8.3 – Cellular Respirationpp. 228-233
Overview of Cellular Respiration
Organisms obtain energy in a process called cellular respiration.
The equation for cellular respiration is the opposite of the equation for photosynthesis.
*Because both plants and animals have mitochondria, both types of organisms carry out cellular respiration.*
Aerobic RespirationIf oxygen is present, the cell undergoes
aerobic respiration.
The steps are:
1. Glycolysis- (only part that is anaerobic...no O2 required)
2. The Krebs Cycle- (aerboic = O2 required)
3. Electron Transport Chain- (aerboic = O2 required)
Glycolysis
It is an anaerobic process of splitting glucose forming two molecules of pyruvate
It occurs in the cytoplasm (outside the mitochondria)
4 molecules of ATP are produced; net yield of 2 since it takes 2 ATP to begin glycolysis.
Krebs Cycle
The series of reactions in which pyruvate (from glycolysis) is broken down into carbon dioxide is called the Krebs cycle.
It occurs inside the mitochondria
The yield from the Krebs cycle is six CO2 molecules and two ATP
Electron Transport
It is the final step in aerobic respiration
It occurs in the mitochondria
It produces the most ATP (24 ATP)
Overall
In eukaryotes, 1 molecule of glucose yields 36 ATP
In prokaryotes,1 molecule of glucose yields 38 ATP. This saves 2 ATP since prokaryotes have no mitochondria. Electron transport occurs in the cell membrane.
Anaerobic Respiration
If there is no oxygen available, the cell undergoes anaerobic respiration. Also known as fermentation.
It occurs in the cytoplasm
It produces small amounts of ATP
The steps are:
1. Glycolysis
2. Fermentation
Aerobic respiration gives much more energy than anaerobic respiration.
There are two types of Fermentation:–Alcoholic Fermentation–Lactic Acid Fermentation
Alcohol Fermentation
It occurs in yeast & some bacteria
Pyruvate is converted to ethyl alcohol and carbon dioxide
Lactic Acid Fermentation
It occurs in skeletal muscles
Pyruvate is converted to lactic acid when the body cannot supply enough oxygen
Why muscles become sore and fatigued
It is produced by microorganisms to make cheese, yogurt, and sour cream
The end products of photosynthesis are the starting materials of respiration
• Photosynthesis light
6CO2 + 6 H2O + energy C6H12O6 + 6O2
• Respiration
C6H12O6 + 6O2 --> 6 CO2 + 6H2O + ATP
Compare and Contrast Photosynthesis and Cellular Respiration
Photosynthesis Cellular Respiration
Function
Location
Reactants
Products
Equation
Type of Cell
Capture energy and store itin sugars
Release energy that wasstored in sugars
Light rxn: thyalokid of ChloroplastsCalvin Cycle: stroma of Chloroplasts
Glycolysis: cytoplasmKrebs Cycle & Electron transport: mitochondria
Water and Carbon dioxide Oxygen and glucose
Oxygen and glucose Water and Carbon dioxide
Plant cells BOTH Plant and AnimalCells
Calvin Cycle
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