B4

B4

1. RESPIRATION

   • Types of respiration
     • AEROBIC RESPIRATION
       • respiration using OXYGEN
       • glucose + oxygen ---> carbon dioxide + water (+energy released)
       • takes place in ANIMAL AND PLANT CELLS (and some MICROORGANISMS)
     • ANEROBIC REPIRATION
       • (some) organisms can still get energy when oxygen is low or absent by ANAEROBIC RESPIRATION
       • occurs in HUMAN MUSCLE CELLS during vigorous excursive, PLANT ROOTS in waterlogged soil, and BACTERIA in deep puncture wounds
       • releases more energy than aerobic
       • glucose ---> lactic acid + ENERGY
       • FERMENTATION
         • type of aerobic respiration used by some microorganisms such as yeast
           • some microorganisms (e.g. yeast, some plants) produce alcohol (ethanol) by fermentation
         • glucose ---> ethonol + carbon dioxide + ENERGY
   • Process: how all organisms RELEASE ENERGY from food
     • RESPIRATION IS NOT BREATHING
     • organisms need energy from respiration for the SYNTHESIS OF LARGE MOLECULES AND MOVEMENT
   • a SERIES of CHEMICAL REACTIONS in CELLS that release energy by BREAKING DOWN LARGE FOOD MOLECULES
   • GLUCOSE broken down in respiration
   • takes place as a series of enzyme-controlled reactions; energy is released in STAGES

2. ENZYMES

   • Are CATALYSTS: produced by living things
     • speeds up the rate of chemical reactions
       • The chemicals enzymes work on are called SUBSTRATES
       • Chemicals Produced: PRODUCTS
   • are PROTEINS
     • Consist of long chains of AMINO ACIDS
   • Assembled by cells using genes ( genes give instructions; genetic code)
   • Need a specific pH and temperature to work at their optimum
     • How do enzymes stop working?
       • inappropriate pH
       • Temp. too high
     • OPTIMUM TEMP. = BODY TEMP. (37 degrees)
       • TEMP INCREASE = CHANGE IN RATE OF ENZYME-CONTROLLED REACTION
         • DENATUREED ENZYMES
           • TEMPERATURE: If it gets too hot, bonds holding the enzyme together break - changing the shape of the ACTIVE SITE; substrates will no longer fit into the enzyme. Its is now DENATURED
             • HIGH TEMP = SHAPE CHANGE
           • pH: enzyme have an optimum pH (often pH 7). If pH is too HIGH OR LOW, it interferes with bonds holding the enzyme together: changes active site shape, DENATURES ENZYME
   • ACTIVE SITE: special shape that substrates fit into (LOCK AND KEY)
   • break down of animal and plant matter

3. CELLS

   • basic process of life depends on CHEMICAL REACTIONS IN CELLS that require energy from RESPIRATION
   • PHOTOSYNTHESIS
     • series of CHEMICAL REACTIONS that use ENERGY from SUNLIGHT to build large food molecules in plant cells and some microorganisms (e.g. phytoplankton)
     • carbon dioxide + water --(light energy)--> glucose + oxygen
       • light energy is to DRIVE the reaction to build up glucose
       • oxygen = waste product
     • SUNLIGHT absorbed by CHLOROPYLL (green chemical found in chloroplasts)
     • GLUCOSE
       • Starch (and also oil) for energy storage
       • respired to release/give energy
       • chemicals for growth of plant cells (e.g. cellulose, protein, chlorophyll)
     • Glucose (photosynthesis) and Nitrates (taken up by plant roots); used to SYNTHESISE AMINO ACIDS which are assembled into PROTIENS
     • rate can be limited by TEMP., LIGHT INTENSITY and CARBON DIOXIDE
   • surrounded by CELL MEMBRANE: controls what enters/leaves cells (gases and water allowed)
   • CYTOPLASM: jelly-like substance where most chemical reactions occur
     • contains MITOCHONDRIA; power-house of a cell. They contain enzymes for the release of energy by aerobic respiration
   • NUCLEUS: contains DNA which contains genetic code
   • CELL WALL: allows water and other chemicals through/protection (in plants its made from cellulose)
   • VACUOLE: storage bubbles (for food, nutrients ect.)
   • DIFFUSION
     • the movement of chemicals from a HIGH to LOW CONCENTRATION
     • PASSIVE (just happens, no energy needed)
     • IN PHOTOSYNTHESIS: water is taken up by plant roots, carbon dioxide enters the plant's leaves by diffusion, oxygen exits the plant's leaves by diffusion
     • OSMOSIS
       • special diffusion involving water
       • the overall movement of water from a dilute to a more concentrated solution (through partially permeable membrane)
         • water to plants roots occurs by osmosis
       • happens when chemicals are separated by a partially permeable membrane
   • ACTIVE TRANSPORT: the overall movement of chemicals across a cell membrane requiring energy from respiration
     • is used by root cells to take up nitrates (can't be done by diffusion since nitrates have a higher concentration than plant cells)
     • minerals absorbed by plant roots are used for essential chemicals for cells

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