INTRODUCTION TO GENETIC DISORDERS AND MUTATIONS MCQs | MCQ Quiz | OmpathStudy Kenya

Question 1

What is the lifetime frequency of genetic disease per 1000 individuals?

Accepted Answer

670 — The lifetime frequency of genetic disease is thought to be 670 per 1000 individuals, which is higher than widely appreciated, meaning approximately 67% of people will develop some genetic-related condition.

Question 2

Approximately how many genes do human beings have?

Accepted Answer

30,000 — Human beings have approximately 30,000 genes, though less than 2% of these actually code for proteins, with more than half being repetitive nucleotide sequences.

Question 3

What percentage of human DNA codes for proteins?

Accepted Answer

Less than 2% — Less than 2% of human DNA codes for proteins. More than half of the genome consists of repetitive nucleotide sequences of mysterious function.

Question 4

What percentage of DNA sequence do individuals share with each other?

Accepted Answer

99.9% — Individuals share 99.9% of their DNA sequence with each other, with only 0.1% (about 3 million base pairs) accounting for the diversity in the human race.

Question 5

Approximately what percentage of early pregnancy miscarriages have demonstrable chromosomal abnormalities?

Accepted Answer

50% — Approximately 50% of early pregnancy miscarriages have demonstrable chromosomal abnormalities, highlighting the significant impact of genetic disorders on early development.

Question 6

What is a point mutation?

Accepted Answer

Substitution of a single nucleotide base by a different base — A point mutation is the substitution of a single nucleotide base by a different base, resulting in substitution of an amino acid within a protein, such as in sickle cell anemia.

Question 7

What type of mutation is exemplified by sickle cell anemia?

Accepted Answer

Point mutation — Sickle cell anemia is caused by a point mutation where a single nucleotide substitution leads to the replacement of glutamic acid with valine in the β-globin chain.

Question 8

What is a frameshift mutation?

Accepted Answer

Insertion or deletion of one or two base pairs altering the reading frame — A frameshift mutation involves insertion or deletion of one or two base pairs that alters the reading frame of the DNA strand, changing all subsequent amino acids in the protein.

Question 9

What type of mutation involves dynamic amplification of a sequence of three nucleotides?

Accepted Answer

Trinucleotide repeat mutation — Trinucleotide repeat mutations involve dynamic amplification of a sequence of three nucleotides (often guanine and cytosine), with the degree of amplification increasing at gametogenesis.

Question 10

Which disorder is an example of trinucleotide repeat mutation?

Accepted Answer

Fragile X syndrome — Fragile X syndrome is the classic example of a trinucleotide repeat mutation, involving expansion of CGG repeats in the FMR1 gene.

Question 11

What are the three major categories of genetic disorders?

Accepted Answer

Mutant genes, multifactorial inheritance, chromosomal aberrations — The three major categories of genetic disorders are: diseases related to mutant genes of large effect, diseases with multifactorial (polygenic) inheritance, and diseases arising from chromosomal aberrations.

Question 12

Which type of mutation affects germ cells?

Accepted Answer

Mutations transmitted to progeny causing inherited diseases — Mutations affecting germ cells are transmitted to progeny and cause inherited diseases, unlike somatic mutations which are not transmitted to offspring.

Question 13

What do somatic cell mutations typically cause?

Accepted Answer

Cancers and some congenital malformations — Mutations affecting somatic cells are not transmitted to progeny but can cause cancers and some congenital malformations in the affected individual.

Question 14

What is functional cloning (classic approach) in molecular genetics?

Accepted Answer

Starting with known affected protein to isolate and clone normal gene — Functional cloning starts with a known affected protein (clinical phenotype), then isolates and clones the normal gene, and determines molecular changes affecting the gene.

Question 15

What is positional cloning (candidate gene approach)?

Accepted Answer

Mapping disease phenotype to chromosome location and cloning DNA from region — Positional cloning involves mapping a disease phenotype to a particular chromosome location, cloning several DNA pieces from the region in vitro, and identifying aberrant proteins from mutated genes.

Question 16

Which of the following is produced using recombinant DNA technology by inserting genes into bacteria?

Accepted Answer

Growth hormone and erythropoietin — Human biologically active agents like soluble TNF receptor, tissue plasminogen activator, growth hormone, and erythropoietin are produced by inserting requisite genes into bacteria or suitable cells in tissue culture.

Question 17

What is gene therapy?

Accepted Answer

Treating genetic diseases by transfer of somatic cells transfected with normal genes — Gene therapy involves treating genetic diseases by transferring somatic cells that have been transfected with normal genes, though questions remain about whether benefits outweigh risks.

Question 18

What is a missense mutation?

Accepted Answer

Point mutation resulting in amino acid substitution — A missense mutation is a type of point mutation where nucleotide substitution results in a different amino acid being incorporated into the protein, potentially affecting protein function.

Question 19

What is a nonsense mutation?

Accepted Answer

Point mutation creating premature stop codon — A nonsense mutation is a point mutation that creates a premature stop codon, leading to truncated protein production and usually loss of protein function.

Question 20

Which diseases are now considered to have genetic components beyond "classic" genetic disorders?

Accepted Answer

Cardiovascular diseases, immunity disorders, cancers — Beyond classic genetic disorders, cardiovascular diseases, disorders of immunity, and cancers are now recognized to have significant genetic components.

Question 21

What characterizes diseases with multifactorial (polygenic) inheritance?

Accepted Answer

Multiple genes plus environmental factors — Diseases with multifactorial or polygenic inheritance result from the interaction of multiple genes along with environmental factors, rather than a single gene defect.

Question 22

What is the key characteristic of trinucleotide repeat mutations?

Accepted Answer

They are dynamic with amplification increasing at gametogenesis — Trinucleotide repeat mutations are dynamic, meaning the degree of amplification increases during gametogenesis, which can lead to anticipation (worsening severity in successive generations).

Question 23

What is genomic imprinting?

Accepted Answer

Epigenetic influences where gene expression depends on parent of origin — Genomic imprinting is an epigenetic phenomenon where the expression of certain genes depends on whether they were inherited from the mother or father, affecting disease transmission.

Question 24

Which category of genetic disorders involves mitochondrial DNA mutations?

Accepted Answer

Other category beyond three major types — Diseases resulting from mutations in mitochondrial DNA constitute a separate category beyond the three major categories, with unique maternal inheritance patterns.

Question 25

How can molecular probes be used in disease diagnosis?

Accepted Answer

For both genetic and nongenetic (e.g., infectious) diseases — Molecular probes can be used in diagnosis of both genetic diseases and nongenetic diseases such as infectious diseases, making them versatile diagnostic tools.

Question 26

What is a permanent change in DNA called?

Accepted Answer

Mutation — Mutations are permanent changes in the DNA sequence that can be transmitted to progeny (if in germ cells) or cause disease in the individual (if in somatic cells).

Question 27

What percentage of DNA is responsible for human diversity?

Accepted Answer

0.1% — Only 0.1% of DNA (approximately 3 million base pairs) accounts for diversity in the human race, while individuals share 99.9% of their DNA sequence.

Question 28

Which nucleotides are typically involved in trinucleotide repeat mutations?

Accepted Answer

Guanine and cytosine — Trinucleotide repeat mutations typically involve sequences containing guanine and cytosine nucleotides, such as CGG repeats in Fragile X syndrome.

Question 29

What application of genetics involves producing tissue plasminogen activator?

Accepted Answer

Production of human biologically active agents — Tissue plasminogen activator is a human biologically active agent produced using recombinant DNA technology by inserting genes into bacteria or tissue culture cells.

Question 30

What is the extremity range of genetic disorders?

Accepted Answer

Varies from mild/hidden to severe/lethal — The extremity of genetic disorders varies widely - some may be mild or remain hidden, while others cause early miscarriage or serious disease in young individuals.

Question 31

What is the main difference between functional and positional cloning?

Accepted Answer

Functional starts with protein; positional starts with chromosome location — Functional (classic) cloning starts with a known affected protein and works toward the gene, while positional (candidate gene) cloning starts by mapping disease to a chromosome location and works toward the protein.

Question 32

What proportion of human genes consists of repetitive nucleotide sequences?

Accepted Answer

More than 50% — More than half ( 50%) of human genes consist of repetitive nucleotide sequences of mysterious function, with less than 2% actually coding for proteins.

Question 33

What raises the question "Do the benefits outweigh the risks?" in medical genetics?

Accepted Answer

Gene therapy — Gene therapy raises important ethical and safety questions about whether the benefits of treating genetic diseases by transferring normal genes outweigh the potential risks.

Question 34

What happens in a frameshift mutation involving deletion of two base pairs?

Accepted Answer

Reading frame altered affecting all downstream amino acids — Deletion of two base pairs in a frameshift mutation alters the reading frame, changing the coding of all amino acids downstream from the mutation site, usually severely affecting protein function.

Question 35

Which genetic disorder category includes diseases like Down syndrome?

Accepted Answer

Chromosomal aberrations — Down syndrome (trisomy 21) is a disease arising from chromosomal aberrations, specifically having an extra copy of chromosome 21.

Question 36

What is the significance of unknown genetic disorders being mild or hidden?

Accepted Answer

True burden of genetic disease may be underestimated — The fact that an unknown number of genetic disorders may be mild or remain hidden suggests that the true burden of genetic disease is likely higher than currently recognized.

Question 37

What type of cells must be affected for a mutation to be inherited?

Accepted Answer

Germ cells — Only mutations affecting germ cells (sperm or egg cells) can be transmitted to progeny and cause inherited diseases. Somatic cell mutations affect only the individual.

Question 38

Which application of genetics helps in understanding the molecular basis of human disease?

Accepted Answer

Functional and positional cloning approaches — Both functional cloning and positional cloning approaches help understand the molecular basis of human disease by identifying genes and proteins involved in disease processes.

Question 39

What is the clinical implication of 50% of early miscarriages having chromosomal abnormalities?

Accepted Answer

Chromosomal abnormalities are major cause of pregnancy loss — The fact that approximately 50% of early pregnancy miscarriages have demonstrable chromosomal abnormalities indicates that chromosomal abnormalities are a major cause of early pregnancy loss and many are incompatible with continued development.

INTRODUCTION TO GENETIC DISORDERS AND MUTATIONS MCQs | MCQ Quiz | OmpathStudy Kenya

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