metabolism

Question 1

Macromolecules

Answer 1

are made from subunits that are linked together in a condensation reaction.

Question 2

the biosynthetic reaction requires an energy input Reducing power supplied by elements donated by _________ energy supplied by hydrolysis of ________.

Answer 2

NADPH

ATP

Question 3

Catabolism

Steps:

Digestion-

Answer 3

• occurs in digestive tract/organelles
• provides small molecules

Question 4

Catabolism

Glycolysis:

Answer 4

• occurs in the cytosol
• does not require oxygen
• basis of anaerobic metabolism

Question 5

Catabolism:

Citric Acid Cycle:

Answer 5

• Occurs in matrix of mitochondria
• requires oxygen

Question 6

Catabolism:

Oxidative Phosphorylation:

Answer 6

• driven by electron rransport across the inner mitochondrial membrane
• generates ATP
• requires oxygen

Question 7

Enzymatic hydrolysis of macromolecules into their subunits:

Answer 7

Fats—>fatty acids

Polysaccharides—> monosaccharides

Polypeptides—–>ammino acids

Nucleic aciids—–> Nucleotides

Question 8

Hydrolysis-

Answer 8

reverse of the dehydration reaction used to attach the subunits together

Question 9

Hydrolysis-

Enzymes responsible-Hydrolytic enzymes

Answer 9

Digestion takes place “ outside” of the cell

Digestive tract (multicellular organisms), Digestive compartments ( within cells)

Question 10

Synthesis of nucleic acids, proteins and polysaccharides

Answer 10

Produced by the repeated addition of a subunit onto one end of a growing chain.

Question 11

Energy from ATP

Mechanism used to link ATP hydrolysis to the monomer addition in condensation reactions in polymer synthesis in cells is very complex and involves:

Answer 11

• Formation of high energy intermediates
• Different routes for ATP hydrolysis

ATP—> ADP + P_i ( ~11-13 kcal/mol)

ATP—-> AMP + PP_i + H₂O—> 2 P_i (~26 kcal/mol)

or

2 ATP nucleoside monophospate —> nucleoside trisphospate —> when added to the chain—> PP_i released —-> + H₂O —-> 2 P_i + additional energy

Question 12

Compartmentalization of Metabolism

Enzymes responsible for the reactions of metabolism are not randomly distributed in the cell.

Cells use various strategies to organize enzymes to increase their efficiency:

Answer 12

* Speed up reactions by spatially arranging enzymes:

• in multienzyme complexes
• within membranes
• on the surface of membranes
• on the surface of cytoskeletal filaments

*Control reactions by separating enzymes from potential substrates

• membrane-bound compartments
• other controlled access compartments
• in different cells

Question 13

Cell-Chemical Factory:

Answer 13

• performs millions of chemical reactions every second
• reactions highly controlled and catalyzed by enzymes
• enzyme-catalyzed reactions usally connected in series -product of one reaction is a substrate for the next reaction—-> formation of metabolic pathway s linked to one another.

Question 14

Cell - chemical factory:

Answer 14

Variety of metabolic pathways linked to one another—-> complex network of reactions —> responsible for cell survival, growth, reproduction and performing cell function.

Question 20

Metabolism-

Answer 20

Metabolism is the sum total of all of the chemical reactions that occur in living cells.

Question 21

Metabolism-

two sets of reactions:

Answer 21

catabolism-

Anabolism(biosynthesis)

Question 22

Metabolism-

Catabolism-

Answer 22

• reactions that break down complex molecules
• release energy that can be used by the cell
• provides building blocks

Question 23

Metabolism-

Anabolism

Answer 23

-reactions that synthesize new molecules using energy and molecules released by catabolic reactions

Anabolism + Catabolism= Metabolism

Question 24

Second Law of Thermodynamics:

Answer 24

• states that the degree of disorder (entropy) in the universe can only increase
• the movement toward disorder is a spontaneous process and requires a periodic effort to reverse it
• The creation of order in living systems is energetically unfavorable and is made possible only by the release of heat from chemical reactions, which increase the disorder ( entropy) of the rest of the universe

Question 25

First Law of Thermodynamics:

Answer 25

-States that energy can be converted from one form to another, but it cannont be created or destroyed, e.g. \* Chemical bond energy---\> heat energy \* LIght ( electromagnetic) energy --\> Chemical bond energy -Chemical bond energy---\> electrical energy--\> kinetic energy \* Kinetic energy---\> heat energy

Question 26

First law od Thermodynamics- The cell can not derive any benefit from the heat energy it produces unless the heat-

Answer 26

generating reactions inside the cell are directly linked to the process that maintain molecular order --\> couling of heat production to an increase in order

Question 27

first law of Thermodynamics- A direct linkage of the " burning" of food molecules to the generation of biological order is necessary for cells to be able to create and maintain an island of order in the universe tending toward disorder.

Answer 27

Light from the sun is the ultimate source of all energy for humans and animals-plants trap energy from sunlight.

Question 28

Photosynthesis-

Answer 28

light energy converted into chemical bond energy in plant cell

Question 29

Photosynthesis- Atoms from inorganic sources + energy --\> formation of chemical bonds between atoms ---\> production of sugars

Answer 29

sugars are used as a source of chemical bond energy and as a source of substrates to make other molecules like amino acids, nucleotides and fatty acids that are converted into macromolecules--\> serve as food for animals

Question 30

Respiration

Answer 30

in plants and animals, energy is extracted from food molecules by a process of gradual oxidation of organic molecules

Question 31

Photosynthesis and respiration - complementary processes-

Answer 31

-C,O,H,N cycle between different living organisms and inorganic world

Question 32

Oxidation and Reduction

Answer 32

Some chemical reactions involve the transfer of electrons from one molecule to another

Question 33

Oxidation and Reduction- Oxidation- Reduction-

Answer 33

- Partial or complete loss of electrons - partial or complete acquisition of electrons

Question 34

Complete Oxidation and Reduction

Answer 34

Fe++ --\> Fe+++ + 1e- cl₂+2e^- --\> 2Cl^- -Oxidation and reduction reactions occure simultaneously. The molecule being oxidized gives up its electrons between atoms lnked by a covalent bond.

Question 35

Oxidation and Reduction Terms "oxidation " and " reduction" also apply when there is only a partial shift of electrons between atoms linked by a covalent bond.

Answer 35

Partial oxidation and Reduction- 2H₂ + O₂ ---\> 2H₂O Protons (H+) are often transferred simultaneously with electrons ( hydrogenation) A + e^- + H^{+--> AH}

Question 36

Oxidation of Carbon

Answer 36

As carbon atom becomes incresingly oxidized, the electrons in the bond spend decreasing amounts of time associated with the carbon atom and increasing amounts of time with the oxygen atom(s)

Question 37

Oxidation of Carbon Second Law of Thermodynamics:

Answer 37

- States that the degree of disorder ( entropy) in the universe can only increase - The creation of order in lining systems is energetically unfavorable and is made possible only by the release of heat from chemical reactions, which increase the disorder ( entropy) of the rest of the universe.

Question 38

Gibbs Free Energy (G)-

Answer 38

The measure of energy potentially available in a molecule to do useful work ( units=kcal/mol)

Question 39

Change in Gibbs Free Energy ( delta G)

Answer 39

A change in G ( delta G) measures the amount of energy released as heat ( lost ) when a reaction takes place. It is also a measure of the relative change in the amount of order

Question 40

changes in Gibbs Free Energy- Negative ( delta G)

Answer 40

\* decrease in order \* an increase in disorder ( heat released) \*indicates that the reaction is energetically favorable

Question 41

Change in Gibbs Free Energy- Positive( delta G)

Answer 41

- an increase in order - an decrease in disorder ( consumes energy) - indicates that the reaction is energetically unfavorable

Question 42

Free Energy and Reactions Energetically Favorable Reactions-

Answer 42

- decrease order ( delta G\<0) - release energy - tend to occur spontaneously

Question 43

Free Energy and Reactions Energetically Unfavorable Reactions:

Answer 43

- Increase order ( delta G \> 0) - do not occur spontaneously Therefore: A chemically unfavorable reaction must be coupled to another reaction(s) with a delta G sufficiently negative to make the net delta G of the coupled reactions negative.

Question 44

Activation Energy-

Answer 44

The energy required to initiate an energetically favorable chemical reaction

Question 45

Activation Energy Sources

Answer 45

\*Heat \*Enzymes

Question 46

Activation Energy Heat

Answer 46

- increases molecular movement - increases the probability that potentially reactive molecules will collide with sufficient energy and orientation to react

Question 47

Activation Energy Enzymes

Answer 47

- Physically bring potential reactants together in the correct orientation - stress bonds - form transient intermediate bonds to facilitate reactions

Question 48

Enzymes

Answer 48

-Enzymes are biological catalysts, responsible for carrying out the chemical reactions that make up metabolism. -

Question 49

Enzymes Functions-

Answer 49

- Lower the activation energy of reactions to allow them to occur at body temperature - Release energy in sufficiently small steps that it can be utilized efficiently. - Enzymes cannot make an energetically unfavorable reaction happen unless it is coupled to an energetically favorable reaction.

Question 50

Enzymes-

Answer 50

-are highly selective ( one enzyme for one out of many possible reactions for a given substrate) \* have unique active ( binding ) sites only particular substrate fits into it

Question 51

Enzymes: Cells use a variety of strategies to control the activities of enzymes:

Answer 51

\* Feedback inhibition \* Covalent modification - phosphorylation -mediated by kianase - dephosphorylation- mediated by phosphates \* Compartmentalization

Question 52

Activated Carriers in cells energetically favorable reaction if used to drive an energetically unfavorable reaction that produces an activated carrier molecule or other useful molecule

Answer 52

Enzymes couple an energetically favorable reaction ( e.g. oxidation of foodstuffs) to an energetically unfavorable reaction ( e.g. generation of an activated carrier molecule)--\> the amount of heat released by an oxidation reaction is reduced by the amount of energy stored in the energy-rich covalent bonds of the activated carrier molecule --\> it will power a chemical reaction elsewhere in the cell

Question 53

Activated Carriers The energy derived from oxidation of food molecules must be _______ \_\_\_\_\_\_\_ stored temporarily before use in production of small organic molecules or macromolecules.

Question 54

Activated Carriers

Answer 54

store energy in an easy exchangeable form ( as a readily transferable chemical group or as high energy electrons) \* Source of both energy and chemical groups for biosynthetic reactions The most important are : ATP, NADH, NADPH

Question 55

ATP

Answer 55

most abundant and most widely used activated carrier molecule in cells

Question 56

ATP Captures chemical energy released from an energetically favorable reaction and uses it to provide energy to drive an energetically unfavorable reaction - often used in condensation reactions.

Answer 56

- synthesized in an energetically unfavorable phosphorylation reaction - Energy supply for cellular pumps and molecular motors \* Energetically favorable reaction of ATP hydrolysis is coupled to many energetically unfavorable reactions in which other molecules are synthesized.

Question 57

ATP ATP hydrolysis often involves the transfer of the terminal phosphate to another molecule--\>

Answer 57

phosphorylation reaction \* used to activate substrates control of cell signaling

Question 58

NADH and NADPH

Answer 58

NADH ( nicotinamide adenine dinucleotide) NADPH ( nicotinamide adenine dinucleotide phosphate)

Question 59

NADH and NADPH

Answer 59

\* differ by a signal phosphate group which allows enzymes to distinguish between them \* serve as carriers for electrons ( reducing power) and protons in oxidation-reduction reactions

Question 60

NADH and NADPH

Answer 60

- participate in many biosynthetic reactions that would be energetically unfavorable \*NADH functions primarily in catabolic reactions- serves as an intermediate in the catabolic system of reaction in the oxidation of food molecules that generate ATP \*NADH functions primarily in anabolic reactions -supplies the high energy electrons needed to synthesize energy-rich biological molecules.

Question 61

Other activated carriers

Answer 61

\* small molecules associated with some enzymes and essential for enzyme activity. \* some are involved in group- transfer reactions \* serve as carriers of other molecules

Question 62

Carriers involved in Group Transfer Reactions: Carrier: Group Transferred

Answer 62

ATP/phosphate NAD,NADP/hydride ion (H-) FADH/hydride ion ( H-) Coenzyme A/acetyl Biotin/carboxyl S-Adenosylmethionine/methyl Uridine diphosphate/glucose