Test 1: Intro, cell membrane, recognition, memb. transportation, memb. communication, E.R., Flashcards
(244 cards)
1
Q
Cell adhesion molecules (CAMS):
A
Family of glycoproteins involved in maintaining tissue integrity.
2
Q
Cadherin
A
Links cells to identical cells.
3
Q
Integrin
A
Links cells to the ECM
4
Q
Many CAMS form cell junctions, what are the 2 proteins called that form these complexes?
A
Cadherins and integrins
5
Q
What are fimbriae?
A
Tiny protein threads used by certain bacteria to attach themselves to a host cell.
6
Q
What do fimbriae connect to?
A
Specific glycolipids on cells of the digestive and urinary tracts (sometimes exploiting this recognition to create infection.
7
Q
The ABO blood system is due to variations in what?
A
Membrane oligosaccharide chains displayed.
8
Q
What are the proteins that cells of the immune system display on their plasma membranes?
A
Human leukocyte antigens (HLA’s)
9
Q
What do HLA class 1 antigens do?
A
Identify infected cells for destruction
10
Q
What do HLA class 2 antigens do?
A
Present foreign material to other defender cells. (head on a pole).
11
Q
What are HLA class 2 antigens presented to?
A
T-helper lymphocyte
12
Q
What does the T-helper lymphocyte signal a B-lymphocyte to do?
A
turn into a plasma cell to build antibodies against the recognizable unique bit of foreign material
13
Q
What do newly formed antibodies do?
A
coat any invaders with the marker antibody, neutralize it, and render it very appealing to cellular attack.
14
Q
What are the 4 basic ways to move things across the plasma membrane?
A
Passive transport
Facilitated transport
Active transport
Vesicular transport
15
Q
Aspects of passive transport:
A
Doesn’t require energy (in any direct way).
May or may not require special hole-forming IMP’s.
By way of free passage or openings/channels/gates.
16
Q
2 aspects of facilitated transport:
A
Doesn’t require energy (in any direct way).
Requires special protein carriers.
17
Q
2 aspects of active transport:
A
Requires energy (directly). Requires special protein carriers or "pumps".
18
Q
4 aspects of vesicular transport:
A
Doesn’t directly require energy (though nearly so).
No carrier proteins required.
Requires receptor proteins.
Large scale and has 2 subtypes. (endocytosis and exocytosis)
19
Q
Diffusion:
A
The net movement of molecules from an area of high concentration to an area of low concentration.
20
Q
Osmosis:
A
The diffusion of water across a semi-permeable membrane.
21
Q
What are the 2 forces that create substantial dynamics on plasma membranes and often drive the entry of a given substance into or out of the cell?
A
Diffusion and Osmosis.
22
Q
What kind of molecules move through a membrane with ease? (diffusion)
A
Small, uncharged (or lipid soluble)
23
Q
Crenation:
A
The shrinking of a cell during osmosis.
24
Q
Hypertonic:
A
When the extracellular pressure rises. (pressure in the cell falls)
25
What will be induced if something cannot move across the membrane?
Osmotic drive
26
If the surrounding fluid has no osmotically active agents, then what will happen?
Water will move into the cell to achieve it's own equilibrium.
27
Lysis:
When a cell expands to the point where it could possibly burst or undergo lysis.
28
Hypotonic
When the pressure in the extracellular solution goes down causing the pressure in the cell to rise.
29
What structure helps with the cells critical capacity to manage transport into or out of the cell?
IMP's
30
Aka "true" free passage.
Passive transport
31
What kind of molecules can diffuse through completely unaided movement? (passive transport)
very small water soluble molecule.
| lipid soluble molecules.
32
3 types of openings for passive transport:
Aquaporins, ion channels, and gap junctions.
33
What is an aquaporin and how does it form?
A pore for water.
| Protein folds up in the lipid bi-layer to combine two "hemi-pores" thus creating a tiny hole in the plasma membrane.
34
5 aspects of ion channels:
Most are gated.
Pores are opened under the right stimuli.
Most ions are small, but many become larger due to hydration.
Very important in electrically excitable cells such as neurons and muscles.
All move ions; therefore, all are critical players in changing membrane potentials.
35
What are the 4 broad sub-types based upon exact mechanism/stimulus to open?
Voltage-gated channels.
Ligand-gated channels.
Mechanically-gated channels.
Chemically gated channels.
36
Voltage-gated channels:
Opened by applying a voltage (can secondarily open other gates).
37
3 aspects of ligand-gated channels:
Opened by docking a ligand (binding agent) on a receptive site.
Facilitates the rate of movement, not the direction.
When the ligand binds and opens the gate, the binding site loses it's affinity for the ligand (so the ligand leaves, thus resetting the receptor/gate).
38
How are mechanically-gated channels opened?
Physically stressing the cell (and it's cytoskeleton).
39
2 examples of mechanically-gated channels:
Touch/pressure sensors in the skin.
| Hair cells in the inner ear.
40
2 ways chemically-gated channels are opened:
Presence of calcium.
| Phosphorylation of the gate.
41
2 examples of chemically gated channels:
Calcium-gated potassium channel used in muscle cells.
| Chloride channel in epithelia.
42
Gap junction:
Used for direct cell to cell transmission.
| Allows for electrical and metabolic coupling of cells.
43
Examples of coupling of cells (gap junction):
Cardiac muscle cells.
Digestive smooth muscle cells.
Diffusion of nutrients to the center of the lens.
44
Connexon
In gap junction. 6 IMP's come together to form a hole and then associate with the 6 IMP's (connexon) of another cell to form a common hole.
45
Facilitated transport
Carrier assisted diffusion. (glucose transported)
46
Active transport
Against gradient pumping. (sodium-potassium exchange pump)
47
Vesicular transport
endo and exocytosis. (receptor-mediated endocytosis)
48
Non-energy dependent aided passage
Facilitated diffusion or facilitated transport.
49
What are the 3 subtypes of facilitated transport and what are they based on?
Uniport agents, Symport IMP's, and Antiport IMP's.
| Based on the number of molecules being moved and the direction.
50
Uniport agents
Move a single molecule at a time.
51
Symport IMP's
Move solutes together in the same direction.
52
Antiport IMP's
Move solutes together in opposite directions.
53
3 aspects of translocation mechanism:
Conformational change in the IMP.
Driven by concentration gradient (often bi-directional).
A lot like enzymes (and some were named with "-ase" at the end).
54
Process for the conformational change in the IMP:
1) High affinity for a particular solute (binding).
2) The IMP carrier translocates the solute.
3) In new conformation, the solute comes loose (release).
4) Without solute, IMP flips back to original state.
55
How is the translocation mechanism a lot like an enzyme?
1) Effectively catalyzes a reaction (movement).
2) Remains unchanged (and used again).
3) Great specificity.
4) Requires no energy (except the concentration gradient).
56
4 advantages for facilitated difusion:
simple, automatic, efficient, and much faster than simple diffusion.
57
What does the bicarbonate-chloride antiporter exchange?
Anion transporter that exchanges a BCO3- for a Cl- in RBC's and stomach acid-producing cells. They are also bi-directional depending on concentration gradient.
58
What does active transport require and why?
ATP (energy).
| B/c it works against a concentration gradient.
59
What do multi-pass IMP's do in active transport?
Physically carry a solute across the plasma membrane into an area of higher concentration.
60
What are the 2 broad types of active transport and what's the difference?
Primary (use ATP directly).
| Secondary (does not use ATP directly but it does need it; aka co-transport).
61
What kind of transport is the sodium-potassium antiport (aka sodium pump)?
Active transport
62
Osmotically active:
A solution that has non-diffusable solutes (like a cell) that will induce water to move.
63
Isomotic:
A solution that has same number of non-diffusable particles.
64
Hyperosmotic:
A solution that has less non-diffusable particles.
65
Hypo-osmotic:
A solution that has less non-diffusable particles.
66
Isotonic:
If a solution results in no net movement of water into or out of the cell.
67
Hypotonic:
If a solution results in net movement of water into the cell (pressure of the solution goes down; cell could lyse).
68
Hypertonic:
If a solution results in net movement of water out of the cell (the pressure of the solution goes up; cell could crenate).
69
What determines osmolality?
The raw number of particles in a solution.
70
What determines tonicity?
Whether the molecules in a solution can move and induce osmosis.
71
What charge do cellular proteins carry?
Negative.
72
Donnan Effect: (osmosis)
An imbalance in the distribution of mobile ions AND causing water to achieve its own equilibrium by moving. (osmosis and osmotic pressure rising inside the cell.
73
How do you solve Donnan swelling (aka the Gibbbs-Donnan Effect)?
Expel something from the cell. Anything will do, but a system evolved to expel the most common ion inside (Na+) using an IMP to rebalance the osmolality.
74
What does cyanide do?
Stops mitochondrial production of ATP (cells then stop the pumps, swell, and then die as K+ leaks out).
75
Sodium-Potassium exchange pump (Na+/K+ ATPase):
The hydrolysis of ATP is used to run the pump.
An antiport IMP moves 3 Na+ OUT for 2 K+ IN per ATP.
It's electrogenic since it moves ionic species.
76
Action Potential:
B/c of the Na+/K+ pumps, the membrane becomes polarized (-60 to -70 mv. The polarized state can be briefly destroyed by the action of voltage-gated ion channels.
77
Calcium Pump:
Uniport IMP that moves Ca+2 OUT per ATP.
B/c Ca+2 is critical for contraction, it's keenly studied in muscle cells.
Primary active transport.
78
Hydrogen-Potassium exchange pump (a "proton pump"):
An antiport imp that moves H+ OUT for K+ IN per ATP.
Critical in acid-secreting cells (stomach parietal cells, osteoclasts).
Primary active transport.
79
Sodium-Glucose symporter (aka SGLT1, 2, and 3):
An IMP that moves 2 Na+ IN with 1 Glucose IN.
Glucose levels usually higher in cells so to move it IN against its gradient, sodium is used (i.e., energy provided by sodium moving down it's own concentration gradient).
SECONDARY active transport (co-transport) since it's dependent on the original sodium pump.
80
Sodium-Hydrogen antiporter:
An IMP that moves H+ OUT with Na+ IN.
SECONDARY active transport (co-transport).
Relies on sodium gradient created by the Na/K ATPase pump.
Common in kidney tubule cells (for body acid-base balance).
81
Vesicular Transport:
```
Utilize membrane (lipid bi-layer) spheres (vesicles) to shuttle thousands/millions of molecules across the cell membrane.
Technically require energy.
```
81
What are the 2 divisions of vesicular transport?
Endocytosis and exocytosis.
82
Exocytosis:
AKA secretion.
Luminal contents released to the ECM.
Membrane-bound proteins or lipids join the plasma membrane.
83
Endocytosis:
Vesicles bud off of plasma membrane toward the interior as a form of "bulk transport".
Less discriminating process than mediated mechanisms.
84
What are the 3 subtypes of endocytosis?
Phagocytosis- Large scale.
Pinocytosis- Small scale.
Receptor mediated endocytosis- Small scale.
85
Phagocytosis:
"Cell eating" (reach out and grab).
| Aggressive defenders of the body.
86
Pinocytosis:
"Cell drinking".
Internal material is invisible in a microscope.
Involves invaginations of the plasma membrane to form "pinocytotic vesicles".
87
Receptor-mediated endocytosis:
A kind of pinocytosis.
Highly specific internalization.
Receptors (IMP's) are required, that must bind to a ligand before being internalized.
88
What method do scientists use in order to visualize the cell membrane?
Since it cannot be seen with light microscopy - instead the require the use of a transmission electron microscope.
89
Describe the physical characteristics of a cell membrane.
Trilaminar "unit membrane" (very consistent in cells and organelles)
* about 75-100A (8-10nm, or 0.000009 mm) thick.
* dark-light-dark layering as a basic framing material.
90
What are cell membranes composed of?
Lipids & Proteins (with some carbohydrate)
* phospholipids (some glycolipids)
* proteins (many actually glycoproteins)
* cholesterol
91
Membranes are variously composed of these special lipids; also considered the "main" building blocks.
Phospholipids: content varies from 25-80% (normally more the 50%)
92
Phospholipids are _______ molecules, meaning they have dual properties.
Amphipathic
93
Describe the 3 physical properties of phospholipids.
* Hydrophilic polar head groups
* Hydrophobic fatty acid chains (tails)
* The hydrophobic and hydrophilic regions linked by a glyceral and phosphate group (in the neck of the molecule).
94
The "hydrophobic effect" of the phospholid determines:
The oranization of phospholipids in a polar environment (of water).
95
To resolve the polarity issues, phospholipids can assemble in these 3 ways:
* Micelle
* Bi-layer
* Liposome
96
Describe the organization of phospholipids in a micelle.
*Spherical cluster of a single layer (no lumen)
*The polar heads face outward
(would be fairly small)
97
Describe the organization of phospholipids in a bi-layer.
* Two sheets
* Much more stable than a micelle
* Polar heads face outward (like most cellular membranes)
98
Describe the organization of phospholipids in a liposome.
* Spherical bi-layer enclosing an aqueous compartment (most like an entire cell).
* Polar heads face inward AND outward.
99
2 basic properties of a lipid bi-layer include:
* They are IMPERMEABLE to most biological molecules.
| * They exhibit random motions characteristic of liquid phase material. (Flexibility often described as a "lipid sea")
100
What makes a lipid bi-layer "Impermeable"? (2)
* Hydrocarbon interior
| * Lipids pack fairly tight
101
What CAN penetrate a lipid bi-layer? (3 generals)
* Most gases (O2 and CO2)
* Water
* Small lipid-soluble molecules (aromatic solvents, small fats)
102
How do Glycolipids differ from phospholipids?
*They have carbohydrate (oligosaccharide) branchs, instead of the polar head, facing the exoplasmic (exterior) of the cell.
103
What is a glycocalyx?
*A coating on cell membranes formed by a collection of glycolipids and glycoproteins.
104
Glycocalyx's are often termed Glycosphingolipids which are:
*A special class of lipids that have a unique fatty acid tail and an exotic tree of sugars on the hydrophilic side.
105
The protein/lipid ratio varies directly with...
The complexity of membrane function.
106
Proteins are:
A sequence of amino acids (connected by peptide bonds and called a peptide or polypeptide) that is assembled in such a way as to be folded or wound up.
107
What determines the structure of a protein molecule?
The specific amino acid sequence.
107
Alpha helices are:
Large spiral sections of amino acid chains that tend to fold up further to form a "globular" structure.
108
(2) Kinds of membrane proteins based on their location...
* Integral membrane proteins (IMPs)
| * Peripheral membrane proteins (PMPs)
109
What is the difference in protein location between the Integral membrane proteins and the peripheral membrane proteins?
The integral membrane proteins (IMPs) are embedded in the lipid sea while the peripheral membrane proteins (PMPs) located on the surfaces of the lipid sea (typically on the cytoplasmic side).
110
5 kinds of proteins based on their structure with the membrane:
* Tripartite (transmembrane) single-pass IMP
* Multipass (transmembrane) IMP
* Non-spanning IMP
* PMP ionically bonded to another IMP or PMP
* PMP ionically bonded to a phospholipid
111
3 things to know about a tripartite (transmembrane) single-pass IMP:
1) hydrophilic regions extend from both sides
2) single hydrophobic region spanning the membrane
3) hydrophobic region has an "alpha helix"
112
2 things to know about a multipass (transmembrane) IMP:
1) Multiple alpha helices span the lipid bilayer
| 2) may contain polar or charged amino acids that contribute to the formation of an aqueous pore.
113
What is the structure of a non-spanning IMP with the membrane?
*It is embedded in one side.
114
What is the more common protein in the membrane?
The multi-pass IMP.
115
What does a glycoprotein have that makes it unique to other proteins?
They have carbohydrate (sugar) branches, attached on the exoplasmic (exterior) side.
116
True or false: Nearly all membrane proteins are really glycoproteins at some level.
True
117
(7) "Kinds" of membrane proteins based on their function (functional "flavors").
* Structural Proteins
* Channels
* Transporters
* Pumps
* Receptors
* Transducers
* Enzymes
118
What is the function of a structural protein?
*Provides structural integrity to the cell or between the cell and its extracellular relatioships.
119
What are the 3 kinds of extracellular relationships that structural proteins assist in?
*Membrane to cytoskeleton
*Cell to cell
Cell to the extra-cellular matrix (ECM)
120
What is the function of a "channel" protein?
*The allow PASSIVE transport of molecules through an opening (sometimes called pores, many of which are "gated" or controlled).
121
Channel proteins are generally found between which two structures of the cell?
*Cytoplasm and the ECM
| sometimes cell to cell
122
What is the function of a transporter protein?
*PASSIVELY transport molecules along their NATURAL concentration gradient.
123
What is the function of pump proteins?
*ACTIVELY transport molecules AGAINST a concentration gradient.
124
What is the function of receptor proteins?
*Allow for specific recognition and binding of a ligand.
125
What is the function of transducer proteins?
They couple a membrane receptor to a cytoplasmic enzyme (and linking molecule)
126
When are tranducers activated?
*When receptor and ligand meet.
127
What it the function of an enzyme?
*They perform cellular work by catalyzing a reaction.
128
How are enzymes often activated?
*Transducers
129
__________ is an added agent involved in membrane fluidity.
*Cholesterol
130
What is cholesterol?
*An amphipathis steroid derivative that is intercalated among membrane phospholipids.
131
True of False: Plasma membranes likely have almost one cholesterol per phospholipid, whereas some membranes lack cholesterol (e.g., bacteria).
True
132
How does cholesterol effect membranes? (2)
*It enhances membrane stability & decreases permeability (to even water).
133
What OTHER 2 functions do many BELIEVE cholesterol to have?
* Helps with packing of the phospholipids
| * Might minimize lateral mobility of molecules - a stabilizing agent.
134
Aside from the barrier function, what other (3) functions must the plasma membrane also be able to engage in?
* Recognition:to FIT IN and play a proper role in tissues.
* Transportation: to MOVE nutrients (etc.) into the cell.
* Communication: to SIGNAL across the membrane from other cells.
137
5 basic categories of chemical secretion (transmission); all involve exocytosis of a transmitter substance into the ECM...
* Endocrine secretion
* Neuro-endocrine secretion
* Paracrine secretion
* Autocrine secretion (won't be emphasized)
* Synaptic transmission
138
What mediates endocrine secretion
Hormones
139
Endocrine Secretion: Method of distribution
*Circulate through the blood
140
Endocrine Secretion: Location and distance to target...
*Cells throughout the body
141
Endocrine secretion: Speed of communication...
*May take several minutes (SLOWEST)
142
What is the key difference between the 5 categories of chemical secretion?
*The distance to the target.
143
Neuro-endocrine secretion: where a neuron secretes into the bloodstream to: (2)
* a relatively nearby target cell (ex: various releasing factors from the hypothalamus of the brain to the anterior pituitary gland)
* the entire body (such as ADH from the posterior pituitary gland),
144
Paracrine secretion: Mediated by...
*Various chemical substances (local hormones)
145
Paracrine secretion: Method of distributaion...
*Released to local ECM
146
Paracrine secretion: Lacation and distance to target...
*Act on self or same cells
147
Paracrine secretion: Speed of communication...
*Variable but generally very fast
148
Synaptic Transmission: Mediated by...
Neurotransmitters
149
Synaptic Transmission: Method of distribution...
*release into "synapse"
150
Synaptic transmission: Location and distance to target...
*"hard-wired" at a synapse
151
Synaptic transmission: Speed of communication...
*VERY fast (milliseconds)
152
The process/route of endocrine secretion:
* Synthesis & exocytosis of a hormone from a source cell
- >Released hormone enters ECM then into the bloodstream where it circulates throughout the entire body
- >Then exits the blood capillaries and in the ECM to land on or enter target cells.
153
Endocrine secretion: Receptor location depends upon...
*Ability to gain entry into the cell, which is a function of hormone type.
154
2 types of hormones involved in endocrine secretion...
* peptide
| * steroid
155
Peptide hormones are ______ soluble.
*Water
156
Peptide hormones: Receptor located...
*On the cell surface
157
Peptide hormones: Receptor Morphology...
*Typically transmembrane IMP's
158
Peptide Hormones: As a result of receptor/ ligand binding... (3)
* Receptor may open a pore for an ion (ion channel)
* receptor may stimulate the production of a second messenger (very common)
* Receptor may directly phosphorylate other proteins inside the cell.
159
Steroid hormones are ______ soluble and easily cross the ______ ________ ______ ____________.
* lipid soluble
| * plama membrane lipid Bi-layer
160
Steroid Hormones: receptor located....
*In cytoplasm or nucleus
161
Steroid hormones: receptor morphology...
*Protein w/ligand & DNA binding sites
162
Steroid hormones: as a result of receptor/ligand binding... (1)
*receptor directly binds to DNA and alters gene expression (transcription)
163
Process/route involved in paracrine secretion...
* Synthesis and exocytosis of a chemical signal (sometimes loosely called a hormone, but best not) from a source cell
- >released chemical enters ECM where it stays locally
- >then lands on nearby target cells
164
What determines the sensitivity in paracrine secretion?
*Receptors on target cells.
165
4 reasons receptors on target cells determine sensitivity in paracrine secretion:
1) receptive fields can very over time and location on the cell
2) numbers can be "up" or "down" regulated (as a feedback)
3) some cells blind/deaf to signal if without the receptor
4) lingand (chemical signal) -> receptor -> intracellular response
166
Paracrine secretion: What is the most powerful vasoconstrictor known?
*Endothelin-1
167
Paracrine Secretion: Where is Endothelin-1 derived from?
*The lining of blood vessels ( a layer of cells called the ENDOTHELIUM)
168
Paracrine secretion: During fetal development, target tissues secrete this neurotrophic factor which serves as a chemo-attractant molecule.
*"Nerve Growth Factor" (NGF)
169
True/False: The information for autocrine secretion is the same as that for paracrine secretion.
*True
170
What does a synapse consist of?
* an association of the transmitting end of neuron; a small intercellular space of ECM; and a receiving cell (a neuron or muscle cell).
171
Synaptic transmission: What is the release of a neurotransmitter stimulated by?
*The arrival of an electrical action potential in the first neuron.
172
What is the process/route involved in synaptic transmission?
*Release of a neurotransmitter -> the neurotransmitter stays very locallin in an area know as the synaptic cleft -> lands on the post-synaptic neuron.
173
What determines sensitivity in synaptic transmission?
*Receptors on the post-synaptic side.
174
4 ways receptors on post-synaptic side determines sensitivity in synaptic transmission?
1) receptive fields can vary over time on the cell
2) numbers can be "up" or "down" regulated (as a feedback)
3) ligand (neurotransmitter) -> receptor -> intracellular response (depolarization of downstream/post-synaptic neuron or muscle cell)
4) a one to one (2) cell relationship that begins electrically, becomes chemical, and ends electrically.
175
What determines whether enough receptors will induce an action potential on the post-synaptic side of a synaptic transmission?
*The concentration in the synapse that is set by the amount of neurotransmitters released.
176
What is a Myoneural junstion (neuro-muscular juction)?
*A synaptic junction between a neuron and another, or between a motor neuron and a skeletal muscle cell.
177
4 basic categories of chemical signaling (reception): they all involve a signaling agent acting as a ligand and then binding to a receptor molecule.
* Steroid hormone receptor mechanism
* Ligand-gated receptor mechanism
* G-protein-linked receptor mechanism
* Enzymatic receptor mechanism
178
Steroid hormone receptor mechanism results in...
*Direct activation of gene transcription
179
Ligand-gated receptor mechanism results in...
*A change in the membrane potential (by opening a channel)
180
G-Protein-Linked receptor mechanism is also known as....
*Signal transduction
181
G-protein-linked receptor mechanism utilizes a ________ __________ to amplify the signal strength.
*Second Messenger
182
G-protein-linked receptor mechanism generates...
*Internal Protein phosphorylation (activation)
183
G-protein-linked receptor mechanism generally consists of these 2 systems:
1) cAMP dependent system
| 2) inositol, diacylglycerol, Ca+2 dependent system
184
The enzymatic receptor mechanism results in...
*Direct protein phosphorylation.
185
How do steroid hormones pass through membranes?
*Since steroids are lipid soluble, they pass right through - no membrane intermediary needed.
186
Steroid hormone receptor mechanism: receptors are where?
*Inside the cells: cytoplasm or nucleus
187
Steroid hormone receptor mechanism: 3 domains a receptor has:
1) Steroid-binding domain
2) DNA-binding domain
3) Gene-regulating domain
188
Process/route involved in steroid hormone receptor mechanism...(5) steps
* Steroid diffuses in and binds to a receptor (special interior protein)
* Receptor undergoes a conformational change
* Receptor loses affinity for inhibitory substance (a protein) from the receptor's DNA-binding site
* "activated" receptor binds to a specific DNA regulatory site
* Gene transcription altered (i.e. a given gene is turned on)
189
True/False: Steroids may remain active in the blood for hours or days.
True
190
The only amplification possible in steroid hormone receptor mechanism is by...
*making many mRNA's and by making many proteins from that gene.
191
Because it is easy to lose track of the organizational complexity of this section in the notes, consider the following flowchart:
Steroid Hormone Receptor Mechanism (p 53)
192
Ligand-gated receptor mechanism: When a ligand binds to the receptor...
*the IMP opens a channel through itself which is used to convert chemical energy into electrical energy.
193
Because it is easy to lose track of the organizational complexity of this section in the notes, consider the following flowchart:
Ligand-gated Receptor Mechanism (p54)
194
What process causes proteins to undergo conformational changes?
*Protein Phosphorylation
195
5 basic pieces to mechanisms that require secondary messengers (i.e. G-Protein-linked receptor mechanism)...
1) Receptor
2) Transducer
3) Amplifier
4) Second Messenger
5) Internal effector
196
What are the 3 observations that need to be explained in any G-Protein-linked model?
* Adjustable sensitivity (up or down regulation)
* Multiple effects from a single signal
* Same effects in a given cell from differing signals
197
The 2 major pathways of G-Protein-Linked receptor mechanisms...
1) cyclic adenosine monophosphate system (cAMP)
| 2) Inositol triphosphate, diacylglycerol, calcium system (IP3, DG, Ca+2)
198
Protein kinases are...
*enzymes that phosphorylate other proteins
199
Protein phosphateses are...
*enzymes that de-phosphorylate other proteins.
200
GPL receptor mechanism: The process known as signal transduction is...
*When a ligand binds to the receptor it stimulates a family of "G-protein" types that serve as membrane transducer molecules.
201
The process of the GPL receptor mechanism starting with the external signal and ending with cellular response...
* External signal (first messenger)
* Receptor
* Transducer
* Amplifier
* Phosphorylated precursor
* Second Messenger
* Internal effector
* Cellular Response (p 56)
202
3 major types of transducer G-proteins and the amplifiers they work with:
* G(s) - Stimulatory, and activates adenylate cyclase (the cAMP system)
* G(i) - Inhibitory, and inhibits adenylate cyclase
* G(p) - Stimulatory, and activates phospholipase C (the IP3, DG Ca+2 system)
203
The most variable and functionally important subunit of G-proteins:
*Alpha subunit
204
GPL receptor mechanism: function of Adenylate cyclase:
*Amplifier that converts ATP into cAMP
205
GPL receptor mechanism: 2 amplifiers...
* Adenylate cyclase
| * Phospholipase C
206
GPL receptor mechanism: function of phospholipase C...
*Converts PIP2 into IP3 (the head piece of PIP2) and DG (the tail pieces of PIP2)
207
GPL Receptor Mechanism: function of cAMP...
*second messenger that stimulates A-kinase
208
GPL receptor mechanism: function of IP3, DG and Ca+2 (all in the same system)...
*Second messenger that stimulates C-kinase and calcium/calmodulin kinase. (some call the Ca+2 the ultimate second messenger)
209
GPL receptor mechanism: 3 internal effectors and what they are activated by...
* A-kinase: activated by cAMP
* C-kinase: activated by DG
* Ca+2/calmodulin kinase(CaM kinase): activated by Ca+2 (through IP3)
210
GPL: cAMP Signal Transduction: Refer to picture
p (58)
211
GPL: This diagram nicely summarizes the G-protein action in the cAMP system...
p (59)
212
GPL: IP3, DG, Ca+2 (Inositol) Signal Transduction reference...
p (61)
213
GPL receptor mechanism: in-activation is when...
*the system is shut down by a number of mechanisms that relate to the continual recycling of molecules. (done by various PHOSPHATASE enzymes available in the cell)
214
Enzyme Receptor Mechanism: 3 domains
* external, ligand-binding domain
* membrane-spanning domain (a-helix)
* Internal, catalytic domain (kinase)
215
Enzyme Receptor Mechanism: most common type of kinase...
*tyrosine
216
Enzyme Receptor Mechanism process...
*Direct protein phosphorylation
217
Insulin, growth-factors, and leptin all use this type of receptor mechanism...
*Enzyme Receptor Mechanism
218
The "proper" term for the interior of a cell is...
*The protoplasm
219
2 interconnected areas of a cell...
* Nucleoplasm
| * Cytoplasm
220
The nucleoplasm is...
*The contents of the nucleus
221
The nucleoplasm consists of (2) ...
* Water (mostly)
| * chromatin
222
The cytoplasm is...
*The bulk of the cell including organelles and Fluid
223
The cytoplasm consists of (3)...
* Fluid called Cytosol
* Cytoskeleton
* Organelles
224
Cytosol consists of...
*Water (mostly) & nutrients
225
Cytoskeleton is...
*an array of proteins that can criss-cross the interior
226
2 forms of the endoplasmic reticulum:
* rough ER (RER)
| * smooth ER (SER)
227
RER: cytoplasmic membrane surfaces are studded with...
*Ribosomes
228
RER appear as...
*flattened and layered stacked sheets with a very small lumens
229
Primary function of the RER...
*Protein synthesis and targeting
230
SER appear as...
* Membranous tubes and/or vesicles with slightly larger luminal space than RER
* Often described as "Tubular" or "Vesicular".
231
What is a ribosome?
*a site of protein synthesis
232
Where is a ribosome found?
*Either free-floating or bound to ER
233
2 specific ribosome subtypes:
* RER ribosomes
| * Free ribosomes
234
RER ribosomes make (3)...
* IMPs (of the ER, Golgi or plasma membrane)
* Lysosomal enzymes
* Secretory proteins
235
Free ribosomes make (3)...
* Cytosolic proteins (including PMPs)
* Some mitochondrial proteins
* nuclear proteins
236
2 major processes involved in protein synthesis...
* Transcription
| * Translation
237
Transcription (in the nucleus) invovles...
*conversion of DNA information (genes) to messenger RNA molecules (mRNA) that leaves the nucleus
238
Translation (on ribosomes) involves...
*the conversion of the mRNA message to a polypeptide sequence (a protein)
239
Hydroxylation is ... and where...
* Done mostly on SER.
* The addition of hydroxyl groups to lipid soluble toxins, converting them to water-soluble molecules that can be easily disposed of. (ex. detoxification)
* Occasionally done to complete the synthesis of certain molecules.
240
Glycosylation is... and where...
* Done mostly by RER
| * The addition of sugar residues (to specific amino acids) in peptide chains
241
Glycogenolysis is... and where...
* Done by SER
| * Breakdown of glycogen to glucose
242
Sterol Metabolism is... and where...
* Done mostly by SER
* Steroid hormone synthesis in Endocrine glands
* Cholesterol synthesis and availability for membrane stability
243
What enzyme is embedded in the smooth ER and faces the cytoplasm?
HMG CoA reductase
244
Calcium storage is done by...
*SER in muscle
