Cell Membrane Structure
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Questions and Answers

What is the primary function of the lipopolysaccharide outer membrane?

  • To recognize and respond to antibodies
  • To provide structural support to the cell
  • To facilitate the transport of molecules into the cell
  • To act as a barrier between the cell and its environment (correct)

    • What is the term for the lipid portion of the lipopolysaccharide molecule?

  • Phospholipid
  • Lipid A (correct)
  • O-antigen
  • Endotoxin

    • What is the function of the O-antigen portion of the lipopolysaccharide molecule?

  • To provide structural support to the cell
  • To recognize and respond to antibodies (correct)
  • To facilitate the transport of molecules into the cell
  • To act as a barrier between the cell and its environment

    • What is the term for the toxic effect of the lipopolysaccharide molecule in a host's bloodstream or gastrointestinal tract?

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

    What is the characteristic of the Gram-negative bacterial cell wall?

    <p>Highly charged</p> Signup and view all the answers

    What is the function of the phospholipid bilayer in the bacterial cell membrane?

    <p>To facilitate the transport of molecules into the cell</p> Signup and view all the answers

    What is the term for the bacterial cytoplasmic membrane?

    <p>Plasma membrane</p> Signup and view all the answers

    What is the characteristic of the lipopolysaccharide molecule?

    <p>Highly charged</p> Signup and view all the answers

    What is the function of the sterols in the membranes of mycoplasmas?

    <p>To add rigidity to the membrane</p> Signup and view all the answers

    What is the term for the lipopolysaccharide molecule that is unique to specific bacterial strains?

    <p>Subspecies-specific marker</p> Signup and view all the answers

    What is the function of porins in the outer membrane?

    <p>To allow for passive transport of ions, sugars, and amino acids</p> Signup and view all the answers

    What is the region between the cytoplasmic and outer membranes called?

    <p>Periplasmic space</p> Signup and view all the answers

    What is the purpose of the lipid portion of the outer membrane?

    <p>To prevent the passage of charged molecules</p> Signup and view all the answers

    What is the location of the proton motive force?

    <p>Across the outer membrane</p> Signup and view all the answers

    What is the role of transport and signaling proteins in the cytoplasmic membrane?

    <p>To transport molecules across the cytoplasmic membrane</p> Signup and view all the answers

    What is the relationship between the periplasmic space and the cytoplasmic membrane?

    <p>Molecules in the periplasmic space can be transported across the cytoplasmic membrane</p> Signup and view all the answers

    What is the function of the outer membrane?

    <p>To regulate the passage of molecules into the cell</p> Signup and view all the answers

    What is the role of the phospholipid bilayer in the outer membrane?

    <p>To prevent the passage of charged molecules</p> Signup and view all the answers

    What is the location of the phospholipid bilayer?

    <p>In the outer membrane</p> Signup and view all the answers

    What is the purpose of the proton motive force?

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

    What is the main purpose of ALPS?

    <p>To provide a framework for assessing and managing risks</p> Signup and view all the answers

    What is the primary goal of the ALPS approach?

    <p>To enhance patient safety</p> Signup and view all the answers

    What is the relationship between ALPS and the Joint Commission?

    <p>ALPS is a framework for meeting Joint Commission standards</p> Signup and view all the answers

    What is the role of the 'B' in ALPS?

    <p>Identifying and analyzing risks</p> Signup and view all the answers

    What is the purpose of the 'S' in ALPS?

    <p>Developing and implementing solutions</p> Signup and view all the answers

    What is the benefit of using ALPS in healthcare?

    <p>Improving patient safety and outcomes</p> Signup and view all the answers

    What is the focus of the 'P' in ALPS?

    <p>Patient safety</p> Signup and view all the answers

    What is the relationship between ALPS and risk management?

    <p>ALPS is a component of risk management</p> Signup and view all the answers

    What is the outcome of using ALPS in healthcare?

    <p>Improved patient safety and outcomes</p> Signup and view all the answers

    What is the benefit of using ALPS in healthcare organizations?

    <p>Improving patient safety and outcomes</p> Signup and view all the answers

    What is the main characteristic of Ribosomes?

    <p>They are the site of protein synthesis</p> Signup and view all the answers

    What is the name of the researcher who discovered the Ribosomes?

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

    What is the size of the smaller subunit of the Ribosome?

    <p>30S</p> Signup and view all the answers

    What is the function of the larger subunit of the Ribosome?

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

    What is the name of the process by which Ribosomes synthesize proteins?

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

    What is the function of the mRNA in protein synthesis?

    <p>To carry genetic information from DNA to Ribosomes</p> Signup and view all the answers

    What is the name of the binding site on the Ribosome where the mRNA attaches?

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

    What is the name of the process by which the Ribosome reads the mRNA?

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

    What is the function of the tRNA in protein synthesis?

    <p>To carry amino acids to the Ribosome</p> Signup and view all the answers

    What is the name of the complex formed by the Ribosome and the mRNA during protein synthesis?

    <p>Ribosome-mRNA complex</p> Signup and view all the answers

    What percentage of substances are dissolved or suspended in water?

    <p>One-fifth</p> Signup and view all the answers

    What is the site of protein synthesis in the cell?

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

    What is the term for the rates at which ribosomes move toward the bottom of a tube when the tube is rapidly spun in an instrument called a centrifuge?

    <p>Sedimentation rates</p> Signup and view all the answers

    What is the rate of whole bacterial ribosomes?

    <p>70S</p> Signup and view all the answers

    What is the effect of certain antibiotics on bacterial protein synthesis?

    <p>They disrupt bacterial protein synthesis</p> Signup and view all the answers

    What is the term for the long chains of ribosomes found in the cytoplasm of bacteria?

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

    What is the main function of ribosomes in the cell?

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

    What is the composition of ribosomes?

    <p>A complex of protein and RNA</p> Signup and view all the answers

    Where are ribosomes often found in the cell?

    <p>Only in the cytoplasm</p> Signup and view all the answers

    What is the effect of certain antibiotics on eukaryotic cells?

    <p>They have no effect on eukaryotic protein synthesis</p> Signup and view all the answers

    What is the main function of the cell membrane?

    <p>To regulate the movement of materials into and out of a cell</p> Signup and view all the answers

    What is the periplasmic space?

    <p>The space between the cell wall and the outer membrane</p> Signup and view all the answers

    What is the function of the proteins in the bacterial cell membrane?

    <p>To respond to chemical substances in the environment</p> Signup and view all the answers

    What is the main component of the cytoplasm in prokaryotic cells?

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

    What is the function of flagella in bacteria?

    <p>To move the bacteria</p> Signup and view all the answers

    What is the difference between Gram-positive and Gram-negative bacteria?

    <p>The presence of a periplasmic space</p> Signup and view all the answers

    What is the function of the cell membrane in terms of material movement?

    <p>To regulate the movement of materials into and out of a cell</p> Signup and view all the answers

    What is the composition of the periplasm?

    <p>Peptidoglycan, protein constituents, and metabolites</p> Signup and view all the answers

    What is the function of the peptidoglycan in the periplasm?

    <p>To provide structural support to the cell</p> Signup and view all the answers

    What is the purpose of the bacterial cell membrane?

    <p>To regulate the movement of materials into and out of a cell</p> Signup and view all the answers

    What is the function of magnetosomes in certain bacteria?

    <p>To help bacteria orientate themselves downwards into favorable conditions</p> Signup and view all the answers

    What type of inclusion body is known for storing sulphur and polyphosphate?

    <p>Volutin or metachromatic granules</p> Signup and view all the answers

    What is the main function of inclusion bodies in bacteria?

    <p>To store food reserves</p> Signup and view all the answers

    What type of inclusion body is responsible for maintaining buoyancy of the cell?

    <p>Gas vacuoles</p> Signup and view all the answers

    What is the term for the process of storing food reserves in inclusion bodies?

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

    What is the main component of magnetosomes?

    <p>Iron oxide</p> Signup and view all the answers

    What type of bacteria are known to have gas vacuoles?

    <p>Blue-green bacteria</p> Signup and view all the answers

    What is the term for the movement of bacteria towards or away from a stimulus?

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

    What is the primary function of the glycocalyx in bacteria?

    <p>To facilitate the attachment of bacteria to host cells</p> Signup and view all the answers

    What is the function of the glycocalyx in bacteria?

    <p>To protect cells from desiccation and aid in attachment to surfaces</p> Signup and view all the answers

    What type of compound is often stored in inclusion bodies?

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

    What is the main function of pili in bacteria?

    <p>To facilitate the transfer of DNA between bacteria</p> Signup and view all the answers

    What is the function of volutin or metachromatic granules?

    <p>To store sulphur and polyphosphate</p> Signup and view all the answers

    What is the primary function of the fimbriae in bacteria?

    <p>To facilitate the attachment of bacteria to host cells</p> Signup and view all the answers

    What is the term for a loose, water-soluble glycocalyx?

    <p>Slime layer</p> Signup and view all the answers

    What is the primary function of the glycocalyx in facilitating the attachment of bacteria to host cells?

    <p>To create a layer of molecules that interacts with the host cell surface</p> Signup and view all the answers

    What is the primary function of a capsule in bacteria?

    <p>To protect cells from desiccation and aid in attachment to surfaces</p> Signup and view all the answers

    What is the primary function of the outer membrane in Gram-negative bacteria?

    <p>To regulate the movement of molecules across the cell membrane</p> Signup and view all the answers

    What is the role of glycocalyx in the ability of pathogenic bacteria to cause disease?

    <p>It plays a crucial role in the ability of bacteria to cause disease</p> Signup and view all the answers

    What is the primary function of ATP in the muscle cells?

    <p>To provide energy for muscle contraction</p> Signup and view all the answers

    What is the composition of a glycocalyx?

    <p>Polysaccharides, polypeptides, or both</p> Signup and view all the answers

    What is the role of ATP in the muscle contraction process?

    <p>To release energy for muscle contraction</p> Signup and view all the answers

    What is the primary function of the periplasmic space in Gram-negative bacteria?

    <p>To create a region between the cytoplasmic and outer membranes</p> Signup and view all the answers

    What is the term for a glycocalyx that is composed of organized repeating units of organic chemicals firmly attached to the cell surface?

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

    What is the result of ATP hydrolysis in muscle cells?

    <p>The release of energy for muscle contraction</p> Signup and view all the answers

    What is the primary function of the phospholipid bilayer in the bacterial cell membrane?

    <p>To regulate the movement of molecules across the cell membrane</p> Signup and view all the answers

    What is the role of slime layers in bacteria?

    <p>To provide a means of attachment to surfaces</p> Signup and view all the answers

    What is the primary source of energy for muscle contraction?

    <p>ATP hydrolysis</p> Signup and view all the answers

    What is the primary function of the lipopolysaccharide molecule in the outer membrane of Gram-negative bacteria?

    <p>To facilitate the interaction of bacteria with the host immune system</p> Signup and view all the answers

    What is the function of the capsule in pathogenic bacteria?

    <p>To provide protection against phagocytic cells and the immune system</p> Signup and view all the answers

    What is the role of calcium ions in muscle contraction?

    <p>To facilitate muscle contraction</p> Signup and view all the answers

    What is the role of glycocalyx in the survival of bacteria?

    <p>It plays a crucial role in the survival of bacteria</p> Signup and view all the answers

    What is the result of muscle contraction?

    <p>The shortening of muscle fibers</p> Signup and view all the answers

    What is the function of myosin heads in muscle contraction?

    <p>To bind to actin filaments and cause contraction</p> Signup and view all the answers

    What is the term for the process of drying in bacteria?

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

    What is the role of actin filaments in muscle contraction?

    <p>To interact with myosin heads and cause contraction</p> Signup and view all the answers

    What is the result of ATP binding to myosin heads?

    <p>The release of energy for muscle contraction</p> Signup and view all the answers

    What is the role of ATP in the muscle relaxation process?

    <p>To recharge myosin heads for the next contraction</p> Signup and view all the answers

    What is the function of the glycocalyx in the bacterial cell?

    <p>To protect the cell from the host's immune system</p> Signup and view all the answers

    What is the term for the toxic effect of the lipopolysaccharide molecule in a host's bloodstream or gastrointestinal tract?

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

    What is the characteristic of the Gram-negative bacterial cell wall?

    <p>Thin peptidoglycan layer</p> Signup and view all the answers

    What is the primary function of fimbriae in bacteria?

    <p>To attach bacteria to surfaces and each other</p> Signup and view all the answers

    What is the main function of endospores?

    <p>To protect the bacteria from extreme environmental conditions</p> Signup and view all the answers

    What is the main difference between pili and fimbriae?

    <p>Pili are longer than fimbriae</p> Signup and view all the answers

    Which of the following bacteria produce endospores?

    <p>Bacillus and Clostridium</p> Signup and view all the answers

    What is the function of the phospholipid bilayer in the bacterial cell membrane?

    <p>To regulate the movement of molecules across the cell membrane</p> Signup and view all the answers

    What is the function of flagella in bacteria?

    <p>To provide locomotion to bacteria</p> Signup and view all the answers

    What is the term for the bacterial cytoplasmic membrane?

    <p>Cytoplasmic membrane</p> Signup and view all the answers

    What is the purpose of autoclaving at 121°C?

    <p>To ensure complete sterility</p> Signup and view all the answers

    What is the characteristic of the lipopolysaccharide molecule?

    <p>Presence of carbohydrates</p> Signup and view all the answers

    What is the composition of the core of an endospore?

    <p>Outer core wall, cell membrane, and nuclear region</p> Signup and view all the answers

    How do bacteria use fimbriae to attach to surfaces?

    <p>By extending a fimbria, attaching to the surface, and then retracting it to pull the bacterium towards the surface</p> Signup and view all the answers

    What is the role of glycocalyces in biofilm formation?

    <p>To adhere to surfaces and other bacteria, helping to form a biofilm</p> Signup and view all the answers

    Why are endospores highly resistant to heat?

    <p>Due to the low water content and the presence of dipicolinic acid and calcium ions</p> Signup and view all the answers

    What is the function of the sterols in the membranes of mycoplasmas?

    <p>To maintain the fluidity of the membrane</p> Signup and view all the answers

    What is the function of the cortex in an endospore?

    <p>To protect the core from environmental stress</p> Signup and view all the answers

    What is the term for the lipopolysaccharide molecule that is unique to specific bacterial strains?

    <p>O-antigen</p> Signup and view all the answers

    What is the function of conjugation pili?

    <p>To mediate the transfer of DNA between bacteria</p> Signup and view all the answers

    What is the characteristic of bacteria that have fimbriae?

    <p>They are capable of adhering to surfaces and each other</p> Signup and view all the answers

    What is the function of porins in the outer membrane?

    <p>To regulate the movement of molecules across the cell membrane</p> Signup and view all the answers

    Which of the following is a characteristic of endospores?

    <p>Low water content and high resistance to heat</p> Signup and view all the answers

    What is the role of fimbriae in biofilm formation?

    <p>To adhere to surfaces and other bacteria, helping to form a biofilm</p> Signup and view all the answers

    What is the region between the cytoplasmic and outer membranes called?

    <p>Periplasmic space</p> Signup and view all the answers

    What is the purpose of the exosporium in an endospore?

    <p>To protect the spore coat from environmental stress</p> Signup and view all the answers

    Why are endospores of pathogens such as Clostridium botulinum resistant to boiling?

    <p>Due to their thick spore coat</p> Signup and view all the answers

    What is the primary function of flagella in conjunction with fimbriae?

    <p>To allow bacteria to move towards or away from surfaces</p> Signup and view all the answers

    What is the result of germination of an endospore?

    <p>Formation of a vegetative cell</p> Signup and view all the answers

    What is the result of the interaction between fimbriae and surfaces?

    <p>The formation of a biofilm</p> Signup and view all the answers

    Study Notes

    Lipid Bilayer and Fatty Acid Chains

    • Lipid molecules in the cell membrane extend their fatty acid chains towards the surface, forming a barrier between the cell and its environment
    • The phosphate-containing ends of the lipid molecules are water-loving (hydrophilic), allowing them to interact with the aqueous environment
    • The fatty acid chains are non-polar (hydrophobic), forming the interior of the membrane
    • This structure allows the membrane to act as a permeability barrier, controlling the movement of molecules in and out of the cell

    Lipopolysaccharides (LPS) in Gram-Negative Bacteria

    • Also called endotoxin, LPS is an important component of the outer membrane in Gram-negative bacteria
    • The lipid A portion is toxic and can be released when the bacterial cell wall is broken down
    • The O-antigen portion consists of sugar molecules and is the primary site recognized by antibodies
    • Variability in the O-antigen chain can cause problems with the immune response
    • The highly charged LPS gives Gram-negative cell walls an overall negative charge

    Bacterial Cell Membrane Functions

    • Acts as a permeability barrier, regulating the movement of molecules in and out of the cell
    • Serves as the location for transport of molecules into the cell
    • Involved in energy conservation by generating a proton motive force
    • Contains the bases of flagella, which cause the flagella to move
    • Some membrane proteins respond to chemical substances in the environment

    Periplasmic Space

    • Many bacteria have a gap between the cell wall and the outer membrane, called the periplasmic space
    • This space can be easily observed in Gram-negative bacteria using electron microscopy
    • The periplasmic space contains peptidoglycan, protein components, and metabolites
    • Periplasmic spaces are rarely observed in Gram-positive bacteria

    Cytoplasm

    • The cytoplasm of prokaryotic cells is the semi-fluid substance inside the cell membrane
    • Prokaryotic cells typically have only a few clearly defined structures, such as chromosomes and ribosomes
    • The cytoplasm is where the majority of cellular activities and processes take place### Cytoplasm Composition
    • Cytoplasm makes up about four-fifths of the water in cells
    • Contains dissolved or suspended substances including:
      • Enzymes and other proteins
      • Carbohydrates
      • Lipids
      • Variety of inorganic ions
    • Many chemical reactions, both anabolic and catabolic, occur in the cytoplasm

    Ribosomes

    • Composed of a complex of protein and RNA
    • Site of protein synthesis in the cell
    • Abundant in bacterial cytoplasm, often grouped in long chains called polyribosomes
    • Nearly spherical, stain densely, and contain a large subunit and a small subunit
    • Serve as sites for protein synthesis
    • Relative sizes of ribosomes and their subunits can be determined by measuring their sedimentation rates
    • Bacterial ribosomes (70S) are smaller than eukaryotic ribosomes (80S)
    • Some antibiotics target 70S ribosomes and disrupt bacterial protein synthesis without affecting 80S ribosomes in eukaryotic cells

    Inclusion Bodies

    • Granular structures found in cytoplasm of certain bacteria
    • Act as food reserves, containing organic compounds like starch, glycogen, or lipids
    • Can also store sulfur and polyphosphate (known as volutin or metachromatic granules)
    • Magnetosomes contain iron oxide to help orient bacteria
    • Gas vacuoles maintain buoyancy in some bacteria

    Glycocalyx and Capsule

    • Some cells have a gelatinous, sticky substance surrounding the outside called a glycocalyx
    • Glycocalyx may be polysaccharides, polypeptides, or both
    • When the glycocalyx is organized into a firm, attached layer, it is called a capsule
    • Capsules and slime layers protect cells from desiccation
    • Present in many pathogenic bacteria, aiding survival and disease-causing ability
    • Slime layers help bacteria attach to surfacesHere are the study notes for the provided text:

    Bacterial Cell Structure and Function

    • Glycocalyx: a layer of carbohydrate molecules on the surface of bacterial cells, and plays a role in adhesion and biofilm formation.

    Fimbriae and Pili

    • Fimbriae: rod-like proteinaceous extensions on the surface of bacterial cells, used for attachment to surfaces and other cells.
    • Pili (also called conjugation pili): longer, thinner structures composed of a protein called pilin, used for DNA transfer between cells.
    • Functions of fimbriae and pili include:
      • Attachment to surfaces and other cells
      • Biofilm formation
      • DNA transfer

    Flagella

    • Flagella: long, hair-like structures used for locomotion in many bacteria.
    • Consist of three main components: basal body, hook, and filament.
    • Function in movement and propulsion of bacterial cells.

    Adhesion and Biofilm Formation

    • Bacteria use fimbriae and glycocalyx to adhere to surfaces and other cells.
    • Biofilms are formed when bacteria adhere to surfaces and produce a matrix of extracellular polymeric substances (EPS).
    • Biofilms provide protection for bacteria from environmental stresses and host immune responses.

    Conjugation and DNA Transfer

    • Conjugation pili are used for DNA transfer between bacterial cells.
    • This process involves the direct transfer of DNA from one cell to another through a specialized pilus.

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    Understand the structure and function of lipid bilayers and fatty acid chains in cell membranes, including their hydrophilic and hydrophobic regions.

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