Cell Structure and Membrane Overview
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Questions and Answers

What is the function of a cell membrane?

  • Produces energy
  • Determines cell boundaries (correct)
  • Stores genetic information
  • Governs metabolic processes
  • Cytoplasmic organelles are non-living structures within the cell.

    False

    Name two examples of membranous organelles.

    Mitochondria and Golgi apparatus

    The size of a typical cell ranges from _____ to _____ micrometers.

    <p>4, 150</p> Signup and view all the answers

    Match the following organelles with their characteristics:

    <p>Mitochondria = Produces energy Ribosomes = Synthesizes proteins Lysosomes = Digestive enzymes Endoplasmic reticulum = Synthesizes fats and proteins</p> Signup and view all the answers

    Which of the following is NOT a characteristic of cytoplasmic inclusions?

    <p>Metabolically active</p> Signup and view all the answers

    Cell shape can include forms like cubical and columnar.

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

    What are the two main types of cytoplasmic organelles?

    <p>Membranous and Non-membranous</p> Signup and view all the answers

    The _____ is the structural and functional unit of life.

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

    Which of the following is an example of a non-membranous organelle?

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

    Which component of the cell membrane is primarily responsible for the structure and fluidity?

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

    Integral proteins span the entire thickness of the phospholipid bilayer.

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

    What type of transport occurs against the concentration gradient?

    <p>Active transport</p> Signup and view all the answers

    The component of the cell membrane that includes sugar chains linked to proteins is called __________.

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

    What is the primary function of the cell coat (glycocalyx)?

    <p>Cell recognition</p> Signup and view all the answers

    Cholesterol is located exclusively on the outer surface of the cell membrane.

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

    Name the two types of proteins found in the cell membrane.

    <p>Integral proteins and peripheral proteins</p> Signup and view all the answers

    Passive diffusion involves the movement of substances __________ their concentration gradient.

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

    Match the transport types to their descriptions:

    <p>Passive diffusion = Movement without assistance Facilitated diffusion = Movement with carrier protein Active transport = Movement against concentration gradient Bulk transport = Transport of large molecules via vesicles</p> Signup and view all the answers

    Glycolipids are formed by linking sugar chains to proteins.

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

    What is the primary process by which a cell absorbs solid particles such as bacteria?

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

    Exocytosis is used for the absorption of nutrients into the cell.

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

    What structure forms to enclose extracellular substances during endocytosis?

    <p>A membrane vesicle or sac</p> Signup and view all the answers

    In receptor-mediated endocytosis, cell membrane receptor proteins bind to specific __________.

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

    Match the forms of endocytosis with their descriptions:

    <p>Phagocytosis = Engulfing of solid particles Pinocytosis = Engulfing of fluid droplets Receptor-mediated endocytosis = Binding with specific substances Exocytosis = Exporting substances out of cells</p> Signup and view all the answers

    What is one of the main functions of cell coat?

    <p>Cell identity recognition</p> Signup and view all the answers

    The process of exocytosis involves the cell taking in fluid droplets.

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

    What is the fate of the vesicle formed during endocytosis?

    <p>Fusion with a lysosome for digestion</p> Signup and view all the answers

    Substances released during exocytosis are enclosed in a small __________.

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

    Which of the following substances are typically secreted through exocytosis?

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

    Study Notes

    Structure of the Cell

    • Cells are the fundamental structural and functional units of living organisms.
    • Size ranges from 4 to 150 micrometers.
    • Shapes include rounded, oval, flat, cubical, columnar, and polygonal.
    • Functions encompass secretion, absorption, sensation, and contraction.

    Cell Components

    • Composed of cytoplasm, nucleus, organelles, and inclusions.

    Cytoplasmic Organelles vs. Inclusions

    • Cytoplasmic Organelles:
      • Living, permanent structures vital for metabolic functions.
      • Examples include mitochondria, endoplasmic reticulum, and Golgi apparatus.
    • Cytoplasmic Inclusions:
      • Non-living, transient structures not essential for cell viability.
      • Metabolically inert with examples including lipids and pigments.

    Types of Cytoplasmic Organelles

    • Membranous Organelles: Surrounded by membranes, contain enzymes.

      • Include cell membrane, mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, and peroxisomes.
    • Non-Membranous Organelles: Not surrounded by membranes, generally lack enzymes.

      • Examples are ribosomes, cytoskeleton (comprising filaments and microtubules), and proteasomes.

    Cell Membrane

    • Acts as the outer boundary of the cell, separating cytoplasm from extracellular fluid.
    • Structure visible under an electron microscope as a trilamellar membrane.
    • Consists of a phospholipid bilayer interspersed with cholesterol, integral proteins, and peripheral proteins.

    Molecular Structure of Cell Membrane

    • Lipid Component:

      • Phospholipids arranged in two layers with hydrophilic heads outward and hydrophobic tails inward.
    • Protein Component:

      • Peripheral proteins are small and located on either surface.
      • Integral proteins span the bilayer, embedding within the phospholipid layers.
    • Carbohydrate Component:

      • Found only on the outer surface; includes glycoproteins (sugar chains linked to proteins) and glycolipids (sugar chains linked to phospholipids).

    Glycocalyx (Cell Coat)

    • Composed of glycoproteins and glycolipids on the outer membrane.
    • Appears fuzzy under an electron microscope.
    • Functions include protection, identity recognition, and interaction with other cells.

    Functions of Cell Membrane

    • Transport of Materials:
      • Passive diffusion allows unassisted movement down a concentration gradient.
      • Facilitated diffusion relies on carrier proteins for transporting ions and small molecules.
      • Active transport moves substances against their concentration gradient (e.g., Na/K pump).
      • Bulk transport (vesicular transport) includes endocytosis and exocytosis.

    Endocytosis

    • Process by which the cell engulfs extracellular substances via a membrane vesicle.
    • The vesicle can fuse with lysosomes for digestion.
    • Types include:
      • Phagocytosis: Engulfment of solid particles.
      • Pinocytosis: Engulfment of fluid droplets.
      • Receptor-mediated Endocytosis: Selective uptake of substances via specific receptor proteins.

    Exocytosis

    • Mechanism for expelling substances from the cell, crucial for secretion of hormones and mucus.
    • Involves vesicles that migrate to the cell membrane and release contents upon fusion.

    Functions of Cell Coat

    • Provides protection and stabilization.
    • Aids in cell identity and recognition.
    • Facilitates cell-cell interactions and acts as receptors for pathogens.

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    Description

    This quiz covers the fundamental aspects of cell structure, including the classification of cytoplasmic organelles and the structure and function of the cell membrane. Designed for students in histology and cell biology, it aims to reinforce key concepts about the cell as a structural and functional unit. Test your understanding of these essential biological principles!

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