Cell Structure and Functions
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Questions and Answers

What is the primary function of the plasma membrane?

  • To provide structural support to the cell
  • To facilitate cellular respiration
  • To store genetic information
  • To control the exchange of materials in and out of the cell (correct)

    • Which component is NOT part of the plasma membrane structure?

  • Integral membrane proteins
  • Nuclear envelope (correct)
  • Phospholipid bilayer
  • Cholesterol

    • What is the composition of cytosol primarily made of?

  • Water, proteins, and salts (correct)
  • Nucleic acids and fatty acids
  • Lipids and carbohydrates
  • Cholesterol and neurotransmitters

    • What role does the nucleus play in the cell?

    <p>It directs all cellular activities (A)</p> Signup and view all the answers

    Which of the following statements about integral proteins is correct?

    <p>They are embedded entirely through the plasma membrane. (A)</p> Signup and view all the answers

    What discovery is attributed to Robert Brown in 1833?

    <p>The nucleus of the cell (C)</p> Signup and view all the answers

    Which function is NOT associated with the cytoplasm?

    <p>Directing cellular activities (C)</p> Signup and view all the answers

    How does cholesterol contribute to the plasma membrane?

    <p>By maintaining membrane integrity and fluidity (D)</p> Signup and view all the answers

    What is the primary component of the cytoskeleton?

    <p>Proteins (C)</p> Signup and view all the answers

    Which of the following best describes peripheral proteins?

    <p>Attached to the surface of the membrane (A)</p> Signup and view all the answers

    What is the primary function of lysosomes in the cell?

    <p>Digestion of cellular materials (D)</p> Signup and view all the answers

    Which process do lysosomes employ to clean up cellular waste?

    <p>Autophagy (C)</p> Signup and view all the answers

    What role do peroxisomes play in a cell?

    <p>Breakdown of fatty acids and detoxification (C)</p> Signup and view all the answers

    What distinguishes the Golgi apparatus from other organelles?

    <p>It modifies and packages molecules. (D)</p> Signup and view all the answers

    How do centrioles function during cell division?

    <p>They assist in assembling spindle fibers. (D)</p> Signup and view all the answers

    Which type of cell would contain the highest concentration of mitochondria?

    <p>Muscle cells (D)</p> Signup and view all the answers

    In what shape are mitochondria typically found?

    <p>Oval (B)</p> Signup and view all the answers

    What happens during the process of phagocytosis?

    <p>Cells take in food. (A)</p> Signup and view all the answers

    What is the primary role of the centrosome in a cell?

    <p>To facilitate microtubule organization. (B)</p> Signup and view all the answers

    What are the 'suicide bags' of the cell referring to?

    <p>Lysosomes (B)</p> Signup and view all the answers

    What is the primary function of the nucleolus within the nucleus?

    <p>Site of ribosome synthesis (B)</p> Signup and view all the answers

    Which organelle is NOT part of the endomembrane system?

    <p>Centrosomes (D)</p> Signup and view all the answers

    What distinguishes rough endoplasmic reticulum from smooth endoplasmic reticulum?

    <p>Presence of ribosomes on its surface (D)</p> Signup and view all the answers

    What role do vacuoles play within a cell?

    <p>Storage of chemicals and breakdown of large molecules (C)</p> Signup and view all the answers

    Why is the smooth endoplasmic reticulum abundant in liver cells?

    <p>For detoxifying hydrophobic chemicals (C)</p> Signup and view all the answers

    How does the endoplasmic reticulum contribute to the function of ribosomes?

    <p>By modifying proteins synthesized by ribosomes (C)</p> Signup and view all the answers

    What type of proteins does the rough endoplasmic reticulum primarily produce?

    <p>Membrane proteins and proteins for export (D)</p> Signup and view all the answers

    Which part of the endomembrane system is mainly responsible for modifying and packaging proteins and lipids?

    <p>Golgi Apparatus (B)</p> Signup and view all the answers

    What is the primary structural feature of the endoplasmic reticulum?

    <p>Series of interconnected membranous sacs and tubules (D)</p> Signup and view all the answers

    What type of environment do vacuoles and lysosomes thrive in?

    <p>Acidic environment (D)</p> Signup and view all the answers

    What is the primary function of the mitochondria's inner membrane?

    <p>To increase surface area for cellular metabolism (A)</p> Signup and view all the answers

    Which structure is not found within the chloroplast stroma?

    <p>ATP Synthase (C)</p> Signup and view all the answers

    What is the role of the outer membrane of the mitochondria?

    <p>To selectively allow certain substances to pass through (A)</p> Signup and view all the answers

    What is found in the intermembrane space of the mitochondria?

    <p>None of the above (D)</p> Signup and view all the answers

    What process occurs in the chloroplasts?

    <p>Photosynthesis (B)</p> Signup and view all the answers

    How is energy released from ATP?

    <p>By hydrolysis of the third phosphate group (B)</p> Signup and view all the answers

    Which of the following is true about the chloroplast's inner membrane?

    <p>It regulates the passage of materials in and out (A)</p> Signup and view all the answers

    What function does the thylakoid system serve in chloroplasts?

    <p>Carrying out the light-dependent reactions of photosynthesis (A)</p> Signup and view all the answers

    What is the approximate thickness of the intermembrane space in chloroplasts?

    <p>10-20 nanometers (A)</p> Signup and view all the answers

    Which component is responsible for transporting molecules in and out of the mitochondria?

    <p>Pores in the outer membrane (C)</p> Signup and view all the answers

    Flashcards

    Plasma Membrane Function

    Controls what enters and exits the cell, protecting internal organelles.

    Plasma Membrane Structure

    A phospholipid bilayer with embedded proteins, cholesterol, and other molecules.

    Cytoplasm Function

    The region between the plasma membrane and the nucleus, containing organelles and cytosol.

    Cytosol Composition

    Fluid component of the cytoplasm, mostly water, proteins, and salts.

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    Nucleus Function

    Controls cell activities and determines cell characteristics.

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    Nucleus Discovery

    Discovered by Robert Brown in 1833.

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    Plasma Membrane Components

    Phospholipids, proteins, cholesterol, cytoskeletal filaments, and more.

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    Cytoplasm Function (2)

    Suspends organelles, determines cell shape, allows cell movement.

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    Cytoplasm Important Note

    The cytoplasm occupies most of the cell's volume.

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    Nucleus Vital Role

    The nucleus directs the cell's functions.

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    Nuclear membrane function

    Encloses the nucleus, keeping it separate from other cell parts.

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    Nucleolus' role

    Site where ribosomes are made.

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    Endomembrane system

    Group of membranes & organelles modifying, packaging, & transporting lipids/proteins.

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    Rough ER function

    Makes membrane proteins and proteins exported out of cell.

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    Smooth ER function

    Synthesizes lipids, detoxifies chemicals.

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    Ribosome function

    Site of protein production.

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    Vacuole function

    Stores chemicals, breaks down some molecules (like lysosomes in animal cells).

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    ER membrane

    Phospholipid bilayer continuous with nuclear envelope.

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    Golgi Apparatus

    Organelle that modifies and packages proteins.

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    Lysosome function

    Organelle capable of breaking down molecules.

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    Lysosomes' self-destruct

    Lysosomes can self-destruct to protect other organelles.

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    Peroxisomes function

    Peroxisomes break down fatty acids and detoxify substances.

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    Golgi Apparatus function

    Modifies, sorts, and packages proteins for storage or transport.

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    Golgi Apparatus structure

    Stacks of flattened sacs called cisternae with a cis and trans side.

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    Centrosome function

    Helps organize microtubules for cell division.

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    Mitochondria function

    Generate ATP (energy) through cellular respiration.

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    Mitochondria structure

    Oval-shaped organelles with a double membrane.

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    Centrosome structure

    Two centrioles and pericentriolar material.

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    Cell Food Intake

    Cells take in food through Phagocytosis.

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    Mitochondrial Membranes

    The mitochondria has two membranes, the outer membrane and the inner membrane. The outer membrane is selectively permeable and surrounds the mitochondria. The inner membrane folds inward creating cristae to increase surface area for cellular metabolism.

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    Cristae Function

    The folds of the inner mitochondrial membrane, called cristae, increase the surface area for cellular metabolism, allowing for more efficient energy production.

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    Mitochondrial Matrix

    The space enclosed by the inner mitochondrial membrane, containing important enzymes, DNA, and ribosomes, involved in cellular respiration.

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    Intermembrane Space

    The narrow space situated between the outer and inner mitochondrial membranes, playing a key role in ATP synthesis.

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    ATP Synthesis

    The process of generating ATP, the main energy currency of the cell, from ADP and inorganic phosphate. This occurs in the mitochondria through the electron transport chain and ATP synthase.

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    Chloroplast Function

    The site of photosynthesis in plants and algae, converting light energy into chemical energy in the form of sugars.

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    Chloroplast Membranes

    Chloroplasts have three membranes: an outer membrane, an inner membrane, and the thylakoid membrane system.

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    Thylakoid System

    A system of interconnected, flattened sacs within the chloroplast, containing chlorophyll and other pigments involved in light-dependent reactions of photosynthesis.

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    Stroma Function

    The fluid-filled space within the chloroplast, containing enzymes involved in carbon fixation and other processes of photosynthesis.

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    Chloroplast DNA

    Circular DNA found within the chloroplast, responsible for coding proteins involved in photosynthesis.

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    Study Notes

    Cell Structure and Functions

    • Cells are the basic units of life
    • Cells have different structures and functions
    • Cells have major parts
    • Each part has unique functions

    Major Parts of the Cell

    • Plasma Membrane: Outer covering that separates a cell's interior from its surroundings.
    • Cytoplasm: Jelly-like substance inside the cell, containing other cellular components.
    • Nucleus: Serves as the cell's control center, directing all its activities.

    Plasma Membrane Details

    • Encloses and protects organelles
    • Protects from harm from foreign materials
    • Made up of phospholipids forming a bilayer, cholesterol, proteins
    • Controls the exchange of essential components
    • Obtains chemical messages from other cells.

    Components of Plasma Membrane

    • Phospholipids: Lipids composed of glycerol, fatty acids, and phosphate-linked head groups.
    • Cholesterol: A lipid with four fused carbon rings, located in the membrane's core.
    • Proteins: Help move large molecules or aid in cell recognition. Peripheral proteins are attached on the surface; integral proteins are embedded completely through the membrane.

    Cytoplasm Details

    • Entire region of a cell between the plasma membrane and the nuclear envelope.
    • Mainly water, proteins, and salts.
    • Organelles are suspended within the cytosol, a gel-like solution within cytoplasm.
    • Cytosol makes up about 70% of cellular content and contains both organic and inorganic compounds.
    • Contains enzymes that break down waste and enable metabolic reactions.
    • Allows for cellular expansion and growth.
    • Together with the cytoskeleton, determines cell shape.
    • Accommodates movement for some cell types.

    Nucleus Details

    • Discovered by Robert Brown in 1833.
    • Most vital part of the cell, dubbed the "control center.”
    • Directs all cell activities, determining the cell's appearance and function.
    • Enclosed by a double layer of nuclear membrane to keep it distinct from other cellular components.
    • Nucleolus is the site of ribosome synthesis.
    • Contains chromosomes with tightly-wrapped and coiled DNA.

    Endomembrane System

    • Group of membranes and organelles in eukaryotic cells, working together to modify, package, and transport lipids and proteins.
    • Organelles are commonly linked by structure.
    • Examples include endoplasmic reticulum, ribosomes, vacuoles, Golgi apparatus, lysosomes, peroxisomes, and centrosomes.

    Endoplasmic Reticulum (ER)

    • Collection of interconnected membranous sacs and tubules
    • Modifies proteins and synthesizes lipids
    • Rough ER has ribosomes; smooth ER does not
    • Rough ER makes membrane proteins and proteins for export out of the cell
    • Smooth ER incorporates proteins into cisternae, transports proteins across cytoplasm, synthesizes fatty acids and phospholipids, and detoxifies hydrophobic chemicals.

    Ribosomes

    • Involved in protein synthesis.
    • Present in both prokaryotic and eukaryotic cells.
    • Abundant in developing muscle cells, skin, and hair.

    Vacuoles

    • Fluid-filled vesicles enclosed by a membrane.
    • Has a selectively permeable membrane that allows water passage while retaining smaller molecules.
    • Stores chemicals in the cell.
    • Ability to break down large molecules makes it comparable to lysosomes in animal cells.

    Lysosomes

    • Serve as digestion slots for cellular materials that are due for expiration or are no longer useful.
    • The cell's reprocessing area, breaking down foreign substances to recycle raw materials.
    • Dubbed “suicide bags” capable of self-destruction to save other organelles from being poisoned.
    • Involved in autophagy, the natural process of organelle destruction
    • Also involved in phagocytosis, where cells take in food, and digesting food and wastes (example: macrophages digest bacteria)

    Peroxisomes

    • Small, round organelles enclosed by a single membrane, resembling lysosomes
    • Responsible for self-damage and breaking down fatty acids, detoxifying many poisons
    • Shields cells from damage caused by reactive oxygen species (ROS) molecules

    Golgi Apparatus

    • Stacks of flattened sacs called cisternae.
    • Have a shipping (cis face) and receiving (trans face) side.
    • Receive proteins from the ER.
    • Packages and modifies those proteins for cells. Proteins package into vesicles to be transported out of the cell.

    Centrosome

    • Composed of two centrioles or cylindrical structures with a central cavity.
    • Surrounded by microtubules arranged side by side.
    • Part of the assembly of spindle fibers at cell division and contributes to the successful outcome of mitosis.
    • Found in all eukaryotic cells; assist in arranging microtubules (hollow proteins) for cell division
    • Enable said microtubules to form part of the cell's cytoskeleton, maintaining shape and stabilizing cell structure.

    Mitochondria

    • Oval-shaped organelles found in eukaryotic cells.
    • Considered the “powerhouses” of the cell.
    • Most plentiful in cells requiring significant amounts of energy (e.g., liver and muscle cells).
    • Has two membranes:
      • Outer membrane: Selectively permeable.
      • Inner membrane: Folds inward (cristae) to increase surface area for cellular metabolism. Contains ribosomes and the mitochondria's DNA. Two enclosed spaces are formed: intermembrane space and matrix
    • Sites of cellular respiration, a metabolic process using oxygen to generate ATP extracting energy from sugars, fats, and other fuels.

    Chloroplast

    • Double membrane-bound organelles found in plants and algae.
    • Sites of photosynthesis, converting solar energy into chemical energy in organic compounds like sugars from carbon dioxide and water.
    • Three membranes: outer, inner, and thylakoid system.
    • Outer membrane is semi-porous.
    • Intermembrane space is between the outer and inner membranes.
    • Inner membrane regulates passage of substances, and fatty acids and other substances are synthesized within the membrane.
    • Stroma: protein-rich, aqueous fluid inside the inner membrane outside the thylakoid space. It contains Chloroplast DNA, ribosomes, thylakoid systems, starch granules and other proteins.
    • Thylakoid System: suspended within the stroma, collection of membranous sacs called thylakoids arranged in stacks called grana. Membranes are sites of light reactions of photosynthesis; chlorophyll is found in the thylakoid membranes.

    Adenosine Triphosphate (ATP)

    • Major energy currency of the cell in most energy-consuming activities.
    • When a phosphate group of ATP is removed by hydrolysis, a substantial amount of free energy is released.

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    Cell Structure and Functions PDF

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    Explore the essential components and functionalities of cells in this quiz. Learn about the major parts, including the plasma membrane, cytoplasm, and nucleus. Each section addresses the unique roles these structures play in maintaining cellular health.

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