key concepts in bio

• Animal cell


  • Nucleus - stores genetic information
  • Cell membrane - controls what enters and exits
  • Mitochondria - responsible for respiration
  • Ribosomes - make essential proteins
  • Cytoplasm - where chemical reactions happen
• Plant cell


  • Cell wall - gives extra strength and protection
  • Vacuole - stores cell sap
  • Chloroplasts - for photosynthesis
• Bacteria cell


  • Ribosomes
  • Cell membrane
  • Cytoplasm
  • Flagellum - acts like a 'tail'
  • DNA floats loose in cytoplasm
  • Plasmid loops - extra DNA
• Prokaryotic cells


  Smaller, simpler, no nucleus
• Eukaryotic cells


  Bigger, more complex, have a nucleus
• Sperm cell


  • Haploid nucleus (23 chromosomes)
  • Lots of nutrients in cytoplasm
  • Acrosome - enzymes to break down egg
  • Mitochondria - provide energy
  • Tail for movement
• Egg cell


  • Haploid nucleus (23 chromosomes)
  • Lots of nutrients in cytoplasm
  • Can change structure after fertilisation
• Ciliated epithelial cell


  • Hair-like cilia structures to help move substances
• Enzymes are highly specific - they can only catalyse one reaction</b>
• Benedict's test for reducing sugars


  Add Benedict's reagent, heat gently, colour change indicates sugar concentration (red, a lot of sugar and yellow, a little sugar)
• Biuret test for proteins

  Add potassium hydroxide and copper sulfate, purple colour indicates presence of proteins
• Emulsion test for lipids


  Add ethanol, shake, pour into water, milky colour indicates presence of lipids
• Iodine test for starch


  Add iodine, blue-black colour indicates presence of starch
• Plant cell


  • Cell membrane responsible for determining which bits go in and out
  • Cell wall important for structure
  • Vacuole important for structure
  • Cytoplasm where most reactions take place
  • Ribosomes responsible for protein synthesis
  • Chloroplasts
  • Mitochondria where energy is produced
  • Nucleus
• Animal cell


  • Cell membrane controlling what goes in and out
  • Mitochondria where energy is produced
  • Ribosomes responsible for protein synthesis
  • Cytoplasm where most reactions take place
  • Nucleus
• Plant cells have features that animal cells don't share, such as cell wall, vacuole, and chloroplasts
• Bacterial cell


  • Cell membrane controlling what goes in and out
  • Cytoplasm where most reactions take place
  • Chromosome (DNA not in nucleus)
  • Flagella for locomotion
  • Ribosomes for protein synthesis
  • Cell wall
• Cells can be highly specialised and differentiated, with a wide range of cell types
• All cells start off looking the same, then various genes are turned on and off, leading to differentiation
• Microscopy techniques


  Varied from basic lenses to sophisticated electron microscopes controlled by computer
• Calculating magnification from microscope images

  Magnification = image height / object height
• Units of measurement


  • Meter (m)
  • Centimeter (cm)
  • Millimeter (mm)
  • Micrometer (μm)
  • Nanometer (nm)
  • Picometer (pm)
• Enzymes


  Work via lock and key mechanism, with a specifically shaped active site that only certain substrates can fit into
• Temperature affects enzyme activity

  Enzyme activity increases up to an optimal temperature, then decreases as enzymes become denatured
• pH affects enzyme activity


  Enzyme activity is optimal at a certain pH, decreasing at too high or too low pH as the active site becomes denatured
• Substrate concentration affects enzyme activity

  Enzyme activity increases as substrate concentration increases, until all active sites are full, then no further increase
• Enzymes as catalysts


  Increase the rate of a reaction, but don't change the final equilibrium point
• Digestive enzymes


  • Lipase (breaks down fats into fatty acids, it is made in pancreas and works in small intestines )
  • Protease (breaks down proteins into amino acids, made in stomach, pancreas and works in the stomach)
  • Amylase (breaks down starch into sugars, made in the salivory glands, stomach and small intestine, and works in the mouth and small intestine)
• Testing for biological molecules

  1. Fats: Emulsion test or filter paper test

  2. Starch: Iodine test

  3. Sugars: Benedict's test

  4. Proteins: Biuret test
• Diffusion


  Movement of gases of any particles dissolved in a solution from high to low concentration down the concentration gradient.
• Osmosis


  Movement of water through a partially permeable membrane from high to low water concentration
• Active transport


  Movement of substances from low to high concentration, against the concentration gradient