chapter 9. energy: the ability to do work in cells, energy is in the chemical form the stored...
TRANSCRIPT
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 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 respiration
Photosynthesis: the conversion of light energy into chemical energy◦Occurs in chloroplasts◦Reactants (IN): CO2, H2O, and energy
◦Products (OUT): O2 and glucose (C6H12O6)
◦6CO2 + 6H2O + light energy → C6H12O6 + 6O2
Photosynthesis Overview
1) Light Reactions (“photo”)◦ Occurs in thylakoid◦ Light from sun excites
electrons◦ O2 is released
2) Calvin Cycle (“synthesis”)◦ Occurs in stroma◦ CO2 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 Respiration◦ Occurs in the mitochondria◦ Reactants (IN): C6H12O6 (glucose) & O2
◦ Products (OUT): CO2 & H2O & ATP (energy)
◦ C6H12O6 + 6O2 → 6CO2 + 6 H2O + 36 ATP
Cellular Respiration Overview
Begins with Glycolysis◦ 1 molecule glucose is split in half into 2 pyruvate
molecules
If O2 is present → Citric Acid (Kreb’s) Cycle & Electron Transport Chain
If O2 is NOT present → Fermentation
Cell Respiration Overview
Occurs when no O2 is present 2 Types:
◦ 1. Lactic Acid Fermentation: Converts pyruvate → lactic acid Helps make yogurt & cheese Creates burning sensation in muscles during exercise
◦ 2. Alcoholic Fermentation: Converts pyruvate → ethyl alcohol Helps make bread, wine & beer
Fermentation