Lecture 2 Review
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What is the primary advantage of using Electron Microscopy over Light Microscopy?

  • It is easier to label specific proteins.
  • It requires less effort to achieve a 3D view.
  • It allows for live cell imaging.
  • It provides a better resolution and more detail. (correct)

    • Which organelle can be visualized using GFP-labeled proteins?

  • Nucleus
  • Mitochondria (correct)
  • Chloroplasts
  • Ribosomes

    • What process allows for compartmentalization of functions within eukaryotic cells?

  • Exocytosis
  • Presence of internal membranes (correct)
  • Cellular respiration
  • Endocytosis

    • Which of the following statements about Electron Microscopy is FALSE?

    <p>It can provide a detailed 3D view of cells easily.</p> Signup and view all the answers

    What limitation does Electron Microscopy have when comparing it to Light Microscopy?

    <p>It is more labor-intensive and cannot be used on live samples.</p> Signup and view all the answers

    What is a role of internal membranes in eukaryotic cells?

    <p>To separate competing biochemical reactions.</p> Signup and view all the answers

    Which technique can visualize organelles through fluorescence?

    <p>Fluorescence Microscopy</p> Signup and view all the answers

    What is one of the challenges presented by Electron Microscopy?

    <p>It is difficult to label specific proteins.</p> Signup and view all the answers

    What is the primary purpose of using an antibody in the context of immunofluorescence?

    <p>To specifically bind to the protein of interest</p> Signup and view all the answers

    What wavelength does a fluorescent molecule absorb to become excited?

    <p>494 nm</p> Signup and view all the answers

    What is the role of detergent in the indirect immunofluorescence process?

    <p>To permeabilize the cell membrane for antibody access</p> Signup and view all the answers

    What is the significance of washing away unbound antibodies during immunofluorescence?

    <p>To ensure only specifically bound antibodies remain</p> Signup and view all the answers

    Which statement is true about the use of green fluorescent protein (GFP)?

    <p>GFP is sensitive enough to detect very low protein concentrations</p> Signup and view all the answers

    What is one limitation of indirect immunofluorescence?

    <p>It can only be performed on fixed (non-living) cells</p> Signup and view all the answers

    How does fluorescence sensitivity compare to other detection methods?

    <p>Fluorescence offers greater sensitivity for detecting target molecules</p> Signup and view all the answers

    What is the result of cross-linking in the fixing process of cells for immunofluorescence?

    <p>Cell structures are stabilized for visualization</p> Signup and view all the answers

    What is the primary function of resolving power in microscopy?

    <p>The ability to distinguish two close objects</p> Signup and view all the answers

    Which type of microscope has the highest resolving power?

    <p>Electron microscope</p> Signup and view all the answers

    Which unit is used to measure structures at the cellular level?

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

    What is the wavelength range of visible light that is relevant for light microscopy?

    <p>400-700 nm</p> Signup and view all the answers

    What technique is used to visualize a specific protein within a cell?

    <p>Indirect immunofluorescence</p> Signup and view all the answers

    If a light microscope can resolve objects about 200 nm apart, what does this indicate about its capabilities compared to an electron microscope?

    <p>It is less effective at resolving closely spaced structures.</p> Signup and view all the answers

    What is the abundance of different types of proteins in human cells?

    <p>Approximately 20,000 different proteins</p> Signup and view all the answers

    How does the resolving power of a microscope depend on the wavelength of illumination?

    <p>Shorter wavelengths provide higher resolution.</p> Signup and view all the answers

    What is one primary function of the plasma membrane?

    <p>Separate the cell from the environment</p> Signup and view all the answers

    Which statement accurately describes the difference between cytoplasm and cytosol?

    <p>Cytoplasm contains organelles, while cytosol is the fluid portion.</p> Signup and view all the answers

    What is the main function of the nucleus in a cell?

    <p>Contains cellular DNA and facilitates replication and transcription</p> Signup and view all the answers

    What is a key function of the endoplasmic reticulum (ER)?

    <p>Modification of secretory proteins</p> Signup and view all the answers

    What defines the outer membrane of mitochondria?

    <p>It separates the mitochondrion from the cytosol.</p> Signup and view all the answers

    Which of the following is NOT a function of mitochondria?

    <p>Modification of secretory proteins</p> Signup and view all the answers

    How do mitochondria relate to the theory of endosymbiosis?

    <p>They evolved from engulfed organelles of other cells.</p> Signup and view all the answers

    What role do nuclear pores play in the cell?

    <p>They facilitate the transport of molecules between the nucleus and cytoplasm.</p> Signup and view all the answers

    What is the primary function of the Golgi apparatus?

    <p>Modify and sort proteins</p> Signup and view all the answers

    What characterizes the inner membrane of mitochondria?

    <p>It is folded into cristae to increase surface area for ATP production.</p> Signup and view all the answers

    Where does most protein synthesis occur in a cell?

    <p>In the cytosol</p> Signup and view all the answers

    What component of the nucleus is involved in ribosome assembly?

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

    Which cellular structure is primarily responsible for lipid synthesis?

    <p>Smooth endoplasmic reticulum</p> Signup and view all the answers

    What do cristae in mitochondria enhance?

    <p>Surface area for ATP production</p> Signup and view all the answers

    Study Notes

    Poll Everywhere Account Setup

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    • Students will respond in real-time when the instructor activates a poll through the app or website.

    Cell Biology Reading: ECB6 1-39, 515-520

    • The expected learning objectives include understanding size scales in cell biology and the uses of light and electron microscopy.
    • Students should also be able to describe major organelles within a cell.

    Size Scales Relevant to Cell Biology

    • The size scales presented include 20 mm, 2mm, 0.2mm, 20 µm, 2 µm, 0.2 µm, 20 nm, 2 nm, and 0.2 nm.
    • Various units of measurement are listed below:
      • 1 m = 10³ mm (millimeter) = 10⁶ µm (micrometer) = 10⁹ nm (nanometer)
      • 1 mm = 10⁻³ m
      • 1 µm = 10⁻⁶ m
      • 1 nm = 10⁻⁹ m

    Resolving Power (Resolution)

    • Resolving power is the ability to distinguish two close objects.
    • Light microscopes use visible light (wavelengths of 400-700 nm) and can distinguish objects approximately 200 nm apart.
    • Electron microscopes use a much smaller wavelength (about 0.003 nm), enabling much higher resolution.
    • Higher magnification (100x, 1000x, and 100,000x) is possible with electron microscopes.

    Visualizing Organelles

    • Cells contain thousands of different proteins.

    • The abundance of each type varies, from a few hundred to millions of copies per cell.

    • Methods like immunofluorescence (IF) can be used to visualize specific proteins within cells.

    • IF uses antibodies tagged with fluorescent molecules to target and mark the proteins of interest.

    Indirect Immunofluorescence (IF)

    • Specificity: The method uses antibodies which bind to a specific protein of interest.
    • Sensitivity: The use of fluorescent molecules in the process aids in a higher sensitivity.

    Fixing and Permeabilizing

    • Cells are fixed to prevent the disruption of their structure and permeabilized to allow antibodies to enter.

    Green Fluorescent Protein (GFP)

    • Proteins fused with GFP can be viewed in living cells.
    • GFP absorbs UV/blue light and emits green light.

    Transmission Electron Microscopes (TEM)

    • TEMs are used to view thin samples in a vacuum.
    • The biological molecules are stained with heavy metals which scatter electrons.

    Organelle Functions

    • Different organelles perform specific functions within cells.

    Cytosolic Components

    • Cytosol contains a large proportion of RNA, proteins and ribosomes

    The Nucleus

    • The nucleus contains most of the cell's DNA (the ‘genome’).
    • Replication and transcription occur within the nucleus.
    • The nucleolus is a region within the nucleus where ribosomes are assembled.

    Nuclear envelope

    • The nuclear envelope surrounds the nucleus.
    • It is made up of two membranes: inner & outer membrane.

    Endoplasmic Reticulum (ER)

    • The ER is a primary site for synthesizing lipids and membrane proteins.
    • The ER secretes proteins.

    Golgi Apparatus

    • The Golgi apparatus modifies secreted proteins.
    • The Golgi apparatus is a sorting station for vesicle trafficking.

    Mitochondria

    • Mitochondria are major sites for ATP production ("oxidative phosphorylation").
    • They also synthesize iron-sulfur clusters.
    • They are essential for producing central metabolites.

    Chloroplasts

    • Chloroplasts contain chlorophyll-containing membranes (thylakoids).
    • Chloroplasts are responsible for photosynthesis.

    Internal Membranes in Eukaryotes

    • Internal membranes allow eukaryotic cells to compartmentalize different reactions
    • Internal membranes increase surface area per volume.

    Cytoplasm vs Cytosol

    • Cytoplasm includes everything between the plasma membrane and the nucleus.
    • Cytosol is the soluble portion of the cytoplasm, excluding the organelles.

    Cellular Organelle Size Estimates

    Values/percentages reflecting the proportion of total cell volume occupied by specific organelles are provided.

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    Related Documents

    L2 Slides - F24 Cell Biology PDF

    Description

    Test your knowledge on microscopy techniques, specifically focusing on Electron Microscopy and immunofluorescence. Understand the advantages, limitations, and applications of these methods in visualizing cellular structures and functions. Whether you're studying organelles or internal membranes, this quiz covers essential concepts in cell biology.

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