Chapter 9. Energy: the ability to do work In cells, energy is in the chemical form The stored chemical energy in cells is called ATP, or adenosine.

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Energy in a Cell

Photosynthesis & Cellular RespirationChapter 9Energy: the ability to do work

In cells, energy is in the chemical form

The stored chemical energy in cells is called ATP, or adenosine triphosphate

Energy is released when ATP is converted into ADP + a phosphate group

Chemical Energy

Plants and animals obtain energy in different ways:

Plants ONLY: make their own energy through the process of photosynthesis

Plants and Animals: get ATP by breaking down organic compounds (proteins, carbs, etc.) through the process of cellular respirationPhotosynthesis: the conversion of light energy into chemical energyOccurs in chloroplastsReactants (IN): CO2, H2O, and energyProducts (OUT): O2 and glucose (C6H12O6)6CO2 + 6H2O + light energy C6H12O6 + 6O2

Photosynthesis Overview

1) Light Reactions (photo)Occurs in thylakoidLight from sun excites electronsO2 is released2) Calvin Cycle (synthesis)Occurs in stromaCO2 is used to make glucose (C6H12O6)

Phases of Photosynthesis

Plant and animal cells make ATP by breaking down organic molecules (sugars, fats, etc.) This process is called Cellular RespirationOccurs in the mitochondriaReactants (IN): C6H12O6 (glucose) & O2Products (OUT): CO2 & H2O & ATP (energy)C6H12O6 + 6O2 6CO2 + 6 H2O + 36 ATPCellular Respiration Overview

Begins with Glycolysis1 molecule glucose is split in half into 2 pyruvate molecules

If O2 is present Citric Acid (Krebs) Cycle & Electron Transport ChainIf O2 is NOT present FermentationCell Respiration Overview

Occurs when no O2 is present2 Types:1. Lactic Acid Fermentation: Converts pyruvate lactic acidHelps make yogurt & cheeseCreates burning sensation in muscles during exercise2. Alcoholic Fermentation: Converts pyruvate ethyl alcoholHelps make bread, wine & beerFermentationOccurs when O2 is presentBreaks down pyruvate molecules (from glycolysis) into smaller molecules As chemical bonds form and break, electrons get moved around & CO2 is releasedThis releases energy, thus making ATP!Citric Acid (Krebs) Cycle & Electron Transport Chain

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