Cell Structure and Functions

• The cell theory was formulated stating that all living things are structurally made up of cells
• The cell theory states that the cell is the fundamental unit of life
• Cells come from the division of preexisting cells
• Main parts of all cells

  • Cell membrane
  • Cytoplasm
  • Nucleus
• Cell membrane


  Separates the internal contents of the cell from its environment
• Cell membrane

  • Phospholipid bilayer
  • Selectively permeable
  • Regulates passage of materials
  • Permits communication with other cells
• The whole region within the cell membrane is the cytoplasm
• Organelles perform their functions in the jelly-like substance called cytosol
• Various metabolic reactions like protein synthesis and breakdown of sugar into ATP take place in the cytoplasm
• Organic materials found in the cytoplasm

  • Glucose
  • Simple sugars
  • Polysaccharides
  • Amino acids
  • Nucleic acids
  • Fatty acids
• Ions dissolved in the cytoplasm

  • Sodium
  • Potassium
  • Calcium
• Centrioles, cytoskeleton, and plastids are specialized organelles in the cytoplasm
• The nucleus is the control center of the cell
• The nucleus regulates and coordinates all activities of the cell
• Chromosomes are found in the nucleus
• DNA that make up the gene that bears the hereditary traits are found within the chromosomes
• Basic organelles found in the cytoplasm

  • Mitochondria
  • Ribosomes
  • Endoplasmic reticulum
  • Golgi apparatus
  • Lysosome
  • Peroxisomes
  • Vacuoles
  • Centrosome
  • Cytoskeleton
  • Plastids
  • Cell wall
• Mitochondria


  Sites for the breakdown of sugar molecules into ATP
• Ribosomes

  Sites of protein synthesis
• Endoplasmic reticulum (ER)


  Specializes in the transport of lipids and membrane proteins
• Golgi apparatus

  Modifies, sorts, and packs macromolecules for secretion or transport
• Lysosome


  Contains digestive enzymes for the breakdown of carbohydrates, proteins, and fats
• Peroxisomes

  Contain oxidative enzymes for oxidizing certain molecules
• Vacuoles

  Large storage sacs in cells
• Centrosome


  Consists of two rod-shaped centrioles
• Cytoskeleton

  Provides the cell’s structural support
• Plastids

  Large membrane-bound organelles found in plant cells

  
• Chloroplast

  • Site for photosynthesis
• Chromoplasts

  • Synthesize and store carotenoid pigments
• Leucoplasts

  • Contain stored food
• Cell wall


  Protects and supports the cells of the plants