6 Cells Lecture Slides

Overview of Chapter 6: A Tour of the Cell

• Various forms of microscopy are used to study cells

• Differences between prokaryotic and eukaryotic cells

• The structure and functions of organelles within eukaryotic cells

• The significance of the extracellular matrix and cell junctions

Key Concepts

Microscopy Techniques

• **Types of Microscopes: **

  • Light Microscope (LM): Uses visible light for magnification, max effective magnification of 1000x.

  • Electron Microscopes (EMs):

    • Scanning Electron Microscope (SEM): 3D images of surface structures.

    • Transmission Electron Microscope (TEM): Studying the internal structure of cells.

• Key Parameters:

  • Magnification: Ratio of image size to real size.

  • Resolution: Clarity of the image, the ability to distinguish two points.

  • Contrast: Differences in brightness in the specimen.

• Recent Advances:

  • Cryo-electron microscopy allows observation of specimens at low temperatures without preservatives.

Types of Cells

• Prokaryotic Cells:

  • Lack a nucleus, have a nucleoid with DNA.

  • No membrane-bound organelles.

• Eukaryotic Cells:

  • Genetic material enclosed in a nucleus.

  • Contain membrane-bound organelles.

  • Typically larger than prokaryotic cells.

Eukaryotic Cell Structure

• Organelles:

  • Nucleus: Contains DNA, site of RNA synthesis.

  • Ribosomes: Protein synthesis, located in cytosol or bound to ER.

  • Endoplasmic Reticulum (ER):

    • Rough ER: Studded with ribosomes, synthesizes glycoproteins.

    • Smooth ER: Synthesizes lipids, detoxifies drugs.

  • Golgi Apparatus: Modifies, sorts, and packages proteins.

  • Lysosomes: Digests macromolecules, performs autophagy.

  • Vacuoles: Storage compartments, varying functions.

Energy Transformation

• Mitochondria:

  • Sites of cellular respiration, generate ATP.

  • Enveloped by double membranes with internal compartments for metabolic reactions.

• Chloroplasts:

  • Found in plants, sites of photosynthesis, contain chlorophyll.

Cytoskeleton Functions

• Three types:

  • Microtubules: Thickest, involved in shape, movement of organelles, chromosome separation.

  • Microfilaments (Actin filaments): Support cell shape, enable motility.

  • Intermediate Filaments: Provide structural support, anchor organelles.

Cell Interactions

• Cell Wall (Plant Cells):

  • Maintains shape, prevents excessive water uptake.

• Extracellular Matrix (ECM) (Animal Cells):

  • Involved in communication and regulation of cell behavior.

• Cell Junctions:

  • Types include tight junctions, desmosomes, and gap junctions, crucial for communication between adjacent cells.

Conclusion

• A cell functions as an integrated unit where components interact, emphasizing the complexity and cooperation required for cellular processes.