Cell Structure & Function Notes

1. Foundations of the Cell

Prokaryotic vs. Eukaryotic

Prokaryotic

  • No nucleus

  • DNA is in the cytoplasm

  • Small and simple

  • Example: bacteria

Eukaryotic

  • Has a nucleus

  • DNA is contained in the nucleus

  • Larger and more complex

  • Examples: plants, animals, fungi

Main Cell Structures

  • Cell membrane — selectively controls what enters and leaves the cell

  • Cytoplasm — jelly-like fluid surrounding organelles; supports chemical reactions

  • Nucleus — control center; contains DNA and directs cell activities

  • Nucleolus — located inside the nucleus; involved in making ribosomes


2. Energy Conversion & Protein Synthesis

Mitochondria

  • Perform cellular respiration

  • Convert chemical energy from food into ATP

  • ATP provides usable energy for the cell

Chloroplasts

  • Found in plants and some algae

  • Perform photosynthesis

  • Convert light energy into chemical energy

  • Produce glucose (C₆H₁₂O₆)

Ribosomes

  • Small structures made of RNA and protein

  • Build proteins by following instructions from DNA

  • Can be attached to the rough ER

Endoplasmic Reticulum (ER)

  • Internal membrane system involved in transporting materials

  • Helps make proteins and lipids

Rough ER

  • Has ribosomes attached

  • Involved in protein synthesis

Smooth ER

  • No ribosomes

  • Involved in making/processing lipids


3. Logistics, Waste & Storage

Golgi Apparatus

  • Modifies, sorts, and packages proteins and other materials

  • Sends materials to their destinations inside or outside the cell

Vesicles

  • Small membrane-bound sacs

  • Transport packaged materials around the cell

Lysosomes

  • Contain digestive enzymes

  • Break down:

    • Lipids

    • Carbohydrates

    • Proteins

    • Old/damaged cell parts

  • Function as the cell’s waste/recycling system

Vacuoles

  • Store materials such as:

    • Water

    • Salts

    • Nutrients

  • Plant cells have a large central vacuole

  • The central vacuole helps maintain turgor pressure, supporting the plant


4. Plant vs. Animal Cells

Both Have

  • Nucleus

  • Cell membrane

  • Cytoplasm

  • Mitochondria

  • Ribosomes

  • ER

  • Golgi apparatus

Plant Cells Have

  • Cell wall — rigid outer layer made of cellulose; provides structural support

  • Chloroplasts — perform photosynthesis

  • Large central vacuole — stores water and maintains turgor pressure

Animal Cells

  • Do not have a cell wall

  • Do not have chloroplasts

  • Have centrioles, which help with cell division

  • Generally have smaller/more numerous vacuoles