Chapter 4 Flashcards
1
Q
Define: Plasma membrane
A
Outer boundary of the cell that separates it from the world is a thin, fragile structure
2
Q
Estimated thickness of plasma membrane
A
5-10 nm
3
Q
Do all membranes have the same ultrastructure?
A
Yes
4
Q
How can you observe the plasma membrane?
A
An electron microscope
5
Q
What are the 7 functions of the plasma membrane?
A
- Compartmentalization
- Scaffold for biochemical activities
- Selectively permeable membrane
- Transport solutes
- Response to external stimuli
- Cell-cell communication
- Energy transduction
6
Q
What is the plasma membrane made of?
A
Lipids and proteins
7
Q
Define: Amphipathic
A
Property of a molecule having both hydrophobic and hydrophilic regions
8
Q
What is insulation for a nerve cell?
A
Myelin sheath
9
Q
Define: Phosphoglycerides
A
Lipids with phosphate group
10
Q
Define: Phosphoglycerides
A
Phospholipids built on glycerol backbone
11
Q
Define: Sphingolipids
A
Derivative of sphingosine
12
Q
Define: Sphingosine
A
An amino alcohol that contains a long hydrocarbon chain
13
Q
Define: Ceramides
A
Basic structural units of all sphingolipids, consists of sphingosine linked to fatty acid by amino group
14
Q
Define: Cholesterol
A
Smaller and less amphipathic molecule
15
Q
What sterol makes up to 50% of animal membrane lipids
A
Cholesterol
16
Q
Can lipid bilayers self-assemble?
A
Yes
17
Q
Liposome functions in the bilayer
A
- deliver drugs within the body
- membrane proteins inserted into liposomes
18
Q
What are membrane carbohydrates?
A
Plasma membrane of eukaryotic cells have carbohydrate, glycoproteins and glycolipids
19
Q
What is the function of membrane carbohydrates?
A
Mediates interactions of cell and the environment
20
Q
What is an example of an important carbohydrate in plasma membrane?
A
Blood type
21
Q
What determines blood type?
A
Glycolipid carbohydrates of RBC plasma membrane
22
Q
Blood type A
A
Adds enzyme V-acetylgalactosamine to end chain
23
Q
Blood type B
A
Adds enzyme galactose to chain terminus
24
Q
Blood type AB
A
Both enzymes present
25
Blood type O
Lacks enzyme capable of attaching either terminal sugar
26
What is integral membrane protein function?
Receptors that bind ligands, channels, or transporters to move ions/solutes across membrane
27
Are integral membrane proteins amphipathic?
Yes
28
What are peripheral membrane proteins?
Associate with membrane by weak electrostatic bonds
29
What are lipid anchored membrane proteins
Covalently bonded to a lipid group that resides within membrane
30
What are lipid rafts?
Outer leaflet of plasma membrane contains specialized regions
31
What is the function of lipid rafts?
Provide favourable environment for cell-surface receptors
32
Phospholipids move in what way?
Laterally
33
Define: Flippases
Enzymes that move certain phospholipids from one leaflet to the other
34
Define: Apical plasma membrane
Absorbs substances from lumen
35
Define: Lateral
Cell contact
36
Define: Basal
Substratum contact, ion gradient
37
Cell with the most highly differentiated structure, covered in continuous plasma membrane
Sperm cells
38
What is Brownian movement
Phospholipids can find for brief periods to certain areas
39
What can detect and demonstrate distribution of different proteins?
Antibodies
40
What is spectrin?
Has alpha and beta subunit, wound around each other and head to tail orientation. Major component of internal membranes skeleton
41
What is ankyrin?
Mediate interaction with interval membrane proteins
42
Where is Actin found?
Present in microfilaments
43
What is glycophorin A?
Transmembrane dimer, each subunit single pass protein, heavily glycosylated
44
What does G3PD stand for?
Glyceraldehyde – three – phosphate dehydrogenase
45
Four basic mechanisms which solute moves across membranes:
1. Passive
2. Active
3. Nonmediated
4. Transporter mediated
46
How do you calculate net flux?
Difference between influx in efflux 
47
Define: Osmosis
Diffusion of water through semi permeable membrane
48
Cells (shrink, swell, stay same) in a hypotonic solution?
Swell
49
Cells (shrink, swell, stay same) in a hypertonic solution?
Shrink
50
Cells (shrink, swell, stay same) in a isotonic solution?
Stay same 
51
Are ions permeable or impermeable to membranes
Impermeable
52
Three ways ion channels can exist
Open, closed, or gated
53
Three major categories of gated channels:
1. Voltage gated channels
2. Ligand gated channels
3. Mecano gated channels
54
Voltage gated channels confirmational state depends on what?
Difference in ionic charge on the two membrane sides
55
Ligand gated channels confirmational state depends on what?
Binding of specific molecules
56
Mecano gated channels confirmational state depends on what?
Mechanical forces applied to membrane
57
Gradients are generated by what?
Active transport
58
Define: Facilitated diffusion
Process by which the diffusion rate of a substance is increased through interaction with a substance specific membrane protein
59
What molecules is facilitated diffusion used for?
Sugars and amino acids
60
Facilitated diffusion transport involves what done to the molecule?
Confirmational changes
61
Can facilitated transporters mediate movement of solutes in both directions?
Yes
62
What is a facilitative transporter?
Transmembrane proteins that bind to specific substance and changes its confirmation so as to facilitate diffusion of the substance down its concentration gradient
63
Define: Active transport
Energy requiring process, a substance binds to a specific transmembrane protein which changes its confirmation to allow passage of the substance through the membrane against the electrochemical gradient
64
What is an active site?
Part of an enzyme molecule that is directly involved in binding the substrate
65
What is an example of primary active transport in humans?
NA/K ATPase, Sodium potassium ATPase
66
What does NA/K ATPase do?
Pumps potassium in, sodium out
67
What is the ratio of sodium: potassium pumped?
3:2
68
What type of pump is ATPase?
P type pump 
69
Describe a P – type pump
Phosphorylation causes changes in confirmation an ion affinity that allowed transport against gradients
70
What is an E1 conformation?
Ion binding sites are accessible to inside of the cell
71
What is an E2 conformation?
Ion binding sites accessible to outside of the cell
72
What is a V type pump?
Actively transport H across walls of cytoplasmic organelles
73
What are ABC transporters?
ATP binding cassette
74
What is co-transport?
Coupling transport to existing ion gradients 
75
What drives cotransport of glucose?
Diffusion of sodium ions down concentration gradient
76
What is the secondary active transport of glucose?
Symport
77
Define: Neurons
Specialized cells for information transmission using changes in membrane potentials
78
Define: Dendrites
Receive incoming information, cell body contains nucleus and metabolic centre of cell
79
Define: Axon
Long extension for conducting outgoing impulses
80
Define: Resting potential
Membrane potential of nerve or muscle cell subject to changes when activated
81
Define: Depolarization
When cells stimulated, sodium channels open
82
Define: Action potential
When cells stimulated, voltage gated sodium channels open
83
Excitable membranes exhibit what type of behavior?
All or none
84
Where are action potential is generated?
Nodes of Ranvier
85
What does the speed of neural impulse depend on?
Axon diameter and weather axon is myelinated
86
Define: Postsynaptic cell
A cell that receives neurotransmitters from another cell across a synapse
87
Define: Synapse
Specialized junction of a neuron with its target cell
88
Define: Presynaptic cell
A cell that sends neurotransmitters to another cell across the synapse
89
Define: Synaptic cleft
Narrow gap between two excitable cells
