CELLULAR RESPIRATION AEROBIC AND ANAEROBIC

energy All cells need energy to carry out their functions. AUTOTROPHS obtain energy by using solar energy and inorganic molecules (CO2 and H20) to produce organic molecules HETEROTROPHS obtain organic compounds by consuming other organisms Organic compounds (carbohydrates, protein, fats, nucleic acids) are used by all organisms for growth and repair and to perform everyday functions.

Cellular respiration ATP Twig clip Cellular respiration is the process by which chemical energy stored in organic compounds is transformed into a usable form of energy. When energy is needed by a cell, the bonds of organic compounds are broken releasing energy which is stored in ATP. ATP molecules are the cell’s store of immediately usable chemical energy required for cellular processes. Has 2 high energy bonds that can be broken Splits into a molecule of ADP and a molecule of phosphate. ADP can combine with ADP to re-form ATP

Energy molecules

glucose Most energy for ATP comes from the breakdown of glucose, lipids and proteins. Glucose, a product of photosynthesis is an energy rich sugar. Chemical energy from glucose is released in a series of steps involving many enzymes. Each energy ‘packet’ can produce an ATP molecule from ADP. Glucose breakdown results in three products: Carbon dioxide Water Energy 40% of the energy released is converted to energy stored in the bonds of ATP during aerobic respiration. The rest is lost as heat. Glucose twig clip

Cellular respiration No further ATP produced

Aerobic respiration Oxygen available Occurs in mitochondria Uses ADP Complete release of energy from glucose: Glycolysis - splitting of glucose into pyruvate Krebs cycle – pyruvate broken down to form carbon dioxide and hydrogen Electron transport – water formed from hydrogen and oxygen ~ The energy given off is used to convert ADP back to ATP. Aerobic respiration twig clip

Aerobic respiration Stage Where is occurs What happens Outputs Glycolysis (does not need oxygen) Cytosol Glucose (6C) is broken down into 2 pyruvate molecules (3C) producing 2ATP & H+ which is picked up by NAD (carrier molecule) 2 pyruvate molecules NADH 2 ATP (small amount) Krebs cycle Inner compartment of mitochondria (matrix) Pyruvate is converted to acetyl CoenzymeA which is then broken down releasing carbon dioxide and H+ which is picked up by NAD & FAD Carbon dioxide FADH2 Electron transport Inner membrane of mitochondria (cristae) Oxygen combines with the H+ (brought in by the carrier molecules) to form water. ATP is released Water 32 ATP

Anaerobic respiration Oxygen unavailable Also known as fermentation Occurs in the cytosol Prevents build-up of pyruvate so glycolysis can continue. Converts pyruvate into: lactic acid (in most animals) carbon dioxide and alcohol (in plants/ microorganisms such as yeasts and bacteria) No more ATP is produced! Anaerobic respiration twig clip

Cellular respiration In cytosol In cytosol In mitochondria No further ATP produced

aerobic and anaerobic respiration summary

Cellular respiration & photosynthesis

Chloroplast twig clip Chlorophyll twig clip Photosynthesis recap Plants obtain energy from the sun to make their own organic compounds (glucose). Water and carbon dioxide are also required. Chloroplasts are the organelles where photosynthesis occurs They are located in mesophyll cells (central part of leaves in vascular plants). In non-vascular plants such as mosses, chloroplasts are found throughout the leaves and often in other parts such as stems. Chloroplasts contain the green pigment chlorophyll (absorbs the light) Photosynthesis occurs in 2 stages: Light-dependent (in grana) Light Independent (in stroma) Parts of a leaf twig clip **Why do leaves change colour???

photosynthesis Photosynthesis is critically important for life on Earth Photosynthesis reaction:

Factors that control the rate of photosynthesis: Light intensity Carbon dioxide concentration Temperature Availability/concentrations limit the rate of photosynthesis. For each factor there is an optimum amount at which photosynthesis occurs at the fastest rate Below optimum – photosynthesis rate is slower Above optimum – photosynthesis rate may also be slower