Microbiology Quiz on Viruses and Bacteria
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Questions and Answers

Which type of virus infects human nerve and epithelial cells?

  • Parvovirus
  • Tobacco Mosaic
  • Reovirus
  • Herpes Simplex I (correct)

    • All viruses have a thin protein coat surrounding their nucleic acid core.

    False

    Name the type of nucleic acid in the HIV virus.

    single-stranded RNA

    Viruses that infect plants are categorized as ______ viruses.

    <p>plant</p> Signup and view all the answers

    Which of the following viruses is known to infect mouse heart cells?

    <p>Reovirus</p> Signup and view all the answers

    Match the following viruses with their characteristics:

    <p>Herpes Simplex I = double-stranded DNA Parvovirus = single-stranded DNA Reovirus = double-stranded RNA Tobacco Mosaic = single-stranded RNA</p> Signup and view all the answers

    What is the shape of the Tobacco Mosaic virus?

    <p>rod-shaped</p> Signup and view all the answers

    Bacteriophages are viruses that specifically infect animal cells.

    <p>False</p> Signup and view all the answers

    What is the primary characteristic of prokaryotic cells like E. coli?

    <p>They do not contain membrane-bound organelles.</p> Signup and view all the answers

    Plasmids are large DNA molecules that contain essential genes for bacterial survival.

    <p>False</p> Signup and view all the answers

    How many genes does the E. coli genome typically code for?

    <p>Approximately 4,400 genes.</p> Signup and view all the answers

    Bacteria can transfer ______ between themselves.

    <p>plasmids</p> Signup and view all the answers

    Match the following characteristics with their corresponding elements in bacteria:

    <p>E. coli = A common bacterium with 4,400 genes Plasmids = Extra small rings of DNA Nucleoid = Dense area of prokaryotic DNA R plasmids = Contain antibiotic resistance genes</p> Signup and view all the answers

    Which organism has the highest number of genes listed?

    <p>Homo sapiens</p> Signup and view all the answers

    What does the DNA in a bacterium usually look like?

    <p>Supercoiled and circular</p> Signup and view all the answers

    All DNA from different organisms has identical sequences of nitrogenous bases.

    <p>False</p> Signup and view all the answers

    The entire E. coli genome contains a significant amount of spacer DNA.

    <p>False</p> Signup and view all the answers

    What is the bond type called that links sugars and phosphates in nucleic acids?

    <p>phosphodiester bond</p> Signup and view all the answers

    What are R plasmids known for?

    <p>They contain antibiotic resistance genes.</p> Signup and view all the answers

    An adenosine bonded to a _____ is an example of nitrogenous base pairing.

    <p>thymine</p> Signup and view all the answers

    How many base pairs does Homo sapiens have?

    <p>3,000,000,000</p> Signup and view all the answers

    Match the following organisms with their genome size in base pairs:

    <p>Haemophilus influenzae = 1,830,137 Mycoplasma genitalium = 580,070 Caenorhabditis elegans = 97,000,000 Homo sapiens = 3,000,000,000</p> Signup and view all the answers

    A hydrogen bond is a strong bond between nitrogenous bases.

    <p>False</p> Signup and view all the answers

    What is the main feature that distinguishes DNA from different organisms?

    <p>the order of nitrogenous bases</p> Signup and view all the answers

    What is the purpose of adding phenol red to cell culture media?

    <p>To monitor the pH of the growth medium</p> Signup and view all the answers

    Viral DNA is considered living due to its ability to infect host cells.

    <p>False</p> Signup and view all the answers

    What changes occur to phenol red in response to acidic conditions?

    <p>It changes from red to gold.</p> Signup and view all the answers

    Viruses that infect bacteria are referred to as __________.

    <p>bacteriophages</p> Signup and view all the answers

    Why do mammalian cell cultures need to be reseeded?

    <p>To provide fresh nutrients and prevent toxicity</p> Signup and view all the answers

    Viruses are larger than mammalian cells.

    <p>False</p> Signup and view all the answers

    What role do nonpathogenic viruses play in biotechnology?

    <p>They serve as vectors to carry DNA between cells.</p> Signup and view all the answers

    Match the following components with their roles:

    <p>Phenol Red = pH indicator for cell culture Bacteriophages = Viruses that infect bacteria Mammalian Cells = Multicellular organisms used in cultures Viruses = Non-living infectious agents</p> Signup and view all the answers

    What is added to laundry detergent to remove proteinaceous stains?

    <p>Enzymes</p> Signup and view all the answers

    Gene therapy involves introducing new genes using a synthetic lipid envelope or a virus.

    <p>True</p> Signup and view all the answers

    What type of mutations can result from treating fungi with chemicals?

    <p>Random mutations in DNA</p> Signup and view all the answers

    The enzyme rSubtilisin is a type of __________ that helps in removing protein stains from clothing.

    <p>protease</p> Signup and view all the answers

    Match the following terms with their descriptions:

    <p>Subtilisin = A recombinant protease used in detergents Gene therapy = A method to correct genetic disorders Mutagenesis = The process of inducing mutations in DNA Liposome = A synthetic lipid envelope for gene delivery</p> Signup and view all the answers

    What can happen as an outcome of mutagenesis?

    <p>Unexpected changes in protein structure</p> Signup and view all the answers

    The main goal of gene therapy is to enhance the mutations in a gene.

    <p>False</p> Signup and view all the answers

    Name one method used to deliver a new gene into target cells in gene therapy.

    <p>Using a virus</p> Signup and view all the answers

    What is the function of RNA polymerase in gene expression?

    <p>To synthesize mRNA from a DNA template</p> Signup and view all the answers

    Structural genes can code for one or more mRNA molecules.

    <p>True</p> Signup and view all the answers

    What is the role of the promoter region in gene expression?

    <p>It is the segment where RNA polymerase attaches to initiate transcription.</p> Signup and view all the answers

    The _____ region is where the RNA polymerase begins the transcription process.

    <p>promoter</p> Signup and view all the answers

    Match the following components of the operon with their functions:

    <p>Structural genes = Code for mRNA molecules Promoter = Site where RNA polymerase attaches Operator = Regulates the expression of structural genes Terminator = Signals the end of transcription</p> Signup and view all the answers

    What happens at the ribosome during protein synthesis?

    <p>mRNA is decoded into a peptide</p> Signup and view all the answers

    The operator region turns genetic expression ON and OFF.

    <p>True</p> Signup and view all the answers

    What is produced during the transcription process?

    <p>mRNA</p> Signup and view all the answers

    Study Notes

    Molecular Biologist/Associate Professor

    • Paul D. Kaufman, PhD
    • University of Massachusetts Medical School, Worcester, MA
    • Studies how eukaryotic cells assemble chromosomes and their function.
    • Focuses on chromatin (DNA and protein complexes in the nucleus).
    • Research includes proteins used in yeast and human cells to deposit histone proteins onto DNA.
    • Also investigates enzymes that chemically modify histone structure and function.
    • Main responsibilities include: scientific discovery, conducting experiments, training graduate students, supervising postdoctoral fellows, reviewing experiments, suggesting improvements, writing papers and grants, reading scientific literature, attending research seminars, and presenting research results at scientific meetings.

    Introduction to Studying DNA

    • Describes the structure and function of DNA, its encoding of proteins, and molecular modeling in studying biomolecules.
    • Explains eukaryotic vs. prokaryotic chromosomal structures and their impact on gene regulation.
    • Discusses bacterial cultures in liquid and solid media and sterilisation techniques.
    • Covers virus characteristics and their importance in genetic engineering.
    • Explains fundamental genetic engineering processes including recombinant DNA technology, site-specific mutagenesis, and gene therapy.
    • Describes gel electrophoresis and how molecule characteristics affect migration.

    DNA Structure and Function

    • The biotechnology industry grew due to methods to transfer DNA between cells and to manipulate them for specific proteins.
    • DNA and RNA codes are central to biotechnology research and development.
    • Genetic information is stored in DNA molecules (Figure 4.1).
    • DNA sequences are transcribed into RNA messages. RNA sequence determines amino acids in proteins (Figure 4.2).
    • The Central Dogma of Biology explains how genetic codes are converted into structures and functions (Figure 4.2).
    • Many biotechnological efforts modify DNA molecules to affect protein production.
    • Proteins can be the desired product (e.g., insulin).
    • Regulatory proteins are needed for necessary cellular functions.
    • The number of genes in humans is about 20,000 to 25,000, directing over 2000 different protein types in one cell.
    • The total genome size varies, but each cell in a given organism has the same genome, except sex cells (Table 4.1).

    Similarities in DNA Molecules Among Organisms

    • All DNA is made of four nucleotides (adenosine deoxynucleotide—A, guanosine deoxynucleotide—G, cytosine deoxynucleotide—C, and thymine deoxynucleotide—T, Figure 4.3a-d).
    • Virtually all DNA forms a double helix (two sides) of repeating nucleotides, several million bp in length. Nucleotides connect other nucleotides in the strand via strong phosphodiester bonds between sugars and phosphates (Figure 4.4 a-d).
    • Hydrogen bonds (H-bonds) between nitrogen bases on complementary strands hold the double helix together (Figure 4.4a-d).
    • Adenine bonds with Thymine (A-T), and Guanine bonds with Cytosine (G-C).
    • Nucleotides are stacked 0.34 nanometers (nm) apart with 10 nitrogen bases per complete turn.

    Sizes of Genomes in Organisms

    • Data is shown comparing numbers of genes and sizes of the genomes (in bp) for different organisms (Table 4.1).

    Variations in DNA Molecules

    • Variations exist in DNA molecules between organisms regarding the following: the number of DNA strands (chromosomes), the length in base pairs, the number and type of genes and non-coding regions, and the shape (circular or linear chromosomes).

    Prokaryotic DNA

    • Prokaryotic cells lack a nucleus and other membrane-bound organelles (Figure 4.7).
    • Bacterial DNA is usually one long, circular molecule floating in the cytoplasm, often attached at one point to the membrane.
    • Some bacteria have extra small rings of DNA called plasmids (Figure 4.8). Plasmids contain a few genes that code for additional characteristics for survival.
    • The transfer of plasmids among bacteria can lead to antibiotic resistance or other new characteristics.

    Viral DNA

    • Viruses are collections of protein and nucleic acid molecules active within a cell (Figure 4.21).
    • They are very tiny, from 25 to 250 nm in size.
    • Viruses are classified based on the type of cell they attack: bacterial, plant, or animal.
    • Viral DNA or RNA is relatively short and easy to manipulate.
    • Recombinant viruses can carry "therapeutic" genes, or correct genes, into cells to treat certain genetic disorders.

    Using Gel Electrophoresis to Study Molecules

    • Gel electrophoresis separates charged molecules such as DNA, RNA, and proteins, based on size, shape, and charge.
    • Agarose is a frequently used gel material for DNA.
    • Samples are loaded into gel wells. 
    • An electric field is applied. Negatively charged molecules (e.g., DNA, RNA) move towards the positive end.
    • Molecular size affects rate of movement; smaller fragments move faster.
    • DNA stains (like ethidium bromide) that fluoresce under UV light are used to visualize separated molecules.

    Running and Visualizing Gels

    • Gel electrophoresis is used to separate DNA fragments (Figure 4.29).
    • DNA stains allow for visualisation under UV light (Figure 4.34).
    • DNA bands appear on a gel and approximate sizes are found based on the comparison with sizing standards (Figure 4.35).

    Additional topics

    • Recombinant DNA technology
    • Site-specific mutagenesis
    • Gene therapy
    • Human cell culture
    • Mammalian cell culture
    • Viral DNA
    • Further topics on how to use bioinformatics tools are also covered.

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    Description

    Test your knowledge on viruses and bacteria with this quiz! Questions cover various aspects, including the types of viruses, characteristics of bacteria, and specific examples such as HIV and E. coli. Challenge yourself to see how well you understand microbial life.

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