Cell Bio Test 1 Flashcards
(132 cards)
1
Q
What are the 6 different kinds of work that cells need energy for?
A
- synthetic work
- mechanical work
- concentration work
- electrical work
- generation of heat
- generation of light
2
Q
All living system require an ongoing supply of ________.
A
energy
3
Q
Energy is the capacity to:
A
Cause specific chemical or physical changes
4
Q
The 4 essential needs of every cell are:
A
- molecular building blocks
- chemical analysts (enzymes)
- information to guide activities
- energy to drive reactions and processes essential to life.
5
Q
Synthetic Work is the changes in _________.
A
chemical bonds
6
Q
biosynthesis
A
- synthetic work
- results in the formation of new chemical bonds and new molecules
- required for growth and maintenance.
7
Q
mechanical work
A
-Involves a physical change in the position or orientation of a cell or some part of it.
- requires one or more appendages, such as cilia or flagella.
8
Q
Examples of mechanical work include:
A
- muscle contraction
- chromosomes movement
- cytoplasmic streaming and movement of organelles and vesicles.
9
Q
Concentration work
A
- The accumulation of molecules/substances within a cell or organelle or removes toxic by-products of cellular activity.
- ACTIVE INWARD TRANSPORT OF MOLECULES.
10
Q
Electrical work
A
- ions are transported across the membrane, resulting in differences in both concentration and membrane potential.
11
Q
Producing heat is a major use of energy in all ______.
A
homeotherms
12
Q
bioluminescence is
A
- the production of light
13
Q
bioluminescence is generated by:
A
the reaction of ATP with luminescent compounds.
14
Q
phototrophs
A
-capture life energy from the sun and transform it into chemical energy, stored as ATP.
-use solar energy to produce all the carbon compounds they need from CO2/photosynthesis.
15
Q
chemotrophs obtain energy by:
A
oxidizing chemical bonds in molecules (organic or inorganic).
16
Q
chemoheterotrophs ingest and use:
A
- chemical compounds (carbs, fats, protein) to provide both energy and carbon for cellular needs.
17
Q
oxidation is the _________ of electrons from a substance resulting in a ____________________.
A
- removal
- release of energy
18
Q
reduction is _________ of electrons to a subtance through addition o f hydrogen and requires an ___________________.
A
- addition
- input of energy
19
Q
Glucose Oxidation
A
-AKA cellular respiration
- C6H12O6 + 6O2 -> CO2 + 6H2O + energy
20
Q
Carbon dioxide reduction
A
- AKA photosynthesis
- energy + 6CO2 + 6H2O -> C6H12O6 + 6O2
21
Q
energy flow is governed by:
A
the principles of thermodynamics
22
Q
exchange of energy between a system and it’s surroundings occurs as either ______ or ______.
A
heat or work
23
Q
What is heat vs. work?
A
heat is not a useful energy source while work is the use of energy to drive a process
24
Q
What is the unit for quantifying energy changes?
A
calories
25
The first law of thermodynamics
- AKA law of conservation of energy
- energy cannot be created or destroyed, only converted from one thing to another.
26
The energy under consideration in any particular case is called the _______, while the rest of the universe is called the _______.
- system
- surroundings
27
Open vs. Closed systems
- closed system: sealed from it's environment and can neither take it nor release energy.
- open system: can have energy added to it or removed from it.
28
The total energy stored within a system is called:
internal energy or E
29
Conservation of Energy in Biological Systems
- the energy that leaves a system must equal that which entered it plus the amount remaining (stored) in the system.
30
If the change in heat is negative a reaction is:
(energy released)
exothermic
31
If the change in enthalpy is positive, a reaction is:
(energy absorbed)
endothermic
32
The second law of thermodynamics
- AKA law of thermodynamic spontaneity
- in every physical or chemical change, the universe tends toward greater disorder or randomness (entropy)
- allows us to predict what direction, how much energy released, and how conditions affect a reaction.
33
thermodynamic spontaneity
measure of whether or not a reaction or process can occur.
34
entropy (S)
- measure or randomness or disorder
- increase when a system becomes more random
-decrease when a system becomes more ordered.
35
_________ is more useful than entropy.
free energy (change in G)
36
Every spontaneous reaction is characterized by a (decrease/increase) in free energy of the system.
Decrease
37
Nearly all cellular reactions Involve protein catalysts called ________.
Enzymes
38
Activation Energy (E sub A) definition
The minimum amount of energy required to give rise to product.
39
Membranes define:
The boundaries of a cell and it’s internal components.
40
5 functions of membranes
1. Define boundaries
2. Sites for biological functions
3. Possess transport proteins
4. Receptors to detect external signals
5. Cell-to-cell contact, adhesion, and communication.
41
Membranes are effective permeability barriers because their interior is ___________.
Hydrophobic
42
Plasma membrane
Surrounds the whole cell
43
Intracellular membrane
Compartmentalize functions within the cell.
44
Membrane proteins regulate:
The transport of substance across the membrane.
45
A cell receives information as ____________.
Chemical or electrical signals at its surface
46
Signal transduction
The way in which signals are transmitted from the outer surface to the interior of a cell.
47
Chemical signal molecules bind to ___________ on the outer surface of the plasma membrane.
- membrane proteins AKA receptors
48
Membrane proteins mediate:
Cell adhesion and cell-to-cell communication
49
3 membrane proteins and functions:
- adhesive junctions: holds cells together
- tight junctions: form seals that block the passage if fluids between cells
- gap junctions: allow for communication between adjacent animal cells
-plasmodesmata in plants
50
What is a Fluid Mosaic Model and 2 key features:
-descriptive of all biological membranes
- envisions membrane as two fluid layers of lipids with proteins within an in the layers
Key Features: a fluid lipid bilayer, mosaic of proteins attached or embedded in the bilayer.
51
Membranes are organized into ____________.
Micro domains
52
Membranes are
-not homogenous , freely Mixing structures
- ordered through dynamic micro domains called lipids rafts
53
_________________ are important components of the “fluid” part of the fluid mosaic model.
Membrane lipids
54
3 main classes of membrane lipids:
1. Phospholipids: most abundant in membranes
2. Glycolipids: formed by the addition of carbohydrates to lipids
3. Sterols: most eukaryote membranes contain up to 50%. Main one is animal cells is cholesterol (stabilizes fluidity and maintained membranes.)
55
Fatty acids are components of all membrane lipids except the ________.
Sterols
56
Fatty acids’ long hydrocarbon provide:
A Barrier to diffusion of polar solutes
They range between 12 and 20 Carbons long
57
Membrane asymmetry is establish during:
The synthesis of the membrane
58
Most of the glycolipids in the plasma membrane of animal cells are in the:
Outerlayer
59
Membrane asymmetry is the
- difference between mono layers
-the kind of lipids present and the degree of saturation of fatty acids.
60
(True or False): Once established, membrane asymmetry does not change much.
True
61
(True or False) Lipids are immobile within their mono layer.
False
62
___________ of phospholipids about their axes can occur.
Rotation
63
Phospholipids can move within the monolayer via _________
Lateral diffusion
64
(True or False): Rotation and lateral movement are rapid and random.
True
65
Phospholipids or flippases are:
Proteins that catalyze the flip-flop (transverse diffusion) of membrane lipids
66
Transverse diffusion occurs rarely without
Phospholipid translocaters/ flippases
67
Fluid lipid Bilayer behaves as
a fluid that permits the movement of both lipids and proteins
68
Lipids can move laterally as much as several _________ per ___________ within the monolayer.
Micrometers per seconds
69
Long chain and saturated fatty acids have (higher/lower) Tm values.
Higher
70
Short chain snd unsaturated fatty acids have (higher/lower) Tm values.
Lower
71
Fluidity of a membrane depends mainly on the:
The fatty acids it contains
- length of fatty acid chains
- the degree of saturation
72
What prevents fatty acids with one or more double bonds from lacking together neatly?
Bends in the chains
73
_______ decrease the permeability of membranes to ions and small polar molecules.
Sterols
74
Cholesterol is a:
Fluidity buffer
- sterols function similarly in other organisms
75
Lipid Microdomains/Lipid rafts are:
- localized regions of membrane lipids in association with specific proteins
- dynamic structures that change in composition as lipids and proteins move into and out of them
76
Three classes of membrane proteins:
1. Integral: embedded in the lipid bilayer because of their hydrophobic regions
2. Peripheral: hydrophilic and located on the surface of the bilayer
3. Lipid-anchored are hydrophilic and attached to the bilayer by covalent attachments to lipid molecules embedded in the bilayer.
77
Where are Integral monotropic proteins embedded in the membrane?
Just one side of the bilayer
78
Where are transmembrane proteins embedded in the membrane?
Span the membrane and protrude on both sides.
79
When a transmembrane protein crosses once its called:
singlepass protein
80
when a transmembrane protein crosses several times its called:
multipass protein
81
Proteins that lack discrete hydrophobic regions do not:
penetrate the lipid bilayer
82
peripheral membrane proteins are bound to membrane surfaces through:
weak electrostatic forces and hydrogen bonds.
83
polypeptide chains of lipid-anchored membrane proteins are located:
on the surfaces of membranes
84
lipid-anchored membrane proteins are covalently bound to:
lipid molecules embedded in the bilayer.
85
lipid-anchored membrane proteins bound to the inner surface of the membrane are linked to:
fatty acids or isoprenyl groups.
86
Electron transport proteins, like cytochromes and iron-sulfur proteins, are related in function to:
enzymes
87
transport proteins facilitate:
the movement of nutrients across membranes
88
channel proteins provide:
hydrophilic passageways through hydrophobic means
89
transport ATPases us the energy of _____ to transport ______ across membranes:
- ATP
- ions
90
What recognizes and mediate the effects of specific chemical signals on the surface of the cell?
receptors
91
What are examples of chemical signals?
- hormones
- neurotransmitters
- growth promoting substances.
92
Proteins involved with intercellular communication include:
- proteins that form connexons at gap junctions in animal cells
- proteins that make up plasmodesmata in plant cells.
93
glycoproteins are:
membrane proteins with carbohydrate chains covalently linked to amino acid side chains
94
the addition of a carbohydrate side chain to a protein is called:
glycosylation
95
glycosylation occurs in the:
ER and Golgi Compartments
96
Glycoproteins are prominent in ________ and play a role in ____________________.
- plasma membranes
- cell to cell communication
97
membrane receptors allow cells to:
recognize, transmit, and respond to signals.
98
A calorie is the:
amount of energy required to raise 1 gram of water by 1 degree centigrade at 1 atmosphere of pressure.
99
Under standard conditions, the change in enthalpy, heat, and free energy of glucose oxidation are:
-Enthalpy: -673 kcal/mol glucose
- heat: -13 kcal/mole
-free energy: -686 kcal/mole
100
Three basic properties of catalysts:
1. increase reaction rates by lowering the Ea required.
2. form transient, reversible complexes with substrate molecules.
3. change the rate at which equilibrium is achieved, not the position of the equilibrium.
101
Organic catalysts are:
enzymes
102
what forms the active site in enzymes?
amino acids
103
What are the 6 amino acids that are involved in active sites?
1. cysteine
2. histidine
3. serine
4. aspartate
5. glutamate
6. lysine
104
Coenzymes are derivatives of _______ and function as ________________.
- vitamins
- function as electron acceptors
105
Enzymes have a very high ________________ because of the shape and chemistry of the active site.
enzyme specificity
106
Most enzymes are active in a pH range of:
3-4 units.
107
Once amino acids are in the active site, the substrate is held in place by:
specific noncovalent interactions
108
The role of the active site is to:
recognize and bind the appropriate substrate and to activate it by providing an environment for catalysis.
(AKA substrate activation)
109
3 common mechanisms of substrate activism:
- bond distortion: makes the bond more susceptible to catalytic attack
- proton transfer: increases reactivity of substrate
- electron transfer: results in temporary covalent bonds between enzyme and substrate.
110
What is another name for Catalytic RNA molecules?
ribozymes
111
enzyme kinetics describes
the quantitative aspects of anzyme catalysis.
112
enzyme kinetic reaction rates are influenced by:
- concentration of substrates
- concentration of the products
- inhibitors
113
What is Initial Reaction Velocity (v)?
the rate of change in product concentration per unit time.
114
Initial reaction velocity depends on the:
substrate concentration (S)
115
The inability of higher substrate concentration to increase the reaction velocity beyond a finite upper valoue is called:
saturation
116
__________ of enzyme is vital for control.
inhibition
117
Vmax can be used to determine the:
turnover number (Kcat)
118
Kcat is the rate:
at which substrate molecules are converted to product by a single enzyme at maximum velocity
- Kcat= V max/ [Et]
119
irreversible inhibitors bind:
enzymes noncovalently and can dissociate from the enzyme.
120
substrate-level regulation
regulation that depends on interactions of substrates and products with an enzyme
121
increases in substrate levels will result in _______ reaction rates:
increased
122
123
feedback inhibition
the final product of an enzyme pathway negatively regulated an earlier step in the pathway.
124
allosteric enzymes two conformations:
- one in which it has an affinity for substrate
- one in which it does not
125
allosteric regulation:
regulates the conformation of the enzyme
126
allosteric effector
regulated enzyme activity by binding and stabilizing one of the conformations.
127
phosphorylation occurs most commonly by:
transfer if a phosphate group from ATP to the hydroxyl group of serine, threonine, or tyrosine residues in a protein.
128
protein kinases
catalyze the phosphorylation of other proteins.
129
covalent modification
activity is regulated by addition or removal of groups such as phosphate, methyl, and acetyl groups.
130
dephosphorylation
the removal of phosphate groups from proteins
131
dephosphorylation is catalyzed by
protein phosphatases
132
