Cell Structure

A2.2 - Cell Structures and Functions

Page 1

  • Cell Structures

  • Organelles

  • Membranes and Membrane Transport

Page 2

  • Cells as Basic Units

    • Cells are the smallest structural units capable of energy use for sustaining life.

    • Cell Theory:

      1. All living organisms are composed of one or more cells.

      2. Cells are the basic unit of life.

      3. Cells arise from pre-existing cells.

    • Exceptions include viruses and atypical cells.

  • Microscopy Skills:

    1. Prepare a thin layer of cells/tissues.

    2. Lay specimen on slide.

    3. Use water or stain for visibility.

    4. Lower cover slip carefully.

    5. Use coarse and fine focus for clarity.

Page 3

  • Calculating Magnification:

    • Magnification = Image Size / Actual Size

    • Examples of calculations for clarity between image and actual sizes in nanometers.

Page 4

  • Developments in Microscopy:

    • Electron Microscopy uses electron beams for higher resolution compared to light microscopes.

    • Differences between Light and Electron Microscopes:

      • Advantages: High resolution, living cells in color, easy to use.

      • Disadvantages: High cost, requires cell killing.

    • Types of Electron Microscopy:

      1. Transmission Electron Microscopy (TEM): Internal structures.

      2. Scanning Electron Microscopy (SEM): Surface structures.

Page 5

  • Cryo-EM and Fluorescent Staining:

    • Cryogenic Microscopy shows proteins in functional states by freezing samples and reducing damage from the electron beam.

    • Immunofluorescence uses fluorescence to highlight specific cell structures for easier visual identification.

Page 6

  • Cell Diagrams:

    • Key parts of Animal and Prokaryotic Cells:

      • Mitochondria, Ribosomes, Plasma Membrane, Nucleus, etc.

Page 7

  • Common Cell Structures:

    • Plasma Membrane, Cytoplasm, DNA, Ribosomes are essential to all living cells.

    • Differences between Prokaryotic and Eukaryotic cells are discussed.

Page 8

  • Eukaryotic Cell Structures:

    • Distinct structures found in plant, animal, and fungal cells with focus on organelle functions like the nucleus, ER, and Golgi Apparatus.

Page 9

  • Differences between Prokaryotic and Eukaryotic Cells:

    • Prokaryotes: Simpler structure, smaller size, binary fission division.

    • Eukaryotes: Complex structure, larger size, mitosis and meiosis division.

Page 10

  • Differences Among Eukaryotic Cells:

    • Variations in structures and functions across animals, fungi, and plants.

Page 11

  • Atypical Cell Structures:

    • Red Blood Cells (anucleate), Aseptate Fungal Hyphae (no separations), Skeletal Muscle (multiple nuclei) are discussed as examples of discrepancies.

Page 12

  • Origin of Eukaryotic Cells - Endosymbiosis:

    • Evidence of evolution from a common ancestor; subjects such as mitochondria and chloroplasts.

Page 13

  • Evidence of Endosymbiosis:

    • Structural and genetic similarity of mitochondria and chloroplasts to prokaryotes.

Page 14

  • Cell Differentiation:

    • Multicellularity allows specialization and larger body size, determined by gene expression patterns.

Page 15

  • Organelles as Subunits:

    • Organelles perform specific functions and may contain various numbers of membranes.

Page 16

  • Compartmentalization Advantages:

    • Controlled conditions allow specific functions, enhancing metabolic efficiency.

Page 17

  • Nuclear Membrane Functions:

    • Protects DNA, regulates transport of materials, and has large pores for macromolecule movement.

Page 18

  • Nuclear Pore Complexes:

    • Enable selective transport between the nucleus and cytoplasm.

Page 19

  • Ribosomes:

    • Role in protein synthesis, differences between free and membrane-bound ribosomes outlined.

Page 20

  • Endoplasmic Reticulum Functions:

    • Structure and function of the Rough and Smooth ER within the endomembrane system.

Page 21

  • Vesicle Formation:

    • Mechanisms of vesicle transport and clathrin's role in vesicle formation.

Page 22

  • Vesicle Fusion:

    • Importance of vesicle membrane merging with cell membranes for transporting substances.

Page 23

  • Role of Gated Ion Channels:

    • Function in nerve cells to control ion flow and maintain membrane potential.

Page 24

  • Plasma Membrane Structure:

    • Bilayer of phospholipids forming selectively permeable barriers for substance regulation.

Page 25

  • Simple Diffusion Mechanism:

    • Describes passive movement across membranes influenced by concentration gradient, temperature, and surface area.

Page 26

  • Membrane Bound Proteins Functions:

    • Various receptor proteins aiding in signal transduction and transport mechanisms.

Page 27

  • Transport Mechanisms:

    • Differences among facilitated diffusion, active transport, and simple diffusion.

Page 28

  • Active Transport Overview:

    • Importance of pump proteins in moving substances against concentration gradients using ATP.

Page 29

  • Membrane Selectivity:

    • Explanation of selective permeability in facilitated diffusion and active transport.

Page 30

  • Fluid Mosaic Model:

    • Describes phospholipid bilayer structure and the hydrophobic/hydrophilic nature of membranes.

Page 31

  • Impact of Fatty Acid Composition:

    • Relationship between fatty acid types and membrane fluidity.

Page 32

  • Cholesterol's Role:

    • Modulates membrane fluidity, essential for maintaining structural integrity at varying temperatures.

Page 33

  • Vesicle Formation and Function:

    • Overview of processes involved in vesicle endocytosis and exocytosis.

Page 34

  • Neuron Function and Gated Channels:

    • Mechanisms behind neuron action potentials, involving Na+/K+ pumps and channel gating.

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