How Organisms Obtain Energy Chapter 8, Section 1

All living organisms use energy to carry out all biological processes Main Idea All living organisms use energy to carry out all biological processes

Thinking Question 1. What types of cellular processes require energy? Macromolecules are being assembled and broken down Substances are being transported into and out of cells Genetic instructions are transmitted Cardiac cells are contracting Nerve cells are transmitting signals

Chemical reactions are constantly being carried out in your cells A. Transformation of Energy Chemical reactions are constantly being carried out in your cells In order for them to occur, energy is required Energy is the ability to do work Thermodynamics is the study of the flow and transformation of energy in the universe

Laws of Thermodynamics First Law – law of conservation of energy Energy cannot be created or destroyed, only transformed into different forms

Laws of Thermodynamics Second Law Energy cannot be converted without the loss of some usable energy The amount of usable energy decreases as it travels from sun to autotrophs to heterotrophs

Autotrophs are organisms that are able to make their own food Chemoautotrophs use chemicals as a source of energy Photoautotrophs (plants) use sunlight as a source of energy and convert it to chemical energy

Heterotrophs (animals/humans) are organisms that need to ingest food to obtain energy Nearly all of the energy for life comes from the sun and travels through other organisms

Metabolism – all of the chemical reactions in a cell B. Metabolism Metabolism – all of the chemical reactions in a cell 2 types of metabolic pathways: Catabolic – release energy by breaking down larger molecules into smaller molecules Anabolic – use energy released by catabolic reactions to build larger molecules from smaller molecules

Energy flows continuously between metabolic reactions of organisms in an ecosystem Photosynthesis is an anabolic pathway Light from sun, carbon dioxide, and water form glucose and oxygen Energy stored in glucose is transferred to heterotrophs when consumed as food Cellular respiration is a catabolic pathway Oxygen is used to break glucose down into carbon dioxide, water, and usable energy

C. ATP: The Unit of Cellular Energy ATP (adenosine triphosphate) – the most important biological molecules that provides chemical energy for living things

ATP Structure ATP is a nucleotide made up of Adenine Ribose sugar 3 Phosphate groups

ATP Function ATP releases energy when the bond between the 2nd and 3rd phosphate groups is broken, forming ADP (adenosine diphosphate) and a free phosphate group Energy is restored in that bond when a phosphate group is added to ADP