Biology: Cell Structure and Microscopes

Cell Types

• Prokaryotic Cells: Lack true nucleus and membrane-bound organelles; contain circular DNA and replicate via binary fission.
• Eukaryotic Cells: Contain a nucleus, linear DNA, and membrane-bound organelles; can be plant or animal cells.

Microscopy Basics

• Eyepiece: Contains a lens with a magnification power of 10x.
• Objective Lenses: Offer various magnifications (4x, 10x, 40x, 100x).
• Coarse Adjustment Knob: Focuses the image at low power; useful for blurry specimens.
• Fine Adjustment Knob: Focuses the image at high power; enables fine detail viewing.
• Stage Clips: Secure the slide in place on the stage.
• Condenser: Focuses light onto the specimen.

Plant Cells

• Cell Structure: Possess cell walls, chloroplasts, and large vacuoles; have a rectangular shape.
• Cilia: Rarely present in plant cells; higher plants lack centrioles.
• Organelles: Chloroplasts are involved in photosynthesis, while large vacuoles aid in storage.

Animal Cells

• Cell Structure: Lack cell walls; generally round, with many small vacuoles.
• Cilia: Commonly present; contain centrioles involved in cellular division.
• Organelles: Have more lysosomes and smaller vacuoles than plant cells.

Organelles and Their Functions

• Nucleus: Control center containing DNA; where chromosomes are located.
• Nucleolus: Site of ribosome production; found in both plant and animal cells.
• Nuclear Pores: Allow material exchange between the nucleus and cytoplasm.
• Cell Membrane: Semi-permeable barrier regulating movement in and out of the cell.
• Cytoplasm: Viscous fluid where organelles are suspended; site for metabolic activities.
• Mitochondria: Known as the powerhouse of the cell; responsible for ATP production through cellular respiration.
• Vacuole: Storage area for water, food, and waste materials.

Endoplasmic Reticulum (ER)

• General Function: Network of tunnels for protein transport and chemical activities.
• Smooth ER: Lacks ribosomes; detoxifies lipids, storage, and synthesis of carbohydrates.
• Rough ER: Contains ribosomes; responsible for protein synthesis and transport.

Other Organelles

• Ribosomes: Protein synthesis sites; can be free or attached to rough ER.
• Golgi Body/Apparatus: Modifies, packages, and distributes proteins and materials received from the ER.
• Peroxisomes: Break down fatty acids and detoxify harmful substances.
• Lysosomes: Contain enzymes for digestion; essential to cellular waste processing.

Cytoskeleton Components

• Microtubules: Provide structural support and pathways for molecules; absent in plant cells.
• Intermediate Filaments: Most stable part of the cytoskeleton; provide structural support for the nuclear envelope; absent in plants.
• Microfilaments: Aid in cell shape and movement; pipe-like structure.

Cell Wall

• Plant Cells: Comprised of cellulose; provides rigidity and allows for a definitive shape.

Centrioles

• Found in animal cells; play a critical role during mitosis by organizing the mitotic spindle.

Chloroplasts and Chlorophyll

• Chloroplasts: Site of photosynthesis; where plant food is produced.
• Chlorophyll: Traps light energy for use in photosynthesis, enabling plant growth.