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Physiology 210 > Cell Physiology > Flashcards

Cell Physiology Flashcards

1
Q

Functions of Plasma Membranes

A
  1. Physical barrier
  2. Cell to Cell communication
  3. Structural support
  4. Transport
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2
Q

Phospholipid Bilayer

A

Spontaneously form bilayer
Polar head faces aqueous environment
Nonpolar tails from hydrophobic core

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3
Q

Steroids

A

Cholesterol maintains membrane fluidity

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4
Q

Glycolipids

A 
Lipids with CHO chain attached
Outer leaflet of plasma membrane 
Amphipathic 
Forms glycocalyx 
-layer of carbs linked to lipids
-identification + interaction between cells
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5
Q

Desmosomes

A

Adhering junctions that anchor cells together in tissues subject to considerable stretching or mechanical stress
Maintain the structural integrity of tissue
Cadherins link cells together

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6
Q

Tight Junctions

A

Occludins form nearly impermeable junctions that link adjacent cells together and limit the movement of molecules between cells

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7
Q

Gap Junctions

A

Links cytoplasm of adjacent cells with connexions
Communicating Junctions
Electrically and metabolically couple cells

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8
Q

Nucleus Function

A

Transmission of genetic information and contains information for protein synthesis

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9
Q

Nucleus Structure

A

Nuclear envelope is made of 2 phospholipid bilayers and has pores that allow molecules to move in and out of the nucleus

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10
Q

Chromatin

A

DNA and associated proteins

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11
Q

Nucleolus

A

Site of synthesis of ribosomal RNA

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12
Q

Ribosome Function

A

protein synthesis

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13
Q

Ribosome Structure

A

Composed of large and small subunit that are not functional when separated

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14
Q

Rough Endoplasmic Reticulum Function

A

Synthesizes proteins and performs post-translational modifications needed for a functional protein

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15
Q

Rough Endoplasmic Reticulum Structure

A

Flattened sacs with ribosomes attached to outer surface

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16
Q

Smooth Endoplasmic Reticulum Function

A

Synthesizes lipids, stores calcium, drug detoxification

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17
Q

Smooth Endoplasmic Reticulum Structure

A

Branched tubular structure with no ribosomes attached to outer surface

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18
Q

Golgi Apparatus Function

A

Modifies proteins made at RER, sorts and packages proteins into vesicles, sends proteins to where it needs to be

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19
Q

Golgi Apparatus Structure

A

Composed of cisternae

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20
Q

Lysosomes

A

Contains hydrolytic enzymes which break large molecules into small subunits
Active at pH of 5

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21
Q

Peroxisomes

A

Contains oxidative enzymes which uses oxygen to remove hydrogen from molecules, breaking them down
Breaks down fatty acids, alcohol, drugs
byproduct is H2O2

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22
Q

Mitochondria

A

Makes energy for the cell
contains double phospholipid membrane
Have own DNA

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23
Q

Cytoskeleton Function

A

Maintain cell shape, position of organelles in cell

24
Q

Cytoskeleton Structure

A

Composed of protein/cytoskeletal filaments
Microfilaments = actin
Intermediate filaments
Microtubules = tubulin

25
Q

Phagocytosis

A

Uses extensions of the plasma membrane called pseudopodia to surround material being brought into the cell
Brings in large particles

26
Q

Pinocytosis

A

Plasma membrane indents below the particles to be brought into the cell
Nonspecific process
Brings in small molecules like ions and nutrients

27
Q

Receptor-mediated Endocytosis

A

Specific process - involves receptors that bind specific ligands brought into the cell
Involves clathrin
-concentrates
-clathrin-coated vesicle is formed

28
Q

Exocytosis

A

Release content from cell using vesicles

  • hormones
  • waste products
29
Q

Chemical Driving Force

A

Chemical driving is due to the concentration gradient of the substance

30
Q

Electrical Driving Force

A

Electrical driving is due to the membrane potential

31
Q

Electrochemical Driving Forces

A

The sum of the electrical and chemical driving forces acting on an ion - depends on net direction of both

32
Q

Simple Diffusion

A

Passive movement of molecules through bilayer
Doesn’t require energy
Moves in concentration gradient

33
Q

What can move by diffusion?

A

small, nonpolar, uncharged = yes
small, polar, uncharged= maybe
large, polar uncharged = no
any molecule with a charge will not move by diffusion

34
Q

Factors Influencing Rate of Diffusion

A
  1. Lipid solubility of the diffusing substance - nonpolar cross easier
  2. Size + shape of substance - smaller, even shaped cross easier
  3. Temperature - hotter=greater membrane permeability
  4. Diffusing distance - how thick distance is
35
Q

Osmosis

A

Passive diffusion of water

Moves from area of low solute concentration to area of high solute concentration

36
Q

Carrier-Mediated Facilitated Diffusion

A

Involves transport proteins called carriers which have a specific binding site for the substance to be transported

  • Bind the substance and move it across plasma membrane from high to low concentration
  • no energy required
37
Q

Channel-Mediated Facilitated Diffusion

A

Selective for a certain molecule (usually an ion)
Electrochemical gradient determines ion flux
In an open or closed state
-voltage gated
-ligand gated
-mechanically gated

38
Q

Active Transport

A

Uses ATP
Involves transport proteins with specific binding sites for the substance transported
Capable of going against concentration gradient

39
Q

Primary Active Transport

A

Energy source for the process is ATP
eg. NA+/K+ pump
-maintains membrane potential + concentration gradient of ions
At rest = high Na+ outside of cell and high K+ inside of cell
3 Na+ in and 2 K+ out

40
Q

Secondary Active Transport

A

Energy source is movement of an ion down its electrochemical gradient
Couples movement of an ion down it’s electrochemical gradient with another substance moving against its concentration gradient
eg. Na+/Glucose cotransporter or Na+/H+ exchanger

41
Q

Unsaturable Transport

A

Simple Diffusion

42
Q

Saturable Transport

A

Mediated transport

43
Q

Signal Transduction

A

Sequence of events between the binding of a messenger to a receptor and the production of a cellular response

44
Q

First Messenger

A

Extracellular chemical messenger that binds to a specific membrane-bound receptor

45
Q

Second Messenger

A

Substance that enters or is generated in the cytoplasm of a cell following the binding of the first messenger to its receptor

46
Q

Properties of Receptors

A

Receptors have specific binding sites for a specific messenger
Receptors show saturation - defined number of binding sites
Receptors bind different messengers with different affinities

47
Q

Lipid-soluble Chemical Messengers

A

Bind to receptors in cytoplasm or nucleus
steriod hormones
alters transcription of mRNA by binding to response element
alters rate of protein synthesis

48
Q

Water-Soluble Chemical Messengers

A

Bind to receptors on extracellular surface or plasma membrane
hormones, neurotransmitters
channel, enzyme, G-linked protein receptors

49
Q

Ligand-gated Ion Channels

A

Membrane-bound receptor
1. 1st messenger binding to receptor opens ion channel
2. ions cross membrane
3. change in electrical properties of cell
Fast, may be a calcium channel

50
Q

Enzyme-Gated Ion Channels

A

Membrane-bound receptor

  • proteins that function as a receptor also have intrinsic enzyme activity
  • receptor tyrosine kinases
  • docking site for cytoplasmic proteins
  • autophosphorylates
  • activation of cytoplasmic proteins by phophorylation
51
Q

G-Protein Linked Receptors

A

Membrane-bound receptors

  • cytosolic surface of plasma membrane
  • bings guanosine nucleotides
  • alpha, beta, gamma subunits - only alpha subunits bind nucleotides
52
Q

Activation of G-Proteins on Ion Channels

A
  1. Binding of 1st messenger to a receptor causes a conformational change in receptor
  2. Affinity of alpha subunit for GTP increases, GDP dissociates, GTP binds
  3. GTP-bound alpha subunit dissociates from beta and gamma, moves to ion channel
  4. Ion channel opens or closes, alters flow of ions across membrane
53
Q

Activation of G-Proteins on Enzymes

A
  1. Binding of 1st messenger to a receptor causes a conformational change in receptor
  2. Affinity of alpha subunit for GTP increases, GDP dissociates, GTP binds
  3. GTP-bound alpha subunit dissociates from beta and gamma, moves to enzyme
  4. Gs protein stimulates enzymes, Gi protein inhibits protein
  5. Alters production of 2nd messenger in cytosol
54
Q

cAMP 2nd Messenger System

A
  1. Gs activates cAMP 2nd messenger system
  2. cAMP is converted to noncyclic AMP by phosphodiesterase
  3. Gi inhibits cAMP 2nd messenger system
55
Q

Calcium as 2nd Messenger

A
  1. Active transporters maintain low cytosolic [Ca2+]
  2. 1st messenger binds to receptor
  3. receptor is ligand-gated ion channel or activates G-protein
  4. Increase in cytosolic [Ca2+]
  5. Ca2+-induced Ca2+ release
  6. Ca2+ is a 2nd messenger
  7. Activates calmodulin
  8. Calcium-calmodulin complex alters activity of enzymes + proteins

Physiology 210 (12 decks)

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