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Physiology 210 > Cell Physiology > Flashcards

Cell Physiology Flashcards

1
Q

Plasma membrane

A

surround the cell
- physical barrier between ICF and ECF
- cell-to-cell communication
- structural support
- transport

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2
Q

Structure of plasma membrane

A

phospholipid bilayer with embedded proteins

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3
Q

Amphipathic molecule and examples

A

Contains polar and non polar regions
- phospholipids, cholesterol, glycolipids

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4
Q

Structure of phospholipid

A

Polar head group - hydrophilic
- phosphate attached to glycerol, nitrogen containing group, and glycerol backbone
Nonpolar tail group - hydrophobic
- fatty acid chain saturated or non saturated

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5
Q

Steroids - Cholesterol

A
  • Embedded in phospholipid bilayer
  • Amphipathic (non polar - CH rings, polar - hydroxyl group)
  • Maintains membrane fluidity
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6
Q

Glycolipids

A
  • Lipids with carbs attached
  • Plasma membrane surface
  • Form glycocalyx: coating around cell attached to protein and lipids
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7
Q

Membrane proteins

A

Integral (intrinsic):
- amphipathic, span full membrane, majority of proteins, transporters, channels
Peripheral (extrinsic):
- not amphipathic, do not penetrate bilayer

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8
Q

Desmosomes

A
  • adhering junctions that anchor cells together
  • maintain structural integrity of tissue
  • made of proteins: plaques, cadherins, intermediate filaments
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9
Q

Plaques, cadherins, intermediate filaments

A

Plaques: on cytoplasmic surface of cell, anchor cadherins
Cadherins: link cells together
Intermediate filaments: anchor cytoplasmic surface of desmosome to components inside cell

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10
Q

Tight junctions

A

Epithelial tissue for molecular transport, cells laid together in sheets, made of occludin proteins

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11
Q

Occludins

A
  • form nearly impermeable junctions
  • link adjacent cells together
  • limit movement of molecules between cells
  • limit movement of integral membrane proteins and lipids
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12
Q

Gap Junctions

A
  • transmembrane channels linking cytoplasms of adjacent cells
  • made of connexon proteins
  • electrically (move ions) and metabolically (move molecules)
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13
Q

Nucleus function

A
  • transmission of genetic info for next generation of cells and info needed for protein synthesis
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14
Q

Nucleus structure

A

Chromatin - DNA and proteins
Nuclear Envelope - double phospholipid bilayer
Nuclear pores - allow molecules to move in and out
Nucleolus - site of synthesis of ribosomal RNA

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15
Q

Cells with nucleus exceptions

A

RBC - no nucleus
Skeletal - many nuclei

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16
Q

Ribosome

A
  • protein synthesis
  • large and small subunit must join to function
  • some are free and some are bound to rough ER
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17
Q

Endoplasmic Reticulum

A

RER - flattened sacs with ribosomes attached to outer surface, synthesis of proteins
SER - branched tubular structure with no ribosomes attached to outer surface, synthesis of lipids and stores calcium

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18
Q

Golgi apparatus

A
  • cisternae (flattened sac)
  • receives protein vesicles and modifies and sorts into packages and secreted
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19
Q

Lysosomes

A
  • vesicle containing hydrolytic enzymes breaking large into small
  • degrade EC and IC debris
20
Q

Peroxisomes

A
  • vesicle containing oxidative enzymes which use oxygen to remove hydrogen
  • break down fatty acids alcohol drugs
  • produces toxic hydrogen peroxide but catalase breaks that down
21
Q

Mitochondria

A
  • makes ATP
  • double phospholipid membrane, inner membrane is called the cristae
  • have own DNA
22
Q

Cytoskeleton

A
  • protein filaments
  • maintain cell shape, maintain position of organelles, and mediate cell motility
23
Q

Cytoskeleton filaments

A

Microfilaments - actin
Intermediate filaments - many proteins
Microtubules - tubulin

24
Q

Endocytosis

A

materials brought into cell using vesicle

25
Q

Exocytosis

A

materials released from cell using vesicle
- secrete hormones
- release waste products
- add to cell membrane

26
Q

Phagocytosis

A
  • cell eating
  • pseudopodia from membrane to surround material
  • large materials
27
Q

Pinocytosis

A
  • cell drinking
  • membrane indents and pinches together
  • nonspecific small molecules, ions, nutrients
28
Q

Steps of phagocytosis

A

Recognition, attachment, pseudopodia, fusion, destruction, release

29
Q

Receptor-mediated endocytosis

A
  • specific process involving specific receptors to ligands
  • protein clathrin
  • binding of ligand causes conformation change and clathrin moves to membrane
  • clathrin coated pit if formed
  • vesicle lined with clathrin and releases clathrin
30
Q

Chemical driving force

A

high concentration of molecules to low concentration
concentration gradient

31
Q

Electrical driving force

A
  • membrane potential (difference in electrical voltage across membrane)
  • charged substance experiences attractive and repulsive forces
  • membrane potential will push or pull charged substance depending on direction and charge
  • neutral particles are unaffected
32
Q

Electrochemical driving force

A

sum of electrical and chemical driving force acting on ion, net direction

33
Q

Simple diffusion

A
  • PASSIVE movement down the gradient
  • small polar and nonpolar uncharged particles can cross
34
Q

Factors influencing simple diffusion rate

A
  • magnitude of driving force
  • membrane surface area
  • membrane permeability: lipid solubility, size/shape, temperature, thickness
35
Q

Osmosis

A

net water movement from high water concentration to low water concentration (low solute to high solute)

36
Q

Carrier mediated facilitated diffusion

A
  • transport proteins with specific binding site
  • passive, move from high to low concentration
  • GLUT moves glucose
37
Q

Channel mediated facilitated diffuion

A
  • selective to specific ions
  • depends on electrochemical gradient of that ion, passive
  • channels exist either open or closed and can be gated (voltage, ligand, mechanically)
38
Q

Active transport

A
  • moves against gradient
  • needs energy
  • proteins have specific binding sitesp
39
Q

Primary active transport

A
  • ATP driven transport process
  • Na+/K+ pump
40
Q

Secondary active transport

A
  • movement of ion down its electrochemical gradient drives transport process
  • Na+/glucose and Na+/H+ cotransporter
41
Q

Chemical messengers and receptors

A
  • specific binding sites
  • show saturation
  • bind different messengers with different affinities
  • found on plasma membrane, intracellularly, cytosol, nucleus
42
Q

Intracellular receptors

A
  • lipid-soluble chemical messengers
  • some act as transcription factors by biding to the response element on a DNA sequence and alter protein synthesis
43
Q

Membrane-bound receptors

A
  • water-soluble chemical messengers
  • 3 types: channel-, enzyme-, G-protein-
  • First messenger: extracellular chemical messenger binds to membrane receptor
  • Second messenger: after first messenger binding, substance that enters or is generated in cytoplasm
  • Protein kinase: enzyme that phosphorylates another protein (adds phosphate group to protein) which alters activity of another protein
44
Q

Steps of signal transduction

A
  1. first messenger binds to binding sites on receptor
  2. ion channel in receptor protein opens
  3. ions move through channel
  4. alter electrical properties of cell and produce a response
45
Q

G-protein linked receptors

A
  • link between receptor in plasma membrane and an effector protein (ion channel or enzyme)
  • alpha subunit of G-protein binds GDP when inactive and GTP when active
    1. binding of first messenger causes conformational change increases affinity for GTP and decreases affinity for GDP
    2. G protein dissociates and alpha subunit is activated and separated from beta and gamma
    3. Activated alpha subunit moves to effector protein to create a response
    4. Alpha subunit is now inactivated and binds to GDP, beta, gama in membrane receptor
46
Q

cAMP second messenger system

A
  1. binding of first messenger causing conformational change increasing affinity of alpha subunit for GTP and decreasing affinity for GDP
  2. activated alpha subunit of Gs protein separates from beta and gamma and binds to adenylyl cyclase (membrane enzyme cytoplasmic)
  3. adenylyl cyclase converts cytosolic ATP to cyclic AMP
  4. Cyclic AMP acts as second messent and diffuses through cytoplasm
  5. cAMP binds and activates protein kinase A (PKA)
  6. Activated PKA catalyzes phosphorylation of cell proteins by transferring phosphate group from ATP to cell proteins
  7. Phosphorylated proteins result in cell response

Physiology 210 (12 decks)

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