Metabolism

Question 1

What is metabolism?

Answer 1

All of the chemical reactions that take place inside cells, including those that use energy and those that release energy, are the cell’s metabolism.

Question 2

What are metabolic pathways?

Answer 2

A linked series of interconnected biochemical reactions occurring within a cell that convert a substrate molecule or molecules, step-by-step, through a series of metabolic intermediates, eventually yielding a final product or products.

Question 3

What is energy?

Answer 3

The ability to do work

Question 4

Endergonic reactions

Answer 4

(“take in”) reactions absorb energy from the surroundings

Question 5

Exergonic reactions

Answer 5

(“release”) reactions release energy to the surroundings

Question 6

Anabolic Pathway

Answer 6

Anabolic pathways are those that require energy to synthesize larger molecules.

Synthesizing sugar from CO2 is an example of an anabolic pathway.

Other examples are the synthesis of large proteins from amino acid building blocks, and the synthesis of new DNA strands from
nucleic acid building blocks.

Question 7

Catabolic Pathway

Answer 7

Catabolic pathways involve the degradation (or breakdown) of complex molecules into simpler ones.

Ex: The breakdown of sugars illustrates how a single molecule of glucose can store enough energy to make a great deal of ATP, 36
to 38 molecules. This is a catabolic pathway.

Question 8

Kinetic Energy

Answer 8

Energy associated with objects in motion (since moving objects capable of work)

Ex: airplane, waterfall

Question 9

Potential Energy

Answer 9

Energy associated with the potential to do work.

Ex: suspended wrecking ball, water behind a dam

Question 10

Chemical Energy

Answer 10

PE that exists within chemical bonds and is released when those bonds are broken. Responsible for providing living cells with energy from food.

-endergonic
-exergonic

Question 11

Metabolites

Answer 11

The reactants, products, and intermediates of an enzymatic reaction are known as metabolites, which are modified by a sequence of chemical reactions catalyzed by enzymes.

Question 12

Activation Energy

Answer 12

Energy that is required for a reaction to proceed. Lower if a reaction is catalyzed but free energy remains the same.

Question 13

What effect do enzymes have on activation energy and free energy in a reaction?

Answer 13

Enzymes lower the activation energy of the reaction but do not change the free energy of the reaction.

Question 14

Energy Coupling

Answer 14

Energy coupling is transfer of energy from catabolism to anabolism, or transfer of energy from exergonic process to endergonic process.
Or free energy (from ATP hydrolysis) is coupled or functionally linked to the energy needs of another chemical reaction.

Ex: The sodium-potassium pump is an example of energy coupling. The energy derived rom exergonic ATP hydrolysis is used to pump sodium and potassium ions across the cell membrane.

Question 15

Substrates

Answer 15

The chemical reactants to which an enzyme binds.

Question 16

Competitive vs Noncompetitive Enzyme Inhibitors

Answer 16

Competitive inhibitors affect the initial rate but do not affect the maximal rate, whereas noncompetitive inhibitors affect the maximal rate.

Question 17

Enzyme Inhibitor

Answer 17

An enzyme inhibitor is a molecule that binds to an enzyme and decreases its activity. Since blocking an enzyme’s activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors.

Question 18

Allosteric Inhibitors

Answer 18

Modify the activation site so that substrate binding is reduced or prevented.

Question 19

Allosteric activators

Answer 19

Modify the active site of the enzyme so that the affinity for the substrate increases.

Question 20

Coenzymes

Answer 20

A small organic molecule, such as a vitamin or its derivative, which is required to enhance the activity of an enzyme

Question 21

Cofactor

Answer 21

A non-protein chemical compound or metallic ion that is required for an enzyme’s activity. Cofactors can be considered “helper molecules” that assist in biochemical transformations.
The rates at which these happen are characterized by enzyme kinetics.

Question 22

What happens during glycolysis, oxidative phosphorylation, and krebs cycle (citric acid cycle)?

Answer 22

In humans, the most important metabolic pathways are:

Glycolysis- glucose oxidation in order to obtain ATP.

Citric acid cycle (Krebs’ cycle) - acetyl-CoA oxidation in order to obtain GTP and valuable intermediates.

Oxidative phosphorylation - disposal of the electrons released by glycolysis and citric acid cycle

Question 23

What is an enzyme?

Answer 23

A substance that helps a chemical reaction to occur is a catalyst, and the special molecules that catalyze biochemical reactions are called enzymes. Almost all enzymes are proteins, made up of chains of amino acids, and they perform the critical task of lowering the activation energies of chemical reactions inside the cell.

Question 24

What are the 3 enzymes needed to breakdown food?

Answer 24

Amylase, protease, and lipase