1. UNIT 4: Enzymes and Cell Energy
WHAT are ENZYMES???
Enzymes…
Are CATALYSTS: __________ chemical reactions that would otherwise happen too ________ to support life. Catalysts _____________ make reactions happen that couldn’t happen by themselves.
Are PROTEINS. Their amino acid sequences determines their ____________, which are important for their functions.
Are _____________________ during the reaction—the same enzyme can be used repeatedly
AND, BECAUSE of its shape, an Enzyme…
Is specific to the _________ it catalyzes. The reactants (called ____________) fit perfectly into a place on the enzyme called the ____________ _____________.
The ___________ of the enzyme active site makes it substrate-specific.
The enzyme may slightly _________ ________ (gives substrates a squeeze in a process called ___________ ______) that allows the reaction to happen.
Finally, the products are __________ from the active site, and the enzyme can be reused over and over again for more reactions.
Only functions in ____________ pH and temperature ranges, where it has the proper shape.
changing the temperature or pH (__________) may change an enzyme’s shape
It may no longer __________________ its substrates, and therefore not function.
An enzyme that has lost its proper shape and does ______________ is said to be denatured.
HOW do Enzymes Work?
TEMPERATURE
PRODUCTS MADE (ENZYME FUNCTION)
37°C
ENZYME WORKS BEST AT THIS CONDITION
DENATURED ENZYME
Favorable chemical reactions involve reactants going through an __________, awkward transition state.
Unfavorable states are considered _______ energy and favorable states are considered _____ energy.
The amount of energy required to overcome the transition state is called the activation energy
Enzymes work when the _________ _____, or squeeze provided by the enzyme, makes the transition state more favorable
In other words, an enzyme __________ the activation energy of a reaction

2. CHEMICAL ENERGY AND LIFE
Enzymes work by making this transition phase more stable. In other words, enzymes lower the activation energy of a reaction. A chemical reaction that might otherwise occur once every thousand years can happen in milliseconds with the help of the proper enzyme.
CHEMICAL ENERGY AND LIFE
ENERGY is the ______________________________.
Cells require energy for ____________ reactions, _____________ transport, _____ ___________, and maintaining _________________.
We obtain energy from __________, but energy ultimately comes from the sun.
Glucose is the preferred energy source, but we can obtain it from _____________, ________ and even ____________
CHEMICAL ENERGY in food is stored in __________ _________ as _______________ energy.
When bonds are broken, energy of _____________ is released. Some is lost as _________, but some portion of it can be converted into a usable form in the bonds of ________.
We use ATP energy to “pay for” ______________ reactions
ATP is a better form of energy because it contains ___________ packets of energy than glucose
If we released the energy from food molecules (like glucose) all at once, it would be ____________ and ________________
ATP, _____________________ is a ______________ composed of:
___________, a nitrogen base
_________, a ____ carbon sugar
_________________ groups
Potential energy is stored in the ___________ _______________________
ATP is like a rechargeable ____________
ATP = “charged” (3 phosphates), ________ PE
ADP = “uncharged” (2 phosphates, _____________ _________________), ______ PE

3. METABOLIC PATHWAYS: CELLULAR RESPIRATION AND PHOTOSYNTHESIS
METABOLISM: the sum of all __________________________ in an organism.
METABOLIC PATHWAYS: a series of sequential reactions in which the ____________ of one reaction is the ______________ for the following reaction.
TWO major metabolic pathways in life:
CELLULAR RESPIRATION
____________ molecules (like glucose) broken down to release ___________ for cell use
PHOTOSYNTHESIS
___________________ from sun is converted to ________________ in the form of glucose
The relationship between these two pathways results in the ___________________________ within an organism as well as within an ecosystem.
Plants and other organisms that can make their own food are known as ________________
Humans and other organisms that have to obtain food are known as ________________
CELLULAR RESPIRATION
CELLULAR RESPIRATION - AEROBIC (requires O2) ENERGY PRODUCTION (pp )
Cellular respiration is the breakdown of ____________ in the presence of ________ to “make” _____.
The oxygen required for cellular respiration is __________ into the ________, ___________ into the _________, and is delivered to the ______________ of the body cells by _________________.
The glucose needed is obtained through _________. The glucose is transported in the blood and enter the body cells via ____________________ by ______________________.
Remember that this happens even in autotrophs like plants, too! (Plants DO require oxygen, but they produce more than they need)
OVERALL EQUATION:
Two major parts:
Glycolysis
Oxidative Respiration. Oxidative respiration can be further divided into two parts:
the Krebs Cycle & the Electron Transport Chain
KEY PLAYERS:
Glucose, a six-carbon monosaccharide
ATP, the final energy molecule
Pyruvic acid, a three-carbon product of glycolysis
O2 gas, the final electron acceptor of the ETC
Electron Carriers: NADH and FADH2, carry high-energy electrons
CO2 gas and H2O

4. start PAYDAY RESPIRATION STEP 1: GLYCOLYSIS
RESPIRATION STEP 2: OXIDATIVE REPSIRATION
Glycolysis – Means _____________________.
Occurs in the ________________ of the cell.
does not require _____________.
The splitting of glucose, or glycolysis, occurs very quickly in a 10-step process with the aid of _________, producing two ___-C molecules known as ___________________.
In addition, when the bonds of glucose are broken, the high energy electrons that are released are caught by __________, a molecule that acts as an ________________. This electron energy will be converted to ATP later in the process.
Glycolysis requires ___ ATP to occur, but results in the formation of ___ ATP, for a net ______ of ___ ATP.
Reaction:
Net Energy Gain = 2 ATP + 2 NADH
Glycolysis releases less than ¼ of the chemical energy stored in glucose. Most of its potential energy remains bound in the ______________ formed from glycolysis.
In aerobic conditions, meaning ___ is available, the pyruvic acid formed from the breakdown of ___________ during ___________ enters the ______________ of the cell where the _________ of oxidative respiration complete the breakdown of glucose to produce _____, _______, and ______.
Reaction: 6 + +6 +6 + 2 + +2 +
+30 + 2 4
STEP 2A: KREBS CYCLE
Series of reactions that occur in the _______________, in which the energy stored in _____________ is released in the form of high-energy ___________ when bonds are broken and pyruvic acid is completely broken down to _______.
There are only _____ additional ATP produced in the Krebs Cycle; most of the energy released is captured in the form of electron energy, producing additional _________. In addition, a second type of electron carrier is utilized, producing 2 “filled” ________.
Net Energy Gain = 2 ATP + 8 NADH FADH2
Wastes Generated = CO2
start
Krebs Cycle
PAYDAY 2
+ 8
+ 2

5. STEP 2B: ELECTRON TRANSPORT CHAIN (“PAY DAY”)
the electron carriers, ________ and _______ “dump” their electrons. These electrons are passed along a series of molecules embedded in the inner membrane of the ______________ of ______________ cells.
This same process occurs in the ________________ of ________________ cells.
As the electrons “fall” down the ETC, the energy they release is used to power an enzyme known as ____________________, which attaches phosphate groups to ________ to produce _______.
This process is known as _______________ phosphorylation because oxygen must be present. It is the ___________________ of oxygen that “pulls” the electrons down the ETC. As the electrons are collected by oxygen, __________ is produced from oxygen.
Net Energy Gain = __~ 32 ATP_______
STAGE
WHERE
# ATP
Needs O2?
Wastes
GLYCOYSIS
CYTOPLASM
KREBS
CYCLE
OUTER
MITOCHONDRIA
ELECTRON
TRANSPORT CHAIN
INNER
ALTERNATIVE PATHWAY : ANAEROBIC (WITHOUT OXYGEN) FERMENTATION
The Krebs Cycle and ETC depend on ______________ (they are aerobic) to take electrons from the electron carriers. If no oxygen is present, ________ and _________ all fill up with high energy _______________ and have no where to put them, and cellular respiration comes to a halt.
A ____________ pathway exists called _____________ fermentation. In anaerobic conditions, the cell still uses ___________ and generates 2 ____ and 2 _____________, along with 2 full _______ The cell can empty the electron carriers by converting the 2 pyruvic acids into other chemicals.
LACTIC ACID FERMENTATION: In human muscle cells, pyruvic acid is converted to __________
Lactic acid buildup contributes to the muscle ___________ experienced during intense exercise
Some bacteria and fungi do this and are important in producing the lactic acid in ______________ and ____________
ALCOHOLIC FERMENTATION: In ___________ and some bacteria, the pyruvic acid are converted to alcohol. This is important in commercial brewing and baking.
Overall, much ________ energy (only 2 ATP compared to 32) is produced by fermentation

6. PHOTOSYNTHESIS
Photosynthesis is the metabolic pathway that provides energy for ____________________
Occurs in the chloroplasts of plants and other photosynthetic eukaryotes like _________
Occurs in _______________—photosynthetic bacteria
Overall Equation:
CHLOROPLASTS: Abundant in the ___________ _______________ of most plants
Structure:
Thylakoids-flattened ______________ ________________ arranged in stacks, where the light-dependent reactions occur
Grana—stacks of ________________
Stroma—_________________ that is outside the ___________, where light-independent reactions take place.
PIGMENTS: light-__________________ colored molecules act like ___________ for absorbing energy
Different pigments absorb different __________________ of light
Chlorophyll—most abundant pigments, absorb __________ _____________ the strongest, ___________ ____________
Accessory pigments—absorb blue and green, __________ _____________________. The pigments we see if fall leaves when ____________ production stops. Ex: Beta-carotene.
Proteins that are part of the thylakoid membrane organize ___________________________ into clusters called __________________________
ENERGY CARRIERS:
Chemical Energy Carrier: ____________
___________ + ______________ + energy - _______________
High Energy Electron Carrier: _______________
___________ + __________ ___________ _____________  __________________

7. STEPS OF PHOTOSYNTHESIS
LIGHT-DEPENDENT REACTIONS: requires _____________
Molecules are part of the ___________ ______________
BEGINS AT PHOTOSYSTEM II…
Chlorophyll in thylakoid membrane absorbs ___________ ______________ and uses it to excite and strip away electrons from __________.
Water is broken apart, forming _____________ gas (_____)
…NEXT TO AN ELECTRON TRANSPORT CHAIN…
High energy electrons are passed to an ETC from one carrier to the next, losing energy that is used to drive the synthesis of __________.
The enzyme responsible for ATP synthesis is called __________________________.
AND ENDS AT PHOTOSYSTEM I !
The now low-energy electron is re-energized by another chlorophyll pigment and light in photosystem II.
The energized electron is passed to ____________, a high energy electron carrier.
CALVIN CYCLE (Light-independent rxns)—does not require ___________, in the stroma
_______ gas is used as a source of __________ and __________ atoms to make glucose.
NADPH used as a source of high energy ___________ and _____________
_______ is used as a source of ___________
(from light-dependent rxns)
(returned to light-dependent rxns)
FACTORS AFFECTING PHOTOSYNTHESIS:
Light—more light, more photosynthetic activity
Water—needed to supply electrons. Not enough water, slow or no photosynthesis
Temperature—photosynthesis functions best at 0-32 C