Exam III Study Guide

Question 1

Know the basic structure of ATP and its role as the energy currency of ALL cells

Answer 1

Adenosine TriPhosphate (ATP) Consists of three phosphate groups, ribose, and adenine

• ATP contains energy in its chemical bonds, and it is the energy currency for all cells!

Question 2

Know and compare Chemotrophs (auto traps vs heterotrophs) and Phototrophs (autotrophs vs heterotrophs).

Answer 2

Chemotrophs: Get their energy from Chemical Compounds

Phototrophs: Get their Energy from Sunlight

Autotroph: Get their Carbon from CO2

Heterotrophs: Get their Carbon from organic compounds

Question 3

Describe and compare the metabolic processes of catabolism an anabolism.

Answer 3

Catabolism: Breakdown of molecules into smaller units to Produce ATP

Anabolism: Building of molecules from smaller units; Requires ATP Energy

Question 4

Know the types of work that cells need to carry out.

Answer 4

Work of a Cell:

1) Synthesizing DNA/RNA/Proteins
2) Moving Vesicles
3) Pumping Substances across Membranes

Question 5

Know and compare kinetic and potential energy

Answer 5

Kinetic Energy: Energy of Motion

Potential Energy: Stored energy, which can potentially be used to do work
* (Chemical Energy is a form of Potential Energy

Question 6

Describe chemical energy

Answer 6

Chemical Energy: Energy stored within the bonds of a molecule. When an energy is broken, it releases energy

• The inverse is also true — it takes energy to form bonds!

Question 7

Know where chemical energy is stored within ATP

Answer 7

Within ATP, the Majority of ATP is stored in the Phosphate Groups!

• The rest of the molecule is just Carbons, Nitrogen’s, and Hydrogens… Which aren’t very electronegative in comparison.

Question 8

Define an open system in the context of thermodynamics

Answer 8

Open System: Energy and Matter can be transferred between the system and its surroundings

Example: Organisms are open systems: I can eat food, and absorb chemical energy — and my body can release thermal energy back into the atmosphere

Question 9

Describe and compare the first and second laws of thermodynamics

Answer 9

First Law of Thermodynamics: Energy is neither creates nor destroyed — it transforms from one form to another

Second Law of Thermodynamics: There is a loss of energy available to do work when energy is transformed

• Less Energy will be available after transforming

Question 10

Define Gibbs Free Energy and describe its relationship to endergonic and exergonic reactions

Answer 10

Gibbs Free Energy: The amount of energy available in a system to “do work”

• Endergonic Reaction: Products have more free energy than reactants; So Gibbs Free Energy is Positive
• Exergonic Reaction: Products have less free energy than reactants; So Gibbs Free Energy is Negative!

Question 11

Describe and compare endergonic and exergonic reactions

Answer 11

Endergonic: Starting Reactants have less energy than the Products (Energy is usually added to a reaction like this)

Exergonic: Starting Reactants have more energy than the products (Energy is lost in this reaction as products are formed, like the production of heat).

Question 12

Know the definition of Gibbs free energy and the equation for calculating ΔG

Answer 12

ΔG= ΔH-T*ΔS

(G): Gibbs Free Energy
(H): Enthalpy, total energy available
(S): Entropy: Degree of Disorder
(T): Temperature: Absolute temperature in Kelvin, influences the movement of molecules and adds to the degree of disorder

Question 13

Describe the relationship between Gibbs free energy and catabolism/anabolism.

Answer 13

Catabolic Reactions (Break one thing into many small parts): Products have less chemical energy than reactants, more disordered, yielding a negative ΔG

Anabolic Reactions (Building a large thing from small parts): The Products have more chemical energy than the reactants (Yielding a Positive ΔG).

Question 14

Know the process of ATP hydrolysis

Answer 14

Adenosine TriPhosphate + Water —> Adenosine Diphosphate + Phosphate

    -ΔG= -ΔH - T*ΔS

    -ΔG: Exergonic Reaction

Question 15

Describe the coupling of endergonic and exergonic reactions

Answer 15

Coupling of Endergonic and Exergonic Reactions allow for the Energy Lost in one reaction (Exergonic Reactions) to fuel the Activation Energy required for an Endergonic Reaction (Products have Greater Energy than Reactants).

Question 16

Define the activation energy of a reaction and describe the role of enzymes

Answer 16

Activation Energy: The minimum input of energy required for a reaction to proceed

Role of Enzymes in Reactions: Reduces the Activation Energy Requirements (making it easier/faster to proceed).

Question 17

Describe the active site of an enzyme (including its formation and interaction with substrate molecules)

Answer 17

Active Site: Region of an enzyme that binds the substrate and converts it to the product.

• Interactions (between Substrate and Active Site) are typically Non-covalent, and help to stabilize the transition state; resulting in a decrease of activation energy.

Question 18

Describe and compare competitive inhibition, non-competitive inhibition, and allosteric activation

Answer 18

Inhibitors: Decreases the activity of enzymes

Competitive Inhibition: The Enzyme binds either its substrate or its inhibitor

Non-Competitive Inhibition: The binding sites of the substrate and inhibitor are different, allowing for the Enzyme to bind to both.

Allosteric Activation: Positive effector binds to an enzyme, shaping its active site to one that is complementary to the substrate.

Question 19

Describe positive and negative feedback

Answer 19

Positive Feedback: A positive feedback loop occurs in nature when the product of a reaction leads to an increase in that reaction. If we look at a system in homeostasis, a positive feedback loop moves a system further away from the target of equilibrium. It does this by amplifying the effects of a product or event and occurs when something needs to happen quickly.

Negative Feedback: A negative feedback loop occurs in biology when the product of a reaction leads to a decrease in that reaction. In this way, a negative feedback loop brings a system closer to a target of stability or homeostasis. Negative feedback loops are responsible for the stabilization of a system, and ensure the maintenance of a steady, stable state. The response of the regulating mechanism is opposite to the output of the event.

Question 20

Know the definition and objective of cellular respiration

Answer 20

Cellular Respiration: The Process in which sugars (glucose) are converted into usable energy (ATP)

Question 21

Know and describe the four stages of cellular respiration, including the order in which they occur relative to one another

Answer 21

The Four Stages of Respiration (in order) Are:

1) Glycolysis (Cytoplasm): Glucose is partially broken down, energy is released (Proteins and Lipids may also be broken down by different pathways.

2) Acetyl-CoA synthesis (Mitochondria): Pyruvate, produced in Glycolysis, is converted into Acetyl-CoA and CO2

3) Citric Acid Cycle (Mitochondria): Acetyl-CoA is broken down releasing CO2 energy, and electron carriers

4) Oxidative Phosphorylation (Mitochondria): Electron carriers from stages 1-3 release high-energy electrons to the electron transport chain, producing ATP

Question 22

Describe oxidation-reduction reactions (including oxidizing agent, reducing agent, oxidized product, reduced product)

Answer 22

Oxidaition: Loss of Electrons (What is getting Oxidized, Making it the Reducing agent of the reaction).
Reduction: Gain of Electrons (What is getting Reduced, Making it the Oxidizing agent of the reaction).

Question 23

Describe the breakdown of glucose relative to an oxidation-reduction reaction

Glucose —-> CO2 and H20

Answer 23

Glucose is broken down into Co2 and H20.

In this reaction, Glucose is the Electron donor (getting oxidized) —> Thus, it is considered to be the Reducing Agent.

Question 24

Describe the process of carbohydrate catabolism

Answer 24

Chemical Energy is stored in bonds. The Chemical Energy of Glucose is transferred to the chemical bonds of ATP and Electron carriers as Glucose goes through Catabolism (broken down into smaller parts).

Question 25

Define, describe, and compare the electron carriers NAD+ and FAD

Answer 25

Electron Carriers: Can accept electrons to become Reduced. Once it is Reduced, it can be used to Synthesize ATP NAD+: Has Nitrogen and 3 rings FAD: Has Fluorine and 3 rings.

Question 26

Describe the process of substrate-level phosphorylation

Answer 26

Phosphorylation: Organic Molecule transfers one of their phosphate groups to ADP, Producing ATP * Substrate-Level Phosphorylation is used to generate all of the ATP during the stages of Glycolysis and the Citric Acid Cycle.

Question 27

•Define glycolysis (and the impact of oxygen on this stage of respiration, is it anerobic or aerobic)

Answer 27

Process of Glycolysis is to take Glucose and refine it into Pyruvate. * Process is anaerobic: Oxygen is not consumed *2 Pyruvate molecules are produced for each glucose molecule used

Question 28

Know the 3 phases of glycolysis and the amounts of ATP, NADH, and pyruvate produced per glucose molecule by the end of glycolysis

Answer 28

Phase I: Preperatory Phase (Consumes 2 ATP) * This Phase traps the molecule in the cell, and destabilizes it in preparation for Phase II Phase II: Cleavage Phase (Refines Fructose-1,6-Biphosphate into Glyceraldehyde 3-Phosphate * Two Molecules of Glyceraldehyde-3-Phosphate are produced Phase III: Payoff Phase (Produces 4 ATP and 2 NADH) * During this phase: 2 Pyruvate are formed, 2 Molecules of NADH are made, 4 Molecules of ATP are produced! Per Glucose: 4 ATP are produced, Net Yield of 2 2 Molecules of NADH are produced 2 Pyruvate are produced

Question 29

For the 3 phases of glycolysis, you will be expected to know the reactants and products for those reactions that (1) require ATP to proceed (2) produce ATP and (3) reduce NAD+ to NADH

Answer 29

• Step 1: Glucose + ATP —> Glucose-6-Phosphate + ADP ◦ The Phosphate group on the glucose will trap it within the Cytoplasm • Step 3: Fructose-6-Phosphate + ATP —> Fructose-1,6-biphosphate + ADP ◦ Purpose was to Destabilize the Sugar • Step 4: Fructose-1,6-biphosphate + ADP —> Glyceraldehyde 3-Phosphate + Dihydroxyacetone Phosphate ◦ Main Cleavage Reaction ‣ Glyceraldehyde 3-Phosphate is directly ready for Phase 3, but Dihydroxyacetone cannot be used in Phase 3… So we must refine Dihydroxyacetone first! • Step 6: (2x) Glyceraldehyde 3-Phosphate + (2) Phosphate+ (2) Nad+ —> (2) 1,3-Biphosphoglycerate + (2) NADH ◦ Starting to Produce NADH ‣ NAD^+ Gains electrons, which means it gets reduced (NAD^+ is also the oxidizing agent). ‣ Glyceraldehyde will be losing electrons, (getting oxidized) making it the Reducing Agent • Step 7: (2) 1,3-Biphosphoglycerate + (2) ADP —> (2) ATP + (2) 3-Phosphoglycerate ◦ Substrate-Level Phosphorylation • Step 10: (2) Phosphoenolypyruvate + (2) ADP —>(2) ATP + Pyruvate

Question 30

Know the basic structure of a mitochondria

Answer 30

Composed of an Inner and Outer membrane. Inter membrane Space: Between the two membranes Mitochondrial Matrix: Inside the inner membrane

Question 31

Know the Acetyl CoA Synthesis reaction; including where it takes place in the cell, its requirement for oxygen, the basic components of the reaction and its catalysis by the Pyruvate Dehydrogenase Complex

Answer 31

In the presence of oxygen, Pyruvate is transported inside of the mitochondrial matrix. Then, Pyruvate is converted to Acetyl CoA - Reaction also releases CO2 * Catalyzed by a group of enzymes called: Pyruvate Dehydrogenase Complex

Question 32

For the Citric Acid Cycle (CAC), you will be expected to know –the reactants and products of those reactions that (i) produce ATP, (ii) reduce NAD+ to NADH and FAD to FADH2, (iii) generate CO2 – the cellular location of the CAC – the compound that is regenerated by the end of the cycle to allow it to proceed again

Answer 32

* CAC takes place inside of the Mitochondrial Matrix * Oxaloacetate is regenerated at the end Step 4: Alpha-Ketoglutarate loses a molecule of CO2 and is oxidized, reducing NAD+ to NADH. • The remaining molecule is attatched to coenzyme A by an unstable bond to form Succinyl CoA Step 5: CoA is displaced by a phosphate group, which is transferred to GDP, forming GTP: A molecule with functions similar to ATP • GTP is used to Generate ATP • The molecule, Succinate, is formed. Step 6:Two hydrogens are transferred from Succinate to Fad, forming FADH2 and oxidizing Succinate to form Fumarate Step 8: Malate is oxidized, reducing NAD+ to NADH and regenerating Oxaloacetate

Question 33

Know how much ATP, NADH and FADH2 is produced per molecule of glucose during the CAC (as well as per molecule of Acetyl CoA that enters into the cycle)

Answer 33

Per Molecule of Glucose Used in Citric-Acid-Cycle (Kreb’s Cycle) produces: * (2) ATP’s * (6) NADH * (2) FADH2 Remember - 1 glucose makes 2 Pyruvate —> 2 Acetyl-CoA. So every Acetyl CoA makes: 1. ATP 2. 3 NADH 3. 1 FADH2

Question 34

Know the flow of electrons during respiration

Answer 34

Electrons go downhill: Glucose —> NADH —> Electron transport Chain —> Oxygen

Question 35

Describe the role of the electron transport chain in controlling the release of energy during oxidative phosphorylation

Answer 35

The electron transport chain passes electrons in a series of steps instead of one explosive reaction

Question 36

Know the location of the electron transport chain and the multi-protein complexes that make up that chain

Answer 36

The electron transport chain is in the inner membrane of the Mitochondrion * It’s composed of Multiprotein Complexes (1-4).

Question 37

Know how the free energy of electrons change as they move through the electron transport chain and combine with the final electron acceptor, oxygen, to form water.

Answer 37

Electrons drop in free energy as they go down the chain —> Until finally passed to O2, reducing it into H2O

Question 38

Know the complexes to which NADH and FADH2 Donate their electrons and describe the path these electrons take as they travel through the electron transport chain

Answer 38

NADH donates an electron to Complex I; FADH2 Donates two electrons to Complex II. Both complex 1 & 2 get reduced to CoQH2; which transfers the electrons to Complex III. Complex III Transfers electrons to Cytochrome C This gets reduced, and interacts with Complex #4. —> Which reduces oxygen and produces water

Question 39

Describe how oxidation and reduction relates to the movement of electrons through the electron transport chain

Answer 39

Oxidation: Losing of electrons Reduction: gaining of Electrons OIL-RIG Oxidation-is-losing & Reducing-is-Gaining. [Electrons]

Question 40

Describe the role of protons in the electron transport chain including the region where they accumulate within the mitochondria

Answer 40

Protons in the inter-membrane space diffuse down their electrical concentration gradients through ATP Synthase into the mitochondrial matrix; this gives power to the ATP Synthase Enzyme and catalyzes the Production of ATP.

Question 41

Describe the Relationship between proton concentrations within the Mitochondria and ATP Synthase

Answer 41

Movement of protons is coupled with ATP synthase. Because F1 subunit uses rotational energy (provided by proton concentration) to catalyze the Synthesis of ATP.

Question 42

Describe how the movement of protons through ATP Synthase generates ATP

Answer 42

Proton flow through F0 causes it to rotate: Converts proton gradient energy into mechanical rotation energy — > Causes a conformational change in ATP Synthase that allows it to Catalyze the synthesis of ATP.

Question 43

Describe and Compare the processes of lactic Acid and Ethanol Fermentation; Including the circumstances during which they occur. Also - the reactions that are carried out in order to make them happen, and the amount of energy they generate

Answer 43

Lactic Acid: This type of Fermentation produces 2 ATP, and it occurs in the absence of oxygen for animals and bacteria. Ethanol Fermentation: Occurs in Plants and Fungi with the Absence of Oxygen; this reaction also produces 2 ATP.

Question 44

Know How Excess glucose is stored in animal and plant cells. Know the process stored glucose (glycogen) undergoes in order to participate in Glycolysis.

Answer 44

In animals, excess glucose is stored in Muscle and liver cells. This allows for the muscles to have the ATP needed to contract. Glycogen in the liver kinda just chills, and waits until it is needed. In Plants, excess glucose is stored as Starch. In order to be used in Glycolysis, glycogen is cleaved - and little glucose molecules are broken off from the ends of the chain. (Originally as Glucose-1-Phosphate). Then, they are converted into glucose 6-phosphate and then can be used in Glycolysis.

Question 45

Know the Contribution of other sugars to Glycolysis

Answer 45

Sucrose, Maltose, Lactose, Galactose, Fructose, and Mannose can also contribute to Glycolysis. Many disaccharides and polysaccharides can be used in Glycolysis, not just Glucose!

Question 46

Describe the Process of Beta-Oxidation and its role in harvesting energy from lipids

Answer 46

Beta Oxidation breaks down Fatty acid chains, by removing 2-carbon units from the ends. This results in the production of NADH, FADH2, and Acetyl-CoA.

Question 47

Describe how ATP levels regulate Cellular Respiration

Answer 47

ATP levels within the cell regulate the rate at which the cell respirates. Low Levels — Cell will activate pathways that lead to ATP Synthesis High Levels — Cell stops/inhibits pathways that lead to ATP Synthesis

Question 48

Describe how the Enzyme Phosphofructokinase-1 responds to varying ATP concentrations in the cell.

Answer 48

When ATP levels are low, PFK-1 is activated, allowing glycolysis to continue When ATP levels are high, PFK-1 is inhibited/de-activated, which slows down Glycolysis.

Question 49

Net Gain for Every Molecule of Glucose That Enters Glycolysis:

Answer 49

2 ATP 2 NADH 2 Pyruvate

Question 50

The Citric Acid Cycle (Krebs Cycle) completes the Breakdown of Pyruvate to Co2. But what does it generate per molecule of Glucose

Answer 50

Well, the Cycle generates 2 ATP 6 NADH 2 FADH2 For every molecule of Glucose that comes into the cycle!

Question 51

Where is the Electron Transport Chain in Oxidative Phosphorylation

Answer 51

Inside the Inner Membrane of the Mitochondria Between the Mitochondrial Matrix and the Inter-Membrane Space

Question 52

Define Photosynthesis:

Answer 52

The biochemical process of building carbohydrates form Sunlight, Carbon Dioxide, and Water

Question 53

Describe the structure of chloroplasts and their role in Photosynthesis

Answer 53

Structure of Chloroplasts: 3 membranes: Outer, Inner, and Thylakoid Membrane Thylakoid membranes for Grana (Flattened sacs that are grouped into stacks) - Within each Grana is the lumen; the area outside of the Grana is the Stroma.

Question 54

Know the Photosynthesis reaction, including components that are reduced/oxidized

Answer 54

6 CO2 + 12 H20 + Light = Glucose + 6 O2 + 6 H20 * CO2 Gets reduced * H20 Gets oxidized

Question 55

Know the main type of electron carrier in Photosynthesis

Answer 55

Main Electron carrier in photosynthesis is NADP+/NADPH

Question 56

Know the two phases of Photosynthesis and describe what happens during each phase

Answer 56

Phase 1: Light Reactions (Occurs in Thylakoid Membrane) * Produces ATP and NADPH to power Calvin Cycle Phase II: Calvin Cycle (Occurs in Stroma) * Formation of Sugar from CO2 using ATP and NADPH * it takes 3 CO2 to produce 1 G3P and sustain the entire cycle

Question 57

Know and Describe the three phases of the Calvin Cycle, including the intermediates that we covered in class

Answer 57

Phase 1: Carbon Fixation * CO2 binds with RUBP to make a 6-carbon-sugar, then it gets split into TWO 3-carbon-sugars. Phase 2: Reduction * Each 3-phosphoglycerate receives a Phosphate from ATP to become 1,3-biphosphoglycerate. * Then, each sugar loses a phosphate group and is reduced to G3P * Phase 1-2 repeats until there is 6 G3P’s available Phase 3: RuBP Production *One G3P is taken as the overall product of the Calvin cycle, the last 5 get combined back into RuBP so that the cycle can continue Summary: In order to synthesize 1 G3P from 3 CO2, the cycle needs 9 ATP and 6 NADPH

Question 58

Describe the Role of Starch in Plant Cells

Answer 58

Start provides photosynthetic cells with a source of carbohydrates that can be used in the absence of sunlight.

Question 59

Describe the role of the lights reactions in photosynthesis

Answer 59

Light Reactions convert Solar Energy into the Chemical Energy of ATP and NADPH

Question 60

Describe the basic properties of lights and how wavelength affects energy

Answer 60

Light is a form of electromagnetic energy Light travels in Rhythmic Waves Wavelength is the distance between crests of waves How does wavelength affect energy? Well, light particles with the smallest wavelengths have the highest energy.

Question 61

Define the electromagnetic spectrum and know the range that drives photosynthesis

Answer 61

Electromagnetic spectrum is the entire range of electromagnetic energy, or radiation Visible light consists of the wavelengths that are used to drive photosynthesis. Ranging from 380-750nm

Question 62

Know the main photosynthetic pigment in plants

Answer 62

Chlorophyll “A” is the main photosynthetic pigment!

Question 63

Know the accessory pigments (in photosynthesis) and describe their functions

Answer 63

Chlorophyll B: Acessory pigment that broadens the spectrum of light used for photosynthesis Carotenoids: Accessory pigments that absorb excessive light that would Damage Chlorophyll

Question 64

Describe how Chlorophyll is excited by light

Answer 64

When pigments inside of Chlorophyll absorbs light, it goes from a stable ground state to an unstable excited state. * When it is excited, it releases heat and another photon, before returning to its ground state * release of this second photon activates other Chlorophyll Molecules

Question 65

Describe the structure and function of a photosystem

Answer 65

Photosystems consist of reaction-center complexes surrounded by light-harvesting complexes * Photosystems provide enough energy to pull electrons from water and then use them to Reduce NADP+ * The photosynthetic electron tranpsort chain connects Photosystem I and Photosystem II

Question 66

Know the two types of Photosystems involved in Photosynthesis, the wavelength of light they optimally absorb, and the name of their respective reaction center Chlrophyll A molecules.

Answer 66

PS1: Absorbs light best at 700nm * The reaction center Chlroophyll A of PS1 is called “P700” PS2: Functions first and is best at absorbing a wavelength of 680nm *The Reaction-center Chlorophyll A of PSII is called “P680”

Question 67

Describe the flow of electrons within and between Photosystems II and I; including any enzymes that are represented, where and how ATP and NADPH production is occurring, and where water is being split

Answer 67

PS #2 gets excited by a new photon, Chlorophyll A pass around the photon until it reaches P680. Then P680 gets excited, and climbs up to the excited state, Then, this primary electron acceptor splits a water molecule — and then enters the electron transport chain. The electron transport chain is made up of the electron carriers: Plastoquinone (Pq), a cytochrome complex (ATP is made here), and Plastyocyanin (Pc) and then reaching PS1. Photoexcited electrons are passed in a series of redox reactions from the Primary electron acceptor of PSI down a second Electron Transport Chain through the protein Ferredoxin (Fd). The enzyme NADP+ reductive catalyzes the transfer of electrons from Fd to NADP+, which is reduced to NADPH (NADPH is produced in the Stroma, and ATP is also produced into the Stroma). Both ATP and NAPDH are produced in the Stroma, so that they can go directly into the Calvin Cycle