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diffusion and membrane Flashcards

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Biology 101 flashcards
1
Q

three types of fibers in cytoskeleton

A

microtubules, microfilaments, intermediate filaments

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2
Q

microtubules

A

thicket, hollow rods constructed from globular proton dimers called tubulin
- grow out of centrioles
- control beating of cilia and flagella

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3
Q

microtubules functions

A

shape and support cell,
guide movements of organelles, separate chromosomes during cell division

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4
Q

flagella (1/few per cell) and cilia (many per cell)

A

differ in beating patterns
- structure: group of microtubules enclosed by plasma membrane, basal body that anchors
- dynein (motor protein) drives bending movement

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5
Q

dynenin

A

dyne arms contact, move and release out microtubules
- microtubules held together by flexible cross-linking proteins

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6
Q

microfilaments (actin filaments)

A
  • thinnest, solid rods built from molecules of globular actin subunits
  • bear tension
  • make up core of microvilli of intestinal cells
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6
Q

centrosome

A

has pair of centrioles, each with 9 triplets of microtubules arranged in a ring

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7
Q

microfilaments functions

A
  • maintain cell shape
  • muscle contraction
  • cytoplasmic streaming
  • cell motility
  • cell division
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7
Q

intermediate filaments

A
  • larger than microfilaments
  • smaller than microtubules
  • only in animals, vertebrates
  • support cell shape and fix organelles in place
  • more permanent than other two
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8
Q

cell junctions

A

neighboring cells in animal or plant often adhere, interact and communicate through direct physical contact
- plasmodesmata
- tight junctions
- desmosomes
- gap junctions

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9
Q

tight junctions

A

forms a water-tight seal between cells

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10
Q

desmosomes

A

act like velcro and fasten cells together

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11
Q

gap junctions

A

act like secret passageways and allow materials to pass between cells

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12
Q

plasma membrane

A

fluid mosaic of lipids and proteins
- selective permeability
- passive transport = no energy investment
- active transport = requires energy
- phospholipids (most abundant lipid in membrane) are amphipathic

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13
Q

fluid mosaic model

A

the membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids with hydrophobic portion protruding
- proteins (more slow) and lipids (rapid) shift laterally

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14
Q

membrane fluidity and temperature

A

as temp cools it becomes solid
- remains fluid at cooler temp if rich in phospholipids with unsaturated hydrocarbon tails

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15
Q

cholesterol effect on temperature

A

at warm it restrains movement, at cool it prevents tight packing

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16
Q

what determines most of the membrane’s specific functions?

A

proteins

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17
Q

integral proteins

A

penetrate hydrophobic interior of bilayer
- hydrophobic part of integral ha non polar HAs coiled into alpha helix

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18
Q

transmembrane proteins

A

integral proteins that span the membrane

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19
Q

peripheral proteins

A

loosely bound to the surface of the membrane

20
Q

six major functions of membrane proteins

A

transport
enzymatic activity
signal transduction
cell-cell recognition
intercellular junction
attachment to cytoskeleton and extracellular matrix (ECM)

21
Q

cell-cell recognition

A

bind to surface of molecule containing carbs on the extracellular surface of membrane
- carbs bonded to lipids (glycolipids) or proteins (makes glycoproteins)

22
Q

Permeability of Lipid Bilayer

A
  • hydrophobic/non polar molecules, like hydrocarbons, cross easily
  • hydrophilic/polar molecules, like sugars, do not cross easily
23
Q

Transport proteins

A

allow passage of hydrophilic substances
- channel proteins
carrier proteins

24
Q

channel proteins

A

aquaporins: facilitate passage of water
Ion channels (gated open and close in response to stimuli)

25
Q

carrier proteins

A

bind to molecule, change shape to shuttle them across

25
Q

diffusion

A

molecules spread out evenly into the available space
- passive transport
- diffuses down the concentration gradient (more concentrated to less)

26
Q

osmosis

A

diffusion of free water across membrane
- low solute concentration too high solute concentration

27
Q

tonicity

A

ability of a surrounding solution to cause a cell to gain or lose water

28
Q

isotonic

A

same solute in and out; no movement of water

29
Q

hypertonic

A

more solute concentration than inside cell; cell loses water

30
Q

hypotonic

A

solute concentration lower than inside cell; cell gains water

31
Q

facilitated diffusion

A

transport proteins speed passive movement of molecules

32
Q

Active transport uses energy to…

A

move solutes agains the grain
- ATP
- sodium potassium pump (2 K+ in, 3 Na+ out)

33
Q

plant example

A

hypotonic: swells until wall opposes; turgid
isotonic: no water movement; flacccid
hypertonic: membrane pulls away from wall; plasmolysis

34
Q

membrane potential and voltage

A

voltage across a membrane
- voltage = distribution of + and - ions across membrane

35
Q

electrochemical gradient

A

drive diffusion of ions across a membrane
- chemical force: ion’s concentration gradient
- electrical force: effect of voltage on ion’s movement

35
Q

electrogenic pump

A

transport protein that generates voltage across a membrane
- sodium potassium pump
- protein pump
- her store energy for cellular work

35
Q

cotransport

A

occurs when active transport of a solute indirectly drives transport of other solutes
- sucrose proton cotransporter

36
Q

bulk transport require…

A

energy and use vesicles for exocytosis and endocytosis

37
Q

exocytosis

A

transport vesicles migrate to the membrane, fuse with and release their contents

38
Q

endocytosis

A

cell brings in molecules/particulate matter by forming new vesicles from the membrane
- phagocytosis (cellular eating)
- pinocytosis (cellular drinking)
receptor-mediated endocytosis

39
Q

metabolism

A

getting energy from food to create all our chemical reactions
- all the chemical reactions that occur in living organisms
- anabolism and catabolism
- metabolic pathway: molecule -> product (each step catalyzed by a specific enzyme)

40
Q

anabolism

A

set of metabolic pathways that construct polymers from monomers
-consume energy

41
Q

catabolism

A

set of metabolic pathways that deconstruct polymers into monomers
- releases energy

42
Q

Energy

A

capacity to cause change
- kinetic, thermal, heat, potential, chemical , light

43
Q

kinetic energy

A

associated with motion

44
Q

thermal

A

kinetic associated with random movement of atoms

45
Q

heat

A

thermal energy transferred from one about to another

46
Q

potential

A

energy because of location or structure

47
Q

chemical

A

potential available for release in a chemical reaction

bio (10 decks)

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