Cell structure and Transport

• Cell


  The basic unit of all forms of life
• Eukaryotic cells


  • Have a nucleus (e.g. animal and plant cells)
• Prokaryotic cells


  • Smaller and do not have a nucleus, their genetic material (DNA) is free and forms a single loop, all bacteria are prokaryotes
• Parts of an animal cell

  • Nucleus
  • Cytoplasm
  • Cell membrane
  • Mitochondria
  • Ribosomes
• Parts of a plant cell

  • Nucleus
  • Cytoplasm
  • Cell membrane
  • Cell wall
  • Chloroplasts
  • Permanent vacuole
• Nucleus


  Controls all cell activity and contains the DNA
• Cytoplasm


  A liquid gel where most chemical reactions take place
• Cell membrane


  Controls the movement of substances into and out of the cell
• Mitochondria


  The site of respiration, releases energy for the cell
• Ribosomes


  Protein synthesis - they make proteins
• Cell wall


  Strengthens the cell, in plant and algal cells it is made of a strong substance called cellulose
• Chloroplasts


  Where photosynthesis takes place, they can trap the sunlight's energy using a green pigment called chlorophyll
• Permanent vacuole


  It is filled with cell sap and helps to keep the cell turgid (swollen and rigid) to support the plant
• Plasmids


  • Small rings of extra bacterial DNA
• Flagella


  A tail-like protein strand that lashes about, allowing the bacterial cell to move around
• Slime capsule


  For protection and to stop the bacterial cell drying out
• Light microscope


  Works by shining light through a specimen slide, the light is then refracted through an objective lens and an eyepiece lens to form a magnified image
• Magnification


  How many times bigger the image is than the actual object you're looking at
• Magnification = Image size / Object size
• Electron microscope

  • Provides much greater resolution than a light microscope, uses a beam of electrons instead of a beam of light, can achieve magnifications of up to 2,000,000x
• Resolution


  The ability to distinguish between two separate points, the greater the resolution the finer the detail that can be seen
• Orders of magnitude: if something is 10 times bigger than something else, it is 1 order of magnitude bigger
• Respiration


  The process of releasing energy from food in cells
• Respiration


  • Involves the intake of substances like oxygen and the release of substances like carbon dioxide
  • Regulates the internal conditions of cells to maintain optimum conditions for function
• Respiration


  1. Intake of substances the cell needs

  2. Release of substances the cell produces

  3. Regulation of internal conditions
• Diffusion


  The net movement of particles from an area of high concentration to an area of low concentration down a concentration gradient
• Diffusion


  • Particles move around randomly and bump into each other, causing movement
  • Factors affecting rate of diffusion: temperature, surface area, concentration gradient
• Osmosis


  The diffusion of water molecules from a dilute solution to a more concentrated solution across a partially permeable membrane
• Osmosis in animal cells

  • Large multicellular organisms cannot get all the nutrients they need just by diffusion due to small surface area to volume ratio
  • Adaptations to increase diffusion rate: large surface area, thin membrane, efficient blood supply, good ventilation
• Active transport


  The movement of substances from an area of low concentration to an area of high concentration against a concentration gradient, requiring energy
• Active transport


  • Absorption of mineral ions into plant root hairs from dilute soil solutions
  • Absorption of glucose molecules from gut into blood with higher glucose concentration
• Active transport is achieved by special protein pumps found in cell membranes
• Osmosis in plant cells can be studied through lab experiments with whole potato tissues