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 Every organism must be able to obtain energy from its
environment
 Autotrophs: make food from sunlight
 Examples?
 Heterotrophs: get food from elsewhere
 Examples?
(Which are you?)
 Energy molecule used by
cells
 Composed of:
 Nitrogen Base
(Adenosine)
 Sugar (Ribose)
 3 phosphate groups
 Energy is RELEASED when a
phosphate group(P) is
REMOVED/BROKEN
 Energy is stored in the bond
between the 2nd and 3rd
phosphate group. When P is
ADDED back, energy is
ADDED/STORED
 ATP  ADP + P + Energy
 ADP: adenosine diphosphate
The P can be reused!
 Photo: light
 Synthesis: to put together
 Process that uses the sun’s energy to make
simple sugars (glucose)
 All energy originates with the sun
(Do you know it?)
 What do plants need?


 What do plants produce or give off?


 6CO2 + 6H2O  C6H12O6 + 6O2
 Carbon Dioxide + Water  Sugar + Oxygen Gas
 Autotrophs carry out
photosynthesis!
 Organelle where
photosynthesis
occurs
 Thylakoids:
Storage sacs of
chlorophyll
 Grana: Stack of
thylakoids
 Stroma: Area
outside the
thylakoids
 Thylakoid membrane
traps the light using
pigments:
 Molecules that absorb
specific light wavelengths
 Chlorophyll absorbs
most wavelengths of
light except for green
 Makes plants look green!
 (Other plant pigments:
 Xanthophyll: yellow
 Carotene: orange)
 2 phases
 Light-dependent reactions
 Convert light energy into chemical energy
 ATP produced is used to fuel the light-independent
reactions
 Light-independent reactions
 Produces simple sugars
So, photosynthesis
 Requires Sunlight, Chlorophyll (to gather
the suns energy) and Water
 Happens in the thylakoid membrane of the
chloroplasts.
 Sunlight and water goes in
 Oxygen, ATP and NADPH comes out
 ATP: Cellular Energy
 NADPH: Energy needed in the Light
Independent Reactions to remove a P group
from ATP.
 Does not require sunlight
 Occurs in the stroma of the chloroplast
 CO2, ATP and NADPH goes in
 Glucose (C6H12O6), ADP + P, and NADP+ comes out
 NADP+ Energy needed in the light reactions to bond a
P+ group to ADP
 (Used to be called dark reactions, but that is
misleading.)
 Where does the plant get…
 sunlight?
 water?
 carbon dioxide (CO2)?
Light Dependent
Light Independent
 Oxygen (O2)
 Sugar (glucose)
 ATP
 ADP + P
 Occurs in ALL living organisms
 Process in which mitochondria break down
sugar to produce ATP
C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy
 Photosynthesis reversed!
1.
Glycolysis: in cytoplasm
This step is anaerobic (no oxygen needed)
2.
Citric Acid Cycle (Kreb’s Cycle):
in mitochondria
3.
Electron Transport Chain: inner
membrane of mitochondria
 Needs 2 ATP to start
 Produces 4 ATP
 Breaks glucose into ATP and pyruvate
 Produces 2 ATP and CO2
 Breaks down a molecule of pyruvate
 Produces 32 ATP (sometimes 34)
 Occurs in the inner membrane of the mitochondria
(cristae)
 Energized electrons release energy as they pass from
one protein to another
Cellular respiration makes a
total of:
36-38 ATP
 If oxygen is not
present ATP can
still be made in
small amounts
using this
anaerobic
process.
 Many foods
are made this
way.
 2 Types of
fermentation
 Lactic Acid
 Alcoholic
 Produces lactic acid and only 2 ATP
 Occurs when the body is under stress and not getting
enough oxygen
 Used by yeast cells and some bacteria to produce:
 CO2
 Ethyl alcohol
 This process is used to make bread and wine
Photosynthesis
Food synthesized
Energy from sun stored
as glucose
Carbon Dioxide taken in
Oxygen given off
Produces sugar
Requires light
Occurs only in the
Chloroplast
Cellular Respiration
Food broken down
Energy of glucose
released
Carbon dioxide given off
Oxygen taken in
Produces CO2 & H2O
Does not require light
Occurs in all living cells