Cell Biology Overview

Cell Theory

• All living things are composed of one or more cells.
• All cells originate from pre-existing cells.
• Cells are the fundamental units of structure and function in living organisms.

Organelles

Cell Membrane

• Surrounds both plant and animal cells.

Cell Wall

• Surrounds plant cells, providing structural support.
• Located as an inner layer.

Cytoplasm

• Gelatinous substance that holds organelles in place within the cell.

Mitochondria

• The "powerhouse" of the cell, responsible for energy production.

Chloroplast

• Site of photosynthesis in plant cells.

Vacuole

• Stores water and nutrients.

Lysosome

• Digests and removes cellular waste.

Ribosome

• Synthesizes proteins.

Nucleus

• Controls cellular activities.

Nucleolus

• Produces ribosomes.

Nuclear Membrane

• Encloses the DNA, providing protection.

Nuclear Pores

• Allow passage of DNA materials.

Smooth Endoplasmic Reticulum

• Synthesizes lipids (fats).

Rough Endoplasmic Reticulum

• Studded with ribosomes involved in protein synthesis.

Golgi Apparatus

• Processes, packages, and transports proteins throughout the cell.

Organelle Interactions

• Organelles work together to maintain cellular functions.

Animal vs. Plant Cells

• Plant cells have a cell wall and a large central vacuole that animal cells lack.

Cell Arrangement Differences

• Plant cells are often arranged in regular shapes due to the cell wall, while animal cells exhibit more varied shapes.
• Vacuoles and cell walls contribute to this differing arrangement.

Microscopy

Microscope Focusing

• Use the coarse adjustment knob with the low objective to initially focus.

Microscope Objective Differences

• Low objective: 40x magnification
• Medium objective: 100x magnification
• High objective: 400x magnification

Microscope Importance

• Enables visualization of structures invisible to the naked eye, such as bacteria.

Diffusion and Osmosis

Solute

• The substance dissolved in a solution.

Solvent

• The substance dissolving the solute.

Solution

• A mixture formed when a solute dissolves in a solvent.

Concentration

• The amount of solute in a given volume of solution.

Diffusion

• Passive movement of particles from high to low concentration across a membrane until equilibrium is reached.

Osmosis

• The passive movement of water across a selectively permeable membrane to equalize solute concentrations.

Active vs. Passive Transport

• Active transport requires energy; passive transport does not.

Distinguishing Diffusion and Osmosis

• Osmosis specifically refers to water movement; diffusion encompasses the movement of any particle across a membrane.

Cell Membrane Structure

• Composed of a phospholipid bilayer.
• Phosphate/glycerol heads are hydrophilic (water-loving).
• Fatty acid tails are hydrophobic (water-repelling).

Semi-permeable Membrane

• Allows certain molecules to pass through but not others.

Types of Solutions

Isotonic Solution

• Same solute concentration compared to inside the cell.

Hypotonic Solution

• Lower solute concentration compared to inside the cell.

Hypertonic Solution

• Higher solute concentration compared to inside the cell.

Cellular Impact (Based on Solution Type)

• Hypotonic solution: Cell swells due to water flowing in.
• Hypertonic solution: Cell shrinks due to water flowing out.

Prokaryote vs. Eukaryote

Prokaryotic vs. Eukaryotic Cells

• Eukaryotes have a membrane-bound nucleus; prokaryotes do not.

Prokaryotes vs. Eukaryotes (Specific Characteristics)

• Prokaryotes tend to be smaller and less complex, while eukaryotes are larger and more intricate.

Prokaryotic vs. Eukaryotic Examples

• Eukaryotic Organisms: Animals, humans (often multicellular)
  • Prokaryotic Organisms: Bacteria (often single-celled)

Prokaryotic vs. Eukaryotic Advantages/Disadvantages

• Prokaryotic: Faster nutrient movement, but unprotected DNA.
• Eukaryotic: Protected DNA, but slow nutrient movement.