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Bio 105 > Lecture 6: Membranes > Flashcards

Lecture 6: Membranes Flashcards

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Biology 101 flashcards
1
Q

is the membrane fluid?

A

yes; phospholipids can move laterally within the membrane

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2
Q

membrane molecules

A

o Proteins are 2nd most common molecule in the membrane and impart most of the function
o Carbohydrate chains also “tag” cells for cell-cell recognition
o Cholesterol: helps maintain fluidity

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3
Q

Membrane proteins

A

o Proteins are the 2nd most common type of molecule in the membrane
o 25% of all genes encode for transmembrane proteins
o membrane proteins participate in transporting cell signaling, secretion, cell recognition, metabolism and cell-cell contact

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4
Q

integral proteins

A

transmembrane, span the membrane

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5
Q

peripheral proteins

A

are on one side of the membrane

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6
Q

fluid mosaic model

A

o Proteins can float around in the membrane but cannot flip from one side to the other

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7
Q

Transport proteins

A

help molecules move through membrane

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8
Q

enzymatic proteins

A

accelerate chemical reactions on cell surface; anchored to the cell’s surface

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9
Q

receptor proteins

A

bind to chemical signals from the extracellular environment

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10
Q

recognition proteins

A

often have a name that starts with CD, which “tag” different types of cells and aid in communication (a

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11
Q

extracellular matrix

A

o Cells taken out of the body and cultured in dishes
• Started to change when taken out of the body
• Developed different features

outside matrix that holds the cells together

unique to animal cells

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12
Q

how is the ECM formed

A

cells secrete protein fibers into extracellular fluid, weave together to form matric

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13
Q

functions of ECM

A

provides strength and rigidity to tissues
o Organize cells, allow them to move or stay in place
o Provide signals to cells to guide function or development
o Cells are able to crawl using ECM

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14
Q

significance of the ECM

A
  • some scientists believe that ECM is actually the functional unit of the body
  • arthritis, infection/inflammation, heart disease and some cancers are all probably ECM diseases
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15
Q

why is the ECM important

A 
o	To little: arthritis
o	Too much: astherosclerosis
o	Changes in: cancer
o	Useful in: infection
o	Boil animal tissues and cells degrade; ECM is left and concentrated: gelatin and glue
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16
Q

Plasma membrane

A

o Separates the cell’s internal environment from external
o Selectively permeable
o Controls entrance and exit from the cell
o Layer of non-polar lipids between two aqueous environments

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17
Q

Diffusion

A

movement of molecules from an area of greater concentration to an area of lesser concentration

passive process

continues until molecules is in dynamic equilibrium

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18
Q

concentration gradient

A

areas of higher and lower concentration of a given molecule

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19
Q

equilibrium

A

no concentration gradient

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20
Q

why do molecules move at all?

A

o Brownian motion and kinetic energy

o As they move around they bounce off of each other

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21
Q

when does diffusion occur faster?

A
  • Concentration gradient is greater
  • Distance is shorter
  • Temp is higher
  • Molecules are smaller
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22
Q

lipophilic

A

nonpolar molecules and can diffuse across the membrane

23
Q

lipophobic

A

polar molecules and cannot simply diffuse across the membrane

24
Q

membrane “permeability”

A

o Membrane is selectively permeable
o Completely permeable to nonpolar/lipophobic molecules
o Selectively permeable to polar, there are ways of getting across, but the membrane can control movement

25
Q

permeable molecules

A
  • O2
  • CO2
  • Lipids
  • Small non polar molecules
26
Q

selectively permeable

A
  • Ions
  • Polar molecules
  • H2O and glucose
  • Large molecules (proteins)
27
Q

osmosis

A

water moves across a semi-permeable membrane in response to a concentration gradient

28
Q

how does water move

A

from higher water concentration to lower water concentration

moves from lower solute concentration to higher solute concentration

29
Q

osmolarity

A

number of particles in a solution

30
Q

higher osmolarity

A

lower concentration in water molecules

31
Q

molarity

A

number of molecules in a solution

32
Q

aquaporins

A

water channels that water moves through in every cell

33
Q

water follows higher ion concentration

A

lower water concentration

34
Q

tonicity

A

osmolarity of any solutions surrounding a cell

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

35
Q

hypotonic

A

too much water in the cell causes cell to swell and burst

plant cell: turgid or normal

36
Q

isotonic

A

equal in both cell and solution

plant cell: flaccid

37
Q

hypertonic

A

not enough water in the cell causes cell to shrivel and water leaves cell

plant cell: plasmolyzed

38
Q

passive transport

A

no cell energy required

39
Q

simple diffusion

A

passive transport

substances diffuse freely across the membrane from greater to lesser concentration

40
Q

mediated diffusion

A

movement from greater to lesser concentration through open channels or other carrier proteins

rate depends on protein concentration

41
Q

what deters passage of ions and polar molecules

A

hydrophobic fatty acid tails

42
Q

what diffuses very slowly across the membrane

A

glucose, water and other small polar molecules

43
Q

what diffuses extremely slowly

A

charged molecules

44
Q

channel proteins

A

transport protein

  • Hydrophilic channel that allows travel through membrane
  • Often gated
  • Aquaporins
45
Q

carrier protein

A

transport protein

• Ligand binding induces shape-change and transport to other side

46
Q

uniporter

A

transports one substance in one direction

47
Q

symporter

A

transports two different substances in the same direction

48
Q

antiporter

A

transports two different substances in opposite directions

49
Q

Active transport

A

o Cell exerts energy
o Cells moves molecules AGAINST concentration gradient
o Always requires transport protein

50
Q

primary active transport

A

against their conc gradient; ATP is used

51
Q

secondary active transport

A

requires another concentration gradient

52
Q

can membranes create gradients?

A

yes
o bc many materials can’t readily cross the membrane build up of material on one side or the other can occur

chemical and electrochemical gradient

53
Q

gradients can be used in a variety of ways

A

• Accomplish secondary active transport
 Create a gradient of Na+ in order to accomplish secondary transport of glucose
• Create communication
 Neurons achieve communication by using electrical gradients

Bio 105 (19 decks)

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