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Cell Metabolism
Energy
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_____________________________ the capacity to do work.
Comes in different forms: ________________________________________
Two types of energy:
o ________________________Energy: is the energy of moving objects; it is energy in use
o ________________________ Energy: is stored energy; energy that has potential to do the work.
A __________________________stores potential energy until it is released in the kinetic form of chemical or
thermal (heat) energy.
___________________________________: the sum of potential and kinetic energy
The amount of _____________________ that could be used to power other chemical reactions.
Oxidation-Reduction Reaction
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Transfer energy between molecules in the form of ________________________________.
The molecules that loses an electron is _____________________________, while the molecule that gains an
electron is _______________________________.
Example: NADH is a common energy carrier within cells. In the equation below, through a chemical reaction with
hydrogen (2H), NAD+ is oxidized to NADH, while hydrogen is reduced to hydrogen ions (H+). In the process, the
reverse direction, with NADH being reduced to NAD+ and hydrogen ion becoming oxidized to hydrogen
NAD+ +2H NADH + H+
Endergonic Reactions
 Store energy within a molecule because the reactants have less free energy than the ______________________.
 These reactions require ________________________________
 Example: The production of glucose from carbon dioxide (CO2) and water (H2O) is an endergonic reaction because it
requires energy input. Because energy is expended in the process, this reaction cannot occur in the reserve
direction.
 6CO2 + 6H2O + energy  C6H12O6 +6O2
Exergonic Reactions
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_________________________________, leaving the reactants with more free energy than the product
Example: The breakdown of glucose into carbon dioxide (CO2) and water (H20) is exergonic reaction because it
results in the release of energy. Because this reaction releases energy, it cannot occur in the reverse directions
C6H12O6 (glucose) + 6 O2  6CO2 +6H2O +energy
Cells often use the energy released from exergonic reactions to power endergonic reactions; these are called
______________________________
ATP
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Adenosine triphosphate, is referred to as the “____________________________________” (cell energy) because it
powers most of the reactions that take place in a cell.
ATP consist of
o _______________________________, an adenine (a type of nucleotide)
o Chain of three________________________________ groups
The bonds that link the second and third phosphate group can be broken down to produce ADP (adenosine
diphosphate), a free phosphate group (P), and a substantial amount of energy used for
_________________________ reactions.
ATP  ADP + P + energy
Example: The human body uses, on average, one kilogram of ATP every hour
Enzymes
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____________________________ reactions require a small initial input of energy, called activation energy, before
the reaction can proceed.
_________________________________ are proteins that lower the activation energy of a reaction.
o _________________________________ of an enzyme binds with the reactants (substrate) and either
changes them in some way or simply brings them in closer proximity to one another.
Chemical reactions do not ________________________________________ the enzyme.
Once the reaction has taken place, the product is _______________________________, and the enzyme is free to
catalyze other reactions
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Enzyme Inhibitors
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The presence of other molecules may inhibit an enzyme, or prevent it from functioning.
Inhibitions can occur in two ways:
o _______________________________: occurs when the inhibitor binds with the active site of an enzyme.
With the active site already occupied, the enzyme cannot bind with the substrate.
o __________________________________: occurs when the inhibitor binds with an allosteric site (any site
other than the active site) and changes the shape of the enzyme so that it no longer bonds with the
substrate.
Example: Inhibitors are often used as drugs, in many cases to prevent detrimental reactions in an organism. Aspirin,
for instance, inhibits the enzymes that causes pain and inflammation. However, inhibitors can also be poisonous.
Cyanide is a lethal toxin because it competitively inhibits cytochrome coxidase, an enzyme involved with cellular
respiration.
Cellular Respiration
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Organisms must obtain their own energy from the environment, usually in the form of
__________________________________ radiation.
The process of converting energy into a form that can be used by cells is called ____________________________.
Two methods of cellular metabolisms:
o __________________________________ and ____________________________________
Cellular respiration converts the energy found in food molecules, especially ________________________, to the
more useable form of ______________.
36 ATP can be produced from a single molecule of Glucose
Cellular Respiration Equation
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_________________________ transfer is not efficient for organisms
Cellular respiration only ____________ energy in glucose is converted to ATP.
Cellular respiration occurs in four stages:
1- _______________________________
2- Oxidation of pyruvate
3- _____________________
4- ___________________________
Glycolysis
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Takes place in the ________________________ (cytosol)
Converts glucose to two molecules of_______________________, the compound from which energy will be
extracted in the Kreb Cycle.
Produces 2____________ and 2 ________________________ (energy carrying molecule). Water is also released in
this reaction.
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Oxidative of Pyruvate
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The two molecules of pyruvate are _____________________ and transformed into molecules of
______________________.
Takes place in _________________________
Also produces one molecule of_____________________
Releases _______________
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Kreb Cycle
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Takes place in matrix of the__________________________
Processes each acetyl CoA to produce 3 ________________, 1 ____________________, and 1
____________________for a total of 6 NADH, 2 FADH2, 2 ATP per glucose.
Carbon dioxide is also released in this reaction.
Kreb Cycle
Mnemonic Device Kreb Cycle (order)
Can
Intelligent
Karen
Solve
Some
Foreign
Mafia
Operations?
Kreb Cycle Quiz on: _________________
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Oxidative Phosphyloration
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After the Kreb Cycle, large amount of __________________ produced from NADH (produces 3 ATP) and FADH2
(produces 2 ATP)
 Requires the presence of oxygen in the mitochondria
Electron Transport Chain
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Is series of molecules embedded in the inner membrane of the mitochondria
The 10 NADH and 2 FADH2 (Produced from previous stages) power the production of the final ______________
___________________________: coupling of the movement of electrons down the electron transport chain with
the formation of ATP.
 ___________________________: A reaction that uses the product of one reaction as part of another reaction.
Steps to the Electron Transport Chain
 1- Electron carriers ___________________________ shuttle electrons to the inner mitochondrial membrane.
 2- NADH and FADH2 donate their electrons to the first in a series of membrane proteins. Each protein uses the
energy in the electron to pump H+ into the intermembrane space of the mitochondrion before passing the electron
the next carrier. The final electron receptor is ________________, which combines with two protons, H+ to form
water
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3- By pumping H+ into the intermembrane space, the electron transport chain sets up a high concentration gradient.
H+ flows down gradient through the ATP synthase, a membrane protein that catalyzes the production of
___________________ from ADP.
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Summary of Cellular Respiration
Stage
Location
Reaction
Glycolysis
Cytosol
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Converts 1 molecule of glucose to 2 molecules of pyruvate
2 ATP and 2 NADH molecules are produced and water is released
Oxidation of
pyruvate
Mitochondria
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Converts 2 molecules of pyruvate to 2 molecules of acetyl CoA
2 NADH molecules are produced and carbon dioxide is released
Kreb Cycle
Mitochondrial Matrix
Electron
Transport Chain
Mitochondria
 Converts 2 molecules of acetyl CoA to 6 molecules of NADH,
2 molecules of FADH2, and molecules of ATP.
 Carbon dioxide is released
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10 NADH molecules and 2 FADH2 are converted to 32 ATP molecules
Oxygen is consumed and water is produced
Fermentation
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Eukaryotic cells can produce ATP through _____________________________.
Fermentation is much less efficient than the four stages of cellular respiration, but allows ATP to produce when
oxygen is ______________________
Begins with glycolysis producing only _______________________.
All other stages cannot be completed without _________________________.
Two types of fermentation:
1- ___________________________________: Pyruvic acid is converted to ethanol.
Used by fungi and some plants
Used to make _____________________________
2- ________________________________________: Pyruvic acid is converted to lactate.
Lactic acid fermentation is used by animals and bacteria
Muscle Cramps (occurs when over exercise your muscles)
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Example: The sour taste of sourdough comes from the lactic acid produced by the fermentation of bacteria
Photosynthesis
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Plants, some protists, and bacteria, create food molecules (sugars) from carbon dioxide and solar energy through
the process of ________________________
Equation for photosynthesis:
Players of Photosynthesis
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Organelle: _____________________
Chloroplast is divded into inner and outer portion of the organelle
____________________________: inner fluid portion
__________________________: Green disk membrane system (first stage of photosynthesis occurs)
__________________________: Flatten channels and disk (thylakoid) arranged in stacks
Label the Chloroplast
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_____________________: Organisms that is self-nourishing.
_______________________: organisms that must consume food.
Bundle Sheath cells: Cells that are tightly wrapped around the veins of a leaf. Site of the Calvin Cycle in C4 plants
______________________: interior leaf
Mesophyll Cells: contains many chloroplast and host the majority of ________________________
_________________________: process by which water is broken up by an enzyme into hydrogen ions and oxygen
atoms. Occurs in the light dependent reaction
________________________________: process by which ATP is produced during light-dependent reaction of
photosynthesis
_______________________________ process by which oxygen competes with carbon dioxide and attaches to RuBP.
Plants that experience this has a lower capacity of growth.
_____________________________: cluster of light-trapping pigments involved in photosynthesis. Photosystem I
and Photosystem II are two most important.
_______________________: a molecule that absorbs light of a particular wavelength. Pigments include carotenoids
(orange), phycobilins, and ________________________
_______________________________: an enzyme that catalyzes the first step of the Calvin Cycle in C3 plants
________________________: Structure through which CO2 enters a plant and water vapor and O2 leave
_____________________: natural process by which plants lose H2O via evaporation of leaves
Light Dependent Reaction
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Convert solar energy into _____________________________, the reduced form of the electron receptor, NADP+.
During these reactions, water is split, leaving _______________________ as a waste product.
Why is oxygen considered to be a waste product?
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These reactions take place in _________________________in the choloroplast.
__________________________ comprise cluster of molecules composed of light-absorbing pigments and a reaction
center, which includes a primary electron acceptor and two chlorophyll a pigment molecules.
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There are two photosystems work sequentially, with light first being absorbed by _________________________ and
later by photosystem I
Steps to the light dependent reactions
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1- Photosystem II absorbs solar energy in the form of _______________________.
2- The solar energy excites electrons in the reaction center of photosystem II, which then enter an
___________________________ chain. These electrons originate from the splitting of water, which produces free
electrons and O2
3- As electrons pass down the electron transport chain, protons are pumped into the thylakoid membrane space of
the chloroplast. Protons diffuse out of the thylakoid membrane space through an ATP synthase, creating ATP.
4- ________________________ accepts electrons from the electron transport chain and uses light energy to excite
the electrons further.
ATP and NADPH made in the light
dependent reaction
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Cellular Respiration and Light Dependent Reaction
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Cellular respiration and light dependent reactions of photosynthesis use similar processes to produce ___________.
Scientist believe that the electron transport chain used in ______________________________ may have evolved
from the transport system used in photosynthesis.
Calvin Cycle
 Uses ATP and NADPH from the light-dependent reaction to convert CO2 into _______________ that the plant can
use.
 CO2 is obtained through the _____________________.
 ________________________: incorporates the CO2 into organic molecules
 The incorporation is completed by the energy rich enzyme ________________ (ribulose biphosphate carboxylase
(RuBP)), a protein made during light-dependent reaction of photosynthesis . Abundant in _________________
 CO2 is split into:
 3 carbon molecule ________________ (3-phosphoglycerate)
 Converts PGA into 3-carbon sugar molecule _____________________________
 Used to make _______________& ___________________
 The production of a single 3-carbon _____________________ molecule require 3 CO2, 9 ATP, 6 NADPH
Calvin Cycle Quiz on:
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Photorespiration
 When the enzyme rubisco incorporates oxygen, rather than CO2, into organic molecules, plants create energy
through the process of _______________________________.
 Occurs most in ____________ regions where plants must close their stomata to prevent _________________ to the
air.
 The results in a buildup of __________________ levels in the leaf, which makes rubisco more likely to bind with the
oxygen.
 Detrimental to plants because it consumes more ATP to produce each 3-carbon ________________.
 Three different categories this type of method: C3 pathway, CAM pathway, and C4 pathway
C3 Plants
 Found in areas with moderate temperature and above ________________________________
 Exacerbated in Hot arid climates, where the rate of photosrespiration increases as the temperature goes up.
 Consequently C3 plants are ___________________ found in these climates
 Located in the __________________ zones
 Examples: Wheat, barley, and sugar beets
C4 Plants
 Use the enzyme PEP carboxylase to fix CO2 in the _______________________cells of their chloroplast.
 The fixed CO2 is then shuttled to specialized structures known as ___________________________, where it is
released and incorporated into the Calvin Cycle.
 Energetically expensive, but limits photorespiration by allowing high concentration CO2 to build up in the bundlesheath cells
 Examples: Corn and sugar cane are common in warm environments
CAM Plants
 Plants reduce photorespiration and conserve ____________________ by opening their stomata only at night.
 ___________________ enters through the stomata and is fixed into organic acids, which are then stored in the cell’s
vacuole.
 During the day, the acids break down to yield high levels of CO2 for use in the Calvin cycle
 Common in ________________ environments
 Examples: Pineapples and cacti