Exam 3

Question 1

Metabolism

Answer 1

Sum of all biochemicals reactions in a living organ or organism

Question 2

Anabolism

Answer 2

Upwards progression. Synthesis and building; Set of metabolism pathways that construct molecules from smaller unit, these reactions REQUIRE ENERGY, known as Endergonic process Ex: Photosynthesis

Question 3

Catabolism

Answer 3

Break down processes; Metabolic pathways that breaks down molecules into smaller units that are either oxidized to release energy or used in other Anabolic Pathways. Ex: Respiration, ATP Hydrolysis

Question 4

Energy

Answer 4

Capacity to do work; kcal/mol, kjoules/mol

Question 5

Kinetic:

Answer 5

Due to movement

Question 6

Potential

Answer 6

due to position, arrangement and bonds

Question 7

First Law (Law of thermodynamics)

Answer 7

Energy in the universe is constant. Energy can be transferred or transformed but it can neither be created or destroyed;

EX: In photosynthesis, the energy is supplied by the sun. Light Energy is absorbed by the cells in plant leaves and converted to chemical energy

Question 8

Second Law (Law of thermodynamics)

Answer 8

Every energy transfer or transformation results in increased randomness in the universe; Loss of energy results in a increase of disorder or entropy; Entropy measures disorder in a closed system , all of the available energy will be useful to the organisms. Entropy increases as energy is transferred.

EX: In photosynthesis, not all light energy is absorbed by the plant. Some energy is reflected and some is lost as heat.

Question 9

△G (free energy) Energy available to do work

Answer 9

EXERGONIC:
~(-△G)
~Net loss or release of free energy
~Spontaneous
~Favorable

ENDERGONIC:
~(+△G)
~Net gain or consumption of free energy
~Nonspontaneous
~Unfavorable

Question 10

△H (ENTHALPY) Heat content/ Total Potential Energy

Answer 10

EXOTHERMIC:
~(-△H)
~Net loss or release of heat content or potential energy

ENDOTHERMIC:
~(+△H)
~Net gain or consumption of heat content or potential energy

Question 11

T△S (ENTROPY) Absolute temp; randomness ~

Answer 11

C+273 (Kelvin)

DECREASE:
~(-△S)
~More orderly or less randomness

INCREASE:
~(+△S)
~Less orderly or more random

Question 12

ATP

Answer 12

Adenosine Triphosphate

Question 13

ATP Hydrolysis

Answer 13

~ATP+ H2O –>ADP+Pi(inorganic phosphate)
~△G= -7.3 kcal/mol

Question 14

ATP hydrolysis is coupled with

Answer 14

1. Movement of cells, vesicles or muscles
2. Active transport. Ex: Na+ (-) K+ pump,
   n+ (-) pump
3. Enzyme reactions that are endergonic

Question 15

Enzymes

Answer 15

Biological catalysts: Speed up reaction without being consumed in the reactions. Mostly proteins. Some are RNA-Ribozymes

Question 16

Factors affecting enzyme activity

Answer 16

1. Temperature: Optimal 37 Celsius body temp
2. pH- (H+): Stomach vs Saliva
3. Salt concentration: Freshwater vs. Sea waster organisms
4. Cofactors:
   ~Organic: NAD+, FAD, C0Q10
   ~Inorganic: Mg, Zn, Cu, Fe

Question 17

Regulation of Enzyme Activity

Answer 17

1. ~Activators: Stimulate
   ~Inhibitor: Slow down/stop
   Reversible Bindings with Enzyme
   ~Competitive Inhibitors: Increase Km
   ~Noncompetitive inhibitors: lower v max
2. Allosteric Regulation
   ~Based on binding to activators,
   inhibitors, or substrate
3. Feedback
4. Chemical Modification

Question 18

Oxidation (OIL)

Answer 18

Loss of electrons or hydrogen and gain of O2

Question 19

Reduction (RIG)

Answer 19

Gain of electrons or hydrogen and loss of O2

Question 20

Why do temperature, pH and salt concentration affect the enzyme activity?

Answer 20

Because all of them can change the 3-D shape of the enzyme

Question 21

Sliced potatoes and apples easily bruise and become brown. This is due to an enzyme called catecholase that makes catechol to protect the sliced parts from bacterial infection. What can you do to prevent this bruising and browning?

Answer 21

Adding lemon juice, salt and keeping in the refrigerator (lowering temperature) can slow down or stop this browning.

Question 22

Given the same concentration of substrate, which of the following reactions will yield the maximum amount of products?

Answer 22

Activator increases the products formed at the Km level compared with enzymes + substrate alone.

Question 23

In an enzyme-catalyzed reaction, which of the following does not change with or without enzyme?

Answer 23

Net change in free energy

Question 24

As you add more and more substrates, the velocity of enzyme reaction increases and as it reaches above a certain point, it plateaus because of what reason?

Answer 24

All enzymes are busy catalyzing the reactions at saturating substrate concentration; When substrate concentration is saturating, the velocity can not increase any more.

Question 25

An enzyme was tested with two different substrates A and B resulting in products X and Y. The Km for substrate A was 10 mM and the Km for substrate B was 100 mM. Which of the following statement is correct?

Answer 25

Substrate B is less effective than substrate A to have same amount of products formed; Lower the Km the stronger the fit or reaction with a higher products formed.

Question 26

If someone is accidentally poisoned by methanol, ethanol is given as an antidote. How does ethanol prevent methanol poisoning? Note: Ethanol is converted to acetaldehyde by Alcohol Dehydrogenase (ADH) and methanol is converted to formaldehyde by the same enzyme.

Answer 26

Ethanol has a lower Km for this ADH and keeps the enzyme busy making acetaldehyde and let methanol be flushed out without being converted to the toxic formaldehyde.

Question 27

What form is energy stores in the food we eat?

Answer 27

Covalent bonds

Question 28

Why do we eat?

Answer 28

We consume molecules by eating food. These molecules are broken down to make ATP and also to build our body.

Question 29

What is/are the main purpose(s) of respiration?

Answer 29

The main purpose of respiration is to make ATP. In addition, the metabolites generated in respiration are used to make other molecules needed by the organism.

Question 30

What is respiration?

Answer 30

Oxidative and exergonic

Question 31

Which of the following are essential to perform glycolysis?

Answer 31

Glucose, NAD+, ADP, Pi (inorganic phosphate), ATP

Question 32

Which output of Glycolysis will enter the next step of Acetyl CoA formation?

Answer 32

Pyruvate

Question 33

More free energy is released during the Krebs cycle than during glycolysis, but only 2 moles of ATP is produced for each mole of glucose undergoing glycolysis. Most of the remaining free energy that is produced during the Krebs cycle is used to

Answer 33

reduce NAD+ and FAD.

Question 34

When mice were fed with radioactive carbon in glucose (C6H12O6) all the 6 CO2 molecules will be released during which of the following process

Answer 34

Take a look at the respiration-flowchart from class. Acetyl CoA is formed from 2 pyruvates and in the process 2 CO2 molecules are released. During Krebs, 4 molecules are released.

Question 35

When one consumes excess amounts of carbohydrates, they gain weight and store excess energy as fat. Conversion of carbohydrates to fat will involve the intermediate

Answer 35

Acetyl CoA; Excess carbohydrates results in more glycolysis so acetyl-CoA will build up. Instead of going on to Krebs, the acetyl-CoA can be converted into fatty acids and fat-storage.

Question 36

Which of the following poison dissipate Δ [H+]?

Answer 36

A chemical that would make the inner mitochondrial membrane leaky to ions; The inner mitochondrial membrane is where the proton gradient is produced, which provides the energy for ATP synthase to make ATP. Making this leaky prevents the gradient from forming and no ATP can be made.

Question 37

Which of the following is an exergonic process that directly helps the endergonic process of ATP synthesis in oxidative phosphorylation?

Answer 37

Chemiosmosis; ATP synthase actually uses the movement of the protons from the intermembrane space back into the matrix (chemiosmosis) as energy to allow it to make ATP from ADP and Pi.

Question 38

When we exercise for a long time without rest, the muscle cells become deprived of oxygen. Which of the following is not produced in a muscle cell under such conditions?

Answer 38

Ethanol; We do not make ethanol because we cannot perform alcohol fermentation.

Question 39

How does the reduction of pyruvate to lactate during fermentation allow glycolysis to continue in the absence of oxygen?

Answer 39

This reaction is coupled to the oxidation of NADH to NAD+.

Question 40

Migratory birds store or carry limited amounts of stored energy or food but fly over long distances. Which of the following process is most utilized in such situations to make the most amount of ATP for their flying?

Answer 40

Oxidative phosphorylation