Life at the Cellular Level 3

Question 1

<p>What is the basic rule of energy?</p>

Answer 1

<p>Energy cannot be created or destroyed, it merely changes its form</p>

Question 2

<p>What are the two laws of thermodynamics?</p>

Answer 2

<ol> <li>Energy can be converted from one form to another but the total energy of the universe remains constant</li> <li>All energy transformations ultimatelty lead to more disorder in the universe, ie, increase in entropy</li></ol>

Question 3

<p>What is entropy?</p>

Answer 3

<p>Degree of disorder in a system, quanitity representing the unavailability of a systems therman energy for conversion into work (measures in J/K)</p>

Question 4

<p>What happens as usable energy decreases and unusable energy decreases?</p>

Answer 4

<p>Entropy increases</p>

Question 5

<p>How do cells create and maintian order?</p>

Answer 5

<p>By performing lots of chemical reactions which require energy</p>

Question 6

<p>How do the reactions within cells obey the second law of thermodynamics (leads to an increase in disorder/entropy)?</p>

Answer 6

<p>Chemical reactions used to create order generate heat which is discharged into the surrounding environment and disorders it, leading to an increase in total entropy</p>

Question 7

<p>What is Gibb's free energy?</p>

Answer 7

<p>Amount of useful, free energy in a system that can be used for work (measured in kJ/mol)</p>

Question 8

<p>What are the 3 quantities that can define free energy?</p>

Answer 8

<p>Enthalpy (H)</p>

<p>Entropy (S)</p>

<p>Absolute temperature (T)</p>

<p></p>

Question 9

<p>What formula expresses free energy?</p>

Answer 9

<p>G = H - TS</p>

Question 10

<p>What is enthalpy?</p>

Answer 10

<p>Total heat content of a system</p>

Question 11

<p>What is absolute temperature?</p>

Answer 11

<p>Temperature measured from absolute zero in kelvin</p>

Question 12

<p>What does enthalpy reflect?</p>

Answer 12

<p>The number/kinds of bonds being broken or formed</p>

Question 13

<p>When can spontaneous reactions occur?</p>

Answer 13

<p>If a system gives up energy</p>

<p>Becomes more random and increases in entropy</p>

Question 14

<p>Why must spontaneous reactions have a negative value for delta G (change in G)?</p>

Answer 14

<p>Because they must decrease enthalpy and/or increase entropy</p>

Question 15

<p>What does a positive and negative delta G mean?</p>

Answer 15

<p>Delta G positive means the reaction requires energy</p>

<p>Delta G negative means the reaction releases energy</p>

Question 16

<p>Why do most biological reactions require a positive delta G?</p>

Answer 16

<p>Because they require order</p>

Question 17

<p>What is energy coupling?</p>

Answer 17

<p>Transfer of energy from catabolism to anabolism</p>

Question 18

<p>How do cells carry out energetically unfavourable reactions?</p>

Answer 18

<p>By using energy coupling</p>

Question 19

<p>How does energy coupling allow energetically unfavourable reactions to happen?</p>

Answer 19

<p>The unfavourable reaction with a positive delta G is driven by the favourable reaction with a negative delta G as the net free energy change is less than 0</p>

Question 20

<p>What is catabolism?</p>

Answer 20

<p>Metabolic pathways that break down moelcules into smaller units releasing energy (negative delta G)</p>

Question 21

<p>What is anabolism?</p>

Answer 21

<p>Synthesis of complex molecules from simper ones using energy (positive delta G)</p>

Question 22

<p>Why do reactions never reach the equilbrium?</p>

Answer 22

<p>Because delta G = 0 is incompatible with life, this doesn't happen because energy is passed from the envionment to the organism and vice versa</p>

Question 23

<p>What is the dyamic steady state?</p>

Answer 23

<p>Flow of energy between molcules, a continuous series of reactions</p>

Question 24

<p>Why do the concentrations of intermediate molecules in a dynamic steady state remain constant?</p>

Answer 24

<p>Because as soon as they are made they are used</p>

Question 25

<p>What does a simple dynamic steady state system look like?</p>

Answer 25

<p>When a=b the system is in a dynamic steady state due to maintaning the concentration of intermediate molecules</p>

Question 26

<p>What is metabolism?</p>

Answer 26

<p>Chemical processes in a living organism where food is broken down and used for energy production</p>

Question 27

<p>What happens during metabolism in terms of free energy?</p>

Answer 27

<p>Flows between catabolic and anabolic processes, with energy being lost as heat</p>

Question 28

<p>Each step of a metabolic pathway is catalysed by an enzyme, what are some of their properties?</p>

Answer 28

<p>They are selective</p>

<p>They can be regulated</p>

Question 29

<p>Why is glucose often used as a food molecule</p>

Answer 29

<p>It has a high potential energy</p>

Question 30

<p>Why does the breakdown of glucose occur in a series of small reactions?</p>

Answer 30

<p>To allow the energy to be extracted in stages, as if it was broken down in one step to much energy would be produced and most of it would be lost to heat</p>

Question 31

<p>How does glucose metabolism begin?</p>

Answer 31

<p>A small amount of energy must be inputed, activated carrier molecules store released energy</p>

Question 32

<p>What does endergonic mean?</p>

Answer 32

<p>Anabolic pathway is supplied with free energy</p>

Question 33

<p>What does exogonic mean?</p>

Answer 33

<p>Catabolic pathway releases free energy</p>

Question 34

<p>How is free energy supplied and stored?</p>

Answer 34

<p>Using the interconversion of ATP and ADP</p>

<p>ATP + H₂O⇔ADP + P_i</p>

Question 35

<p>Is ATP to ADP + P_iexogonic or endogonic?</p>

Answer 35

<p>Exogonic</p>

<p>Decrease in free energy</p>

<p>Delta G is negative</p>

Question 36

<p>Is ADP + P_ito ATP exogonic or endergonic?</p>

Answer 36

<p>Endergernic</p>

<p>Requires free energy input</p>

<p>Delta G is positive</p>

Question 37

<p>How to enzymes allow us to do reactions that would otherwise be impossible?</p>

Answer 37

<p>By lowing the activation energy</p>

Question 38

<p>Why does potential energy in food molecules arise?</p>

Answer 38

<p>Because they contain large amounds of H atoms</p>

Question 39

<p>What steps following the oxidaiton (breakdown) of glucose?</p>

Answer 39

<p>Releases electrons that flow through a series of intermediate steps to another spiecies, such as O₂</p>

<p>Can be described as an electromotive force (EMF)</p>

Question 40

<p>What carrier molecules do cellular redox reactions use?</p>

Answer 40

<p>NAD⁺</p>

<p>FAD⁺</p>

<p>NADP⁺</p>

Question 41

<p>What do activated carriers acts as in biochemical pathways to fuel oxidation and biosynthesis?</p>

Answer 41

<p>Coenzymes</p>