Cellular Physiology and Communication
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Questions and Answers

What is produced during alcoholic fermentation?

  • Pyruvate and NADH
  • Ethanol and carbon dioxide (correct)
  • Ethanol and glucose
  • Lactic acid and oxygen
  • What is the primary function of fermentation?

  • To convert glucose into oxygen
  • To produce energy from sunlight
  • To reoxidize NADH for glycolysis to continue (correct)
  • To generate ATP at a higher rate than respiration
  • Where does photosynthesis occur in eukaryotic cells?

  • Chloroplasts (correct)
  • Nucleus
  • Cytoplasm
  • Mitochondria
  • What is produced during the light phase of photosynthesis?

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

    Which pigment is primarily responsible for capturing light energy during photosynthesis?

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

    In the Calvin cycle, carbon dioxide is converted into which substance?

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

    What type of enzymes play a crucial role in regulating metabolic activities?

    <p>Allosteric enzymes</p> Signup and view all the answers

    What byproduct is released during photosynthesis?

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

    What is the primary function of Na+ and K+ gradients in cells?

    <p>To maintain membrane potential and excitability</p> Signup and view all the answers

    Which type of junction is specifically designed to prevent the passage of materials between adjacent cells?

    <p>Tight junctions</p> Signup and view all the answers

    What type of reaction is characterized by the synthesis of complex molecules from simpler substances?

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

    Which of the following statements about cellular metabolism is accurate?

    <p>Catabolic reactions release energy and support anabolic processes.</p> Signup and view all the answers

    What is the primary role of gap junctions in cell communication?

    <p>To allow ion and small molecule transit</p> Signup and view all the answers

    Which component is essential for the formation of ATP?

    <p>Adenosine and three phosphate groups</p> Signup and view all the answers

    What is the connection found in plant cells that allows communication through cell walls?

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

    Which of the following is characteristic of desmosomes?

    <p>They consist of a dense plaque connected to keratin fibers.</p> Signup and view all the answers

    What is the total number of ATP required to produce one molecule of glucose by fixing 6 CO₂?

    <p>18 ATP</p> Signup and view all the answers

    Which type of organisms utilize solar energy for organic production?

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

    What process allows a prokaryotic cell to divide?

    <p>Binary fission</p> Signup and view all the answers

    What is the purpose of mitosis in eukaryotic cells?

    <p>Growth and renewal of tissues</p> Signup and view all the answers

    What do heterotrophic organisms require from their environment?

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

    How does cell division differ between prokaryotes and eukaryotes?

    <p>Eukaryotes have complex division involving chromosomes</p> Signup and view all the answers

    What is the form of DNA found in prokaryotic cells?

    <p>Circular DNA</p> Signup and view all the answers

    What is produced through the process of meiosis in eukaryotes?

    <p>Reproductive cells</p> Signup and view all the answers

    What is the mode of inheritance for colour blindness?

    <p>X-linked recessive</p> Signup and view all the answers

    Which of the following disorders is inherited in an autosomal dominant pattern?

    <p>Huntington's disease</p> Signup and view all the answers

    Individuals with which genetic disorder are considered healthy carriers?

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

    What characterizes achondroplasia?

    <p>Shortened bones leading to dwarfism</p> Signup and view all the answers

    Which of the following conditions results from the accumulation of phenylalanine in the bloodstream?

    <p>Phenylketonuria (PKU)</p> Signup and view all the answers

    What is the primary cause of alkaptonuria?

    <p>Disorder affecting the metabolism of tyrosine</p> Signup and view all the answers

    Which genetic disorder primarily affects skin, hair, and iris pigmentation?

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

    What is unique about the leading strand during DNA replication?

    <p>It is synthesised continuously using a single primer.</p> Signup and view all the answers

    Which of the following is a likely symptom of galactosemia?

    <p>Lack of an enzyme converting galactose to glucose</p> Signup and view all the answers

    What are Okazaki fragments associated with during DNA replication?

    <p>Synthesis of the lagging strand.</p> Signup and view all the answers

    What function does DNA polymerase serve when it encounters an incorrect nucleotide?

    <p>It reverses direction to remove incorrect nucleotides.</p> Signup and view all the answers

    Which hypothesis was originally formulated by Beadle and Tatum?

    <p>One gene – one enzyme hypothesis.</p> Signup and view all the answers

    What modification was made to the 'one gene – one enzyme' hypothesis?

    <p>One gene – one protein.</p> Signup and view all the answers

    Which term is used to describe changes in genetic information of an organism?

    <p>Mutations.</p> Signup and view all the answers

    What do DNA repair nucleases do after DNA replication?

    <p>Identify and replace incorrect nucleotides.</p> Signup and view all the answers

    How are proteins related to genes according to the most current hypothesis?

    <p>Each gene codes for one polypeptide chain.</p> Signup and view all the answers

    Study Notes

    • Na+ and K+ Gradients

      • The gradients of Na+ and K+ play a crucial role in maintaining cell membrane potential, regulating cell volume, and contributing to nerve and muscle cell excitability.
      • These gradients are also involved in the transport of essential nutrients like sugars and amino acids.

      Cell Communication

      • Distant cells communicate indirectly through chemical messengers transported in the bloodstream.
    • Cells in close proximity can communicate directly through junctions.

    • Plant cells use plasmodesmata, channels connecting the cytoplasm of adjacent cells.

    • Animal cells have various types of junctions.

      • Desmosomes: Anchoring junctions that provide tissue continuity and strength.
      • Tight junctions: Seal spaces between cells, preventing material passage.
      • Gap junctions: Contain protein complexes forming channels that allow the passage of ions and small molecules between cells.

    Cellular Metabolism

    • Cellular metabolism encompasses reactions transforming matter and energy within cells.
    • Catabolism: Breakdown of complex molecules into simpler substances.
    • Anabolism: Synthesis of cellular components from simple compounds.
    • Catabolic reactions release energy, fueling cellular processes.
    • Anabolic reactions require energy, supplied by catabolic reactions through ATP.

    ATP: The Energy Carrier

    • ATP is formed from adenosine linked to three phosphate groups.

    Fermentation

    • In the absence of oxygen, cells undergo fermentation, a process using NADH to reduce pyruvate.
    • Alcoholic Fermentation: Pyruvate is transformed into ethanol and CO2.
    • Lactic Fermentation: Pyruvate is transformed into lactic acid.

    Regulation of Metabolism

    • Allosteric enzymes play a critical role in regulating metabolic activities by binding to molecules at specific sites, acting as activators or inhibitors.

    Photosynthesis

    • Plants and some prokaryotes perform photosynthesis, converting solar energy into chemical energy in the form of glucose.
    • Light energy is used for carbon fixation, the transformation of CO2 into glucose.
    • Photosynthesis involves the absorption of CO2 and H2O, producing glucose and releasing O2.
    • The key equation representing this process is: 6CO2 + 6H2O + energy → C6H12O6 + 6O2.
    • In eukaryotes, photosynthesis occurs in chloroplasts.
    • Chlorophyll and carotenoids capture light energy embedded in thylakoid membranes.
    • Two phases of photosynthesis:
      • Light Phase: Occurs in thylakoids; light energy is converted into chemical energy (ATP and NADPH).
      • Dark Phase: Occurs in the stroma; ATP and NADPH energy reduce CO2 to produce glucose via the Calvin cycle.

    Autotrophic and Heterotrophic Organisms

    • Autotrophs: Produce organic substances from inorganic substances.
      • Photoautotrophs: Use solar light as an energy source.
      • Chemoautotrophs: Utilize energy from redox reactions.
    • Heterotrophs: Obtain organic molecules from the environment by feeding on autotrophs, heterotrophs, or organic substances.

    Cell Division and Chromosomes

    • Cell division is the process of a cell giving rise to two daughter cells.
    • DNA duplicates before cell division, ensuring each daughter cell receives identical genetic information.
    • Cell division ensures equitable distribution of DNA, cytoplasm, and organelles.
    • Prokaryotes have a single DNA molecule, undergoing simple binary fission.
    • Eukaryotes have multiple DNA molecules in the form of chromosomes.
      • Mitosis: Cell division ensuring the fair distribution of genetic material.
      • Cytokinesis: Cell division ensuring the fair distribution of cytoplasmic material.
      • Meiosis: Specialized cell division occurring in germ cells to form reproductive cells.

    Cell Division in Prokaryotes

    • Prokaryotic cells contain a single circular DNA molecule located in the cytoplasm, associated with the plasma membrane at the mesosoma.
    • They divide by binary fission:
      • DNA duplicates while the cell grows.
      • The cell elongates, and the duplicated DNA molecules separate.
      • The cell divides into two daughter cells, each containing a complete copy of the DNA molecule.

    Chromosomes in Eukaryotes

    • Eukaryotic cells have multiple linear DNA molecules that are packaged into chromosomes during cell division.
    • Chromosomes consist of DNA tightly wound around proteins called histones.

    DNA Replication

    • DNA replication occurs prior to cell division to ensure each daughter cell receives a complete copy of the genome.
    • The process is semi-conservative; each new DNA molecule consists of one original strand and one newly synthesized strand.
    • Replication proceeds in the 5' to 3' direction; one strand is synthesized continuously (leading strand), while the other is synthesized discontinuously in fragments (lagging strand).
    • DNA polymerase adds nucleotides to the growing chain and proofreads for errors.
    • DNA repair nucleases scan for and correct remaining errors.

    The One Gene – One Enzyme Hypothesis

    • Beadle and Tatum demonstrated that mutations in genes result in the corresponding enzyme functioning abnormally.
    • They proposed the "one gene – one enzyme" hypothesis, stating that a specific gene is responsible for the synthesis of a specific enzyme.
    • Later modified to "one gene – one protein" and then "one gene – one polypeptide chain".

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    Description

    This quiz covers essential concepts in cellular physiology, focusing on Na+ and K+ gradients, cell communication methods, and cellular metabolism. Understand how these elements contribute to cell function and intercellular interactions. Test your knowledge on the mechanisms that sustain cellular health and communication.

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