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Energy in a Cell
Terms
ChemosyntheticOrganisms that obtain cellular energy by breaking down inorganic chemicals
Autotroph creates their own food through photosynthesis or chemosynthesis. These organisms are producers.Heterotroph
depends upon other organisms for nutrition. These organisms are consumers. Some organisms, such as the Euglena, will be photosynthetic in the presence of light and heterotrophic without light.
Energy Carriers ATP
temporary energy storage molecule in all cells
NADHH+ and e- carrier moleculeNAD + + H+ + e- NADH
FADH2
H+ and e- carrier moleculeFAD + 2H+ + e- FADH2
Think of NADH and FADH2 as taxi cabs!
NADH and FADH2
All Cells Need Energy
Cells need energy to do a variety of work:Making new moleculesBuilding 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
A Simple Review
What basic unit of what organic compound is pictured to the right?
Adenine
Ribose
P
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 + 12H2O C6H12O6 + 6O2 + 6
H2O
Reactants Products
light
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
Cellular Respiration The process of breaking down
food molecules to release energy. Aerobic respiration occurs in the
mitochondria. Two types:
Aerobic – requires oxygen.Anaerobic – requires an absence of oxygen.
Cellular Respiration – Chemical Equation
C6H12O6 + 6 O2 _ CO2 + _ H2O + 36-38 ATPenzymes
Cellular Respiration
Cellular Respiration Steps Glycolysis Citric Acid Cycle Electron Transport Chain
1. Glycolysis Glucose is split to form pyruvate. Takes place in the cytoplasm of
the cell. ATP and NADH are byproducts.
Glycolysis Chemical Equation
Glucose + 2 NAD+ + 2 ADP + 2 Pi 2 pyruvate + 2 NADH + 2 ATP + 2 H2O
Enzymes
GlycolysisC6H12O6
C3H3O4
+
NAD+
NADH
2 ATP
ReviewWhat are the inputs for Glycolysis?
Glucose2 ATP
C6H12O6 (6 carbon molecule)2 NAD+ (coenzyme)
2 ADP+P
What are the outputs for Glycolysis?2 pyruvic acid (3 carbon molecules)
2 NADH2 ATP (makes 4 but 2 are needed in the
process)
Anaerobic 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.
Aerobic Respiration2. Citric Acid Cycle A.K.A. Kreb’s
Cycle Pyruvate is used to build citric acid (a
carbon compound), which is broken down to release ATP. (# Net 2 ATP)
Takes place in the cristae (the folded membrane in the mitochondrion)
CO2 is released, and NADH & FADH2 carry electrons and hydrogen ions to the electron transport chain.
Each glucose molecule takes two trips around the cycle!
Inputs
Pyruvate
NAD+
FAD
ADP + Pi
Outputs
4 NADH
1 FADH2
1 ATP
3 CO2
Each glucose
molecule takes 2 turns
through the cycle!
Outputs
8 NADH
2 FADH2
2 ATP
6 CO2
3. Electron Transport Chain
Electron Transport Chain Electrons are reduced, and that energy
forms large amounts of ATP. (#32-34 ATP) Takes place in the inner membrane
of the mitochondrion The used ions are combined with
oxygen to form H2O.
Electron Transport System
36-38 ATP
NADH
NAD+
FADH2 FAD
H2O
O2
ReviewWhat are the inputs for the Krebs cycle?
1 Pyruvate (3 carbon molecule)
4 NAD+
1 FAD
1 ADP + Pi
What are the outputs for the Krebs cycle?
(Per 1 pyruvate – 1 glucose yields 2X)4 NADH
1 FADH2
1 ATP
3 CO2
ReviewWhat are the inputs for the ETS per one molecule of
glucose?
10 NADH: 8 from Krebs, 2 from glycolysis
2 FADH2 : from Krebs cycle
O2
What are the outputs for the ETS?
32-24 ATP molecules
H2O
Total ATP Production
36 -38 ATP molecules
C6H12O6 + 6 O2 6 CO2 + 6 H2O + 36-38 ATPenzymes
MITOCHONDRION
CO2
H2O
O2 ATP
NADHFADH2
HeatElectron
TransportSystem
ATP
NAD+
FAD
Pyruvate
GlucoseATP
Sunlight
Photo-System
I
Photo-system
II
NADP+
ADPNADPHATP
CalvinCO2
H2O
O2
ATP
ATP
NAD+
FAD
NADHFADH2
ElectronTransportSystem
Cycle
CitricAcid
Heat
CHLOROPLAST MITOCHONDRIONATP
Glycolysis
Glucose Pyruvate
Cycle
Cycle
CitricAcid
Sunlight
Photo-System
I
Photo-system
II
NADP+
ADPNADPHATP
CycleCalvin CO2
H2O
O2
ATP
ATP
NAD+
FADNADHFADH2
ElectronTransportSystem
Heat
CHLOROPLAST MITOCHONDRION
Glucose
ATP
Pyruvate
Glycolysis
Cellular Respiration
C6H12O6 + O2 CO2 + H2O + 36-38 ATP6 66
Oxidation - Reduction
Oxidation is the loss of elecrons from an atom or molecule. It is also the loss (removal) of hydrogen atoms from a molecule. A loss of energy is associated with the loss of electrons or hydrogen atoms.
Reduction is the gain of electrons or the gain of hydrogen atoms. This process stores energy.
Oxidation - Reduction
Oxidation and reduction occur together. When a atom or molecule is oxidized, another must be reduced.
Example: Na + Cl ® Na+Cl- - The Na is oxidized; the Cl is reduced.