Unit 3 Cellular Energetics

Question 1

What are enzymes and what is their role?

Answer 1

proteins that have a tertiary shape that must be maintained

Enzymes speed up biochemical reactions by lowering activation energy requirements.

Question 2

How is enzyme structure related to enzyme function?

Answer 2

The structural characteristics of an enzyme make the enzyme very reaction specific.

Question 3

What determines whether a substrate can interact with an enzyme?

Answer 3

The shape and charge of the substrate must be compatible with the active site of an enzyme for a reaction to occur.

Question 4

What happens to an enzyme after the completion of a reaction?

Answer 4

Enzymes are not consumed by the reaction. Enzymes are reused. (not chemically changed)

Question 5

what is a substrate?

Answer 5

a molecule that interacts with an enzyme

Question 6

How do enzymes facilitate chemical reactions in cells?

Answer 6

Enzymes are biological catalysis that facilitate chemical reactions in cells by lowering activation energy requirements.

Question 7

What is activation energy in a chemical reaction?

Answer 7

Activation energy is the initial energy required for a reaction to occur.

Question 8

What does it mean for an enzyme to be denatured?

Answer 8

Denaturation of an enzyme occurs when the protein structure is disrupted, eliminating the ability to
catalyze reactions.

Question 9

Explain how the cellular environment affects enzyme activity.

Answer 9

Environmental pH can alter the efficiency of enzyme activity, including through the disruption of hydrogen bonds that provide enzyme structure. Can lead to the enzyme becoming denatured

Higher environmental temperatures increase the speed of movement of molecules in a solution,
increasing the frequency of collisions between enzymes and substrates and therefore increasing the
rate of reaction.

Decreasing temperature outside the optimum range will result in slowed reaction rates but will not denature

Question 10

How do changes in enzyme concentrations affect the rate of reactions?

Answer 10

Increased enzyme concentration increase reaction rate. Decreased enzyme concentration will decrease reaction rate.

Question 11

How do changes in substrate and product concentrations affect the rate of reactions?

Answer 11

Increasing substrate concentration will initially increase reaction rate. Substrate saturation will not result in a continued increase in reaction rate. Reaction rate will remain constant if substrate saturation levels are maintained.

Question 12

How do competitive inhibitors affect enzyme activity?

Answer 12

The competitive inhibitor binds to the active site and changes shape to prevent the substrate from binding there. reaction can’t perform.

Question 13

How do noncompetitive inhibitors affect enzyme activity?

Answer 13

noncompetitive inhibitors bind to a different site on the enzyme; attaches itself to another part of the enzyme, thereby changing the overall shape of the site for the normal substrate so that it does not fit as well as before, which slows or prevents the reaction taking place.

Question 14

What do living things use chemical energy for?

Answer 14

Living things use the chemical energy stored in molecular bonds of macromolecules and ATP to perform necessary life functions.

Question 15

How is energy efficiently transferred in a biological pathway?

Answer 15

Pathways in biological systems are sequential (preform or used in a sequence) to allow for a more controlled and efficient transfer of energy.

Question 16

Explain what happens in photosynthesis.
what are the products? where does it occur?

Answer 16

occurs in the chloroplast

(light dependent)
light is absorbed by the chloroplast, electrons become excited, passes them through the thylakoid membrane the movement of the electrons form ATP water splits into
h +ions and oh releasing oxygen 2 atp are formed and h+ions attach to nadp to form carrier molecules Nadph

During the light independent reaction (Calvin cycle) carbon dioxide binds to a 5-carbon molecule making it an unstable 6-carbon molecule which quickly breaks down into a stable 2-3-carbon molecule some make glucose some restart the cycle, 2 ATP formed and NADH and FAHD, are produced.

Question 17

What is the photosynthesis equation?
What is the cellular respiration equation?

Answer 17

CO2 +H2O + sunlight→ C6H12O6 + O2.

C6H12O6 + O2 → CO2 + H2O

Question 18

What is the function of the electron transport chain?

Answer 18

The electron transport chain allows for the efficient transfer of energy from electrons to a proton gradient.

Question 19

What is the role of NADH and FADH,?

Answer 19

NADH and FADH carry electrons to the E.T.C

Question 20

How does the electrochemical / proton gradient power ATP synthase?

what are the protons and where do they come from?

Answer 20

Protons flow down their concentration gradient into the matrix through the membrane protein ATP synthase, causing it to spin (like a water wheel) and catalyze conversion of ADP to ATP.

H+ ions and they come from photosynthesis

Question 21

What is the importance of decoupling during respiration?

Answer 21

When decoupling occurs during cell respiration, heat is released and can be used for thermoregulation.

Question 22

What processes do all forms of life use to produce ATP?

Answer 22

All living things use fermentation and cellular respiration to produce ATP.

Question 23

How is an electrochemical/proton gradient formed
during cell respiration?

Answer 23

As the electrons pass through the
ETC, an electrochemical gradient of protons (hydrogen ions) is established across the internal
membrane (the matrix)

Question 24

What is the purpose of glycolysis?

Answer 24

To break down glucose to form 2 molecules of pyruvate, 2 ATP and NADH. h+ ions are picked up and transported to the etc.

Question 25

What happens to the pyruvate?

Answer 25

Pyruvate is transported to the mitochondria where it is oxidized.
(link reaction the acetyl group)

Question 26

Explain what happens in the Krebs cycle (The Citric Acid cycle) ?

Answer 26

The pyruvate is first oxidized forming acetyl coA a 2-carbon molecule then attaches to a 4-carbon molecule forming a 6-carbon molecule. co2 is then released and carrier molecules FADH and NADH are formed along with 2 ATP

Question 27

How does fermentation differ from aerobic cellular respiration?

Answer 27

Fermentation allows glycolysis to occur without oxygen and produces ethanol or lactic acid.

Question 28

What does fitness refer to?

Answer 28

Fitness, on an organism level, refers to the ability to survive AND reproduce.

Question 29

How does molecular variation within cells provide organisms with increased ability to respond to a variety of environmental stimuli?

Answer 29

Variation at the molecular level provides organisms with the ability to respond to a variety of environmental stimuli.

allows populations to adapt to a wider range of environmental conditions.

Question 30

How does molecular variation within cells provide organisms with increased fitness

Answer 30

Variation at the molecular level can provide organisms with fitness advantages under changing environment conditions.

Question 31

The First Law of Thermodynamics states?

Answer 31

Energy cannot be created nor destroyed. It can only change form or be transferred from one object to another.

Question 32

Second Law of Thermodynamics?

Answer 32

Every energy transfer that takes place will increase the entropy of the universe and reduce the amount of usable energy available to do work.

(energy can be converted from one form to another with the interaction of heat, work and internal energy, but it cannot be created nor destroyed, under any circumstances.)

Question 33

Third Law of Thermodynamics?

Answer 33

At absolute zero nothing moves

Question 34

Explain how changes to the structure of an enzyme may affect its function.

Answer 34

Change to the molecular structure of a component in an enzymatic system may result in a change of
the function or efficiency of the system

Question 35

explain what happens when the environment of an enzyme changes

what happens? can it be reversed?

Answer 35

Environmental temperatures and pH outside the optimal range for a given enzyme will cause changes to its structure, altering the efficiency with which it catalyzes reactions.

In some cases, enzyme denaturation is reversible, allowing the enzyme to regain activity.

Question 36

what happens in the E.T.C

where does it occur

Answer 36

mitochondria cristae

Electron acceptor molecules transport electrons (H ions) to the inner membrane of the mitochondria

The electrons are passed from one electron acceptor to another stronger one. and each time the electron is passed energy is given off

Approx. 32 ATP are formed