BIO 1140 - Cell Metabolism

Question 1

What is Energy?

Answer 1

capacity to cause change, especially to do work (to move matter against an opposing force).
- Different forms of energy are interconvertible

Question 2

What is Kinetic Energy?

Answer 2

energy associated with the relative motion of objects

Question 3

What is Chemical Energy?

Answer 3

energy available in molecules for release in a chemical reaction (= potential energy)

Question 4

What is Thermal Energy?

Answer 4

kinetic energy due to the random motion of atoms and molecules (= heat)

Question 5

What is Potential Energy?

Answer 5

energy that matter possesses as a result of its location or spatial arrangement

Question 6

What is the First Law of Thermodynamics?

Answer 6

thetotal amountof energyin theuniversemustalways bethesame

Question 7

What is the Ultimate Source of Energy?

Answer 7

Light Energy
- Universal source is the sun
- Used in photosynthesis
- the radiant energy of sunlight sustains all life, with few exceptions

Question 8

What type of Energy do All Animals live on?

Answer 8

All animals live on energy stored in the chemical bonds of organic molecules (from food)
- Animals eat plants or eat other animals that eat plants.
- Plants obtain their energy directly from sunlight.

Question 9

How does Solar energy enter the living world?

Answer 9

Solar energy enters the living world through photosynthesis in plants

Question 10

What is Photosynthesis?

Answer 10

Photosynthesis is a process that converts the electromagnetic energy in sunlight into chemical-bond energy in organic molecules.

Question 11

What is Cellular Respiration?

Answer 11

Cellular Respiration is a process that extracts energy from organic molecules (food) by gradual oxidation.

Question 12

What is Oxidation?

Answer 12

The addition of oxidizing agent
- Takes away electrons
- Most common agent is oxygen

Question 13

What is Reduction?

Answer 13

The converse reaction, called reduction, involves the addition of electrons to an atom.

Question 14

What is the Second Law of Thermodynamics?

Answer 14

Living cells create and maintain order in a universe that is tending always toward greater disorder.

Question 15

What is Entropy?

Answer 15

Measure of system’s disorder
- Requires constant energy for cell function + organization
- creates more favourable environments for cell systems
- Order is necessary for survival

Question 16

When is Disorder increased?

Answer 16

The increased order inside the cell is accompanied by increased disorder in the cells’ surroundings
- Disorder increases when useful energy that could be harnessed to do work (free energy) is dissipated as heat

Question 17

What is Gibb’s Free Energy?

Answer 17

amount of energy available in a molecule to do work in a system when the temperature and pressure are uniform
- measured in in kcal/mole.
- can also be expressed in joules (1 cal = 4.184 joules

Question 18

Where is Gibb’s Free Energy Stored?

Answer 18

stored in the bonds between individual atoms of a molecule

Question 19

What does Gibb’s Free Energy cause?

Answer 19

causes vibration, rotation and movement of the molecule through space

Question 20

What are the Two ways Chemical Reactions in a cell can Cause Disorder?

Answer 20

1. The reaction can decrease the amount of order in the cell
2. Changes of bond energy of the reacting molecules can cause heat to be released, which disorders the environment around the cell

Question 21

What does the Free-Energy Change determine?

Answer 21

The free-energy change for a reaction determines whether it can occur

Question 22

What does the Change in Free Energy measure?

Answer 22

measures theamount ofdisordercreated in the universewhen areactioninvolving these moleculestakesplace
- the change inorder inside the cell and the change in order of the surroundings

Question 23

What is the Free Energy of a Spontaneous Reaction?

Answer 23

A chemical reaction that occurs spontaneously must have a negative ΔG
- The disorder of the universe can only increase.
- ΔG is negative if the disorder of the universe (reaction plus surroundings) increases
- Exergonic Reaction
- Favourable

Question 24

What happens to Reactions at Equilibrium?

Answer 24

the rates of the forward and reverse reactions are equal
- Reactions will eventually reach a chemical equilibrium
- ΔG = 0, so the reaction will not proceed forward or backward

Question 25

What is Standard Free Energy used to predict?

Answer 25

Standard free energy change (ΔG°) is used to predict the outcome of a reaction
- The ΔG° is independent of concentration
- it depends only on the intrinsic characters of the reacting molecules

Question 26

What does Standard Free Energy represent?

Answer 26

the gain or loss of free energy as one mole of reactant is converted to one mole of product under “standard conditions”
- all molecules present at a concentration of 1 M and pH 7.0

Question 27

What are Coupled Reactions?

Answer 27

A reaction that is unfavorable (has a positiveΔG°) can be driven by a second, highly favorable reaction.

Question 28

What are Exergonic and Endergonic Reactions?

Answer 28

A reaction with negative change in free energy (ΔG<0) is considered exergonic

A reaction with positive change in free energy(ΔG>0)is considered endergonic

Question 29

What is an Exergonic Reaction?

Answer 29

Spontaneous reactions are exergonic: they release energy (∆G <0)
- energetically favorable reactions
- reaction product has a lower free energy level (more stable)
- Can release the free energy (potential energy) contained in bonds

Question 30

What are Endergonic Reactions?

Answer 30

Non-spontaneous reactions are endergonic: they require energy (∆G >0)
- energeticallyunfavorablereactions
- The reaction product has a higher free energy level than the substrate
- Can store energy in molecules

Question 31

What are Activated Carriers?

Answer 31

Activated carriers can store energy either as a readily transferable chemical group or as readily transferable (“high energy”) electrons
- ATP, NADH and NADPH are the most important activated carriers.

Question 32

What is Catabolism and Anabolism?

Answer 32

Catabolism: The breakdown of complex molecules into a more simple form (building blocks)

Anabolism: The synthesis of complex molecules from simple forms (building blocks)

Question 33

What is ATP?

Answer 33

ATP is the most widely used activated carrier
- adenosine triphosphate
- 1 adenosine (nitrogenous base) + 1 ribose (sugar) + 3 phosphate groups

Question 34

How is ATP synthesized?

Answer 34

ATP is synthesized in an energetically unfavorable phosphorylation reaction
- a phosphate group is added to ADP (adenosine 5ʹ-diphosphate)

Question 35

What are Enzymes?

Answer 35

Activation of enzyme is required to start chemical reactions
- cells control enzymes
- inhibitors

Question 36

What are the two types of Inhibition?

Answer 36

1. Competitive Inhibition
2. Allosteric inhibition

Question 37

What is Competitive Inhibition?

Answer 37

Competes with substrate to active site
- blocks substrates from binding

Question 38

What is Allosteric Inhibition?

Answer 38

Attach to enzyme to change its conformation
- non-competitive
- Deactivates enzyme

Question 39

How do Enzymes help reactions?

Answer 39

Enzymescatalyze reactions and speed up their rate, but they cannot change theΔG°of a reaction.
- A spontaneous reaction is not necessarily an instantaneous reaction

Question 40

What is Activation Energy?

Answer 40

Even energetically favorable reactions require activation energy to get them started
- energy required to start a reaction
- Prevents unnecessary / unwanted reactions from occurring
- Enzymes act as catalysts and lower the activation energy

Question 41

Where does the varying Activation Energy come from?

Answer 41

The varying energies come from collisions with surrounding molecules, which make the substrate molecules jiggle, vibrate, and spin.
- produces heat
- increase in temp
- increase in kinetic energy

Question 42

What is a Metabolic Pathway?

Answer 42

A series of enzyme-catalyzed reactions forms a metabolic pathway
- Each enzyme catalyzes a chemical reaction involving a particular molecule.
- Chemical reactions involve making, breaking and rearranging covalent bonds.

Question 43

What is Metabolism?

Answer 43

Metabolism is the sum total of all the chemical reactions inside the cell
- Metabolic pathways are linked to one another, forming a complex web of interconnected reactions.