Prokaryotic Cell Structure
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Prokaryotic Cell Structure

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Questions and Answers

What is the process called by which a single endospore forms within some bacteria?

  • Dipicolination
  • Endosporulation (correct)
  • Sporulation
  • Peptidoglycanation
  • What is the function of dipicolinic acid in endospore formation?

  • To facilitate the release of the endospore from the mother cell
  • To create the spore coat
  • To stabilize the proteins and DNA in the endospore (correct)
  • To form the peptidoglycan cortex
  • What is the structure that surrounds the core of the endospore?

  • Peptidoglycan cortex
  • Outer membrane
  • Spore coat
  • Inner membrane (correct)
  • What is the final stage of endospore formation?

    <p>Dehydration and maturation</p> Signup and view all the answers

    What is the unique feature of the endospore that is not found in vegetative cells?

    <p>Exosporium, spore coat, cortex, and core wall</p> Signup and view all the answers

    What is the purpose of the cortex in the endospore?

    <p>To protect the endospore from UV light and harsh chemicals</p> Signup and view all the answers

    What is the approximate percentage of water in the cytoplasm of a prokaryotic cell?

    <p>80%</p> Signup and view all the answers

    What is the primary function of the cytoplasm in a prokaryotic cell?

    <p>Site of most bacterial metabolism</p> Signup and view all the answers

    What is the function of mesosomes in prokaryotic cells?

    <p>Increase plasma membrane surface area and enzymatic content</p> Signup and view all the answers

    What is the characteristic of the chromosome in a prokaryotic cell?

    <p>Single circular chromosome of double-stranded DNA</p> Signup and view all the answers

    What is the function of plasmids in prokaryotic cells?

    <p>Confer protective traits to the host</p> Signup and view all the answers

    What is the role of some plasmids in antibiotic resistance?

    <p>They encode proteins that degrade antibiotics</p> Signup and view all the answers

    What is the function of conjugative plasmids?

    <p>They allow the exchange of DNA between bacterial cells</p> Signup and view all the answers

    What is the characteristic of the nucleoid in a prokaryotic cell?

    <p>It has no nuclear membrane or nucleoli</p> Signup and view all the answers

    What is the primary function of ribosomes in all organisms?

    <p>To synthesize proteins</p> Signup and view all the answers

    What is the purpose of plasmids in genetic engineering?

    <p>To insert specific genes</p> Signup and view all the answers

    What is unique about the 70S ribosomes found in prokaryotes?

    <p>They are composed of a 50S subunit and a 30S subunit</p> Signup and view all the answers

    What is the function of mRNA in protein synthesis?

    <p>To attach to the 30S subunit</p> Signup and view all the answers

    What is the purpose of inclusion granules in bacteria?

    <p>To store reserve deposits</p> Signup and view all the answers

    What is unique about endospores?

    <p>They are resistant to adverse conditions</p> Signup and view all the answers

    What is the function of tRNA in protein synthesis?

    <p>To carry anti-codons and amino acids</p> Signup and view all the answers

    What is the purpose of Bacillus stearothermophilus spores in quality control?

    <p>To test for heat sterilization equipment</p> Signup and view all the answers

    Study Notes

    Bacterial Internal Structures

    • Cytoplasm: a gel-like matrix composed of 80% water, containing nucleic acids, enzymes, amino acids, carbohydrates, lipids, inorganic ions, and low molecular weight compounds, and is the site of most bacterial metabolism that leads to growth and replication.
    • Mesosomes: plasma membrane infoldings that aid in:
      • Cell wall formation
      • DNA replication in prokaryotes
      • Increasing plasma membrane surface area and enzymatic content
      • Transferring chromosomes to daughter cells
    • Nucleoid:
      • A region with a single circular chromosome of double-stranded, supercoiled DNA
      • No nuclear membrane or nucleoli
      • Chromosome size varies from 580,000 base pairs in Mycoplasma gallinarum to 9,140,000 bp in Myxococcus xanthus

    Plasmids

    • Small, nonessential, extra-chromosomal DNA molecules that:
      • Can confer protective traits such as drug resistance or toxin production
      • Can be passed on during conjugation
      • Replicate independently
      • Can be gained or lost by bacteria
    • Conjugative plasmids allow for the exchange of DNA between bacterial cells
    • Plasmids are useful tools in genetic engineering/rDNA Technology

    Ribosomes

    • The most abundant component in the cytoplasm, with up to 15,000 ribosomes
    • Site of protein synthesis in all organisms
    • Prokaryotic ribosomes are 70S, composed of a 50S subunit and a 30S subunit
    • Function as a workbench for protein synthesis, translating mRNA into proteins

    Inclusion Granules

    • Nonliving components that do not possess metabolic activity
    • Not bounded by membranes
    • Examples:
      • Volutin granules (inorganic phosphate)
      • Polysaccharide granules (glycogen or starch)
      • Lipid inclusions (e.g., PHB granules)
      • Sulfur and nitrogen granules
      • Gas vacuoles (in some aquatic bacteria)

    Endospores

    • Dormant, resistant structures produced intracellularly upon starvation
    • Resistant to:
      • High temperatures
      • Irradiation
      • Cold
      • Organic solvents
    • Contain calcium dipicolinate
    • Not a mechanism of reproduction
    • Examples: Bacillus and Clostridium sp.

    Endosporulation

    • Process of forming an endospore, involving:
      • DNA replication
      • Formation of a spore septum
      • Pinching off of the plasma membrane to form a double membrane around the DNA
      • Incorporation of calcium dipicolinate
      • Formation of a peptidoglycan cortex and spore coat
      • Dehydration and maturation of the endospore

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    Description

    This quiz covers the internal structures of a prokaryotic cell, including the composition and functions of the cytoplasm, nucleic acids, and other components.

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