Cell Structures
Organelles
Membranes and Membrane Transport
Cells as Basic Units
Cells are the smallest structural units capable of energy use for sustaining life.
Cell Theory:
All living organisms are composed of one or more cells.
Cells are the basic unit of life.
Cells arise from pre-existing cells.
Exceptions include viruses and atypical cells.
Microscopy Skills:
Prepare a thin layer of cells/tissues.
Lay specimen on slide.
Use water or stain for visibility.
Lower cover slip carefully.
Use coarse and fine focus for clarity.
Calculating Magnification:
Magnification = Image Size / Actual Size
Examples of calculations for clarity between image and actual sizes in nanometers.
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:
Transmission Electron Microscopy (TEM): Internal structures.
Scanning Electron Microscopy (SEM): Surface structures.
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.
Cell Diagrams:
Key parts of Animal and Prokaryotic Cells:
Mitochondria, Ribosomes, Plasma Membrane, Nucleus, etc.
Common Cell Structures:
Plasma Membrane, Cytoplasm, DNA, Ribosomes are essential to all living cells.
Differences between Prokaryotic and Eukaryotic cells are discussed.
Eukaryotic Cell Structures:
Distinct structures found in plant, animal, and fungal cells with focus on organelle functions like the nucleus, ER, and Golgi Apparatus.
Differences between Prokaryotic and Eukaryotic Cells:
Prokaryotes: Simpler structure, smaller size, binary fission division.
Eukaryotes: Complex structure, larger size, mitosis and meiosis division.
Differences Among Eukaryotic Cells:
Variations in structures and functions across animals, fungi, and plants.
Atypical Cell Structures:
Red Blood Cells (anucleate), Aseptate Fungal Hyphae (no separations), Skeletal Muscle (multiple nuclei) are discussed as examples of discrepancies.
Origin of Eukaryotic Cells - Endosymbiosis:
Evidence of evolution from a common ancestor; subjects such as mitochondria and chloroplasts.
Evidence of Endosymbiosis:
Structural and genetic similarity of mitochondria and chloroplasts to prokaryotes.
Cell Differentiation:
Multicellularity allows specialization and larger body size, determined by gene expression patterns.
Organelles as Subunits:
Organelles perform specific functions and may contain various numbers of membranes.
Compartmentalization Advantages:
Controlled conditions allow specific functions, enhancing metabolic efficiency.
Nuclear Membrane Functions:
Protects DNA, regulates transport of materials, and has large pores for macromolecule movement.
Nuclear Pore Complexes:
Enable selective transport between the nucleus and cytoplasm.
Ribosomes:
Role in protein synthesis, differences between free and membrane-bound ribosomes outlined.
Endoplasmic Reticulum Functions:
Structure and function of the Rough and Smooth ER within the endomembrane system.
Vesicle Formation:
Mechanisms of vesicle transport and clathrin's role in vesicle formation.
Vesicle Fusion:
Importance of vesicle membrane merging with cell membranes for transporting substances.
Role of Gated Ion Channels:
Function in nerve cells to control ion flow and maintain membrane potential.
Plasma Membrane Structure:
Bilayer of phospholipids forming selectively permeable barriers for substance regulation.
Simple Diffusion Mechanism:
Describes passive movement across membranes influenced by concentration gradient, temperature, and surface area.
Membrane Bound Proteins Functions:
Various receptor proteins aiding in signal transduction and transport mechanisms.
Transport Mechanisms:
Differences among facilitated diffusion, active transport, and simple diffusion.
Active Transport Overview:
Importance of pump proteins in moving substances against concentration gradients using ATP.
Membrane Selectivity:
Explanation of selective permeability in facilitated diffusion and active transport.
Fluid Mosaic Model:
Describes phospholipid bilayer structure and the hydrophobic/hydrophilic nature of membranes.
Impact of Fatty Acid Composition:
Relationship between fatty acid types and membrane fluidity.
Cholesterol's Role:
Modulates membrane fluidity, essential for maintaining structural integrity at varying temperatures.
Vesicle Formation and Function:
Overview of processes involved in vesicle endocytosis and exocytosis.
Neuron Function and Gated Channels:
Mechanisms behind neuron action potentials, involving Na+/K+ pumps and channel gating.