Chapter 6 : Model of cells

• Unicellular cells

  e.g. Bacteria
• Multicellular organisms are made up of many different types of cells working together

  e.g fishes are multicellular animals

  e.g lettuce is a multicellular plant

  e.g penicillium is a multicellular fungi
• Levels of organization (Cell)

  A cell is a basic unit of life. It is specialized to carry out a specific function.
• Levels of organisation (Tissue)

  A tissue is made up of a group of similar or different cells that work together to carry out a specific function
• Levels of organisation (Organ)

  An organ is made up of different tissues that work together to carry out a specific function.
• Levels of organisation (System)

  A system is made up of several related organs that work together to carry out a specific function
• Levels of organization (Organism)

  A multicellular organism is made up of organ systems that work together to keep the organism alive
• Levels of organisation (Human) ft. cell

  Heart muscle cell

  • contracts and relaxes rhythmically to pump blood around the body
• Levels of organisation (Human) ft. tissue

  Heart muscle tissue

  • Many heart muscle cells come together to form heart muscle tissues
  • Contract and relax rythmically at a steady rate
• Levels of organisation (Human) ft. Organ

  Heart

  • Heart muscle tissues, nerve tissues, and connective tissues collectively form the heart which pumps oxygen rich in blood to all cells in the body
• Levels of organisation (Human) ft. System

  Circulatory system

  • Heart arteries and veins work together to transport blood to all parts of the body
• Levels of organisation (Human) ft. Organism

  Human

  • Circulatory system works with other organ systems to ensure that human body functions properly
• Levels of organisation (Plant) ft. cell

  Regularly-shaped plant cells

  • Densely packed with chloroplast
  • Found mainly at upper layer of the leaves
• Levels of organization (Plant) ft. Tissue

  Tissue in leaf

  • Regularly shaped cells are grouped together in neat rows to form a type of tissue in leaf.
  • This leaf tissue makes food through photosynthesis
• Levels of organisation (Plant) ft. Organ

  Leaf

  • Different types of leaf tissues from a leaf -- an organ where food substances are formed through photosynthesis
• Levels of organisation (Plant) ft. System

  Root and shoot systems

  • Root system takes in water and dissolved mineral salts from the soil into the plant.
  • Shoot system transports water to leaf where it is required for photosynthesis
• Levels of organisation (Plant) ft. Organism

  Plant

  • Root and shoot systems work together to help plant grow and function properly
• Division of labor

  definition ; The breakdown of work into small and specific tasks for maximum efficiency

  • Various functions can be carried out efficiently and at the same time
  • Occurs withing cells (different organelles) and in multicellular organisms (levels of organisation)
• Division of labor

  In cells, work is also divided among each cell part to ensure the survival of the cell
• Cells (Cell membrane )

  • Function : controls the movement of substances into and out of the cell
  • serves as a boundary between the cell and external environment
  • Partially permeable structure that only allows small, soluble substances to pass through its pores
• Cells (Cytoplasm)

  • Function : site where most chemical reactions take place.
  • Jell-like substance that fills a cell.
  • Contains chemicals and organelles that carry out special functions
• Cells (Nucleus)

  • Function : contains deoxyribonucleic acid (DNA) and controls all cellular activities.
  • Spherical-shaped, usually the largest structure in an animal cell
  • DNA is the hereditary genetic material living things passed down from parents to offspring
• Cells (Vacuole)

  • Function : stores liquids, food and waste materials.
  • Is a fluid-like space within the cytoplasm, surrounded by a membrane

  Animal : Usually small and numerous

  Plant : Usually one large central vacuole
• Cells (Cell wall)

  • Function : protects the plant cell from injury and gives it a fixed shape.
  • Is a tough outer layer surrounding the cell membrane, made up of carbohydrate called cellulose
  • Is fully permeable to allow substances to pass through
• Cells (Chloroplast)

  • Function : Site of photosynthesis
  • Contains chlorophyll, a green pigment that absorbs light energy for photosynthesis.