test 2 Flashcards
1
Q
What is selective permeability?
A
it allows some substances to cross it more easily than others
2
Q
what is the plasma membrane?
A
is the boundary that separates the living cells from its surroundings
3
Q
What does amiphipathic mean?
A
contains both hydrophobic and hydrophilic regions
4
Q
are phospholipids amphipathic?
A
ye
5
Q
what is a fluid mosaic model?
A
a membrane is a fluid structure with a “mosaic” of various proteins embedded in it.
6
Q
what affects the fluidity of membranes?
A
cholesterol and the fatty acid makeup
7
Q
what are peripheral proteins?
A
they are bound to the surface of the membrane
8
Q
What are integral proteins?
A
they penetrate the hydrophobic core
9
Q
what are transmembrane proteins?
A
they are integral proteins that span the membrane
10
Q
What makes up the hydrophobic regions of an integral protein?
A
one or more stretches of nonpolar amino acids, often coiled into alpha helices
11
Q
what are the 6 major functions of membrane proteins?
A
transport, enzymatic activity, signal transduction-relaying signals, cell-cell recognition, intercelluar joining, and attachment to the cytoskeleton and extracellular matrix
12
Q
____ ______ molecules like hydrocarbons can dissolve in the lipid bilayer and pass through the membrane rapidly without involvement of proteins
A
small hydrophobic
13
Q
What type of molecules go through transport proteins?
A
hydrophilic molecules including small ions and polar molecules
14
Q
passive transport= _____, and goes tom ____ to _____ concentration.
A
diffusion, high to low
15
Q
what goes through passive transport?
A
small hydrophobic molecules
16
Q
What is facilitated diffusion?
A
transport proteins are used to transport ions, water, small hydrophilic molecules
17
Q
what is active transport?
A
it takes energy and is not based on diffusion, it goes against concentration gradient
18
Q
what is diffusion?
A
the tendency for molecules to spread out evenly into the availible space
19
Q
what happens during dynamic equilibrium?
A
equal amount of molecules crossing over
20
Q
what is osmosis?
A
the diffusion of water across a selectively permeable membrane, low to high
21
Q
What is the ability of a surrounding solution to cause a cell to gain or lose water
A
tonicity
22
Q
what is a solute concentration that is the same as that inside the cell; no net water movement across the plasma membrane
A
isotonic solution
23
Q
what is the type of solution where the solute concentration is greater than that inside the cell; cell loses water
A
hypertonic solution
24
Q
what is the type of solution where the solute concentration is less than that inside the cell; cell gains water
A
hypotonic solution
25
what is the control of solute concentrations and water balance and is a necessary adaption for life in such enviroments?
osmoregulation
26
What proteins provide corridors that allow a specific molecule or ion to cross the membrane and does not undergo any change when transporting?
channel proteins
27
what facilitates the diffusion of water?
aquaporins
28
what facilitates the diffusion of ions?
ion channels
29
what ion channels open or close in response to a stimulus?
gated channels
30
which proteins undergo a subtle change in shape that translocates the solute-binding site across the membrane?
carrier proteins
31
facilitated diffusion is ____ transport
passive
32
what is active transport?
moves substances against their concentration gradients; requires energy usually in the form of ATP
33
review the sodium potassium pump rn bitch
ok
34
what is the voltage difference across a membrane
membrane potential
35
what causes voltage?
differences in the distribution of positive and negative ions across a membrane
36
what drive the diffusion of ions across a membrane?
electrochemical gradient
37
what are the two combined forced in the electrochemical gradient?
chemical (ion's concentration gradient) and electrical (the effect of the membrane potential on the ion's movement)
38
what is an electrogenic pump?
a transport protein that generates voltage across a membrane
39
what is a proton ppump?
the main electrogenic pump of plants, fungi, and bacteria
40
what is the major electrogenic pump for animal cells?
sodium-potassium pump
41
what is cotransport?
it occurs when active transport of a solute indirectly drives transport of other substances
42
what is exocytosis?
where transport vesicles migrate to the membrane, fuse with it, and release their contents outside the cell
43
what is endocytosis?
where the cells takes in macromolecules by forming vesicles from the plasma membrane
44
what are the three types of endocytosis?
phagocytosis, pinocytosis, and receptor-mediated endocytosis
45
what happens in receptor-mediated endocytosis?
binding of ligands to receptor triggers vesicle formation
46
what is any molecule that binds specifically to a receptor site of another molecule?
ligand
47
what is metabolism?
the totality of an organisms's chemical reactions and the sum of its anabolic and catabolic reactions
48
What is a anabolic reaction?
complex molecules are made from simple molecules; energy input is required
49
what is a catabolic reaction?
complex molecules are broken down to simpler ones and energy is released
50
what are catabolic pathways?
they release energy by breaking down complex molecules into simpler compounds
51
what is cellular respiration?
the breakdown of glucose in the presence of oxygen; an example of a pathway of catabolism
52
what are anabolic pathways?
they consume energy to build complex molecules from simpler ones; an example would be the synthesis of a protein from amino acids
53
what is energy?
the capacity to cause change
54
what is kinetic energy?
energy associated with motion
55
what is potential energy
the energy that matter possesses because of its location or structure
56
what is heat (thermal) energy?
the kinetic energy associated with random movement of atoms or molecules
57
what is chemical energy?
the potential energy stored in chemical bonds available for release in a chemical reactions
58
what is thermodynamics?
the study of energy transformations
59
an ____ system, like liquid in a thermos, is unable to exchange energy or matter with its surroundings.
isolated
60
in an ____ system, energy and matter can be transferred between the system and its surroundings.
open; some examples are organisms and cells
61
what is the 1st law of thermodynamics?
energy can be transferred and transformed but it cannot be created nor destroyed; the energy of the universe is constant
62
are energy transformations 100% efficient?
naw son
63
what is the second law of thermodynamics?
every spontaneous energy transfer or transformation increases the entropy (disorder) of the universe
64
what are spontatneous processes?
they occur without energy input; they can happen quickly or slowly
65
when a process occurs without energy input then it must _____ the entropy of the universe
increase
66
what is the energy that is available to do work called?
free energy or gibbs free energy
67
what's the equation of free energy?
delta g= g of products - g of reactants
68
when is delta g positive?
when the products are greater; free energy is consumed
69
when is delta g negative?
when the reactants are greater; free energy is released
70
what is the other equation of free energy?
delta g= delta H-temp(delta s)
h=enthalpy, s=entropy
71
processes with a ____ delta g are spontaneous
negative
72
what is an exergonic reaction?
proceeds with a net release of free energy and is spontaneous
73
what is an endergonic reaction?
it absorbs free energy from its surroundings and is non spontaneous
74
what are the three main kinds of work by a cell?
chemical, transport, and mechanical
75
what is energy coupling?
the use of an exergonic process to drive an endergonic one; mediated by atp
76
what is atp?
the cell's energy shuttle, composed of a ribose, adenine, and three phosphate groups
77
how is energy released from atp?
when the terminal phosphate bond is broken by hydrolysis. the energy comes from the chemical change to a state of lower free energy
78
the three types of celluar work (transport, chemical, and mechanical) are powered by ________.
the hydrolysis of atp
79
how does atp drive endergonic reactions?
by phosphorylation, transferring a phosphate group to some other molecule. the recipient molecule is called phosphorylated intermediate
80
atp hydrolysis leads to a change in ______
protein shape and binding ability
81
what does atp do in trnasport work?
atp phosphorylates transport proteins
82
whart does atp do in mechanical work?
atp binds noncovalently to motor proteins and then is hydrolyzed
83
what is a catalyst?
a chemical agent that speeds up a reaction without being consumed by the reaction
84
what is an enzyme?
a catalytic protein in cells
85
what is the initial energy needed to start a chemical reaction?
energy of activation or activation energy
86
how do enzymes work?
they catalyze reactions by lowering the activation energy
87
in both endergonic and exergonic reactions, ____ are needed to lower the energy of activation
enzymes
88
do enzymes change free energy?
no!
89
are enzymes substitutes for atp coupling?
hell no!
90
what is a substrate?
the reactant that an enzyme acts on
91
what forms when an enzyme binds to its substrate?
enzyme-substrate complex
92
what is the region on the enzyme where the substrate binds?
active site
93
what is induced fit?
brings chemical group of the active site into positions that enhance their ability to catalyze the reaction
94
how can the active site lower an activation energy barrier?
orienting substrates correctly, straining substrate bonds, providing a favorable microenviroment, covalently but transiently bonding to the substrate
95
what factors can affect an enzymes activity?
environmental factors like temperature and pH
96
what are cofactors?
nonprotein enzyme helpers
97
what is an organic cofactor called?
coenzyme, include vitamins
98
what are competitive inhibitors?
they bind to the active site of an enzyme, competing with the substrate
99
what are non competitive inhibitors?
they bind to another part of an enzyme, causing the enzyme to change shape and making the active site less effective
100
what would happen if a cell's metabolic pathways were not tightly regulated?
chemical chaos
101
what is allosteric regulation?
may either inhibit or stimulate an enzymes activity
102
when does allosteric regulation occur
when a regulatory molecule binds to a protein at one site and affects the protein's function at another site
103
what are aollsterically regulated enzymes are of?
polypeptide subunits
104
what is feedback inhibition?
the end product of a metabolic pathway shuts down the pathway; prevents a cell from wasting chemical resources by synthesizing more product than needed
105
what is localization?
structures within the cell help bring order to metabolic pathways, some enzymes act as structural components of membranes
106
the breakdown of organic molecules and catabolic pathways are generally ____
exergonic
107
what is aerobic respiration?
consumes organic molecules and oxygen and yields ATP
108
what respiration consumes compounds other than fermentation is in oxygen
anaerobic
109
what is fermentation?
a partial degradation of sugars that occurs as part of aerobic respiration in absence of available oxygen
110
how do catabolic pathways release stored energy?
by breaking down complex molecules (oxidizing organic fuels)
111
the transfer of _____ during chemical reactions releases energy stored in organic molecule?
electrons
112
what are chemical reactions that transfer electrons between reactants?
redox reactions
113
what happens in oxidation?
a substance loses electrons,
114
what happens in reduction?
a substance gains electrons,
115
what is the electron donor called?
reducing agent
116
what is the electron acceptor called?
oxidizing agent
117
what are the 3 stages of cellular respiration?
glycolysis, pyruvate oxidation and citric acid cycle, and oxidative phosphorylation
118
what is glycolysis?
breaks down glucose into 2 molecules of pyruvate in the cytoplasm
119
what is pyruvate oxidation and citric cycle?
completes the breakdown of glucose in the mitochondrial matrix
120
what is oxidative phosphorylation?
accounts for most of the atp synthesis on the mitochondrial cristae
121
oxidative phosphorylation is powered by _____ reactions and account or ~___% of the ATP generated
redox; 90
122
glycolysis occurs in 2 major phases
energy investment and energy payoff
123
look at the energy investment and payoff diagram
okie dokie yo
