Chapter 4, Section 2 Cell Processes and Energy: RESPIRATION

KEY IDEA How do cells obtain energy from the food that an organism eats?

What is CELLULAR RESPIRATION? The process by which cells obtain energy from glucose The cells of ALL living things continuously carry out respiration During respiration, cells break down simple food molecules such as sugar and release the energy they contain

Energy in cells is like money in a bank The sun’s energy is taken in by the leaves of a plant and is stored in the cells as carbohydrates (sugars and starches) The food we eat is similarly stored in cells in our bodies When cells need energy, they “withdraw” it by breaking down the carbohydrates in the process of respiration. Storing and Releasing Energy Table Talk: What organelle acts as a storage closet in a cell?

Don’t Be Confused About Respiration… There are two meanings! Respiration = Breathing The movement of air in and out of the lungs Cellular Respiration The respiration process that take place inside cells

Quickwrite: In your own words, write a short paragraph about the difference between respiration and cellular respiration.

The Two Stages of Respiration STAGE 1: _____________________ STAGE 2: Glucose is broken down into smaller molecules in the cytoplasm A SMALL amount of energy is released In the mitochondria, the smaller molecules combine with oxygen to produce water (H2O) and carbon dioxide (CO2) This reaction releases a LARGE amount of energy Table Talk: why do you think that stage 2 would take more energy than stage 1?

The Respiration Equation The raw materials for respiration are sugar and oxygen Plants undergo photosynthesis to make their own sugar The glucose (sugar) in the cells of animals comes from the foods they eat The oxygen comes from the air or water surrounding the organism This equation is the opposite of photosynthesis! sugar + oxygen  carbon dioxide + water + energy

Together, photosynthesis and respiration form a cycle that keeps the levels of oxygen and carbon dioxide fairly constant in Earth’s atmosphere! See BrainPop, “Cellular Respiration” or science/Connecting-Cellular- Respiration-and-Photosynthesis-in- Life- Science/lesson/user:sschultz/Conne cting-Cellular-Respiration-and- Photosynthesis/r1 science/Connecting-Cellular- Respiration-and-Photosynthesis-in- Life- Science/lesson/user:sschultz/Conne cting-Cellular-Respiration-and- Photosynthesis/r1 end