, ahead of the replication fork
