biology EXAM #3 pt.2 Flashcards

1
Q

The living cell is a

Cellular respiration extracts

Cells apply this energy to

Some organisms even convert

A

miniature chemical factory where thousands of reactions occur

energy stored in sugars and other fuels

perform work

energy to light, as in bioluminescence

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2
Q

An organism’s metabolism transforms ¡

Metabolism
Is the totality of an

Arises from

A

matter and energy, subject to the laws of thermodynamics

organism’s chemical reactions

interactions between molecules

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3
Q

A metabolic pathway has many steps

That begin with a ___________ and end with a ________

That are each catalyzed by a

A

specific molecule; product

specific enzyme

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4
Q

Change of free energy ΔG => free energy indicates

-ΔG then = ___________ reaction
+ ΔG then = __________ reaction

A

the portion of the system’s energy that can perform work when To and pressure are uniform throughout the system.

exergonic
endergonic

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5
Q

Catabolic pathways:

-Break down

-Release

  • example of a pathway of catabolism?
A

complex molecules into simpler compounds

energy

Cellular respiration

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6
Q

Anabolic pathways:

consume energy to

For example, the synthesis of

Bioenergetics is the study of

A

build complex molecules from simpler ones

protein from amino acids is an anabolic pathway

how energy flows through living organisms

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7
Q

Energy:
Is the

Exists in various forms, of which some can perform work
Kinetic energy is _____ energy: is the energy associated with ________

Potential energy is _______ energy: is stored in the…
Includes energy stored in

A

-capacity to cause change

-solar energy; associated with motion

-chemical energy, food: location of matter
molecular structure

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8
Q

Thermodynamics:
Is the study of

According to the first law of thermodynamics – the principle of

Energy can be
Energy cannot be

*hacer flashcards de los law of thermodynamics

A

energy transformations

conservation

-transferred and transformed
-created or destroyed

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9
Q

According to the second law of thermodynamics – every…

Spontaneous changes that do not require outside energy increase

There is loss of usable energy in the form of ____

A

energy transfer or transformation increases the entropy of the universe

the entropy, or disorder, of the universe.

heat

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10
Q

Living cells unavoidably convert

Spontaneous processes occur without ____ _____; they can happen :

For a process to occur spontaneously, it must:

Processes that decrease entropy are _____________; they will occur only if :

A

organized 
forms of energy to heat, a more disordered form of energy

energy input; they can happen quickly or slowly

increase the entropy of the universe

nonspontaneous; they will occur only if energy is provided

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11
Q

Organisms create ordered structures from

Organisms also replace…with…

For example, animals consume complex molecules in their food and release smaller, lower energy molecules and heat into the surroundings

A

less organized forms of energy and matter

ordered forms of matter and energy in their surroundings with less ordered forms

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12
Q

Living systems: increase the…

Use energy to :

ATP- energy for … (meaning of the abvr)
Generated from:

ATP structure:
“_____ ______” compound because :
Releases:

A

entropy of the universe

maintain order

cells; Adenosine triphosphate; ADP + P

Modified adenine, ribose, 
and 3 phosphates
“high energy” compound because 
the terminal phosphate group is 
easily removed

7.3 kcal per mole

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13
Q

Advantages of ATP as energy carrier:

Provides a

Breakdown of ATP to ADP+P releases

ATP breakdown is coupled to

A

-common energy currency for many reactions

-sufficient energy for biological processes- little wasted

-endergonic reactions in such a way that it minimizes energy loss

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14
Q

The free-energy change of a reaction tells us whether

A living system’s free energy is energy that

The change in free energy, ∆G during a biological process is related directly to the

A

the reaction occurs spontaneously

can do work under cellular conditions, when temperature and pressure are uniform, as in a living cell

system’s enthalpy change or total energy (∆H) and the change in system’s entropy (∆S)

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15
Q

ΔG is negative for all ___________ ___________; processes with zero or positive ΔG are never __________

A

spontaneous processes; spontaneous

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16
Q

Spontaneous processes can be harnessed to

Organisms live at the expense of

During a spontaneous change free energy …

A

perform work

free energy

decreases and the stability of a system increases

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17
Q

Free energy is a measure of

During a spontaneous change, free energy

Equilibrium is a

A process is spontaneous and can perform work only when

A

a system’s instability, its tendency to change to a more stable state

decreases and the stability of a system increases

state of maximum stability

it is moving toward equilibrium

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18
Q

Reactions in a closed system eventually reach

The concept of free energy can be applied to

A

equilibrium which is considered maximum stability and can then do no work

the chemistry of life’s processes

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19
Q

Cells are not in __________; they are:

A defining feature of life is that

A catabolic pathway in a cell releases

A

equilibrium; they are open systems experiencing a constant flow of materials

metabolism is never at equilibrium

free energy in a series of reactions

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20
Q

An exergonic reaction :

An endergonic reaction is one that :

A

net release of free energy and is spontaneous

absorbs free energy from its surroundings and is nonspontaneous

21
Q

Cells in our body experience a constant flow of….., preventing :

A

flow of materials in and out, preventing metabolic pathways from reaching equilibrium

22
Q

ATP powers

A cell does three main kinds of work:

A

cellular work by coupling exergonic reactions to endergonic reactions

Mechanical —such as contraction of muscle cells
Chemical —pushing endergonic reactions
Transport —pumping substances against the direction of spontaneous movement

23
Q

To do work, cells manage energy resources by

ATP drives _________ reactions by ____________, which is:

The recipient molecule is now called a

Most energy coupling in cells is mediated by

A

by energy coupling, the use of an exergonic rxn to drive an endergonic rxn

endergonic reactions by phosphorylation, which is transferring a phosphate to other molecules

phosphorylated intermediate

ATP

24
Q

The three types of cellular work are powered by:

In the cell, the energy from the exergonic reaction of

Overall, the coupled reactions are

A

the hydrolysis of ATP

ATP hydrolysis can be used to drive an endergonic reaction

exergonic

25
Q

ATP is a renewable resource that is

The energy to phosphorylate ADP comes from

The ATP cycle is a revolving door through which energy

Catabolic pathways drive the :

A

renewable resource that is regenerated by addition of a phosphate group to adenosine diphosphate (ADP)

catabolic reactions in the cell

passes during its transfer from catabolic to anabolic pathways

regeneration of ATP from ADP and phosphate

26
Q

A catalyst is a

An enzyme is a

Enzymes do not affect the change in ___________; instead, they:

A

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

catalytic protein that speed up metabolic reactions by lowering energy barriers without being consumed by the reaction

free energy (ΔG); instead, they hasten reactions that would occur eventually

27
Q

Induced fit of a substrate
The active site is the region on the enzyme where

Brings chemical groups of the active site into __________ that :

A

the substrate binds

positions that enhance their ability to catalyze the chemical reaction

28
Q

Every chemical reaction between molecules involves:

An example of a chemical reaction is the

A

both bond breaking and bond forming

hydrolysis of sucrose

29
Q

The activation energy
Is the:

Is often supplied

An enzyme catalyzes reactions by

A

initial amount of energy needed to start a chemical reaction

in the form of thermal energy or heat that the reactant molecule absorbs from the surroundings in a system

lowering the EA barrier

30
Q

The enzyme binds to __ ________, forming an ____________

The active site can lower an EA barrier by:

(4)

A

binds to its substrate, forming an enzyme-substrate complex

1)Orienting substrates correctly
2)Straining substrate bonds
3)Providing a favorable microenvironment
4)Covalently bonding to the substrate

31
Q

In an enzymatic reaction, the substrate binds to the

Enzymes are extremely

Very small amounts of enzyme can have

A

active site of the enzyme

fast acting and emerge from reactions in their original form

huge metabolic effects because they are used repeatedly in catalytic cycles

32
Q

The catalytic cycle of an enzyme

A

1) Substrates enter active site; enzyme
changes shape so its active site
embraces the substrates (induced fit).

2) Substrates held in
active site by weak
interactions, such as
hydrogen bonds and
ionic bonds.

3) Active site (and R groups of
its amino acids) can lower EA
and speed up a reaction

4) Substrates are
Converted into
Products.

5) Products are
Released.

6) Active site
Is available for
two new substrate
Mole.

33
Q

The activity of an enzyme is affected by

Each enzyme has an

Has an optimal ____ in which it can function

A

general environmental factors

optimal temperature in which it can function

pH

34
Q

Cofactors - molecule which
-Are…
-_____ such as zinc, iron and copper in ionic and vitamins

Organic nonprotein cofactors are called

A

helps enzyme function
-nonprotein enzyme helpers
-Inorganic

coenzymes

35
Q

Factors affecting enzymatic rate
Enzyme inhibition occurs when:

Activity of cell enzymes is regulated by

Ex: when product is abundant it binds to the enzyme’s active site and blocks further production
When product is used up, it is removed from the active site

In a more complex type of inhibition,

A

enzyme cannot bind its substrate

feedback inhibition

product binds to a site other than the active site, which changes the shape of the active site

36
Q

Competitive inhibitors bind to the

Noncompetitive inhibitors bind to…., causing:

Some examples of inhibitors are:

A

active site
 of an enzyme, competing with the substrate

another part of an enzyme, causing the enzyme to change shape and making the active site less effective

toxins, poisons, pesticides, and antibiotics

37
Q

Competitive inhibitors like:

Bind to the

A

morphine

active site of an enzyme, competing with the substrate

38
Q

Noncompetitive inhibitors bind to

A noncompetitive inhibitor binds to the
enzyme __________________, altering
the….. so that:

A

another part of an enzyme, changing the function

away from the active site; altering
the conformation of the enzyme so that its
active site no longer functions.

39
Q

Inhibitors act as

DDT, parathion, nerve gas – inhibitors of enzymes of the nervous system

Antibiotics – inhibit specific enzyme´s active site that produce cell walls of bacteria.

A

regulators of enzyme activity

40
Q

Enzymes are

Changes (mutations) in genes lead to

Altered amino acids, particularly at the active site, can result in

A

proteins encoded by genes

changes 
in amino acid composition of an enzyme

novel enzyme activity or altered substrate specificity

41
Q

Under environmental conditions where the new function is beneficial, natural selection would favor the mutated allele

For example, repeated mutation and selection on the β-galactosidase enzyme in E. coli resulted in a change of sugar substrate under lab conditions

A
42
Q

Regulation of enzyme activity helps

A cell’s metabolic pathways must be ________, for example with:

A

control metabolism

tightly regulated, allosteric regulation and feedback mechanisms

43
Q

Allosteric regulation is the term used to describe

Many enzymes are

A

any case in which a protein’s function at one site is affected by binding of a regulatory molecule at another site

allosterically regulated

44
Q

Most allosterically regulated enzymes are made from

The enzyme complex has

The binding of an activator stabilizes the

The binding of an inhibitor stabilizes the

They change shape when

A

polypeptide subunits, each with its own active site

active and inactive forms

active form of the enzyme

inactive form of the enzyme

regulatory molecules bind to specific sites, affecting function

45
Q

Cooperativity is a form of

One substrate molecule primes

Cooperativity is allosteric because

A

allosteric regulation that can amplify enzyme activity

an enzyme to act on additional substrate molecules more readily

binding by a substrate to one active site affects catalysis in a different active site

46
Q

In feedback inhibition
:

The end product of a metabolic pathway:

Feedback inhibition prevents

A

shuts down the pathway

a cell from wasting chemical resources by synthesizing more product than is needed

47
Q

Within the cell, enzymes may be: (3)

A

Grouped into complexes
Incorporated into membranes
Contained inside organelles

48
Q

Enthalpy =

A

(the sum of the internal energy E) + ( pressure p x volume V). Using the symbol H for the enthalpy:

H = E + p * V