Download Energy in the cell

Energy in a
Cell
All Cells Need Energy
 Cells
need energy to do a
variety of work:
 Making new molecules.
 Building membranes and
organelles.
 Moving molecules in and out
of the cell.
 Movement.
Where Does A Cell Get
Energy?
 Food
is broken down to a form
the cell can use.
 Extra energy is stored in an
ATP molecule, a nucleotide.
What Is ATP?
 ATP
– adenosine triphosphate is a
molecule made up of an adenine,
ribose, and 3 phosphate groups.
Adenine
Ribose
How Does ATP Work?
Energy is stored in the bond
between the second and third
phosphate group.
 When the bond is broken, energy
is released and ADP is formed.

Adenine
Ribose
ATP – Energy Currency
•
•
Within a cell, formation of ATP
from ADP and phosphate
occurs over and over, storing
energy each time.
As the cell uses energy, ATP
breaks down repeatedly to
release energy and form ADP
and phosphate.
Making Energy
 Cells
make energy in two
ways:
 Photosynthesis – takes place
in the chloroplasts.
 Respiration – takes place in
the mitochondria.
Photosynthesis
 Autotrophs
make their own
food by trapping light energy
and converting it to chemical
energy (carbohydrates).
Photosynthesis
 Using
light from the sun, plants
combine water and carbon
dioxide to make sugar .
 General
Equation:
6CO2 + 6H2O + energy
Reactants
C6H12O6 + 6O2
Products
Photosynthesis
2
Reactions
 Light Reactions
 Calvin Cycle
Photosynthesis
 Light
Reactions – Light energy
is converted to chemical
energy to split hydrogen from
water.
 Takes place in the grana of
the chloroplasts (the coinlike stacks of sacs).
 Byproducts are oxygen,
NADPH, and ATP.
Photosynthesis
 Calvin
Cycle – ATP and NADPH
from the light reactions are used
along with CO2 to form a simple
sugar (glucose).
 Takes place in the stroma of the
chloroplasts (the liquid filling).
 Byproducts are C6H12O6
(glucose), ADP, and NADP+
(which return to the light
Sunlight
O2
NADP+
ADP
ATP
H2O
NADPH
CO2
CHLOROPLAST
Chemosynthesis
 Some
autotrophs can convert
inorganic substances to energy.
 Most are adapted to live in
conditions where there is no
oxygen.
 Marshes.
 Lake sediments.
 Digestive tracts of mammals.
 Deep in the ocean.
Respiration
 The
process of breaking down food
molecules to release energy.
 Occurs in the mitochondria.
 Two types:
 Aerobic – requires oxygen.
 Anaerobic – requires an absence
of oxygen.
Respiration
 Two
types of anaerobic respiration:
 Fermentation – occurs when
bacteria break down plants
(vegetables and fruit) and release
alcohol or vinegar.
 Lactic Acid Fermentation – occurs
in muscles – a buildup of lactic
acid causes soreness.
Respiration
 Steps
 Glycolysis
 Citric
Acid Cycle
 Electron Transport Chain
Respiration
 Glycolysis
– glucose is split to
form pyruvate.
 Takes place in the cytoplasm
of the cell.
 ATP is a byproduct.
Respiration
 Citric
Acid Cycle – pyruvate is used
to build citric acid (a carbon
compound), which is broken down
to release ATP.
 Takes place in the cristae (the
folded membrane in the
mitochondrion).
 CO2 is released, and NADH
carries hydrogen ions to the
electron transport chain.
Respiration
 Electron
Transport Chain –
hydrogen ions are stripped of their
energy, and large amounts of ATP
are formed.
 Takes place in the inner
membrane of the mitochondrion.
 The used ions are combined with
oxygen to form H2O.
Heat
O2
H2O
CO2
Glucose
ATP
Pyruvate
Electron
Transport
System
NAD+
ATP
NADH
ATP
MITOCHONDRION
Sunlight
Heat
Photosystem
II
NADP+
ADP
O2
PhotoSystem
I
ATP
H2O
NAD+
NADPH
ATP
NADH
CO2
Calvin
Cycle
Glycolysis
Glucose
CHLOROPLAST
Electron
Transport
System
Citric
Acid
Cycle
ATP
Pyruvate
ATP
MITOCHONDRION
Sunlight
Heat
Photosystem
II
NADP+
ADP
O2
PhotoSystem
I
ATP
H2O
Electron
Transport
System
NAD+
NADPH
ATP
NADH
CO2
Calvin
Cycle
Citric
Acid
Glycolysis
Cycle
ATP
Glucose
Pyruvate
CHLOROPLAST
ATP
MITOCHONDRION