Photosynthesis and Cellular Respiration

ATP: adenosine triphosphate --main energy molecule for cells --recycled in the cell --made of adenosine and 3 phosphates All organisms require energy for Active transport Cell division Movement Production of proteins

Photosynthesis Process that uses the sun’s energy to make glucose Carried out by green plants and some bacteria (autotrophs) Purpose is to trap sun’s energy and store it in glucose (food for the plant) Photosynthesis occurs in the chloroplast

Photosynthesis Chloroplast Structure: Stroma: Space inside the chloroplast Thylakoid: Green disk in the chloroplast Granum stack: Stack of green thylakoids

Chloroplasts Thylakoids are green because they contain chlorophyll Chlorophyll: green pigment in plants that absorbs light energy Looks green because it reflects green light and absorbs other wavelengths (colors) Pigment: light-absorbing compound

Overall Reaction 6CO2 + 6 H2O + light energy → C6H12O6 + 6O2 Carbohydrate made is glucose

Steps of Photosynthesis 1. Light reaction (Light-dependent reaction) --First step of photosynthesis that traps sunlight and makes electrons and ATP to run the dark reaction --occurs in the thylakoids 2. Dark reaction (Light-independent reaction) --Second step of photosynthesis that uses ATP and electrons from the light reaction and carbon dioxide from the air to make glucose --occurs in the stroma

Harvesting Chemical Energy energy enters food chains (via autotrophs) how do organisms use that energy to fuel their bodies Plants and animals both use products of photosynthesis (glucose) for fuel Heterotrophs: must take in energy from outside sources, cannot make their own e.g. animals When we take in glucose (or other carbs), proteins, and fats-these foods don’t come to us the way our cells can use them

Cellular Respiration The process by which mitochondria break down glucose to make ATP Two types Aerobic respiration: requires oxygen and carried out by plants, animals, and some bacteria Anaerobic respiration: requires no oxygen and carried out by yeast, some bacteria, and sometimes animals

Cellular Respiration These reactions proceed the same way in plants and animals. Overall Reaction: C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP

Mitochondria Aerobic respiration occurs in the mitochondria Makes energy for the cell through aerobic respiration Structure of a mitochondria Inner membrane Outer membrane Cristae: Fold in the inner membrane

Steps of aerobic respiration 1. Glycolysis: First step breaks down glucose into pyruvate --(Intermediate step: Change pyruvate to acetyl CoA) 2. Citric Acid Cycle: Second step uses the acetyl CoA to make electrons for the last step 3. Electron transport chain: Third step uses the electrons to make a lot of ATP (36)

Anaerobic Cellular Respiration Some organisms thrive in environments with little or no oxygen Marshes, bogs, gut of animals, sewage treatment ponds No oxygen used= ‘an’aerobic End products such as ethanol and CO2 (single cell fungi (yeast) in beer/bread) or lactic acid (muscle cells)

Anaerobic respiration (requires no oxygen) Also called fermentation 2 types: alcoholic fermentation and lactic acid fermentation Only 2 ATP are made in anaerobic respiration so it is not as good as aerobic respiration (36 ATP) Both begin with glycolysis No citric acid cycle or electron transport chain

Alcoholic fermentation Pyruvate  ethyl alcohol + carbon dioxide Carried out by yeast and some bacteria Used in brewing beer, making wine, and baking bread and cakes

Lactic acid fermentation Pyruvate  lactic acid Carried out by your muscles when you’re exercising hard (need ATP) and can’t get oxygen into you fast enough (can’t do aerobic respiration) Causes muscle cramps and soreness

Energy Tally 36 ATP for aerobic vs. 2 ATP for anaerobic Glycolysis 2 ATP Kreb’s 2 ATP Electron Transport 32 ATP 36 ATP Anaerobic organisms can’t be too energetic but are important for global recycling of carbon

Photosynthesis and respiration are the opposite of each other Plants -- chloroplast * use sunlight to make glucose * take in carbon dioxide * give off oxygen *carbon dioxide + water + sunlight  glucose + oxygen Respiration Animals and plants -- mitochondria * eat plants to get glucose * take in oxygen * give off carbon dioxide *glucose + oxygen  carbon dioxide + water + ATP