Energy in a Cell

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• Energy in a Cell

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• Terms

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.
Chemosynthetic Organisms that obtain cellular
energy by breaking down inorganic chemicals
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• Energy Carriers

• ATP
• temporary energy storage molecule in all cells
• NADH
• H and e- carrier molecule
• NAD H e- NADH
• FADH2
• H and e- carrier molecule
• FAD 2H e- FADH2
• Think of NADH and FADH2 as taxi cabs!

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NADH and FADH2
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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

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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.

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What Is ATP?

• ATP adenosine triphosphate is a molecule made
  up of an adenine, ribose, and 3 phosphate groups.

phosphate groups
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A Simple Review
What basic unit of what organic compound is
pictured to the right?
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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
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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.

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Making Energy

• Cells make energy in two ways
• Photosynthesis takes place in the chloroplasts.
• Respiration takes place in the mitochondria.

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Photosynthesis

• Autotrophs make their own food by trapping light
  energy and converting it to chemical energy
  (carbohydrates).

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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
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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

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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.

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Cellular Respiration Chemical Equation
enzymes
C6H12O6 6 O2 _ CO2 _ H2O
36-38 ATP
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Cellular Respiration

• Cellular Respiration Steps
• Glycolysis
• Citric Acid Cycle
• Electron Transport Chain

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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
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Glycolysis
C6H12O6
NAD
2 ATP
NADH
C3H3O4

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Review

• What are the inputs for Glycolysis?

Glucose 2 ATPC6H12O6 (6 carbon molecule)2 NAD
(coenzyme) 2 ADPP
What are the outputs for Glycolysis?
2 pyruvic acid (3 carbon molecules)2 NADH2 ATP
(makes 4 but 2 are needed in the process)
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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.

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Aerobic Respiration

• 2. Citric Acid Cycle A.K.A. Krebs 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!

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Each glucose molecule takes 2 turns through the
cycle!

• Inputs
• Pyruvate
• NAD
• FAD
• ADP Pi

• Outputs
• 4 NADH
• 1 FADH2
• 1 ATP
• 3 CO2

• Outputs
• 8 NADH
• 2 FADH2
• 2 ATP
• 6 CO2

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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.

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NADH
H2O
NAD
O2
FADH2
FAD
36-38 ATP
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Review

• What 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
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Review

• What 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
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Total ATP Production

• 36 -38 ATP molecules

enzymes
C6H12O6 6 O2 6 CO2 6 H2O
36-38 ATP
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Heat
Electron Transport System
O2
ATP
H2O
NADH FADH2
NAD FAD
CO2
citric acid cycle
Glucose
ATP
Pyruvate
MITOCHONDRION
ATP
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Sunlight
Heat
O2
Photo- System I
Photo- system II
Electron Transport System
ATP
H2O
ATP
NADH FADH2
NADP ADP
NADPH
NAD FAD
CO2
Calvin
Citric Acid
Cycle
Cycle
ATP
Glucose
Pyruvate
CHLOROPLAST
MITOCHONDRION
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Citric Acid
Cycle
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Cellular Respiration
C6H12O6 O2 CO2 H2O 36-38 ATP
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6
6
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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.

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Oxidation - Reduction

• Oxidation and reduction occur together. When a
  atom or molecule is oxidized, another must be
  reduced.
• Example Na Cl   NaCl-  - The Na is oxidized
  the Cl is reduced.