Unit 3 Cellular Energetics 12-16%

Question 1

Metabolism

Answer 1

All the chemical reactions that occur within an organism.

Question 2

Catabolic Pathways

Answer 2

Break down complex molecules into simpler components, releasing energy.

Question 3

Anabolic Pathways

Answer 3

Use energy to synthesize complex molecules from simpler ones.

Question 4

Function of Enzymes

Answer 4

Speed up chemical reactions without being consumed.
Ex. Lactase catalyzes the hydrolysis of lactose into glucose & galactose.

Question 5

All chemical reactions that involve breaking & forming bonds require ________.

Answer 5

Energy

Question 6

Activation Energy

Answer 6

Energy needed to start a chemical reaction.

Question 7

Enzyme Effect on Activation Energy

Answer 7

Lower the activation energy required for a reaction, making it occur at a faster rate.

Question 8

Enzymes Specificity

Answer 8

Enzymes typically catalyze only one specific type of chemical reaction.

Question 9

Substrate

Answer 9

Specific reactant that an enzyme acts upon.
Ex. In the reaction catalyzed by lactase, lactose is the substrate.

Question 10

Active Site Binding

Answer 10

Substrate binds to the enzyme’s active site.

Question 11

Induced Fit Model

Answer 11

Enzyme’s active site changes shape upon substrate bonding → more precise fit & enhanced catalytic activity.

Question 12

Conversion & Release of Products

Answer 12

Substrate is transformed into the products of the reaction → released from the active site.

Question 13

Reusability of the Enzyme

Answer 13

After the products are released, the active site becomes available for new substrate molecules to bind.

Question 14

Effect of Temperature on Enzyme Activity

Answer 14

Higher temperatures increase collisions between substrates & enzymes → increased reaction rate.
Excessively high temperatures lead to denaturation where the enzyme loses its shape & becomes inactive.

Question 15

Effect of pH on Enzyme Activity

Answer 15

Deviation from optimal pH range causes denaturation.

Question 16

Effect of Substrate Concentration on Enzyme Activity

Answer 16

Higher substrate concentrations increase the reaction rate until the enzyme is saturated (all active sites are occupied) → max rate of reaction.

Question 17

How to increase the rate of reaction in high substrate concentrations?

Answer 17

Add More Enzymes

Question 18

Effect of Enzyme Concentration on Enzymatic Activity

Answer 18

Higher enzyme concentration will increase the reaction rate until all of the substrate is bound → levels off.

Question 19

How to increase the rate of reaction in high enzyme concentrations?

Answer 19

Add More Substrate

Question 20

Competitive Inhibitation

Answer 20

Inhibitor binds to the enzyme’s active site, preventing the substrate from binding.

Question 21

Noncompetitive Inhibition

Answer 21

Inhibitor binds to a different part of the enzyme (allosteric site)
causing a conformational change.

Question 22

Law of Conservation of Energy

Answer 22

Energy cannot be destroyed or created, but is converted from one form to another.

Question 23

Second Law of Thermodynamics

Answer 23

In every energy transfer, some energy is lost as heat, increasing the overall entropy of the universe.

Question 24

Entropy

Answer 24

Measures the disorder/randomness of a system, and the amount of energy that is unavailable for doing work.

Question 25

How do livings things not violate the second law of thermodynamics?

Answer 25

Living things become more ordered as they grow, decreasing their own entropy. However, they release energy back into the environment, increasing the overall entropy of the universe.

Question 26

Exergonic Reactions

Answer 26

Release Energy Ex. Cellular respiration

Question 27

Endergonic Reactions

Answer 27

Absorb Energy Ex. Photosynthesis

Question 28

Photosynthesis

Answer 28

Anabolic process that converts light energy into chemical energy, storied in sugars.

Question 29

Historical Context of Photosynthesis

Answer 29

First evolved in prokaryotic cyanobacteria which significantly contributed to the oxygenation of Earth's atmosphere.

Question 30

Photosynthesis Equation

Answer 30

6CO2 + 6H2O + light energy → C6H12O6 + 6O2

Question 31

What are the two stages of photosynthesis and where do they occur?

Answer 31

1. Light-dependent reactions (thylakoids). 2. Calvin Cycle (stroma).

Question 32

Function of Chlorophyll

Answer 32

Absorbs light energy in the form blue & red wavelengths.

Question 33

Photosystem II

Answer 33

1. Light excites electrons, which are then transferred to an electron acceptor. 2. Water is split to replace the lost electrons, releasing H+ protons & oxygen.

Question 34

Electron Transport Chain

Answer 34

Electrons move from PSII to PSI → pumps H+ into the thylakoid → proton gradient for ATP synthesis.

Question 35

Photosystem I

Answer 35

Light re-excites the electrons before they are transferred to NADP+ → reduces it into NADPH.

Question 36

ATP Synthesis

Answer 36

H+ protons flow back into the stroma through ATP synthase → adds a phosphate group to ADP → ATP.

Question 37

Light dependent reactions convert ________ into ________ in the form of ________ and ________, which will be used in the ________.

Answer 37

Light energy → chemical energy, ATP & NADPH, Calvin Cycle

Question 38

Products of the Light Dependent Reactions

Answer 38

ATP, NADPH, & Oxygen

Question 39

Calvin Cycle

Answer 39

Uses ATP & NADPH to convert CO2 into glucose (G3P) → returns ADP & NADP+ to the light reactions.

Question 40

Cellular Respiration

Answer 40

Catabolic process by which cells generate ATP through the breakdown of glucose.

Question 41

Cellular Respiration Equation

Answer 41

C6H12O6 + 6O2 → 6CO2 + 6H2O + energy (ATP)

Question 42

Aerobic Respiration

Answer 42

Requires oxygen to produce ATP (more efficient).

Question 43

Anaerobic Respiration

Answer 43

Occurs in the absence of oxygen and produces less ATP.

Question 44

Fermentation

Answer 44

Type of anaerobic respiration that uses glycolysis to break down glucose into pyruvate, which is then converted into different products.

Question 45

Alcohol Fermentation

Answer 45

Yeast cells break down pyruvate into ethanol.

Question 46

Lactic Acid Fermentation

Answer 46

Pyruvate is broken down into lactate.

Question 47

What are the three stages of cellular respiration and where do they occur?

Answer 47

1. Glycolysis (cytoplasm) 2. Citric Acid/Krebs Cycle (mitochondrial matrix) 3. Oxidative Phosphorylation (inner mitochondrial membrane)

Question 48

Glycolysis

Answer 48

Breaks down glucose into 2 pyruvate, ATP, & electrons (accepted by NAD+ to form NADH) → if oxygen is present, pyruvate will enter the Krebs Cycle.

Question 49

Krebs Cycle

Answer 49

Pyruvate is converted into acetyl-CoA, which is further broken down into ATP, NADH, & FADH2 (FAD) + CO2 as a waste product.

Question 50

Oxidative Phosphorylation

Answer 50

NADH & FADH2 donate electrons to the ETC, which pumps H+ into the intermembrane space → proton gradient. Oxygen is the final electron acceptor → H2O. Proton gradient drives protons back into the mitochondrial matrix through ATP synthase → ATP.

Question 51

Phosphorylation

Answer 51

Adding a phosphate group to ADP to form ATP.