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Flashcards in Chapter 8 Deck (68)
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1

Living cell is a ...

miniature factory where thousands of reactions occur that convert energy into work

2

Energy

the capacity to do work

3

Some organisms can convert ___ to light

energy to light

i.e. bioluminescent of jellyfish

4

Some organisms can convert light into___

chemical energy

i.e. in plants

5

Organism's metabolism

transforms matter and energy, subject to the laws of thermo, into the ability to perform work

6

Metabolism

the totality of an organism's chemical reactions that arises from interactions between molecules

7

Metabolic Pathway

has multiple steps that begin with a specific molecule and end with a product that is catalyzed by specific enzymes (highly specific)

8

Catabolic Pathways

break down complex molecules into simpler compounds during a process that release energy

i.e. during cellular respiration, glucose i broken down into CO2 and H2O in the presence of O2

9

Anabolic Pathways

build complicated molecules from simpler ones during a process that consumes energy

10

Energy

- the capacity to cause change and exists in various forms some of which can perform work

- can be converted from one form to another

11

Kinetic Energy

the energy associated with motion

12

Potential Energy

stored in the location of matter and includes chemical energy stored in molecular structures, such as glucose

13

Thermodynamics

The study of energy transformations and life is subject to the laws of thermodynamics

14

1st Law of Thermodynamics

states that energy can be transferred and transformed, but energy cannot be created or destroyed

(Conservation of energy)

15

Entropy

- the quantity of disorder or randomness
- the more random a collection of matter, the greater the entropy

16

2nd Law of Thermodynamics

states that every energy transfer or transformation increases the entropy of the universe

17

Order may increase locally; however,

the universe tends towards randomness

in other words, spontaneous changes do not require outside energy to increase the entropy, or the amount of disorder

18

Living systems create ordered structures from...

less ordered starting materials and decrease the entropy of the universe and
use energy to maintain order

i.e. aa are ordered into polypeptide chains which are ordered into proteins which are ordered into organelles, etc.

19

Free energy

the energy that can do work under cellular conditions (constant temp and pressure)

20

Free-Energy Change (∆G)

of a reaction tells us whether the reaction is spontaneous or not

21

Spontaneous Reaction

Spontaneous changes do not require energy which is preferred for cellular reactions
(create energy)

22

∆G equation

∆G = ∆H - T∆S

where H = enthalpy
S = entropy

23

Organisms live at the expense of free energy during a spontaneous change,

free energy decreases and the stability (order) of a system increases

i.e. - ∆G becomes a negative #

24

A system at equilibrium is...

at maximum stability

25

2 classifications of chemical reactions

1) exergonic
2) endergonic
based on their free energy (∆G) state

26

Exergonic reaction

proceeds with a net release of free energy and is a spontaneous reaction (- ∆G)

27

Endergonic reaction

one that absorbs free energy from its surroundings and is non spontaneous
(+ ∆G)

28

Reactions in a closed system

- eventually reach equilibrium
- can perform no work
- is a dead cell

29

Reactions in an open system

Cells tend to maintain a state of disequilibrium, which are capable of constantly exchanging matter with their surroundings

30

Coupling Reactions

ATP powers the coupling of exergonic and endergonic reaction as a way to manage their energy resources to do work

31

3 kinds of work a cell does

1) Mechanical
2) Transport
3) Chemical

32

1) Mechanical

the beating of cilia or contraction of muscles

33

2) Transport

the pumping of substances across membranes

34

3) Chemical

driving endergonic reactions such as the synthesis of polymers from monomers

35

ATP (adenosine triphosphate)

the cell's energy shuttle and provides energy for cellular functions

36

Energy released from ATP

when the terminal phosphate bond is broken by hydrolysis and favorable products are produced

releases 7.3kcal of energy/mole of ATP with a (- ∆G)

37

ATP hydrolysis can be

coupled to other reactions to make the overall runs favorable of the cell

i.e. glutamic acid + ammonia => glutamine (G: +3.4kcal/mol) with
ATP + H2O => ADP + P ( G: -7.3kcal/mol)
= total G -3.9kcal/mol

38

ATP drives endergonic reactions by

phosphorylation: transferring a phosphate to other molecules creating a more reactive (less stable) than the original unphosphorylated molecule

39

The hydrolysis of ATP powers three types of

cellular work
1) Mechanical: place P on protein=> activate (i.e. myosin); ATP phosphorylates motor proteins
2) Transport: active transport; ATP phosphorylates transport proteins
3) Chemical: coupling or adding P on substrates; ATP phosphorylates key reactants

40

ATP is a renewable resource that

can be regenerated by the addition of a phosphate group to ADP
- the energy to phosphorylate ADP comes from various catabolic pathways that drive the regeneration of ATP from ADP and phosphate

41

Enzymes

- speed up metabolic reactions to make them biologically relevant by lowering energy barriers

- a catalytic protein capable of speeding up reaction rates by lowering energy barriers (make reactions go faster)

42

Catalyst

a chemical agent that speeds up a reaction without being consumed by the reaction

43

Enzymes regulate

reactions in metabolic pathways by bond breaking and forming
"reorganization"

44

Enzymes within a cell may be groups into

complexes, incorporated into membranes, or contained inside organelles (i.e. the mitochondria)

45

Ribosome

is an enzyme made up of protein and RNA

46

Every chemical reaction between molecules involves both

bond breaking and bond forming and enzymes help break and reform chemical bonds

47

Sucrase

an enzyme that catalyzes the hydrolysis of sucrose is a chemical reaction involving the breaking of the bond between glucose and fructose and the formation of new bonds with hydrogen and hydroxyl ions with water

48

Activation Energy (Ea)

the initial amount of energy needed to start a chemical reaction
- the energy to push the reactants over the energy barrier

49

At the summit of the reaction, the molecules are in an unstable condition known as

transition state

50

Enzyme and activation energy

an enzyme will catalyze/speed up reactions by lowering Ea barrier but not the ∆G

51

Energy profile or "reaction coordinate" for an exergonic reaction

releases energy into its surrounding

52

Enzymes accelerate

reactions and lower their Ea by providing an environment for the chemical reaction to proceed

53

Substrate

the reactant or molecule an enzyme acts on

54

Enzyme binds to substrate

forming an enzyme-substrate complex during which the catalytic action of the enzyme converts the substrate to the product or products

- binds at the active site which is a specific region on the enzyme where the substate binds

55

Induced fit of a substrate

brings chemical groups of the active site into positions that enhance or tighten their ability to catalyze the chemical reaction wth their substrates

56

Active Site can lower Ea barrier by

1) orienting substrates correctly,
2) straining substrate bonds,
3) providing a favorable microenvironment
4) covalently bonding to the substrate

57

the activity of an enzyme is affected by general environment factors

temperature and pH

58

Each enzyme has an optimal temperature and pH in which it can function

i.e. Taq (temperature)
Trypsin (pH 8 , intestinal pH)

59

Cofactors

nonprotein enzyme helpers (inorganic)

60

Coenzymes

organic cofactors for enzymes

61

Competitive inhibitors

bind tot eh active site of an enzyme competing with the substrate

62

Noncompetitive inhibitor

bind to another part of an enzyme, changing the function

63

Metabolic pathways

must be tightly regulated and enzyme activity is essential to control cellular metabolism

64

Allosteric regulation

a protein's function at one site is affected by binding of a regulatory molecule at another site

65

Many enzymes are allosterically regulated

to become more stable (active) or inhibited (stop/block) depending on the needs of the cell

66

Allosteric enzymes

change shape when regulatory molecules bind to specific sites, affecting function

67

Cooperativity

a form of allosteric regulation that can amplify enzyme activity
- enzymes with multiple cattail units can become stabilized upon substrate binding which factors additional substrate binding and activity

i.e. oxygen binding and transport protein hemoglobin

68

Feedback inhibition

- the end product of metabolic pathway feeds bask upon itself and shuts down the pathway
- prevents a cell from wasting chemical energy

i.e. Isoleucine will feedback and inhibit threonine deaminase