Cells And Specialized Cells

• Cell


  The building unit of living organisms
• Tissue


  A group of similar cells working together to perform a specific function
• Organ


  A group of different tissues that work together to perform a specific function or group of functions
• Animal cell


  • Irregular in shape
  • Has cell membrane
  • Has cytoplasm
  • Has nucleus, ribosomes, mitochondria, endoplasmic reticulum
• Plant cell


  • Regular in shape
  • Has cell wall made from cellulose
  • Has chloroplast
  • Has large permanent vacuole
  • Has cell membrane
  • Has cytoplasm
  • Has nucleus, ribosomes, mitochondria, endoplasmic reticulum

  
• Nucleus


  • Contains the genetic material
  • Controls cell activities
  • Controls cell division
• Cell membrane


  • Made from proteins and lipids
  • Acts as a barrier
  • Keeps the cell contents inside
  • Controls the movement of substances in and out of the cell
• Cytoplasm


  Site of chemical reactions
• Mitochondria


  Site of aerobic respiration to release energy
• Ribosomes

  • Attached to the endoplasmic reticulum
  • Site of protein synthesis
• Endoplasmic reticulum


  Transports material around the cell / out of cell
• Chloroplast


  • Contains chlorophyll
  • Absorbs light energy
  • Carries out photosynthesis
• Vacuole


  • Contains a sap solution (water with dissolved salts and sugars)
  • Provides turgor pressure to keep the cell turgid
• Cell wall


  • Made from cellulose
  • Gives strength and support
  • Prevents the cell from bursting
  • Helps keep the cell's shape and stay turgid
• Specialised animal cells


  • Red blood cells: Biconcave shape, no cell organelles, same size as capillaries, flexible
  • Ciliated epithelial cells: Goblet cells secrete mucus, cilia beat to sweep mucus out of lungs
  • Sperm cells: Middle part full of mitochondria, flagellum for movement, acrosome secretes enzymes to help penetrate egg
  • Egg cells: Jelly coat, cytoplasm with food storage for early embryo development
• Specialised plant cells


  • Palisade mesophyll cells: Packed with chloroplasts for photosynthesis
  • Root hair cells: Cytoplasmic extensions for larger surface area, thin cell wall for faster water/mineral absorption, many mitochondria for active uptake

  
• Xylem vessels


  • Made from dead hollow cells with no cytoplasm, nucleus or organelles
  • No end walls for free water flow
  • Thick walls with lignin for support and waterproofing
  • Pits allow lateral water movement
• Leaf is an organ
• Mesophyll is the tissue in a leaf
• Palisade mesophyll layer is made from palisade mesophyll cells
• Palisade mesophyll cells are the site of photosynthesis
• Root hair cells function is absorption of water and minerals
• Xylem vessels function is to transport water and minerals, and provide support to the plant

  
• Command words

  • Explain
  • Describe
  • Suggest
  • State
  • Outline
  • Discuss
  • Evaluate
• Explain means to give a direct answer using knowledge from the notes
• Describe means to provide information (same as explain but with more details)
• Describe can also mean to describe graphs and tables
• Suggest means to link to your understanding
• State means to give a brief, short answer to the point
• Outline means to explain more briefly
• Discuss means to describe data, provide evidence (for and against), and give explanation
• Evaluate results means to consider the pros and cons, validate if it is valid or not, and determine if it is reliable or not