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