ENERGY IN THE CELL
ENERGY IN
THE CELL
Is about
ENERGY
CONVERSIONS
Starting with
PHOTOSYNTHESIS
Transformed by
CELLULAR
RESPIRATION
Converted to
ATP for cell usage
Plants &
photosynthesis
Photosynthesis
 Photosynthesis takes place in specialized structures
inside plant cells called chloroplasts
 Light absorbing pigment molecules e.g. chlorophyll
Photosynthesis
 Method of converting sun energy into chemical energy
usable by cells
 Autotrophs: self feeders, organisms capable of
making their own food
 Photoautotrophs: use sun energy e.g. plants
photosynthesis-makes organic compounds (glucose)
from light
 Chemoautotrophs: use chemical energy e.g. bacteria
that use sulfide or methane chemosynthesis-makes
organic compounds from chemical energy contained in
sulfide or methane
Equation for photosynthesis
light
 6CO2 + 6 H2O
C6 H 12O6 + 6O2
Overall Reaction
 6CO2 + 12 H2O + light energy → C6H12O6 + 6O2+ 6H2O
 The Carbohydrate made is glucose
 Water appears on both sides because 12 H2O molecules are
required and 6 new H2O molecules are made
 Water is split as a source of electrons from hydrogen atoms
releasing O2 as a product
 Electrons increase potential energy when moved from water
to sugar therefore energy is required (endergonic reaction)
Harvesting Chemical Energy
 So we see how energy enters food chains (via
autotrophs) we can look at how organisms use that
energy to fuel their bodies.
 Plants and animals both use products of
photosynthesis (glucose) for metabolic fuel
 Heterotrophs: must take in energy from outside
sources, cannot make their own e.g. animals
 When we take in glucose (or other carbs), proteins,
and fats-these foods don’t come to us the way our
cells can use them
ENERGY FOR LIFE PROCESSES
RADIANT
ENERGY
CHEMICAL
ENERGY
CHEMICAL
ENERGY
PHOTOSYNTHESIS & CELLULAR RESPIRATION
 CONVERTS RADIANT SOLAR ENERGY INTO CHEMICAL ENERGY STORED
IN THE BONDS OF ORGANIC COMPOUNDS ( GLUCOSE)
 ENERGY FOR MOST LIVING ORGANISMS COMES FROM THE SUN AND IS
CONVERTED TO USABLE FORM THROUGH PHOTOSYNTHESIS &
CELLULAR RESPIRATION.
SUN
Photosynthesis
By autotrophs
Respiration by
autotrophs &
heterotrophs
Cell
activities
Cellular respiration:
 IS A SET OF CHEMICAL REACTIONS THAT OCCUR
INSIDE EVERY ORGANISM’S CELLS.
 DURING CELLULAR RESPIRATION, FOOD MOLECULES ARE
BROKEN DOWN TO RELEASE THE ENERGY IN THEIR BONDS.
(EXCERGONIC REACTION).
 THE ORGANIC COMPOUNDS MADE BY PLANTS
( CALVIN CYCLE) DURING PHOTOSYNTHESIS ARE
THE FOOD THAT SUPPLIES THE ENERGY USED BY
AUTOTROPHS & HETEROTROPHS FOR LIFE.
CELLULAR RESPIRATION
 2 TYPES OF CELLULAR RESPIRATION:
- ANAEROBIC – DOES NOT NEED OXYGEN
- AEROBIC – NEEDS OXYGEN.
CYTOPLASM
GLYCOLYSIS
ANAEROBIC
GLUCOSE
2 PYRUVIC
ACID
MITOCHONDRIA
AEROBIC
ALCOHOLIC
FERMENTATION
ETHYL ALCOHOL +
CO2
LACTIC ACID
FERMENTATION
KREB’S
CYCLE
ELECTRON
ELECTRON
TRANSPORT
TRANSPORT
CHAIN
CHAIN
LACTIC
ACID
CO2
H2O
ATP
CELLULAR RESPIRATION
GLYCOLYSIS:

BOTH ANAEROBIC AND AEROBIC RESPIRATION BEGINs WITH GLYCOLYSIS

OCCURS IN CYTOPLASM

PRODUCES ATP - adenosinetriphosphate
FERMENTATION:

THE PROCESS OF BREAKING DOWN PYRUVIC ACID WITHOUT THE USE OF OXYGEN

DOES NOT PRODUCE ATP
LACTIC ACID FERMENTATION: ANAEROBIC respiration

CONVERSION OF PYRUVIC ACID TO LACTIC ACID.

EX. MUSCLE SORENESS
ALCOHOLIC FERMENTATION: ANAEROBIC respiration

SOME PLANT CELLS AND UNICELLULAR ORGANISMS CONVERT P YRUVIC ACID TO
ETHYL ALCOHOL.

BEER AND WINE DEPEND ON YEASTS TO PRODUCE ALCOHOL THROUGH
FERMENTATION.
AEROBIC RESPIRATION
 REQUIRES OXYGEN
 OCCUR INSIDE THE MITOCHONDRIA
 KREBS CYCLE RESULTS IN THE FORMATION OF
ATP
 CO2 , H2O , ATP ARE ALL PRODUCTS OF AEROBIC
RESPIRATION
FORMULA FOR CELLULAR
RESPIRATION:
C6 H12O6 + 6 O2
6CO2 + 6H2O + 36 ATP