Cells

• Cells


  The smallest living units of an organism
• Things all cells have in common


  • Cell membrane
  • Cytoplasm
  • DNA
• Eukaryotic cells


  • Have organelles, including nucleus
  • More advanced complex cells, such as those found in plants and animals
• Prokaryotic cells


  • Don't have a nucleus or membrane-enclosed organelles
  • Have genetic material not contained within a nucleus
  • Always one-celled or unicellular organisms, such as bacteria
• Organelles


  Specialized parts of a cell that have unique jobs to perform
• Nucleus


  • Control center of the cell
  • Contains DNA or genetic material
  • DNA dictates what the cell will do and how
  • Contains a nucleolus where ribosomes are made
• Chromatin


  • Tangled, spread-out form of DNA found inside the nuclear membrane
• Chromosomes


  • DNA condenses into these structures when a cell is ready to divide
• Ribosomes


  • Synthesize or make proteins
  • May wander freely in cytoplasm or attach to endoplasmic reticulum
• Endoplasmic reticulum (ER)


  • Membrane-enclosed passageway for transporting materials
  • Rough ER has ribosomes attached, smooth ER doesn't
• Golgi apparatus


  • Receives proteins and other materials from ER
  • Customizes proteins into usable forms by folding them or adding lipids/carbohydrates
• Vacuoles


  • Sac-like structures that store different materials, like water in plant cells
• Lysosomes


  • Garbage collectors that break down damaged or worn-out cell parts
• Mitochondria


  • Powerhouse of both animal and plant cells
  • Make ATP molecules that provide energy for cell activities
  • Cells that need more energy have more mitochondria
• Cytoskeleton


  • Maintains cell shape
  • Includes microfilaments and microtubules
• Chloroplasts


  • Where photosynthesis happens in photoautotrophic organisms like plants
  • Contains chlorophyll pigment
• Plant cell wall


  • Outside of cell membrane, shapes, supports, and protects plant cells
  • Animal cells don't have a cell wall
• Other unique cell structures

  • Cilia in human respiratory tract cells
  • Flagella in some bacteria and human sperm cells
• DNA stands for deoxyribonucleic acid and is the genetic material of all living things