Chapter 7

Question 1

Anabolism

Answer 1

Biochemical process in metabolism where the simple molecules combine to generate complex molecules

Question 2

Pathway

Answer 2

A series of actions among molecules in a cell that leads to a certain product or a change in the cell.

Question 3

The first law of thermodynamics

Answer 3

Energy is never created or lost, it is simply converted from one form to another.

Question 4

The second law of thermodynamics

Answer 4

In every energy transfer, some energy is ‘lost’ in the form of heat.

Question 5

Induced fit

Answer 5

An enzyme’s shape and conformation changing over time in response to substrate binding.

Question 6

Active site

Answer 6

The specific region of an enzyme where a substrate binds and catalysis takes or where chemical reaction occurs.

Question 7

Substrates

Answer 7

The surface on which an organism (eg: plant, fungus, or animal) lives or the substance on which an enzyme can act.

Question 8

Products

Answer 8

End substances after a biological process has occurred.

Question 9

Competitive inhibition

Answer 9

Phenomenon in which a substrate molecule is prevented from binding to the active site of an enzyme by a molecule that is very similar in structure to the substrate.

Question 10

noncompetitive inhibition

Answer 10

A specific type of enzyme inhibition characterized by an inhibitor binding to an allosteric site resulting in decreased efficacy of the enzyme.

Question 11

Catabolism

Answer 11

The break down of complex molecules

Question 12

Exergonic

Answer 12

Reaction that releases free energy in the process of the reaction.

Question 13

Endergonic

Answer 13

Absorbing energy in the form of work.

Question 14

Phosphorylation

Answer 14

The transfer of phosphate molecules to a protein.

Question 15

Substrate-level phosphorylation

Answer 15

When a phosphoryl group is transferred from a substrate to ADP or GDP to form ATP or GTP, coupled with the release of free energy.

Question 16

Oxidative phosphorylation

Answer 16

A cellular process that harnesses the reduction of oxygen to generate high-energy phosphate bonds in the form of adenosine triphosphate (ATP).

Question 17

Photophosphorylation

Answer 17

The process of producing ATP molecules from ADP during the biological process of photosynthesis in the presence of light energy.

Question 18

Glycolysis

Answer 18

The process in which glucose is broken down to produce energy.

Question 19

Investment phase

Answer 19

Due to its usage of two ATP molecules.

Question 20

Pay off phase

Answer 20

Where the net creation of ATP and NADH molecules occurs.

Question 21

Fermentation

Answer 21

Another anaerobic (non-oxygen-requiring) pathway for breaking down glucose.

Question 22

Anaerobic

Answer 22

Without oxygen

Question 23

Lactic acid fermentation

Answer 23

A type of anaerobic respiration (or fermentation) that breaks down sugars to produce energy in the form of ATP.

Question 24

Alcohol Fermentation

Answer 24

A type of cellular respiration which does not require oxygen (anaerobic respiration), and involves the breaking down of glucose to pyruvic acid and then finally ethanol.

Question 25

Respiration

Answer 25

Is defined as a metabolic process wherein, the living cells of an organism obtains energy (in the form of ATP) taking in oxygen and liberating carbon dioxide from the oxidation of complex organic substances

Question 26

Decarboxylation

Answer 26

A chemical reaction that eliminates a carboxyl group and liberates carbon dioxide (CO2).

Question 27

Krebs cycle

Answer 27

A sequence of reactions in the living organism in which oxidation of acetic acid or acetyl equivalent provides energy for storage in phosphate bonds.

Question 28

Terminal electron acceptor

Answer 28

The last compound to receive an electron in an electron transport chain.

Question 29

Proton gradient

Answer 29

Set up in mitochondria membrane, where the proton concentration is higher outside the inner membrane than inside the membrane.

Question 30

Anaerobic respiration

Answer 30

A respiratory process that occurs in both prokaryotes and eukaryotes in which cells break down the sugar molecules to produce energy without the presence of oxygen.

Question 31

Distinguish between anabolic and catabolic metabolic pathways and give examples of each.

Answer 31

Anabolic metabolic pathways involve the building or synthesis of larger molecules from smaller ones, requiring energy input. Examples include the synthesis of proteins from amino acids and the formation of glucose through gluconeogenesis.

Catabolic metabolic pathways involve the breakdown of larger molecules into smaller ones, releasing energy. Examples include the breakdown of glucose through glycolysis and the oxidation of fatty acids in cellular respiration.

Question 32

Understand the first law of thermodynamics in a biological context

Answer 32

The first law of thermodynamics, also known as the law of conservation of energy, states that energy cannot be created or destroyed, but it can be converted from one form to another. In a biological context, this means that the energy within living organisms is constantly being transformed and transferred, but the total amount of energy remains constant.

Question 33

Understand the second law of thermodynamics in a biological context

Answer 33

The second law of thermodynamics states that in any energy transfer or transformation, there is always an increase in the overall entropy, or disorder, of the system. In biological systems, this means that energy transformations are not 100% efficient, and some energy is always lost as heat. This law also explains why energy flows in one direction, from higher energy levels to lower energy levels, and why maintaining order and organization in living organisms requires a constant input of energy.

Question 34

Understand how ATP is used by the cell as an energy source.

Answer 34

ATP, or adenosine triphosphate, is a molecule that serves as the primary energy source for cellular activities. It is like a rechargeable battery that stores and releases energy when needed. When a cell requires energy, ATP is broken down into ADP (adenosine diphosphate) and inorganic phosphate (Pi), releasing energy that can be used for various cellular processes. This energy release happens through hydrolysis, where a water molecule is used to break the bond between the second and third phosphate groups in ATP. This process releases energy that can be used to drive chemical reactions, transport molecules across cell membranes, and perform mechanical work, such as muscle contractions. Once ATP is hydrolyzed and energy is released, the ADP and Pi can be recycled back into ATP through cellular respiration, where energy from nutrients is used to regenerate ATP molecules. This continuous cycle of ATP hydrolysis and regeneration allows cells to have a constant supply of energy to carry out their functions. In summary, ATP acts as a portable and readily available energy currency within cells, providing the necessary energy for various cellular processes.

Question 35

Explain how enzymes function as molecular catalysts and how different forms of inhibition works

Answer 35

Enzymes are like super helpful little helpers in our cells! They function as molecular catalysts, which means they speed up chemical reactions without being used up themselves. They do this by lowering the activation energy required for a reaction to occur. Now, let’s talk about inhibition. There are different forms of inhibition that can affect enzyme activity. Competitive inhibition happens when a molecule competes with the substrate for the active site of the enzyme, blocking it from binding. Non-competitive inhibition occurs when a molecule binds to a different site on the enzyme, causing a change in its shape and making it less effective. Another type is feedback inhibition, where the end product of a metabolic pathway acts as an inhibitor of an earlier enzyme in the pathway, regulating the overall rate of the pathway. In summary, enzymes play a crucial role as molecular catalysts, speeding up reactions in our cells. Different forms of inhibition can regulate enzyme activity, ensuring that cellular processes are finely tuned and balanced

Question 36

Describe the overall chemical reaction of glucose catabolism

Answer 36

It’s the process of breaking down glucose to release energy. The overall chemical reaction of glucose catabolism is called cellular respiration. In the presence of oxygen, glucose is oxidized through a series of reactions, ultimately producing carbon dioxide, water, and energy in the form of ATP. This process occurs in three main stages: glycolysis, the Krebs cycle (also known as the citric acid cycle), and oxidative phosphorylation. Each stage contributes to the overall breakdown of glucose and the production of ATP.

Question 37

Understand the stages in the breakdown of glucose, including glycolysis, fermentation, and respiration

Answer 37

1) Glycolysis: This is the first stage of glucose breakdown and occurs in the cytoplasm. Glucose is converted into two molecules of pyruvate, generating a small amount of ATP and NADH in the process.

2) Fermentation: In the absence of oxygen, fermentation can occur. This is an anaerobic process where pyruvate is converted into either lactic acid or ethanol and carbon dioxide. Fermentation helps regenerate NAD+ to keep glycolysis going.

3) Respiration: If oxygen is present, the pyruvate from glycolysis enters the mitochondria for further breakdown. It goes through the Krebs cycle, where it is completely oxidized, generating more ATP and electron carriers (NADH and FADH2). The electron carriers then participate in oxidative phosphorylation, where ATP is produced through a series of electron transport chain reactions

Question 38

Explain the purpose for fermentation

Answer 38

Fermentation serves an important purpose when there’s no oxygen available for cellular respiration. It allows the cells to continue producing energy in the form of ATP, even in anaerobic conditions. Fermentation helps regenerate NAD+ from NADH, which is necessary for glycolysis to continue. It’s like a backup plan for cells when oxygen is scarce!

Question 39

Relate these topics to high-and low- energy electrons

Answer 39

When it comes to high and low-energy electrons, we can relate it to the process of cellular respiration. In cellular respiration, high-energy electrons are generated during the breakdown of glucose. These electrons are carried by molecules like NADH and FADH2, which then enter the electron transport chain. As the electrons move through the chain, their energy is gradually released, allowing the production of ATP. On the other hand, low-energy electrons are those that have already released their energy and are ready to be accepted by an electron acceptor, such as oxygen. So, high-energy electrons are crucial for ATP production, while low-energy electrons are ready to be “recharged” in cellular respiration.

Question 40

What are the three methods of phosphorylation?

Answer 40

1. Substrate-level phosphorylation
2. Oxidative phosphorylation
3. Photophosphorylation