Week 4 Flashcards
1
Q
What are the components of a glycerophospholipid?
A
fatty acid tail, glycerol backbone, phosphate head
2
Q
what is the linkage between the fatty acid tail and glycerol in a glycerophospholipid?
A
ester linkage
3
Q
type of steroid that intercalates between phospholipids with the -OH closest to the aqueous interface
A
cholesterol
4
Q
what happens when there are smaller amounts of cholesterol in the membrane
A
“stiffens” the membrane which leads to decrease fluidity
5
Q
what happens when there are higher amounts of cholesterol in the membrane
A
it interferes with the interactions between lipid tails which leads to increase fluidity
6
Q
type of lipid with a backbone of sphingosine and when a slightly different shape can decrease the membrane fluidity
A
Sphingolipids
7
Q
proteins (glycoproteins) and lipids that are bound to carbohydrates that vary in size
A
Glycocalyx
8
Q
what are the two different formations of membrane lipid called?
A
Micelles and bilayer
9
Q
which membrane lipid formation is more favourable as the concentration of phospholipids increase?
A
bilayer formation is more favourable over michelles
10
Q
the ? is key to the survival and normal function of the cell
A
integrity of the plasma membrane
11
Q
the loss of integrity of the cell membrane leads to ?
A
threatening of cell survival
12
Q
functions of membrane proteins
A
signaling, protection, structure and movement, transport and general homeostasis
13
Q
key forces that work across the cell membrane
A
diffusion and osmosis
14
Q
what is diffusion
A
the movement of molecules from a region of higher concentration to lower concentration
15
Q
what is osmosis
A
diffusion of water through a semi-permeable membrane
16
Q
allows water to pass through, but is impermeable to at least one solute
A
semi-permeable
17
Q
explain Na+/K+ ATPase
A
key plasma membrane transporter, pumps 3 Na+ out of the cytosol into the extracellular fluid (ECF) and pumps 2 K+ into the cytosol (ICF) and uses ATP -> ADP +Pi for hydrolysis. This establishes a gradient of charge across the membrane
18
Q
A protein moves a substance across a membrane against a concentration gradient using ATP
A
Active transport
19
Q
A protein forms a channel that allows a substance across the membrane, along its concentration gradient
A
passive transport
20
Q
a protein carrier binds to a substance and transports it across a membrane, allowing it to follow its concentration gradient
A
facilitated transport
21
Q
the transport of 2 substances (X and Y) are coupled using the same protein. the concentration gradient of X favours movement into the cell, Y is “pulled” along, even if the gradient for Y does not favour cell entry
A
Co-transport
22
Q
X and Y move in opposite directions across the cell membrane - the gradient of one of the molecules supplies the energy to drive the transport
A
counter-transport
23
Q
separate cells into apical and basal compartments, commonly regulates movement across membranes and other epithelial structures
A
tight junctions
24
Q
types of anchoring junctions
A
Desmosome, Hemi-desmosome, adherens
25
Parts of Desmosome
intracellular component: plaque formed of molecules that are associated with cadherins and intermediate filaments bind to the plaque
extracellular component: cadherins on one cell interact with cadherins on a neighboring cell
26
difference between hemi-desmosome and desmosome
hemi-desmosome's extracellular component involves integrin instead of cadherins
27
parts of adherins
junction can be either cadherins or integrins, no intermediate filaments, instead have actin filament
28
functions of the cytoskeleton
cellular movement, organization of cellular components/organelles, cellular structure, communication
29
role of intermediate filaments
overall structural integrity of the cell, variety of molecules, variety of molecules
30
microtubules
trafficking of organelles and cell division, organization of overall cellular structure, cellular movement, tubulin
31
microfilaments
cellular movement, structural organization of the plasma membrane, actin
32
features of the cytoskeleton
dynamic, tightly regulated, can generate force
33
what is the subunit/monomer of actin?
G-actin
34
what is a polymer of actin?
F-actin
35
two forms of F-actin
linear arrangement and mesh-like nets
36
how does F-actin degrade?
spontaneously degrades, G-actin hydrolyzes ATP to ADP, which makes it more likely that it will fall off the F-actin strand
37
factors that affect the stability of F-actin
- concentration of G-actin
- "caps" that can prevent disassembly
- proteins that speed up or slow down the rate that G-actin hydrolyzes its ATP
- nucleating factors or inhibitory factors that modify the formation of F-actin
38
what is the monomer of microtubules
tubulin
39
what are the two types of tubulin that form dimers
alpha and beta tubulin
40
what type of structure is alpha-beta dimers organized as?
helical tube
41
dynamic instability
when the beta monomer of tubulin cleave GTP to GDP +Pi, the dimer tends to "fall off" the microtubule and it falls apart
42
functions of microtubules
cellular organization (MTOC), cellular movement, cell division, signaling
43
what is the unique shape of centrioles called?
tubulin triplet structure ( 9 tubulin triplets, "9X3" structure)
44
"molecular motors"
can move along on F-actin and microtubules which form a network of dynamic filaments and they use ATP to move along it
45
what kind of protein can walk along microfilaments (F-actin)
myosin
46
what kind of proteins can move along microtubules and cause the "whipping" movements of cilia and flagella
dyneins and kinesins
47
types of intermediate filaments
lamins, keratins, vimentin family (vimentin, desmin, GFAP), neurofilaments
48
what is responsible for the shape of microvilli
actin filaments
49
What are the 2 main classes of lipids structurally?
fatty acid and isoprenoid
50
the 3 components of a phospholipid
hydrocarbon chain, backbone, and phosphate-alcohol head group
51
two types of backbone for phospholipids
glycerol and ceramide
52
Phospholipids with a glycerol backbone
phosphoglycerides
53
phosphatidate
if both fatty acids are linked to the glycerol backbone with an esterlinke
54
plasmalogen
if one fatty acid is linked to the glycerol backbone with an ester link while the other has an ether link
55
what is the basic structure of a phospholipid called?
phosphatidic acid
56
sphingomyelin
phospholipid that contains a ceramide backbone, also be classified as a sphingolipid
57
where does phospholipid synthesis occur?
primarily on the luminal surface of the smooth ER and the inner mitochondrial membrane
58
what are the steps to phospholipid synthesis
1. synthesis of glycerol backbone
2. attachment of fatty acids to backbone via ester linkage
3. addition of head group
4. exchange/modification of head group
59
flippase
special enzyme that moves phospholipids across the ER membrane to the cytosolic side
60
the 5 carbon structural unit of isoprenoids
isoprene unit
61
Cholesterol
steroids are complex molecules made from 6 isoprene units
62
how many fused rings does cholesterol have?
4
63
sterols
steroids with a hydroxyl group at C3
64
where does cholesterol synthesis occur?
ER
65
what are the steps of cholesterol synthesis?
1. Condensation of 3 acetyl CoA into mevalonate
2. formation of isopentenyl pyrophosphate
3. creation of squalene
4. cyclization of squalene into cholesterol
66
what enzyme is the main regulatory enzyme in cholesterol synthesis pathway and catalyzes the rate limiting step?
HMG CoA reductase
67
what promotes the dephosphorylation of HMG-CoA reducatse, activating the enzyme, and in turn promoting cholesterol synthesis
insulin
68
what promotes phosphorylation of HMG-CoA reductase, inhibiting the enzyme and in turn inhibit cholesterol synthesis
Glucagon
69
what is key in detecting extracellular signals and modifying cell funcation based on those signals?
receptors in the cell membrane
70
transduction
the intracellular events that transform the extracellular signal into an intracellular signal
71
what is the model of intracellular signalling?
the concentration of first messenger increase -> binds to cell membrane receptor -> receptor activates resulting in activation of intracellular protein associated to receptor -> protein activates mechanism to increase activation of second messenger -> second messenger binds to/activates another protein -> protein will activate or inactivate other biochemical signalling cascades
71
what is the largest family of cell membrane receptor?
GPCR
72
how many times does the GPCR span through the membrane?
7 times
72
what activates G-Protein coupled receptors?
when a protein with a guanine nucleotide binds to the receptor
73
what are the 3 protein subunits fo the G protein?
alpha, beta, and gamma subunits
74
explain unstimulated alpha subunit in GCPR pathway
unstimulated alpha is bound to GDP, and beta-gamma is bound to alpha
75
explain stimulated alpha subunit in GCPR pathway
alpha subunit releases GDP, replacing it with GTP and the alpha subunit disengages from the beta-gamma subunits
76
what is the mechanism of Gs GPCR?
1. a ligand binds to a receptor associated with a GS G-protein
2. Gs releases GDP and binds GTP at the alpha subuniit and the beta-gamma subunit detaches from the G-protein
3. Gs binds to and activates adenylyl cyclase which is the membrane-bound enzyme that converts ATP to cAMP
4. cAMP binds to protein kinase A (PKA) - CAMP binds to inhibitors of PKA, whch then detaches, and allows the activates PKA
5. PKA phosphorylates a multitude of effector proteins
77
what inactivates cAMP and what does it become
cyclic AMP phosphodiesterase converts cAMP to 5'-AMP
78
explain Gq GPCR pathway
1. a ligand binds to a receptor assocated with a Gq G protein
2. Gq-alpha activates phospholipase C
3. Phospholipase C cleaves a membrane lipid (PIP2) into IP3 and diacylglyceral (DAG)
4. IP3 activates a Ca2+-release channel in the ER which leads to movements of Ca2+ from ER into the cytosol
5. Both Ca2+ and DAG work together to activate membrane-bound protein kinase C (PKC)
6. PKC (the 2nd messenger-activated effector) can modulate the activity of many other effectors and Ca2+ can also bind to other molecules such as calmodulin
79
What inhibits and down regulates the activity of Gs
Gi GPCR pathway
80
What does the Gi alpha and bet-gamma subunits do?
Gi-alpha inactivates adenylyl cyclase and Gi-beta gamma opens a K+ channel
81
What happens when the Gi beta gamma subunit opens a K+ channel?
it brings the cell closer to its nernst potential of K+, this is very negative membrane potential - it tends to cause most cells to be "less" activated
82
What is the Nernst potential for K+?
-90 mV
83
Explain the Receptor Tyrosine Kinases (RTKs) pathway
1. ligand binds to receptor monomers
2. receptor dimerizes and each half phosphorylates the tyrosine residues on the other half
3. signalling proteins then bind to the phosphorylated receptor and become activated leading to signal cascade
84
Explain the Ras-RTK pathway
1. Ras is a small, intracellular G-protein that is not physically associated with any receptors, whe it encounters an activated RTK, it binds to GTP and gets activated
2. Ras activates Raf
3. activated Raf activates MAP kinases which can phosphorylate transcription factors and enzymes
4. Ras inactivates itself by cleaving GTP -> GDP
85
T or F: Ras has no typical 2nd messengers produced
True
86
Which pathway is key to insulin signaling?
PI3K -> Akt system
87
Explain the PI3K to Akt system pathway
1. RTK is activated and this causes activation of nearby phosphoinositide-3-kinase (PI3K)
2. PI3K attaches an additional phosphate to PIP2 to form PIP3
3. PIP3 accumulates and forms "lipid" rafts in the membrane (PIP 3is the second messenger)
4. akt and PDK1 accumulate and cluster together at the site of the PIP3 rafts and PDK1 becomes activated by PIP3
5. when PDK1 is activated, it activates Akt by phosphorylating it
6. Akt is the effector and it influences a huge range of intracellular targets
88
what is the 2nd messenger in the PI3k pathway?
PIP3
89
Explain Nitric oxide-mediated signaling
1. cytosolic calcium increases
2. increased intracellular calcium activates NOs
3. NOs produces NO from L-arginine
4. NO binds to activates guanylyl cyclase (GC) -> production of cGMP from GTP (cGMP is also a second messenger)
5. elevation in cytosolic cGMP activates a protein kinase (usually PKG) which changes in cellular activtiy
90
define flow
movement of a substance from one point in a system (A) to another point in the system (B)
91
how is flow measured
amount of substance (volume, moles, charge) that moves over time (seconds, minutes)
92
flow is directly related to what
the size of the energy gradient, the greater the gradient the greater the flow
93
which law determines the rate of flow
Poiseuille's law
94
according to the poiseuille's law, what will increase flow when it increases
hydrostatic pressure and radius
95
according to the poiseuille's law, what will decrease flow when it increases
length of the tube, the viscosity of the fluid
96
what is the most important determinant of resistance?
radius
97
Which law quantifies how the rate of diffusion is affected by various parameters
Fick's Law
98
Flux
the amount of solute moving across a barrier per unit time
99
the rate of flow of charges across a membrane
Ohm's Law
100
Ohm's law equation
I = V/R, I = current, V = voltage, R = resistance
101
According to Ohm's law, current increases when this increases
Voltage
102
according to Ohm's law, current decreases when this increases
Resistance
103
what is the "back of the nose and throat" that leads to the larynx
Nasopharynx
104
cartilaginous structure that contains the vocal folds
Larynx
105
midline, non-paired conducting airway
trachea
106
branching airways that contain variable amounts of cartilage
bronchi
107
branching airways that lack cartilage but are surrounded by smooth muscle
bronchioles
108
delicate, balloon-like structures that are the main sites of gas exchange
alveoli
109
ventilation
conducting zone, movement of gas is driven by pressure gradients
110
respiratory or "exchange" zone
movement of gas is driven by concentration gradients
111
what is part of the ventilatory apparatus?
lungs, chest wall and muscles
112
What happens during inspiration?
the external intercostals (ribs move up and out) and diaphragm contract (descends)
- the volume of the thoracic cavity increases -> decrease in the intrathoracic pressure, the drop in intrathoracic pressure leads to drop in pressure of the airspaces of the lungs -> movement of air from atmosphere into lungs
113
what happens during expiration?
the diaphragm (rises) and external intercostals (ribs move down and in) relax
- the volume of the thoracic cavity decreases -> an increase in the intrathoracic pressure which leads to airspaces of the lungs increase pressure, movement of air from lungs back to the atmosphere
114
Pleural cavity
contains a small amount of fluid and the fluid "connects" the chest wall to the delicate alveoli
115
what happens when you move your thoracic cage and diaphragm?
changes in the pleural cavity pressure which in turn will change the alveolar pressure
116
pleural effusion
fluid in the pleural space, can be either unilateral or bilateral
117
"gunk" in the airways and alveoli
Consolidation
118
when you hear coarse crackles in a patient with consolidation
pathological fluid in large airways
119
when you hear fine crackles in a patient with consolidation
smaller airways usually
120
wheeze
when a small airway is narrowed or constricted, you hear a high-pitched, musical sound on expiration
121
stridor
when a large airway is narrowed or constricted, you hear a louder, harsher sound on inspiration and sometimes on expiration
