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metabolism Flashcards

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1
Q

Macromolecules

A

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

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2
Q

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

A

NADPH

ATP

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3
Q

Catabolism

Steps:

Digestion-

A
  • occurs in digestive tract/organelles
  • provides small molecules
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4
Q

Catabolism

Glycolysis:

A
  • occurs in the cytosol
  • does not require oxygen
  • basis of anaerobic metabolism
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5
Q

Catabolism:

Citric Acid Cycle:

A
  • Occurs in matrix of mitochondria
  • requires oxygen
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6
Q

Catabolism:

Oxidative Phosphorylation:

A
  • driven by electron rransport across the inner mitochondrial membrane
  • generates ATP
  • requires oxygen
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7
Q

Enzymatic hydrolysis of macromolecules into their subunits:

A

Fats—>fatty acids

Polysaccharides—> monosaccharides

Polypeptides—–>ammino acids

Nucleic aciids—–> Nucleotides

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8
Q

Hydrolysis-

A

reverse of the dehydration reaction used to attach the subunits together

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9
Q

Hydrolysis-

Enzymes responsible-Hydrolytic enzymes

A

Digestion takes place “ outside” of the cell

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

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10
Q

Synthesis of nucleic acids, proteins and polysaccharides

A

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

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11
Q

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:

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

ATP—> ADP + Pi ( ~11-13 kcal/mol)

ATP—-> AMP + PPi + H2O—> 2 Pi (~26 kcal/mol)

or

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

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12
Q

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:

A

* 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
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13
Q

Cell-Chemical Factory:

A
  • 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.
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14
Q

Cell - chemical factory:

A

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

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15
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A
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16
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17
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18
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19
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20
Q

Metabolism-

A

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

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21
Q

Metabolism-

two sets of reactions:

A

catabolism-

Anabolism(biosynthesis)

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22
Q

Metabolism-

Catabolism-

A
  • reactions that break down complex molecules
  • release energy that can be used by the cell
  • provides building blocks
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23
Q

Metabolism-

Anabolism

A

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

Anabolism + Catabolism= Metabolism

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24
Q

Second Law of Thermodynamics:

A
  • 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
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25
Q

First Law of Thermodynamics:

A

-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

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26
Q

First law od Thermodynamics-

The cell can not derive any benefit from the heat energy it produces unless the heat-

A

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

27
Q

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.

A

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

28
Q

Photosynthesis-

A

light energy converted into chemical bond energy in plant cell

29
Q

Photosynthesis-

Atoms from inorganic sources + energy –> formation of chemical bonds between atoms —> production of sugars

A

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

30
Q

Respiration

A

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

31
Q

Photosynthesis and respiration -

complementary processes-

A

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

32
Q

Oxidation and Reduction

A

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

33
Q

Oxidation and Reduction-

Oxidation-

Reduction-

A
  • Partial or complete loss of electrons
  • partial or complete acquisition of electrons
34
Q

Complete Oxidation and Reduction

A

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.

35
Q

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.

A

Partial oxidation and Reduction-

2H2 + O2 —> 2H2O

Protons (H+) are often transferred simultaneously with electrons ( hydrogenation)

A + e- + H+–> AH

36
Q

Oxidation of Carbon

A

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)

37
Q

Oxidation of Carbon

Second Law of Thermodynamics:

A
  • 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.
38
Q

Gibbs Free Energy (G)-

A

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

39
Q

Change in Gibbs Free Energy ( delta G)

A

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

40
Q

changes in Gibbs Free Energy-

Negative ( delta G)

A

* decrease in order

* an increase in disorder ( heat released)

*indicates that the reaction is energetically favorable

41
Q

Change in Gibbs Free Energy-

Positive( delta G)

A
  • an increase in order
  • an decrease in disorder ( consumes energy)
  • indicates that the reaction is energetically unfavorable
42
Q

Free Energy and Reactions

Energetically Favorable Reactions-

A
  • decrease order ( delta G<0)
  • release energy
  • tend to occur spontaneously
43
Q

Free Energy and Reactions

Energetically Unfavorable Reactions:

A
  • 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.

44
Q

Activation Energy-

A

The energy required to initiate an energetically favorable chemical reaction

45
Q

Activation Energy

Sources

A

*Heat

*Enzymes

46
Q

Activation Energy

Heat

A
  • increases molecular movement
  • increases the probability that potentially reactive molecules will collide with sufficient energy and orientation to react
47
Q

Activation Energy

Enzymes

A
  • Physically bring potential reactants together in the correct orientation
  • stress bonds
  • form transient intermediate bonds to facilitate reactions
48
Q

Enzymes

A

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

-

49
Q

Enzymes

Functions-

A
  • 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.
50
Q

Enzymes-

A

-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

51
Q

Enzymes:

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

A

* Feedback inhibition

* Covalent modification

  • phosphorylation -mediated by kianase
  • dephosphorylation- mediated by phosphates

* Compartmentalization

52
Q

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

A

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

53
Q

Activated Carriers

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

A
54
Q

Activated Carriers

A

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

55
Q

ATP

A

most abundant and most widely used activated carrier molecule in cells

56
Q

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.

A
  • 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.

57
Q

ATP

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

A

phosphorylation reaction

* used to activate substrates control of cell signaling

58
Q

NADH and NADPH

A

NADH ( nicotinamide adenine dinucleotide)

NADPH ( nicotinamide adenine dinucleotide phosphate)

59
Q

NADH and NADPH

A

* 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

60
Q

NADH and NADPH

A
  • 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.

61
Q

Other activated carriers

A

* small molecules associated with some enzymes and essential for enzyme activity.

* some are involved in group- transfer reactions

* serve as carriers of other molecules

62
Q

Carriers involved in Group Transfer Reactions:

Carrier: Group Transferred

A

ATP/phosphate

NAD,NADP/hydride ion (H-)

FADH/hydride ion ( H-)

Coenzyme A/acetyl

Biotin/carboxyl

S-Adenosylmethionine/methyl

Uridine diphosphate/glucose

63
Q
A

cell Bio (14 decks)

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