Photosynthesis & Cellular Respiration Biology: 2010

 Cells perform many important activities ◦ Growing ◦ Repairing structures ◦ Creating new cell parts ◦ Reproducing  ALL of these activities require Energy! ◦ Sun gives us Energy in the form of light, needed for things like vitamin D. ◦ The food you eat gives you Energy in the form of nutrients

Why do we need to learn about these two cell processes? Every cell of our body needs energy (metabolism) Cells only run on a certain sized battery (energy)! We need to consume carbohydrates to make these batteries. Plants cannot consume carbohydrates. Plants need to make these carbohydrates first, then turn them into batteries that will “fit” into their cells.

Energy Flow in the Living World What is the ultimate source of energy for living organisms? Sunlight Organisms that capture energy directly from sunlight perform the process of photosynthesis. These organisms make their own food and are called autotrophs, or producers. (plants) The organisms that get their energy by consuming other plants or animals are called heterotrophs, or consumers. (animals) Heterotrophs use a process called cellular respiration. Mitochondria break down food molecules to produce ATP (energy), which is needed for life processes.

Carbohydrates – contains carbon, hydrogen, and oxygen; used for energy Glucose – monosaccharide, one molecule of sugar that is needed in order to make energy for the mitochondria (C 6 H 12 O 6 ) Starch – polysaccharide, a chain of glucose molecules; how plants store their food energy

Chloroplast – where plants make their own food (forms of carbohydrates) Mitochondria – “powerhouse of the cell” where plants and animals turn their food into energy Atom – smallest unit of matter Molecule – two or more atoms covalently bonded together (ex: H 2 O) Covalent Bond- electrons are shared

Chemistry Review *Why is water (H 2 O) considered a molecule? hydrogen and oxygen are covalently bonded Example: How many atoms of hydrogen and oxygen are in one molecule of H 2 O? H 2 O = 2 atoms hydrogen, 1 atom oxygen Determine the number of each atom in each of the following molecules. 6CO 2 C 6 H 12 O 6 6H 2 O 6O 2

Chemical Reaction – making and breaking of chemical bonds to form different substances; Examples: photosynthesis and cellular respiration are chemical reactions. Reactants – what goes into the reaction Products – what comes out of the reaction Reactants Products You read a chemical equation, “reactants yield products” Note: the arrow always points at the products.

 Chemical reactions within cells drive all activities associated with life.  FOR EXAMPLE: ◦ When you eat a baked potato: Chemical reactions in your mouth and stomach break down your food into smaller molecules. Eventually they are converted from starch into glucose and leave the digestive system. They then head into the blood stream to reach other cells in your body. Other reactions break down glucose and release energy that your body can use to do work.