CHAPTER 6 CELLULAR RESPIRATION: OBTAINING ENERGY FROM FOODGeneral 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)

Energy investment phase

Carbon atomPhosphategroup

High-energyelectron

Key

Glucose

2 ATP2 ADP

INPUT OUTPUT

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