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Biology-151 2025 > Exam 4: Enzymes and Cellular Respiration > Flashcards

Exam 4: Enzymes and Cellular Respiration Flashcards

1
Q

What are some examples of potential energy?

A

Carbohydrates and lipids

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2
Q

What are some examples of kinetic energy?

A

Cellular respiration

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3
Q

What are the different forms of energy?

A

Light, heat, chemical and mechanical energy.

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4
Q

1st Law of Thermodynamics

A

Energy can be neither created nor destroyed.
Energy is the universe is constant and may be transformed.

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5
Q

2nd Law of Thermodynamics

A

More usable energy is transformed into less usable energy (heat)

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6
Q

Entropy

A

Measure of disorder or randomness in a system. Energy in the universe tends to move towards disorder. Continuously increasing.

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7
Q

Thermodynamics

A

The study of energy transformations

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8
Q

Closed system

A

Allows energy to be exchanged with its surroundings but not matter.

Example? sealed water bottle

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9
Q

Open System

A

Both energy and matter can be exchanged with the surroundings.

Example? Plants and animals

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10
Q

Autotrophs

A

Organisms that produce their food.

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11
Q

Heterotrophs

A

Consumers who depend on other sources for their food.

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12
Q

What is a top consumer?

A

Organisms at the end of a food chain that has no natural predators.

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13
Q

How much of the energy is available to the next higher trophic level?

A

10%

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14
Q

Why is 90% of energy unavailable?

A

Not all was consumed
Some are used for metabolism
Not all was digested
Converted to heat.

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15
Q

How many trophic levels are food chains limited to?

A

3-5, due to less and less energy being available. Short chains are more efficient.

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16
Q

Biological magnification

A

Toxins accumulate in tissues of top consumers!

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17
Q

Catabolism

A

Breaking down complex molecules into simpler ones.

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18
Q

What is an example of catabolism?

A

Cellular respiration

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19
Q

Anabolism

A

Building of complex molecules

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20
Q

What is an example of anabolism?

A

Photosynthesis

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21
Q

What is free energy in a living organism?

A

It is energy that can do work when temperature and pressure are uniform, as in a living cell.

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22
Q

Free energy must be ________ for chemical events to occur spontaneously.

A

Negative

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23
Q

If free energy is ______, it must supply energy from an outside source.

A

Positive

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24
Q

Free energy is a measure of….

A

A systems instability, its tendency to change to a more stable state.

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25
Exergonic Reactions
-Spontaneous -Catabolic -ΔG is negative -Energy is released. -Reactants have more free energy than products. Example? Cellular Respiration
26
Endergonic Reaction
-Non-spontaneous -Anabolic -ΔG is positive -Energy is trapped -Products have more free energy than the reactant Example: Photosynthesis
27
Energy Coupling
Utilization of energy released from an exergonic reaction (release of energy) to drive an endergonic reaction (requires energy)
28
Oxidation
Loss of electrons
29
Reduction
Gaining of electrons (and hydrogen)
30
Catalyst
A substance that increases the likelihood of chemical reactions taking place speeds up chemical reactions.
31
Substrate
The reactants that the enzyme reacts upon.
32
Why does a specific substrate interacts with a specific enzyme active site?
Because of its shape and its charge
33
What is activation energy?
Enzymes bind to their substrate and lower the amount of energy needed to get the reaction going.
34
What are some examples of enzyme-catalyzed reactions?
-Releasing energy from food molecules -Destroying toxic waste - Stain remover breaks down stains in clothing. - Making corn syrup from corn starch. -Meat tenderizer
35
Biochemical (or metabolic or enzyme) pathway
Enzymes work in a series of steps of enzyme-catalyzed chemical reactions within a cell, where the product of one reaction becomes the reactant for the next, ultimately transforming an initial substrate into a final product.
36
How does enzyme concentration affect enzyme activity?
When enzyme concentration increases, collisions between enzyme and its substrate increase, creating more product at a faster rate. Continue until the enzyme concentration exceeds the available substrate, at which the rate of reaction briefly levels off. As the substrate is used up, the rate of reactions decreases because the rate of collision decreases.
37
How does substrate concentration affect enzyme activity?
Given an excess of the enzyme, a substrate concentration increases, and collisions between the substrate and enzyme increase, resulting in more product at a faster rate. Continues until the substrate concentration begins to exceed the available enzyme, till the rate of reaction levels off. Enzymes work at max velocity, remain at a constant reaction rate and does not decline.
38
How does pH affect enzyme activity?
At pH extremes, enzymes are interfered with by an excess of H+ or OH-. These strongly charged ions can attach to the active site, reducing the rate of reaction. At even higher pH extremes, they can cause the enzyme to be denatured. Work best at a pH of 7.
39
How does temperature affect enzyme activity?
Cold body temp = movement of molecules is slow, collision is low. low production of products. As temp rises the rate of molecular movement speeds up, increasing collision, and product is formed rapidly. increases until the optimum is reached.
40
Cofactors
mineral or metals. Example? Iron, copper and magnesium
41
What do cofactors do?
Aid with enzyme function, helping form an active site and attract substrate.
42
Coenzymes
Large organic molecules Example? Niacin (b vitamin) forms NAD+
43
What is the function of coenzymes?
Transport a product from one enzyme to another enzyme's active site.
44
Phosphorylation
Adding a phosphate to a molecule usually involves energy transfer. ATP is hydrolyzed to remove the outer phosphate, and energy is transferred by attaching.
45
What are the two ways of forming ATP?
Chemiosmotic Synthesis and substrate level phosphorylation
46
What organisms produce energy using aerobic respiration?
most plants, fungi, protists, bacteria, and animals
47
What organisms produce energy using anaerobic transport?
Certain bacteria
48
What organism produce energy using alcohol fermentation ?
Yeast and plants, and some bacteria. End product is ethanol and carbon dioxide
49
What organisms produce energy using lactate fermentation?
Animals and many bacteria End product is lactic acid.
50
Glycolysis
-Occurs in cytoplasm -Glucose is split into 2 PGAL using 2 ATPs -PGAL is oxidized by NAD+ to form NADH -Phosphate attaches to PGAL -2 ADPs remove phosphates to form 2 ATPs from each PGAL. -2 PGALs have now been converted to 2 pyruvate molecules.
51
Oxidation of Pyruvate
-Occurs in mitochondrial Matrix -CO2 splits off each pyruvate as waste. -NAD+ oxidizes to form NADH. -Remaining 2-carbon acetyl group is bonded to by a coenzyme A to form acetyl-coenzyme A. - 2 acetyl-coenzyme A is moved to Kreb's cycle.
52
Krebs Cycle
-Occurs in the matrix of the mitochondrion -Acetyl-Coenzyme A enters, bonds with the 2-carbon acetyl-group to 4-carbon oxaloacetate to form 6-carbon citric acid. -Repeated oxidation by NAD+ to form NADH and FAD to form FADH2 (as this occurs CO2 is released) -Oxaloacetate is regenerated, glucose molecule has been entirely degraded, and 1 ATP was formed from each acetyl group. -2 ATP yield
53
Niacin (B3)
NAD+
54
Riboflavin (B2)
For FAD (redox reactions)
55
Pantothenic Acid (B5)
Coenzyme A
56
What is the function of fermentation?
Regenerates NAD+ to keep glycolysis going in the absence of oxygen. It is performed in the cytoplasm.
57
What are the end products of alcoholic fermentation?
CO2 and Ethanol
58
What organisms do alcohol fermentation?
Yeast, plants and certain bacteria For brewing and baking
59
What are the end products of lactic acid fermentation and what organisms do this form of fermentation?
Lactic acid Animals and many bacteria Muscle tiredness and added to milk
60
Cellular respiration -amount of energy -efficiency
30-32 ATP 34% of glucose energy rest of the energy is turned into heat
61
Fermentation -Amount of energy -Efficiency
2 ATP 2% glucose energy Rest of the energy is produced as a waste product such as ethanol or lactic acid.
62
Metabolic Mill
Glucose is not the only molecule used in energy production; other carbs, fats, and proteins are used.
63
Fats and proteins usually broken down into ?
2-carbon acetyl groups to enter kreb's cycle
64
AMP (from ADP)
activator, turns on the activation of ATP
65
ATP is..
Inhibitor, stop the production of ATP.
66
When ATP is low...
ADP and AMP are high
67
When ATP is high
ATP inhibits its own production!
68
Citric Acid inibitor
It slows or stops enzymes in glycolysis; it keeps Kreb's and glycolysis in sync.
69
how is cellular respiration controlled?
Through negative feedback
70
What is was being measure to calculate respiratory rate during cellular respiration lab?
Measured carbon dioxide amount indirectly
71
Which had the greatest respiratory rate and why?
The fish had the greatest respiratory rate due to movement. The more movement the higher the CO2 production.
72
What is the significance of a negative respiratory rate?
Plants in light tend to have a negative respiratory rate because they remove carbon dioxide.

Biology-151 2025 (11 decks)

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