Block 9 Micro Dr Schleg Questions Prt 2

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Block 9 Micro Dr Schleg Questions Prt 2 - Quiz

Questions and Answers
  • 1. 

    In the process of transformation

    • A.

      DNA is transferred from one cell to another by a virus

    • B.

      Cells take up DNA from their environment

    • C.

      DNA is transferred between cells via a pilus.

    • D.

      DNA “jumps” from one location in the genome to another

    • E.

      Cells lose part of their DNA and enter a dormant state

    Correct Answer
    B. Cells take up DNA from their environment
    Explanation
    Cells can take up DNA from their environment through a process called transformation. This occurs when cells absorb free-floating DNA molecules from their surroundings. Once the DNA is inside the cell, it can be incorporated into the cell's own genome and potentially alter its genetic makeup. This mechanism is commonly observed in bacteria, where they can acquire new genetic material from their environment, allowing them to adapt and survive in different conditions.

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  • 2. 

    Will a bacterium that receives chromosomal DNA via conjugation from a donor Hfr bacterium likely become capable of passing this DNA on to other bacteria?

    • A.

      Yes, due to transfer of the tra genes

    • B.

      Yes, due to transfer of the oriT element

    • C.

      Yes, due to transfer of the Hfr locus

    • D.

      No, because the tra genes are not transferred.

    • E.

      No, because the mob element is not transferred

    • F.

      No, because the tra genes in the donor are present on a plasmid not on the chromosome.

    Correct Answer
    D. No, because the tra genes are not transferred.
    Explanation
    The tra genes are responsible for the transfer of DNA during conjugation. If the tra genes are not transferred from the donor Hfr bacterium to the recipient bacterium, then the recipient bacterium will not have the ability to pass on the DNA to other bacteria. Therefore, the bacterium that receives chromosomal DNA via conjugation from a donor Hfr bacterium will not likely become capable of passing this DNA on to other bacteria.

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  • 3. 

    In conjugation, F+ cells

    • A.

      Serve as recipient cells

    • B.

      Contain an F plasmid

    • C.

      Do not have conjugation pili.

    • D.

      Can transfer DNA only to other F+ cells

    • E.

      Contain "jumping genes."

    Correct Answer
    B. Contain an F plasmid
    Explanation
    F+ cells are cells that contain an F plasmid. The F plasmid is a circular DNA molecule that can replicate independently from the bacterial chromosome. It carries the genes necessary for conjugation, a process by which genetic material is transferred from one bacterial cell to another. Therefore, F+ cells can transfer DNA to other cells through conjugation because they possess the F plasmid.

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  • 4. 

    At the ends of transposons is a(n)

    • A.

      Complex transposon

    • B.

      Bacteriophage.

    • C.

      Insertion sequence

    • D.

      Inverted repeat

    • E.

      Transposase.

    Correct Answer
    D. Inverted repeat
    Explanation
    An inverted repeat refers to a sequence of nucleotides that is repeated in the opposite orientation. In the context of transposons, inverted repeats are found at the ends of the transposon DNA. These inverted repeats play a crucial role in the transposition process by providing recognition sites for transposase enzymes, which are responsible for cutting and rejoining the DNA during transposition. Therefore, the presence of inverted repeats at the ends of transposons is a characteristic feature of these mobile genetic elements.

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  • 5. 

    How does short interference RNA (siRNA) work?

    • A.

      It binds to and inactivates a target nucleic acid sequence

    • B.

      It binds RNApol and inactivates it.

    • C.

      It binds to a regulatory protein, which in turn inactivates a gene

    • D.

      It creates frameshift mutations that produce nonfunctional versions of proteins

    • E.

      It converts heterochromatin to euchromatin.

    Correct Answer
    A. It binds to and inactivates a target nucleic acid sequence
    Explanation
    Short interference RNA (siRNA) works by binding to and inactivating a specific target nucleic acid sequence. It does not bind RNApol or a regulatory protein, nor does it create frameshift mutations or convert heterochromatin to euchromatin. Instead, siRNA molecules are able to recognize and bind to complementary sequences of mRNA, leading to the degradation of the mRNA and preventing the production of the corresponding protein. This process is known as RNA interference (RNAi) and is a powerful tool used in gene silencing and gene regulation studies.

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  • 6. 

    Binding of an autoinducer peptide to the sensor kinase of a quorum sensing system in a Gram-positive bacterium leads to altered regulation of genetic loci present on different parts of the chromosome and transcribed in different directions. Which of the following would best describe the organization of the genes targeted by this quorum-sensing system?

    • A.

      Divergent operons

    • B.

      Regulon

    • C.

      Contrary operons

    • D.

      Divergent regulation

    • E.

      Indirect regulation

    Correct Answer
    B. Regulon
    Explanation
    The organization of the genes targeted by this quorum-sensing system is best described as a regulon. A regulon is a set of genes or operons that are controlled by a common regulatory protein or mechanism. In this case, the binding of the autoinducer peptide to the sensor kinase leads to altered regulation of genetic loci present on different parts of the chromosome and transcribed in different directions. This suggests that the genes targeted by the quorum-sensing system are organized as a regulon, where they are coordinately regulated by the same signaling pathway.

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  • 7. 

    The SOS response is a DNA repair mechanism that responds to extreme DNA damage

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    The SOS response is a well-known and documented DNA repair mechanism in bacteria. It is activated in response to extreme DNA damage, such as double-strand breaks or extensive UV-induced lesions. The SOS response involves the upregulation of a set of genes that are involved in DNA repair, recombination, and replication. These genes help to repair the damaged DNA and prevent further mutations. Therefore, the statement "The SOS response is a DNA repair mechanism that responds to extreme DNA damage" is true.

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  • 8. 

    Which 3 of the following could be required or produced by an organism using anaerobic respiration?

    • A.

      Organic acids

    • B.

      Cytochromes

    • C.

      Nitrite

    • D.

      Oxygen

    • E.

      Sulfate

    Correct Answer(s)
    B. Cytochromes
    C. Nitrite
    E. Sulfate
    Explanation
    Answer: B., C. and E. Organic acids are produced by fermentative pathways. Anaerobic respiration does not require oxygen as terminal electron acceptor—this function is taken by other molecules not derived from glycolysis (sulfate, nitrate, fumarate, ferric ion, etc). Anarobic respiration DOES require an ETC (hence cytochromes), an electron acceptor such as sulfate, and will produce a reduced form of that acceptor, such as nitrite.

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  • 9. 

    In generalized transduction, viruses carry random DNA sequences from one cell to another

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    Generalized transduction is a type of horizontal gene transfer where viruses, known as bacteriophages, transfer random fragments of DNA from one bacterial cell to another. These random DNA sequences can be incorporated into the recipient cell's genome, leading to genetic variation. Therefore, the statement that in generalized transduction, viruses carry random DNA sequences from one cell to another is true.

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  • 10. 

    A(n) __________ is a specific sequence of nucleotides that codes for a protein or an RNA molecule.

    • A.

      Transposons

    • B.

      Gene

    • C.

      Competent

    • D.

      Missense

    • E.

      Anticodon

    Correct Answer
    B. Gene
    Explanation
    A gene is a specific sequence of nucleotides that codes for a protein or an RNA molecule. Genes contain the instructions for building and functioning of an organism. They determine the characteristics and traits of an individual by encoding the information necessary for the synthesis of proteins or functional RNA molecules. Genes are the basic units of heredity and are passed down from parents to offspring.

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  • 11. 

    If the codon AUG, coding for methionine, were mutated to AAG, coding for lysine, this would be an example of a(n) __________ mutation.

    • A.

      Transposons

    • B.

      Gene

    • C.

      Competent

    • D.

      Missense

    • E.

      Anticodon

    Correct Answer
    D. Missense
    Explanation
    A missense mutation is a type of mutation where a single nucleotide change in the DNA sequence results in a different amino acid being incorporated into the protein. In this case, the mutation of the codon AUG to AAG changes the amino acid from methionine to lysine. Therefore, this is an example of a missense mutation.

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  • 12. 

    The __________ of a transfer RNA molecule is complementary to a codon in a messenger RNA molecule.

    • A.

      Transposons

    • B.

      Gene

    • C.

      Competent

    • D.

      Missense

    • E.

      Anticodon

    Correct Answer
    E. Anticodon
    Explanation
    The anticodon of a transfer RNA molecule is complementary to a codon in a messenger RNA molecule. The anticodon is a sequence of three nucleotides on the tRNA molecule that pairs with the corresponding codon on the mRNA during translation. This complementary base pairing ensures that the correct amino acid is added to the growing polypeptide chain during protein synthesis.

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  • 13. 

    Cells that are able to perform transformation are said to be __________.

    • A.

      Transposons

    • B.

      Gene

    • C.

      Competent

    • D.

      Missense

    • E.

      Anticodon

    Correct Answer
    C. Competent
    Explanation
    Cells that are able to perform transformation are referred to as "competent". This term is used to describe cells that have the ability to take up and incorporate foreign DNA into their own genetic material. Competent cells are commonly used in genetic engineering and molecular biology research to introduce new genes or genetic material into a host organism.

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  • 14. 

    "Jumping genes" that can move from one location to another in an organism's genome are called __________.

    • A.

      Transposons

    • B.

      Gene

    • C.

      Competent

    • D.

      Missense

    • E.

      Anticodon

    Correct Answer
    A. Transposons
    Explanation
    Transposons are "jumping genes" that have the ability to move from one location to another within an organism's genome. These genetic elements can change their position within the genome, leading to genetic rearrangements. They can have important implications for evolution and the regulation of gene expression. Therefore, the correct answer is transposons.

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  • 15. 

    The OmpR response regulator is activated in the presence of high solutes. One of the genes activated by OmpR is micF, whose nucleic acid product binds the ompF message and ends up reducing OmpF protein production, thereby reducing solute uptake. Which of the following terms would best describe micF and the stage at which it regulates OmpF production?

    • A.

      An antiterminator, acts on transcription

    • B.

      A kinase, regulates post-translationally

    • C.

      An antisense RNA, alters translation

    • D.

      An RNA stabilizing protein, alters translation

    • E.

      Sigma factor, acts on transcription

    Correct Answer
    C. An antisense RNA, alters translation
    Explanation
    The product of micF is a nucleic acid, so the most likely way it would bind to mRNA would be by sequence complementarity. The fact that it binds mRNA means that it is working AFTER transcription. Of the options presented, it would have to be an antisense RNA (also, all of the other options are proteins)

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  • 16. 

    During translation, the growing polypeptide is positioned in the __________ of the ribosome

    • A.

      Promoters

    • B.

      Triphosphate deoxyribonucleotides

    • C.

      P site

    • D.

      Replication fork /bubble

    • E.

      Leading strand

    Correct Answer
    C. P site
    Explanation
    During translation, the growing polypeptide is positioned in the P site of the ribosome. The P site, also known as the peptidyl site, is one of the three binding sites on the ribosome. It is where the tRNA carrying the growing polypeptide chain binds to the ribosome. The P site is responsible for holding the tRNA with the growing polypeptide chain while a new amino acid is added to the chain during protein synthesis.

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  • 17. 

    dATP and dCTP are examples of __________, the building blocks of DNA molecules

    • A.

      Promoters

    • B.

      Triphosphate deoxyribonucleotides

    • C.

      P site

    • D.

      Replication fork /bubble

    • E.

      Leading strand

    Correct Answer
    B. Triphosphate deoxyribonucleotides
    Explanation
    dATP and dCTP are examples of triphosphate deoxyribonucleotides, which are the building blocks of DNA molecules. Triphosphate deoxyribonucleotides are nucleotides that contain a deoxyribose sugar, a phosphate group, and a nitrogenous base (in this case, either adenine or cytosine). These nucleotides are joined together through phosphodiester bonds to form the DNA molecule. They provide the necessary components for DNA replication and synthesis.

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  • 18. 

    The point at which a DNA double helix is "unzipped" is the __________.

    • A.

      Promoters

    • B.

      Triphosphate deoxyribonucleotides

    • C.

      P site

    • D.

      Replication fork /bubble

    • E.

      Leading strand

    Correct Answer
    D. Replication fork /bubble
    Explanation
    The replication fork/bubble is the point at which a DNA double helix is "unzipped" during DNA replication. This is where the two strands of the double helix separate and new strands are synthesized. The replication fork is formed by the unwinding of the DNA helix and the action of enzymes called helicases. The bubble refers to the region of unwound DNA where replication is actively occurring.

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  • 19. 

    The __________ is the DNA strand that is synthesized continuously during DNA replication.

    • A.

      Promoters

    • B.

      Triphosphate deoxyribonucleotides

    • C.

      P site

    • D.

      Replication fork /bubble

    • E.

      Leading strand

    Correct Answer
    E. Leading strand
    Explanation
    The leading strand is the DNA strand that is synthesized continuously during DNA replication. This is because the leading strand is oriented in the 3' to 5' direction, which allows for continuous synthesis by DNA polymerase in the 5' to 3' direction. In contrast, the lagging strand is synthesized discontinuously in small fragments called Okazaki fragments.

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  • 20. 

    RNA polymerase initiates transcription by recognizing specific nucleotide sequences called __________. .

    • A.

      Promoters

    • B.

      Triphosphate deoxyribonucleotides

    • C.

      P site

    • D.

      Replication fork /bubble

    • E.

      Leading strand

    Correct Answer
    A. Promoters
    Explanation
    RNA polymerase initiates transcription by recognizing specific nucleotide sequences called promoters. Promoters are regions of DNA that signal the start of a gene and provide binding sites for RNA polymerase. When RNA polymerase binds to the promoter, it begins transcribing the DNA into RNA. Promoters play a crucial role in regulating gene expression by controlling when and how often transcription occurs.

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