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Patho Phys Exam 1 > Cell Membranes, Transport, and signaling > Flashcards

Cell Membranes, Transport, and signaling Flashcards

1
Q

Composition of cell membrane (general)

A

Fluid mosaic model composed of a lipid bilayer and some cholesterol

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2
Q

The phospholipids of the cell membrane

A

3 carbon glycerol backbone, 2 fatty acid tails into the membrane, P and Alcohol

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3
Q

inner leaflet borders what

A

the cytoplasm

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4
Q

outer leaflet borders what

A

ECF

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5
Q

the head group of the fatty acids are ____ and made of what

A

charged/polar-composed of phosphate and alcohol into ECF (aqueous)

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6
Q

Fatty acid tails are ____

A

nonpolar- for the inner membrane/cytoplasm

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7
Q

Amphipathic

A

Polar headgroup borders aqueous environment, fatty acids for nonpolar tails (it has one end with a charge and one without)

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8
Q

Cholesterol (describe structure and function)

A

6 ringed strucuture to regualte and stabalize fluidity and can regulate bound peripheral proteins

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9
Q

Integral proteins

A

crosses one or more sides of the membrane (i.e. transport protein/channel/hormone receptor)

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10
Q

Peripheral proteins

A

loosely associated with the membrane, does not permeate into the bilayer

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11
Q

location of carbs on/in cell wall

A

outside-can connect to ECM

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12
Q

Carbohydrates

types-2, and functions-3

A

glycolipids and glycoproteins-

  1. regulate prt function
  2. attach protein to ECM
  3. marks cell as self
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13
Q

marks cell as self

A

carbs

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14
Q

Simple diffusion

A

From high to low [c], random thermal motion, rate depends on concentration and stops at equilibrium

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15
Q

Factors that determine if something will diffuse and which cross easier through cell membranes?

A

Size (smaller go faster/easier)

Polarity (nonpolar cross easier)

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16
Q

Osmosis

define, stops when?

A

simple diffusion of water, water moves from high concentration to low concentration and stops moving when the hydrostatic P exactly opposes osmotic pressure

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17
Q

Facilitated diffusion will move via

A

Carrier proteins (transporters or exchnagers)

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18
Q

Can cholesterol cross membrane via simple diffusion? (it is large)

A

YES, because it is very nonpolar

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19
Q

Passive facilitated diffusion

A

down a concentration gradient from high to low

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20
Q

Substrate Size moved via facilitated diffusion

A

larger molecules

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21
Q

The transport maximum velocity is known as what? Define it

A

Vmax: when all carrier molecules (protein transporters) are saturated, therefore transport cannot happen any faster

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22
Q

150 mm NaCl is how many mosm

A

150x2=300

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23
Q

150mm glucose is how many mOsm

A

150x1=150

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24
Q

Tonicity

A

considers whether or not a molecule can cross the membrane- only considers osmolarity of inactive molecules

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25
Q

Osmolarity Calculation

A

(molar concentration) x (# of osmotically active particles)

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26
Q

Does urea matter for tonicity?

A

No-it crosses readily

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27
Q

Tonicity and Osmolarity of 150mM NaCl, 300mM urea

A

300ton, double NaCl and ignore urea

Osmolarity=600

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28
Q

**I will use urea in the example

A

ignore for ton

use for osmolarity

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29
Q

isotonic ton

A

normal (300)

30
Q

hypertonic ton?

A

high (>300)

31
Q

Hypotonic ton

A

low (<300)

32
Q

Do Na+ and K- cross the membrane? Urea? Why does it matter?

A

Na and K Do not! so consider these for tonicity

Urea does
though! So DO NOT count for ton

33
Q

Cell in hypotonic solution

A

Swells, H20 goes in

34
Q

How to calculate tonicity

A

molar concentration x number of osmotically active particles, IMPERMEANT particles

(DO NOT COUNT UREA)

35
Q

Cell in hypertonic solution does what

A

shrinks-cell volume will go down (lose H20)

36
Q

Hypernatremia/water intoxication

A

low plasma sodium, increases water concentration inside and there is too much in the blood and moves into the tissue!

37
Q

kidney and liver disease clinical relevance

A

lose protein via urine, can get edema b/c maybe not making enough protein

38
Q

Specificity of carrier proteins

A

chemical binding to just one amino acid or molecule-competition is also to be considered

39
Q

Does facilitated diffusion require energy

A

It is passive-uses concentration gradients (from high to low)

40
Q

3 main types of ion channels (acvtivated by..)

A

NT, voltage, or stretch

41
Q

Ion channels move substances how

A

down concentration gradients

42
Q

specificity of ion channels

A

Very specific/selective

43
Q

Rate of ion channels

A

VERY HIGH RATES of flow-moves millions of ions/s

44
Q

Size of ions moving through ion channels

A

SMALL

45
Q

Rate of ion channel vs transporter

A

Ion channel much faster-does not need to change conformation in order to transport–just like an open door!

46
Q

Primary Active Transport and give ex

A

Uses ATP energy to move molecules against a gradient and directly uses ATP (ex Na/K ATPase)
-cell loses ATP

47
Q

Secondary Active Transport and ex

what are the two types?

A

Use energy, but not directly using ATP.
-Uses energy from a gradient that was previously built up/existed.

i.e. Moves Na down its gradient and harnesses that energy by coupling with molecule transport

2 types= symport and antiport

48
Q

Symport Secondary Active Transport

A

The two molecules are moved in the same direction

49
Q

Antiport

A

The two molecules are moving in opposite directions

50
Q

Vesicular transport (define)

A

pinching off of the cell membrane into or out of the cell

51
Q

endocytosis-vesicular transport

What are the 3 types?

A

large molecules-slow (pino, phago, and RM endocytosis)

3 types;
pino, phago, and receptor mediated endocytosis

52
Q

Exocytosis

A

vesicle inside the cell fuses with the PM and releases its contents into the ECM

53
Q

Second Messenger systems

why use them? What do they cause?

A

They get the signals across the cell membrane and to the target cell

They cause intracellular amplification via cascade pathways allowing one signal molecule to create 1000s of signaling molecules

54
Q

Adenyly cyclase/cAMP

explain the process

A

Can be stimulatory (Rs) or inhibitory (Ri):

the receptor for stimulatory hormone cAMP couples to G protein –> modifies Gs protein –> this binds to adenlyl cyclase –> converts ATP to cAMP

55
Q

increase in cAMP causes what

A

increased cAMP dep PKA which phosphorylates proteins (not sure we need to know this)

56
Q

Phospolipase C/inositol triphosphate (IP3)

Explain the pathway… (long)

A

The first messenger binds to magic 7 receptor

–> receptor changes
conformation

–> One G protein subunit (Gq) dissociates and bonds to phospholipase C
(PLC, signaling lipid)

–> PLC cleaves PIP2 into IP3 and DAG

–> IP3 is hydrophilic and goes into the endoplasmic reticulum

–> IP3 mobilizes Ca++ from intracellular stores (releases Ca++)

–> Ca++ affects smooth muscle/release vesicles

57
Q

Tyrosine Kinase

Function and explain pathway

A

attach a phosphate group to tyrosine residues in proteins

i. receptor is an integral protein, needs an agonist, has an enzyme that will phosphorylate tyrosine on proteins
ii. this phosphorylated tyrosine kinase protein can then be an enzyme and phosphorylate other proteins – ex: insulin, growth factors

58
Q

ion channels (indirect action):

A

hormone may directly bind to ion channels or might have a 2nd messenger that modulates these channels

59
Q

Hormone Regulation of gene expression

What? How do they? Function?

A

This applies to hormones that act on cytosolic and nuclear receptors (steroid hormones) thus need no secondary messenger-

They can get to the nucleus via carrier or membrane proteins and turn on the gene increasing translation of protein and leads to a biological effect

60
Q

Cell osmolarity is ~?

A

300mosm

61
Q

Isosmotic

A

Solution has same osmolarity as cell (=300mOsm)

62
Q

Hyposmotic

A

Solution has less solutes than cell (<300mOsm)

63
Q

Hyperosmotic

A

Solution has more solutes than cell (>300mOsm)

64
Q

Size of molecules moved via carrier proteins

A

Relatively large molecules (sugars, drugs, AAs)

65
Q

Transport Maximum Velocity (Vmax) and facilitated diffusion

A

when all carrier proteins are saturated with molecules the process cannot go any faster

66
Q

Compare the rate of ion channels vs carrier channels

A

Ion channels are much faster!! They are just like an open door

67
Q

PDE: Phosphpodiesterse

A

degrades cAMP to AMP

68
Q

Hormone pathway that requires a secondary messenger (pathway)

A

The hormone binds the receptor –> G protein –> effector protein –> secondary messenger is released –> goes through ion channel

69
Q

IP3 mobilizes Calcium.. this will result in what

A

Ca++ released from the ER/SR increase intracellular [Ca++] and act on calmodulin

Calmodulin will then bind to other proteins and increase their activity

70
Q

Hormone Regulation of gene expression

Rate? Longevity?

A

Slow-but long lasting

71
Q

Hormone Regulation of gene expression

location of receptors

A

cytosolic and nuclear receptors IN the cell

the hormone enters through a carrier protein or channel

Patho Phys Exam 1 (14 decks)

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