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XIO > Traffic - Week 2 (ch. 3) > Flashcards

Traffic - Week 2 (ch. 3) Flashcards

1
Q

Plasma Membrane Structure - what it’s made of

A

phospholipid bilayer

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2
Q

Plasma membrane structure consists of…

A

hydrophilic (water loving) heads are polar,
face outward toward water
hydrophobic (water fearing) tails are nonpolar, face inward away from water

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3
Q

(in plasma membrane)

A

(1) barrier to diffusion - stops water soluble
molecules from passing through. water is small enough and it’s responsible for membrane fluidity
2. cholesterol
a. between phospholipids b. contributes to fluidity and stability

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4
Q

protein in membrane

A

a. some span the membrane - bridge spans the bay
(1) selective channels
(2) carrier proteins

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5
Q

proteins on one side of membrane

A

CRMFG

1) cell adhesion molecules (CAMs
2. receptors
(3) membrane bound enzymes
(4) filamentous meshwork
5. glycoproteins

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6
Q

Carbohydrates in plasma membrane

A

a. only on outer surface, bound to membrane proteins and lipids (glycoproteins, glycolipids)
b. important in recognition of cells of same type and tissue organization
c. involved in tissue growth (cells won’t overgrow) - won’t grow over side of petri dish

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7
Q

cell to cell adhesion

A

carbohydrates on membrane surface help arrange cells into groups, which are held together in various ways

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8
Q

types of cell to cell adhesion (FEECC)

A

FEECC

  1. CAMs (a protein and carbohydrate)
  2. extracellular matrix (only connective tissues)
    a. cells not joined directly to other cells, but in matrix of carbohydrates and protein fibers
    (1) collagen - resists tension (e.g., skin)
    (2) elastin - stretch and recoil (e.g., skin, lungs)
    (3) fibronectin - holds cells in position (all over body)
    b. substances diffuse through, going between blood and tissues
    c. important in normal cell functioning
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9
Q

Specialized junctions (TGD)

A

desmosomes, tight junctions and gap junctions

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10
Q

desmosomes (specialized junction)

A

cells join at particular spots, found all over body, particularly where stretch occurs (e.g., skin, muscle)

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11
Q

tight junctions

A

impermeable barrier, common in epithelial sheets where they prevent leakage. Looks sewn together

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12
Q

gap junctions

A

cells linked by protein tunnels, allows small molecules to pass between cells, important in some cells that transmit electrical activity (e.g., cardiac muscle)

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13
Q

Membrane transport - what determines it

A

two factors influencing transport - solubility of the substance in lipid, and size of substance

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14
Q

Passive transport

A

diffusion-molecules move down their concentration gradient (greater ➝ lesser concentration), charged particles move down electrochemical gradients. No ATP is used.

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15
Q

Types of Diffusion

A

FOS

a. simple diffusion -substance moves through lipid bilayer or protein channels (e.g., O2, CO2, some ions)
b. osmosis - water moves down its concentration gradient
c. facilitated diffusion uses a carrier protein that binds to the molecule to be transported and brings it to the other side of the membrane (e.g., glucose)

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16
Q

How different types of membrane transport work (small & big cars)

A

small, uncharged or nonpolar molecules move through lipid bilayer (e.g., O2 CO2, fatty acids)
ions and small polar molecules (like glucose) can move through channels or by carrier proteins if the right transporter exists
substances too big or without a special protein transporter need special mechanisms to get through the membrane

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17
Q

Filtration

A 
Also passive transport - water and solutes forced through membrane
by pressure (e.g., in kidneys)
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18
Q

Net diffusion

A

Diffusion from area A to area B minus diffusion from area B to area A
: Differences in arrow length, thickness, and direction represent the relative magnitude of molecular movement in a given direction.

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19
Q

Diffusion occurs if…

A

a substance can permeate the membrane

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20
Q

No diffusion occurs if…

A

If the membrane is impermeable to a substance

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21
Q

osmosis

A

H2O moves from side 1 to side 2 down its concentration gradient

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22
Q

Isotonic conditions

A

No net movement of water; no change in cell volume

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23
Q

Hypotonic conditions

A

Water diffuses into cells; cells swell

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24
Q

Hypertonic conditions

A

Water diffuses out of cells; cells shrink

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25
Q

Types of Active Transport (ATP used)

A
  1. carrier proteins transport substance against its concentration gradient (needs ATP to change conformation)
    a. primary active transport
    b. secondary active transport
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26
Q

primary active transport

A

energy from ATP used directly to transport a substance (e.g. Na+-K+ pump, in all cells)

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27
Q

secondary active transport (bus)

A
  • driven by gradients set up by primary active transport
    (1) in the digestive tract glucose and amino acids are “dragged along” with Na+ diffusing into cell (Na+ gradient set up by Na+-K+ pump) uses ATP as a 2nd step
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28
Q

Symport

A

When the transported molecule and cotransported ion move in the same direction

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29
Q

Antiport

A

When the transported molecule and cotransported ion move in opposite directions

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30
Q

Primary Active Transport in Sodium potassium pump

A

establishes Na+ concentration gradient from lumen to cell, which drives secondary active transport

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31
Q

Secondary Active Transport (about glucose)

A

creating glucose concentration gradient from cell to blood used for Facilitated Diffusion. Glucose hitches a ride with Na.

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32
Q

vesicular transport (bulk transport) - active transport

A

large molecules or multimolecular substances enclosed in pieces of membrane. endocytosis and exocytosis

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33
Q

what is Intercellular communication and signal transduction

A

cells must communicate so they can coordinate their activities (maintain homeostasis, control growth and development)

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34
Q

3 types of intercellular communication

A

gap junctions, signal molecules, chemical messengers

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35
Q

gap junctions

A

a. small molecules and ions directly exchanged between cells
b. important in spread of electrical signals (cardiac
and smooth muscle, very rarely neurons)

36
Q

signal molecules

A

on cell surface allow direct interaction
a. WBC - phagocytes (body defense cells) recognize and
kill invading cells

37
Q

4 types of chemical messengers

A

PHNN

paracrines, neurotransmitters, hormones, neurohormones

38
Q

paracrines

A

act locally (e.g., histamine in inflammatory response)

39
Q

neurotransmitters

A

act locally; nerve cells release them to other nerve cells, muscles, or glands

40
Q

hormones

A

acts over long distances, released into blood by endocrine glands

41
Q

neurohormones

A

act over long distances, released into blood by special nerve cells (neurosecretory neurons)

42
Q

Pathways of chemical messengers

A
  1. specialized protein receptors on plasma membrane bind with a particular messenger
  2. channel regulation
  3. tyrosine kinase pathway
  4. second messenger systems (most common pathway). triggers events and many possible responses
43
Q

3 general ways of eliciting a response - chemical messengers

A

(1) opening (most commonly) or closing
chemically- gated receptor channels in the membrane (regulates movement of ions in/out of cell)
(2) activating receptor-enzymes
(3) transferring signal to second messenger (most common) (an intracellular chemical messenger) which initiates a series of events inside cell

44
Q

channel regulation (this is a pathway for chemical messengers)

A

a. channel proteins open/close (act like gates)
b. receptor binding site is part of the channel, messenger binds ➝ channel opens
c. eg., neurotransmitters trigger movement of Na+,K+, or both across the membrane, which changes the electrical activity of cell (muscle and nerve cells)

45
Q

tyrosine kinase pathway

A

a. messenger binds and activates a receptor-enzyme (usually a protein kinase that phosphorylates another protein)
b. creates a chain reaction that activates a particular protein that brings about the response
c. eg., insulin and growth factors

46
Q

all second messenger systems (most common pathway - chemical messengers)

A

(1) messenger binds to receptor (G-protein- coupled receptor)
(2) enzyme on inside of membrane activated by G-protein
(3) intracellular second messengers are activated, and diffuse through the cell to trigger appropriate response
(4) typically a cascade is initiated and response accomplished by altering structure/function of particular proteins

47
Q

cAMP pathway (2nd messenger system)

A

(1) messenger binds to receptor
(2) activates G protein which activates adenylyl cyclase (on cytoplasm side)
(3) ATP ➝ cAMP, which diffuses through cell
(4) cAMP-dependent protein kinase activated, then phosphorylates a particular intracellular protein (this changes the protein’s shape/function, bringing about the appropriate response)
(5) can switch cellular processes on or off, eg., heart rate changes, formation of sex hormones in typical female, breakdown of stored glucose in liver, water conservation in kidneys

48
Q

Ca2+ pathway (2nd messenger system)

A

(1) messenger binds to receptor
(2) activates G protein which activates phospholipase C (on cytoplasmic side of membrane)
(3) PIP2 ➝ DAG + IP3 (phosphatidylinositol bisphosphate,
diacylglycerol, inositoltriphosphate)
(4) IP3 increases Ca2+ in cytosol (from stores in ER), Ca2+ diffuses through cell and binds to the protein calmodulin, which in turn activates another protein, bringing about the appropriate response
(5) pathway important in cell movement such as smooth muscle contraction

49
Q

very low concentrations of first messengers…(chemical messengers)

A

trigger large responses - one messenger molecule can result in millions of product molecules

50
Q

receptors can be

A

regulated (number, affinity for messenger)

51
Q

the two major second messenger systems can

A

interact, and there are others

52
Q

Apoptosis

A

an interesting example of a signal transduction (just transmitting signals)
pathway
2. programmed cell death

53
Q

reason for programmed cell death

A

development

b. tissue turnover
c. immune system (infected cells and worn- out phagocytes)
d. old, damaged or mutated cells

54
Q

how apoptosis works

A

cell detaches from neighboring cells and shrinks, killed from the inside by caspases (little scissor), which take apart DNA, cytoskeleton, etc.
a. cells normally receive signals for survival,which block the pathway causing apoptosis
(1) absence of growth factors or detachment from
extracellular matrix act as triggers
b. can receive “death signals” that override life pathway.

55
Q

Diseases associated with apoptosis

A

problems in pathways likely involved in Alzheimer’s, Parkinson’s and AIDS

d. not enough apoptosis may play role in cancer. mitochondria play a role (release cytochrome c which activates caspases)
4. does not trigger an inflammatory response

56
Q

Membrane Potential

A

separation of charges across a plasma membrane

57
Q

membrane potential (just separation of charges)

A
  1. separated charges have the potential to do work - electrical force of attraction can be harnessed
  2. measured in millivolts (mV) –
    more charges separated ➝ greater potential
  3. all plasma membranes have potential
  4. due to unequal distribution of a few key ions
58
Q

Ions involved in membrane potential

A
  1. Na+
  2. K+
  3. A- (large anionic intracellular proteins)
59
Q

Na+-K+ pump

A
  1. responsible both directly and indirectly for establishing membrane potential
60
Q

Na+-K+ pump Directly

A
  1. directly generates about 20% of membrane potential
    a. actively transports 3 Na+ out for every 2 K+ in
    (1) leaves cell slightly negative inside
    (2) establishes concentration gradients (Na+ high outside, K+ high inside)
    (3) passively, Na+ ➝ in, K+ ➝ out
61
Q

how Na+-K+ pump indirectly creates membrane potential

A

a. membrane is more permeable to K+than to Na+ (more K+ channels open)
b. K+ will passively flow out,increasing membrane potential
(1) K+ flows out until concentration gradient is
balance by electrical gradient (negative charges inside attract K+)
c. very little Na+ leaks back in (closed channels) leads to resting membrane potential of -70mV in a typical nerve cell (sign means more negative inside)

62
Q

Other effects of membrane potential

A
  1. A- cannot leave the cell (too large)
    a. contributes to negative charges that balance leakage
    of K+ out of cell
  2. Cl- distribution influenced by membrane potential a. high outside
    b. negative charge inside cell drives Cl-out (cells
    permeable to Cl-, but most do not actively transport it)
63
Q

membrane potential does what to muscles?

A

nerve impulses muscle contraction and secretory cells

b. significance in other cells not understood

64
Q

selective protein channel

A

to transport substances across membrane (e.g., ions), opening filled with water, channel is specific

65
Q

carrier protein

A

also transport specific molecules across membrane

66
Q

receptors

A
  • bind with molecules on outer surface and initiate changes in cell (chemicals in blood only influence cells with the right receptors)
67
Q

(protein on one side) membrane-bound enzymes

A

chemical reactions at inner or outer membrane surface

68
Q

filament meshwork

A

on inner side bind with cytoskeleton to maintain cell shape and for movement

69
Q

CAMS

A

stick out from outer surface and secure cell to other cells (cadherins “zip” cells together in tissues/organs), also cell communication (growth, defense responses), integrins span the membrane and link cytoskeleton to external environment and relay regulatory signals.

70
Q

more solutes =

A

less water

71
Q

Phosphorelate

A

ATP is used

72
Q

Chloride likes to hang out with

A

sodium, so it will be outside the cell

73
Q

endocytosis (pino/phagocytosis) - bulk transport

A

(1) fuse with lysosomes which break down
substance and release products to cell (e.g.,
bacteria)
(2) vesicle travels to opposite side of cell and
releases contents (cells lining capillaries)

74
Q

exocytosis - bulk transport

A

(1) secretion of large polar molecules like
hormones and enzymes
(2) adding components to membrane

75
Q

Phospholipid heads

A

polar, want to face water

76
Q

phospholipid tails

A

non-polar, away from water

77
Q

fluid mosaic model

A

The fluid mosaic model describes the cell membrane as a tapestry of several types of molecules (phospholipids, cholesterols, and proteins) that are constantly moving.

78
Q

pump

A

active transport is used

79
Q

not enough apotosis

A

cancer

80
Q

ending in “ase”

A

means enzyme

81
Q

80% of membrane potential comes from

A

passive flow of ions

82
Q

cellular respiration is how…

A

we get energy from food, glucose.

83
Q

ATP is just

A

stored energy

84
Q

cellular respiration is…

A

glycolysis, citric acid cycle and electron transport

85
Q

in diffusion, charged particles move down…

A

electrochemical gradients

86
Q

some proteins on one side of membrane…

A

Usually glycoproteins - some allow cells to recognize “self” and interact with one another.

87
Q

Dynamic equilibrium

A

Diffusion from area A to area B
Diffusion from area B to area A
No net diffusion

XIO (372 decks)

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