Biology - Module 4

Biology - Module 4

1. enzymes

   • enzymes are proteins that speed up chemical reactions - instructions for making them in DNA
   • very specific - usually one speed up one reaction - substrate has to be the correct shape to fit in active site for this to work
   • a substrate is a molecule that is changed in a reaction - the substrate fits in the enzymes active site
   • lock and key model - substrate fits like a key into a lock
   • need to be kept at a specific constant temperature to work at their optimum
     • also have optimum ph and same happens like temp
   • if temp gets too hot - bonds holding enzymes break - changes enymes active shape - substrate cant fit - enzyme wont work no reaction - DENATURED

2. photosynthesis

   • series of chemical reactions that uses energy from sunlight to produce food
   • food - glucose - sugar
   • happens in green plants - leaf cells and some phytoplankton
   • chlorophyll is needed - green substance which absorbs sunlight and allows the energy to be used to convert co2 and water into glucose
   • oxygen - waste product
     • light meter - measure level of light - sensor - accurate
   • carbon dioxide + water ---> (light energy) glucose + oxygen
   • 6CO(2) + 6H(2)O ----> (light energy) C(6)H(12)O(6) + 6O(2)
   • organisims that photosynthisise start the food chain - energy transferred
   • glucose - respiration - releases energy
   • glucose - chemicals for growth - 1 converted to cellulose for making cell walls. 2 Combined with nitrogen to make amino acids - proteins. 3 Used to help make chlorophyll
   • glucose is stored as starch - stored in roots, stems, leaves - good in winter
   • light, co2, temperature affect rate of photosynthesis - any can become limiting factor - stops it from happening faster - depends on environmental conditions
     • not enough light - slows down - light provides energy - if light increased rise steadily but only certain point as other factors will be limiting
     • too little co2 - slow down - raw material needed
     • temperature has to be right - too low enzymes wont work properly or denature too hot
   • transect - way of investigating how something changes across an area - use a tape measure between 2 points ad collect data between them
   • quadrat - quicker easier - square frame divided in grid - estimate % coverage by counting covered squares
   • identification key - series of questions to figure out what a plant is - narrow down until one species

3. cell structure & functions

   • animal cell
     • nucleus - contains DNA - instructions for making proteins
     • cytoplasm - gel like substance where proteins like enzymes are made - anaerobic rep takes place here
     • cell membrane - holds cells together and controls what goes in and out - gases and water get in freely but acts as a barrier
     • mitochondria - enzymes for aerobic resp found and where reactions take place
   • plant cell
     • plant cells also have a nucleus, cytoplasm, cell membrane and mitochondria
     • rigid cell wall - made of cellulose - supports and strengthens
     • vacuole - contains cell sap - weak solution of sugar and salts
     • chloroplasts - where reactions for photosynthesis takes place - contain green substance - chlorophyll
   • yeast - single celled - make bread and whine
   • bacteria - simple cell structure
     • don't have nucleus - have a circular molecule of DNA floats around cytoplasm
       • don't have mitochondria - respire aerobically

4. anaerobic respiration

   • anaerobic - without oxygen
   • takes place in animal and plant cells and some microorganisms whens theres little or no oxygen
   • lactic acid is produced - glucose --> lactic acid (+energy released)
   • glucose --> Ethanol + Carbon dioxide (+energy released)
     • in plant cells and some microorganisms - yeast - ethanol - co2
     • fermentation - microorganisms break down sugars in other products so they can respire anaerobically.
       • biogas - fuel - heat - light. lots of microorganisms can produce it. they ferment plant and animal waste - carbohydrates. mainly made up of methane and co2
       • bread - yeast - ferment carbohydrates in flour - release co2 - rise
       • alcohol - yeast ferment sugar - alcohol - ethanol
   • in human cells - vigorous exercise - not enough oxygento muscles for aerobic
   • in plant cells - if soil is waterlogged - no oxygen available for roots
   • in bacteria cells - under skin little oxygen in wounds - have to resp anaer to survive

5. aerobic respiration

   • respiration - series of chemical reactions that release energy by breaking large food molecules - happens in every living cell
   • aerobic - with oxygen
   • releases more energy per glucose molecule than anaerobic
   • use most of the time - takes place in both animals and plants and in some microorganisms
   • glucose + oxygen --> carbon dioxide + water (+energy released)
     • C(6)H(12) + 6O(2) --> 6CO(2) + 6H(2)O (+energy released)
   • movement - energy is needed for muscles to contract
   • active transport - uses energy to move some substances in and out of cells
   • synthesis of large molecules - glucose is joined together to make starch and cellulose in plant cells. glucose and nitrogen joined to make amino acids - amino acids join together to make protein

6. diffusion, osmosis, active transport

   • diffusion - passive overall movement of particles from a region of their higher concentration to a region of their lower concentration
   • osmosis - overall movement of water from a dilute to a more concentrated solution through a partially permeable membrane
     • water molecules
     • partially permeable membrane - allows certain substances to diffuse through it
     • plants take in water by osmosis - higher conc of water in soul than plant - drawn in in by roots
   • active transport - overall movement of chemicals across a cell membrane from a region of lower conc to a region of higher conc usimg energy released by respiration
     • plants take in minerals - nitrates through roots by AT. Conc of minerals in soul higher than plant - energy from respiration mover minerals into roots