Free ASCP Technologist in Molecular Biology Questions and Answers 1 — Questions and Answers
Question 1: Which of the following would best identify the presence of metabolites in bodily fluids? Mitochondrial abnormalities can be identified by the presence of metabolites in the bloodstream, urine, or cerebral spinal fluid.
- Western-blot
- Mass spectrometry (Correct answer)
- PCR
- In-situ hybridization
Correct answer: Mass spectrometry
Mass spectrometry is a powerful analytical technique used to identify and quantify metabolites in complex biological samples such as blood, urine, or cerebrospinal fluid. For mitochondrial abnormalities, which often involve defects in metabolic pathways, mass spectrometry can detect abnormal levels or patterns of specific metabolites. Its high sensitivity and specificity make it an ideal tool for diagnosing metabolic disorders.
Question 2: Which technique can assist in identifying a poisonous drug present in a person's bloodstream?
- Agarose gel electrophoresis
- PCR
- Mass spectrometry (Correct answer)
- Western blotting
Correct answer: Mass spectrometry
Mass spectrometry is a highly sensitive and specific analytical technique widely employed in toxicology for identifying and quantifying drugs and their metabolites in biological samples, such as blood. It works by ionizing molecules and separating them based on their mass-to-charge ratio, creating a unique 'fingerprint' that allows for the precise identification of unknown substances, including poisonous drugs, in a person's bloodstream.
Question 3: A collection of cells absorbs DNA that is floating freely in their surroundings. Here's an illustration of:
- Transduction
- Horizontal gene transfer (Correct answer)
- Conjugation
- Vertical gene transfer
Correct answer: Horizontal gene transfer
Horizontal gene transfer (HGT) is the process by which genetic material is transferred between unrelated organisms, rather than from parent to offspring (vertical gene transfer). The absorption of free DNA from the surroundings by a cell is a specific type of HGT known as transformation. This mechanism allows bacteria to acquire new genetic traits, such as antibiotic resistance, from their environment.
Question 4: What kind of horizontal gene transfer is the foundation for the process known as electroporation, which enables cells to absorb large molecules like DNA?
- Transformation (Correct answer)
- Conjugation
- Transduction
- Binary fission
Correct answer: Transformation
Electroporation is a laboratory technique that uses an electrical pulse to create temporary pores in cell membranes, allowing large molecules like DNA to enter the cell. This process is a form of artificial transformation, which is a type of horizontal gene transfer where a cell takes up naked DNA from its environment. Therefore, electroporation fundamentally relies on the principle of transformation to introduce foreign DNA into cells.
Question 5: What kind of sequencing of DNA use dideoxynucleotides as sequence terminators?
- High Throughput (HTS) sequencing
- All of these
- Ion Torrent Sequencing
- Sanger sequencing (Correct answer)
Correct answer: Sanger sequencing
Sanger sequencing, also known as chain-termination sequencing, utilizes dideoxynucleotides (ddNTPs) as chain terminators. These ddNTPs lack a 3'-hydroxyl group, preventing the addition of further nucleotides once incorporated into a growing DNA strand. This causes termination of DNA synthesis at specific bases, allowing for the determination of the DNA sequence by separating fragments of different lengths.
Question 6: Because of Meselson and Stahl's research, it is acknowledged that DNA replicates by:
- Conservative replication
- Dispersive replication
- All of these
- Semi-conservative replication (Correct answer)
Correct answer: Semi-conservative replication
Meselson and Stahl's classic experiment definitively demonstrated that DNA replicates through a semi-conservative mechanism. They showed that each new DNA molecule consists of one original (parental) strand and one newly synthesized strand. This model ensures that genetic information is accurately copied and passed on to daughter cells during cell division.
Question 7: Which kind of domination is exemplified by the blood type of humans?
- Sex-linked dominance
- Incomplete dominance
- Complete dominance
- Codominance (Correct answer)
Correct answer: Codominance
Human ABO blood types are a classic example of codominance. In individuals with the AB blood type, both the A and B alleles are fully and equally expressed, resulting in the presence of both A and B antigens on the surface of red blood cells. Neither allele masks the other, which is the defining characteristic of codominance.
Question 8: A eukaryotic cell lacks spliceosomes by nature. The gene products that resulted would probably:
- Undergo alternative splicing
- Have an abundance of introns (Correct answer)
- Be unaffected by the lack of spliceosomes
- Have an abundance of exons
Correct answer: Have an abundance of introns
In eukaryotic cells, spliceosomes are crucial complexes responsible for RNA splicing, the process of removing non-coding intron sequences from pre-mRNA and ligating the coding exon sequences together. If a eukaryotic cell lacks functional spliceosomes, introns would not be removed from the pre-mRNA. This would result in mature mRNA transcripts that retain an abundance of introns, likely leading to non-functional or altered proteins.
Question 9: Because RNA polymerase was never separated from the gene-mRNA complex, a transcription reaction is unable to be completed. What phase of transcription is this error most likely to have happened in?
- Termination (Correct answer)
- Initiation
- Promotor region blinding
- Elongation
Correct answer: Termination
Transcription involves three main stages: initiation, elongation, and termination. If RNA polymerase is unable to separate from the gene-mRNA complex, it signifies a failure in the process of ending transcription and releasing the newly synthesized RNA strand. This specific error points directly to a problem occurring during the termination phase of transcription.
Question 10: Which of the following best describes a mutation involving base substitution? AGTCGA is the initial DNA sequence.
- ATCGA
- AGTAGA (Correct answer)
- ATGTCGA
- None of these represent a base substitution mutation.
Correct answer: AGTAGA
A base substitution mutation involves the replacement of one nucleotide base with another within a DNA sequence. The original sequence is AGTCGA. In the option AGTAGA, the 'C' at the fourth position has been replaced by a 'T', while the overall length of the sequence remains unchanged. This is a clear example of a base substitution mutation.
Question 11: Which two polymerizing agents are typically utilized in the casting process of polyacryamide gels?
- TEMED and APS (Correct answer)
- Sodium chloride and TEMED
- DMSO and APS
- Sodium chloride and Ethanol
Correct answer: TEMED and APS
TEMED (N,N,N',N'-tetramethylethylenediamine) and APS (ammonium persulfate) are the essential polymerizing agents for creating polyacrylamide gels. APS generates free radicals, and TEMED acts as a catalyst, accelerating the formation of these radicals. This chemical reaction initiates the polymerization of acrylamide and bis-acrylamide monomers, forming the porous gel matrix required for electrophoretic separation.
Free ASCP Technologist in Molecular Biology Questions and Answers 1
Which of the following would best identify the presence of metabolites in bodily fluids? Mitochondrial abnormalities can be identified by the presence of metabolites in the bloodstream, urine, or cerebral spinal fluid.