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.