Cell Biology MCQs | BIO201 MCQs | Set 5
Cell Biology MCQs | BIO201 MCQs | Set 5
MCQs (Multiple Choice Questions)
1) To carry out translational-level control, miRNAs bind to _______ of their target mRNAs.
a) intergenic sites
b) 5'
c) exonuclease sites
d) 3'
Correct Answer:
The correct answer is 'd'.
Explanation:
MiRNAs typically bind to the 3' untranslated region (3' UTR) of their target mRNAs to regulate gene expression at the translational level by either inhibiting translation or promoting mRNA degradation.
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2) Some bacteria and birds orient themselves to Earth's magnetic poles due to ______
a) All given
b) Force of gravity
c) Magnetism
d) Gravitational force
Correct Answer:
The correct answer is 'c'.
Explanation:
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3) ______ can be used to stain DNA for visualization under UV light in gel electrophoresis.
b) Ethidium bromide
d) Crystal violet
Correct Answer:
The correct answer is 'b'.
Explanation:
Ethidium bromide is commonly used to stain DNA for visualization in gel electrophoresis because it binds to DNA molecules by intercalating between the base pairs of the DNA double helix. When exposed to ultraviolet (UV) light, ethidium bromide-bound DNA fluoresces and emits a visible orange-red light. This fluorescence makes it possible to see the DNA bands in the gel, allowing scientists to visualize and analyze the results of electrophoresis experiments. Ethidium bromide is widely used for this purpose in molecular biology and genetics laboratories.
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a) regulation
b) mutation
c) lactose-effect
d) glucose-effect
Correct Answer:
The correct answer is 'd'.
Explanation:
In the presence of glucose, the lac operon is typically under positive control, meaning that transcription of the lac genes is enhanced in the presence of lactose when glucose is absent. This is known as catabolite repression and is often referred to as the "glucose effect." When glucose is available, it can repress the transcription of the lac operon, even in the presence of lactose, because glucose is a more favorable energy source for the cell.
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5) AGGAGG is named
a) Beadle-Tatum sequence
b) Watson-Crick sequence
c) Shine-Dalgarno sequence
d) Hershey-Chase sequence
Correct Answer:
The correct answer is 'c'.
Explanation:
The AGGAGG sequence is most commonly associated with the Shine-Dalgarno sequence, which is a sequence of nucleotides in prokaryotic mRNA that is complementary to a sequence of nucleotides in the 16S ribosomal RNA. The Shine-Dalgarno sequence helps to position the ribosome on the mRNA so that translation can begin.
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6) Some complex moves into the nucleus, it associates with other gene ____ proteins.
a) Regulatory
b) Activated
c) Inhibitory
d) Binding
Correct Answer:
The correct answer is 'a'.
Explanation:
Regulatory proteins are often involved in controlling gene expression by interacting with other proteins and elements within the nucleus. They can activate or inhibit gene expression, depending on the specific regulatory mechanisms.
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7) _________ are removed during RNA maturation.
a) Promoter region only
b) Introns
c) Exons
d) Intron-Exon boundries
Correct Answer:
The correct answer is 'b'.
Explanation:
Introns are non-coding regions in a pre-mRNA molecule that are transcribed from the DNA but are not included in the final mature mRNA. Instead, they are removed during a process called RNA splicing as part of RNA maturation. This process leaves only the exons (coding regions) to be included in the mature mRNA, which will be translated into proteins. The removal of introns is a crucial step in generating a functional and accurate mRNA for protein synthesis.
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8) How is the genetic material expressed?
a) By replication and transcription
b) By mutation and transposition
c) By transcription and
translation
d) By translation and
modification
Correct Answer:
The correct answer is 'c'.
Explanation:
The process of gene expression involves the transcription of DNA into RNA, followed by the translation of RNA into proteins. This sequence of events is how genetic information is ultimately used to produce functional proteins in an organism.
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9) Frame shift mutation is a :
a) Deletion of nucleotide in a DNA sequence
b) Insertion of nucleotide in a DNA sequence
c) Reading frame of nucleotide in a DNA changed
d) Substitution among nucleotide
Correct Answer:
The correct answer is 'c'.
Explanation:
Frame shift mutations occur when the reading frame of the nucleotides in a DNA sequence is altered due to the insertion or deletion of nucleotides. This can result in a significant change in the resulting protein's amino acid sequence and is a type of mutation that can have a significant impact on the gene's function.
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10) Primer is a short ______sequence of nucleotides.
a) Parallel strand
b) Double strand
c) Single strand
d) Anti-parallel strand
Correct Answer:
The correct answer is 'c'.
Explanation:
A primer is a short, single-stranded sequence of nucleotides because it serves as a starting point for DNA replication. It provides a free 3' end that DNA polymerase can attach to and begin synthesizing the complementary strand of DNA. In DNA replication, only one strand, called the leading strand, is synthesized continuously, while the other strand, the lagging strand, is synthesized in short, discontinuous segments called Okazaki fragments. Primers are necessary for the initiation of both the leading and lagging strand synthesis. Being single-stranded, the primer can bind to the template strand and provide the necessary free 3' end for DNA polymerase to add new nucleotides and extend the DNA strand.
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