CHAPTER 6
CELLULAR RESPIRATION:
OBTAINING ENERGY FROM FOOD
General Biology
CM Lamberty
BIOLOGY AND SOCIETY
ENERGY FLOW AND CHEMICAL CYCLING


Animals depend on plants to covert solar energy
to
Photosynthesis
PRODUCERS AND CONSUMERS

Plants and other autotrophs (self-feeders)

Heterotrophs (other-feeders)

Producers

Consumers
CHEMICAL CYCLYING: PHOTOSYNTHESIS
AND CELLULAR RESPIRATION

Chemical ingredients for photosynthesis

Chloroplasts

Cellular respiration
CHEMICAL CYCLYING: PHOTOSYNTHESIS
AND CELLULAR RESPIRATION

Waste products of cellular respiration

Animals

Plants
CELLULAR RESPIRATION : AEROBIC
HARVEST OF FOOD ENERGY

Respiration

Cellular respiration
OVERALL EQUATION OF CELLULAR
RESPIRATION

Glucose

Many chemical steps
ROLE OF OXYGEN IN CELLULAR
RESPIRATION

38 ATP for each glucose
REDOX REACTIONS

Chemical reactions involving transfer of electrons
Loss of electrons:
 Gain of electrons:

Cellular respiration is a fall of electrons
 Results in release of energy

NADH AND ELECTRON TRANSPORT CHAINS
Path of electrons from glucose to oxygen
 NAD+ (nicotinamide adenine dinucleotide)


NADH transfers electrons via electron transport
chain
OVERVIEW OF CELLULAR RESPIRATION

Metabolic pathway

Three stages of cellular respiration

Glycolysis

Citric acid cycle (Krebs cycle)

Electron transport
THREE STAGES OF CELLULAR
RESPIRATION

Stage 1: Glycolysis

(w/ most of E)
INPUT
OUTPUT
2 ATP
2 ADP
Glucose
Key
Carbon atom
Phosphate
group
High-energy
electron
Energy investment phase
Figure 6.7-1
THREE STAGES OF CELLULAR
RESPIRATION

Stage 2: Citric Acid Cycle
THREE STAGES OF CELLULAR
RESPIRATION

Stage 3: Electron Transport
VERSATILITY OF CELLULAR RESPIRATION

Cellular respiration can also “burn”:
Diverse types of carbohydrates
 Fats
 proteins

ADDING UP THE ATP FROM CELLULAR
RESPIRATION
Remember up to 38 ATP/glucose
 Glycolysis and citric acid cycle each contribute 2
ATP by direct synthesis
 Remaining from “fall” of electrons in transport
chain

Each pair dropped down from NADH = 3 ATP
 Each pair dropped down from FADH2 = 2 ATP

FERMENTATION: ANAEROBIC HARVEST OF
FOOD ENERGY
Cells can work for short periods w/o O2
 Fermentation is anaerobic harvest of food energy

FERMENTATION IN HUMAN MUSCLE
CELLS
FERMENTATION IN MICROORGANISMS
Fermentation alone is able to sustain many
microorganisms
 The lactic acid produced by microbes is used to
produce:

LIFE BEFORE AND AFTER OXYGEN
Glycolysis used by ancient bacteria to make ATP
when little oxygen available and before
organelles evovled
 Today glycolysis

Occurs in almost all organisms
 Is a metabolic heirloom of the first stage in the
breakdown of organic molecules
