Unit 3: Cells and Cell Transport Quiz

Unit 3: Cells and Cell Transport Study Outline

• Scientists and Cell Theory:
  • Anton Van Leeuwenhoek: First microscope, "animalcules"
  • Robert Hooke: First compound microscope, observed cork cells, coined the term "cell"
  • Matthias Schleiden and Theodor Schwann: All plants and animals are made up of cells.
  • Rudolf Virchow: Cells come from preexisting cells.

Microscope Parts and Functions

• Ocular Lens/Eyepiece: Magnifies the image
• Objective Lenses (Scanning, Low, High Power): Magnify the image
• Body Tube: Connects eyepiece to objective lenses
• Nosepiece: Holds the objective lenses
• Coarse Adjustment: Focuses image at low power
• Fine Adjustment: Sharpens image at all powers
• Arm: Supports the microscope, used for carrying
• Base: Supports the microscope, used for carrying
• Stage: Platform for the slide
• Stage Clips: Hold the slide in place
• Diaphragm: Controls the amount of light passing through the specimen

Microscope Procedure

• Start with the lowest power (scanning).
• Use the coarse adjustment to bring the image into focus.
• Center the image before changing to a higher power.
• Use the fine adjustment knob for higher powers.
• Note image is upside down and backwards.

Calculating Total Magnification

• Multiply the ocular lens power (typically 10x) by the objective lens power.

Troubleshooting

• Image too dark: Adjust the diaphragm.
• Image fuzzy: Use the fine adjustment knob.
• Only part of the image visible at high power: Center the image before increasing power.

Techniques

• Wet Mount: Apply a coverslip at a 45-degree angle to avoid trapping air bubbles.
• Applying a stain or solution: Place a paper towel on one side of the coverslip and the stain/solution on the opposite side.

Cell Theory

• All living organisms are composed of one or more cells.
• The cell is the basic unit of structure and organization in organisms.
• Cells come from preexisting cells.

Exceptions to Cell Theory

• Mitochondria and chloroplasts: Have their own DNA and can replicate independently.
• Viruses: Cannot replicate on their own and are not composed of cells.

Cells and Organelles

• Prokaryotes: Simpler cells, fewer organelles, no nucleus (bacteria).
• Eukaryotes: More complex cells, membrane-bound organelles, nucleus (plants, animals, fungi, protists).

Organelles (Animal and Plant Cell):

• Nucleus: Contains DNA, controls cell processes.
  • Nucleolus: Ribosome production site.
  • Nuclear membrane: Controls what enters and exits the nucleus.
• Ribosomes: Protein synthesis sites.
• Rough Endoplasmic Reticulum: Contains ribosomes, makes proteins.
• Smooth Endoplasmic Reticulum: Makes lipids.
• Golgi Apparatus: Modifies, packages, and transports proteins.
• Lysosomes: Contain digestive enzymes.
• Cytoskeleton: Internal support and scaffolding.
• Mitochondria: Site of cellular respiration.
• Vacuole: Stores materials (large in plant cells).
• Chloroplasts: Site of photosynthesis (plant cells only).
• Centrioles: Involved in cell division (animal cells only).
• Cell Wall: Provides support (plant cells only).
• Plasma Membrane: Controls what enters and exits the cell.
• Cytoplasm: Fluid inside the cell.

Cell Membrane

• Fluid Mosaic Model: Phospholipid bilayer with embedded proteins.
• Selective Permeability: Allows some substances to pass through, but not others.
• Phospholipid Bilayer: Two layers of phospholipids with hydrophilic heads and hydrophobic tails.
• Proteins: Receptor, transport, and enzymes.
• Passive Transport: No energy required; molecules move from high to low concentration (diffusion and facilitated diffusion, osmosis).
• Active Transport: Requires energy (ATP) to move molecules against the concentration gradient. (Ex: Endocytosis/Exocytosis)

Cell Membrane Transport:

• Active transport: requires energy (ATP) to transport molecules across the membrane.
• Passive transport: does not require energy; molecules move from high to low concentration.
  • Diffusion: Movement of molecules from an area of high to low concentration.
  • Osmosis: The diffusion of water across a selectively permeable membrane.
    • Hypertonic: Solution with higher solute concentration. Water moves out of the cell.
    • Hypotonic: Solution with lower solute concentration. Water moves into the cell.
    • Isotonic: Solution with equal solute concentration. There is no net movement of water.
• Facilitated Diffusion: Movement of molecules through transport proteins.

Cell Membrane Transport: Specific Methods

• Endocytosis: Taking materials into the cell.

  • Phagocytosis: Engulfing large solid particles (e.g., food).
  • Pinocytosis: Engulfing liquids.
  • Receptor-mediated endocytosis: Taking in specific molecules.

• Exocytosis: Materials leaving the cell.

Diffusion Through a Membrane State Lab

• Artificial Cells

  • Dialysis tubing mimics selectively permeable membranes.
  • Starch does not diffuse, glucose and iodine do.
  • Results are observed through indicator solutions (iodine as starch indicator, Benedict's solution for glucose).

• Red Onion Cells:

  • Osmosis observations in the onion cells and effects of salt/water solution.

Test your knowledge on the foundational concepts of cells and cell transport. This quiz covers important scientists in cell theory and the various parts of a microscope along with their functions. Perfect for students studying biology and cell structure!