Download l] energy

DIFFUSION, MEMBRANES, AND METABOLISM
What Is a Concentration Gradient?
What Determines Diffusion Rates?
Membrane Crossing Mechanisms
rmrl Your Liver
INPUTS AND OUTPUTS OF ENERGY
The
Flow of Energy
and Down the Energy Hills
ATP~The Cell's Energy Currency
INPUTS AND OUTPUTS OF SUBSTANCES
The Nature of Metabolic Reactions
Redox Reactions
of Metabolic
HOW ENZYMES MAKE SUBSTANCES REACT
ENZYMES DON'T WORK IN A VACUUM
Effects of
and
HOW THE MEMBRANE TRANSPORTERS WORK
Passive Transport
Active Transport
WHICH WAY WILL WATER MOVE?
Movement of Water
Effects of Tonicity
Effects of Fluid Pressure
MEMBRANE TRAFFIC TO AND FROM THE CELL
SURFACE
Endocytosis and Exocytosis
Membrane
[pp.72-73]
[pp.7 Ll-75]
[pp.76-77]
For additional practice, use the interactive vocabulary exercises linked with your BiologyNow CD-ROM.
Selected Words: "alcohol" [p.n], alcoholic hepatitis [p.72], alcoholic cirrhosis [p.72], binge drinking [p.73],
"entropy" [p.74], el1dergonic [p.74], "energy hill" [p.75], exergol1ic [p.75], coupling [p.75], reactants [p.76],
intermediates [p.76], products [p.76], energy carriers [p.76], enzymes [p.76], cofactors [p.76], transport proteins
[p.76], "redox" reactions [p.76], biosynthetic [p.77], degradative [p.77]
Boldfaced
[p.73] metabolism _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _~
L
[p.7 l] energy
==========--_________________===========
How Cells Work
55
[p.74] first law of thermodynamics _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
[p.74] second law of thermodynamics _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
[p.75] ATP _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
[p.75] phosphorylations
[p.75] ATP / ADP cycle _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
[p.76] catalysts
[p.76] chemical equilibriulTt _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
[p.76] oxidation-reduction reactions _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
[p.T7] electron transfer chains
[p.77] metabolic pathways
Match each of the following terms with its definition. [All are from pp.72-73.]
1. alcoholic hepatitis
2. catalase
3. alcoholic cirrhosis
4. binge drinking
5. acetaldehyde
6. metabolism
a. The cell's capacity to acquire energy and use it in
controlled ways
b. A breakdown product of alcohol that is toxic to cells
c. A disease characterized by inflammation of the liver
d. The consumption of large amounts of alcohol in short
periods
e. The liver enzyme that assists in the breakdown of
alcohol
f. The permanent scarring of the liver due to alcohol abuse
If the statement is true, write a "T" in the blank. If the statement is false, correct it by crossing out the
underlilted word(s) and writing the correct word(s) in the answer blank. [p.74]
_____ 7. The first law of thermodynamics states that entropy is constantly increasing in the universe.
_____ 8. The conversion of energy from one form to another is always 100 percent efficient.
_____ 9. Energy may be converted between forms.
10. The entropy of the universe is decreasing.
56 Chapter Five
In the blank preceding each item, indicate which law of thermodynamics applies [p.74]
a. first law of thermodynamics
b. second law of thermodyn.anLics
_____ 11. Corn plants producing starch molecules
_____ 12. Oak logs burning in a fireplace
_____ 13. The death and decay of an organism
_____ 14. The use of energy to power muscle movement
Indicate whether each of the following is an example of an [pp.74-75]
a. endergonic reaction
b. exergonic reaction
_____ 15. The release of energy from chemical bonds
_____ 16. The process of photosynthesis
_______. 17. The storage of energy in chemical bonds
18. The process of aerobic respiration
All cells stay alive by (19)
[p.75] energy inputs to energy outputs, mainly with adenosine
triphosphate, or (20)
(21)
[p.75]. This nucleotide consists of the
[p.75], the base (22)
groups. ATP readily gives up a (24)
sugar
[p.75], and three (23)
[p.75]
[p.75] group to other molecules and primes them to
react. These transfers are known as (25)
ATP is the (26)
five~carbon
[p.75].
[p.75] in a cell's economy. Cells earn it by investing in (27)
_ _ _ _ _ _ [p.75] reactions. They spend it in (28)
energy~
energy~
[p.75] reactions that keep
them. alive,
When ATP gives up a phosphate, (29)
inorganic (30)
is called the (31)
[p.75] forms. ATP can form when ADP binds to
[p.75] or to a phosphate group that was split from a different molecule. This
[p.75] cycle.
Match each of the following terms with its definition. [All are from p.76.]
_ _ _ _ 32. products
_ _ _ _ 33. metabolic pathways
_ _ _ 34. enzymes
- _ _ _ 35. cofactors
36. chemical equilibrium
_ _ _ 37. transport proteins
_
38. reactants
_
39. intermediates
a.
b.
c.
d.
e.
The starting substances of a chemical reaction
The end products of a chemical reaction
Enzyme assistants
An ordered, enzyme~assisted series of reactions
Exists when the forward and reverse rates of a
chemical reaction are equal
f. Substances that are formed during a chemical
reaction
g. Catalysts that speed up the rate of a chemical
reaction
h. Move solutes across membranes
How Cells Work 57
For each of the following, choose whether the statement refers to a or b. [p.77]
a. degmdative pathway
b. biosynthetic pathway
_ _ _ _ 40. Anabolic reactions
_ _ _ _ 41. The process of aerobic respiration
_ _ _ _ 42. Catabolic reactions
_ _ _ _ 43. The process of photosynthesis
_ _ _ _ 44. Requires an input of energy
_ _ _ _ 4S. Results in a release of energy
Fill in the Blanks
Individual cells capture free (46) _ _ _ _ _ _ [p.76], store it, and then release it in manageable bits.
They (47)
[p.76] the energy they require to maintain themselves, grow, and
(48)
[p.77]. Cells release energy efficiently by electron transfers, or (49) _ _ _ _ __
[p.76]. In these reactions, one molecule gives up electrons, or is (SO)
[p.76], and another
gains them, or is (Sl) _ _ _ _ _ _ [p.76]. Corrunonly, (52) _ _ _ _ _ _ [p.76] atoms are released at
the same time.
Start thinking about redox reactions because they are central to photosynthesis and aerobic respiration.
In the next two chapters, you'll see how (S3) _ _ _ _ _ _ [p.77] pick up electrons and H+ stripped fronl.
substrates and deliver them to (54)
[p.77]. Such chains are membrane-bound arrays of
(S5) _ _ _ _ _ _ [p.77] and other molecules that accept and give up electrons in sequence. Electrons are
at a (S6)
[p.77] energy level when they enter a chain then when they leave.
[pp.78-79]
[pp.80-81]
Terms: functional group tmnsfers [p.78], electron transfers [p.79], rearml1gements [p.79], condensation
[p.79], cleavage [p.79], "binding energy" [p.79],free radicals [p.80], allosteric [p.80]
Boldfaced Terms
[p.78] activation energy _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
[p.78] substrates _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
58
Chapter Five
[r.7S] active sites
[r.79] transition state _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
[r.79] induced-fit model _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
[r.SO] coenzymes
[r.SO] antioxidants _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
[r.SO] feedback inhibition _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
In the diagram
choose the correct term for each label. [p.78]
1.
2.
lJ,
3.
!:i.
a. Total energy released by the reaction
b. Activation energy with enzyme activity
c.
level of the starting substance
Activation energy without enzyme
level of the product
5
forward reaction _ _
:2
~----~---~------
How Cells Work
59
Each of the terms listed or described in the following table represents a type of
Complete the table by supplying each missing term or description. [pp.78-79]
enzyme~mediated
reaction.
DescriptioJ1
Terlll
A larger molecule splits into smaller ones.
6.
7. functional group transfers
One or more electrons are stripped from one molecule
and donated to another.
8.
9. rearrangements
10. condensation
Match each of the following terms with its definition. [pp.78-79]
11. induced-fit model
12. active site
13. activation energy
ILl binding energy
15. substrates
16. transition state
a.
b.
c.
d.
The site where the specific reactions of an enzyme occur
The reactants of a chemical reaction
The nriI)imum energy required to get a reaction going
The point at which the bonds in the substrate are at their
breaking point
e. Interactions between the substrate and the enzynce that
change the shape of the enzyme
f. The energy that stabilizes the transition state
Four mechanisms work alone or in combination to get substrates to the transition state. First, subsh'ate
molecules rarely react at (17)
substrate (18)
[p.79] concentrations. Binding at an active site boosts local
[p.79l by as much as ten millionfold. Second, on their own, substrates collide
from random directions. By contrast, weak but extensive bonds at a(n) (19) _"__"_""_ _ _ [p.79] put reactive groups close together.
Third, because of its ability to form (20)
[p.79l bonds so easily, water can interfere with
the breaking and formation of bonds during reactions. Some (21)
[p.79] are populated by
(22) _ _ _ _ _ _ [p.79] amino acid residues. The (23) _______ [p.79] groups keep water away
from the active site and reactions. Fourth, weak interactions between the enzyme and its
(24) _ _ _ _ _ _ [p.79] may induce the enzyme to change its shape. By the (25) _________ [p.79l, a
substrate is not quite complementary to an active site. The enzyme bends and optimizes the fit; in doing so,
it pulls the substrate to the (26) _ _ _ _ _ _ [p.79] state.
60
Chapter Five
Match each of the following definitions with the correct term. Some answers may be used more than once.
[p.80]
_____ 27. Assists in the neutralization of free radicals
a.
b.
c.
d.
_ _ _ _ 28. When the final product of the pathway has the ability
to shut down the pathway
feedback inhibition
allosteric
coenzymes
antioxidants
_____ 29. Organic cofactors
_ _ _ _ 30. All vitamins belong to this group
_____ 31. A regulatory site on an enzyme that is used in
feedback inhibition
(32)
[p.81] is the measure of molecular lTlOtion. As it rises, it boosts (33) _ _ _ _ __
[p.81] both by increasing the likelihood that a substrate will bump into an enzyme and by raising a
(34)
[p.81] molecule's internal energy. Above or below the range of temperature that an
enzyme can (35)
(37)
[p.81], weak bonds break and enzyme (36)
[p.81] can no longer bind to the (38)
[p.81] changes.
[p.81], and reaction rates fall
sharply.
In the human body, m.ost enzymes work best when the pH is between (39)
and
_ _ _ _ _ [p.81]. Most enzymes don't work well when the fluids in which they are dissolved
are (flO)
(L11)
[p.81] or less salty than their range of tolerance. Too rnuch or too little
[p.81] interferes with the (42)
_ _ _ _ _,_ [p.81] bonds that help hold an enzyn,e
in its three-dimensional shape.
[pp.82-83]
[pp.84-85]
gradient [p.82], passive tral1sport [p.83], "facilitated" diffusion [pp.83-84], active transport
[p.83], exocytosis [p.83], endocytosis [p.83], net direction of movement [p.84]
Boldfaced
[p.82) selective permeability _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
[p.82] concentration gradient _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
[p.82) diffusion _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
[p.83] electric gradient _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
How Cells Work
61