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General Biology I E2 > Chapter 7 > Flashcards

Chapter 7 Flashcards

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1
Q

Plasma membrane

A
  • the boundary that separates the living cell from its nonliving surroundings
  • exhibits selective permeability allowing some substances to cross more easily than others
    ?-extracellular matrix is nonliving
    -size, charge, shape, what’s on the surface of a cell can determine what can get in
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2
Q

Cellular membranes are a…

A
  • bilayer

- fluid mosaics (mixture) of lipids, proteins, and carbohydrates

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3
Q

Phospholipids structure

A

the most abundant lipid in the plasma membrane

  • are amphipathic molecules
  • arranged according to the fluid mosaic model
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4
Q

Amphipathic

A

contains both hydrophobic and hydrophilic regions

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5
Q

Fluid Mosaic Model

A

a membrane is a fluid (flexible/moveable) structure with a “mosaic” of various proteins embedded in it
-dynamic

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6
Q

Phospholipids in the plasma membrane

A
  • can readily move within the bilayer
  • with the proteins drifting within the bilayer
  • can move laterally really fast (x10^7per sec/ spontaneously)
  • can flip-flop very slowly (once per month)/ not spontaneous
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7
Q

Membrane fluidity

A

influenced by specialized motor proteins, temperature, and lipid composition

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8
Q

Flippases

A
  • enzyme that catalyze the phospholipid flip-flop from one side to another
  • help accelerate to move phospholipids quicker
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9
Q

The type of hydrocarbon tails in phospholipids affects …

A

the fluidity of the plasma membrane

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10
Q

Saturated fatty acids

A
  • are less fluid than unsaturated fatty acids

- are more tightly packed

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11
Q

Unsaturated fatty acids

A

are more fluid

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12
Q

steroid (cholesterol)

A

has different effects on membrane fluidity at different temperatures

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13
Q

?what affects the fluidity

A
  • type of fatty acids
  • type of steroid
  • specialized proteins
  • temperature
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14
Q

Warm temperatures (37C)

A

cholesterol restrains (“holds on” because of hydrophobicity) the movement of phospholipids and reduces fluidity

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15
Q

Cool temperatures

A
  • cholesterol maintains fluidity by preventing packing

- molecular motion slows down, doesn’t let the phospholipids compress

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16
Q

Membrane is a collage of …

A

different proteins embedded in the fluid matrix of the lipid bilayer that help to determine the membrane’s specific functions

i.e. collagen proteins help hold cells together

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17
Q

The cellular membrane is composed of two pieces/layers

A

1) inner layer (cytoplasmic side)
2) outer layer (extracellular side)
AKA. leaflets

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18
Q

Integral Proteins

A
  • embedded within
  • penetrate the hydrophobic core of the lipid bilayer
  • often transmembrane proteins that completely span the membrane
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19
Q

Peripheral Proteins

A
  • appendages loosely bound to the surface of the membrane
  • are loosely attached to surface of the cell
  • can come-and-go
  • doesn’t go all the way through the membrane
  • may embed in one of the leaflets
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20
Q

6 major functions of membrane proteins

A

1) Transport
2) Enzymatic Activity
3) Signal Transduction
4) Cell-Cell Recognition
5) Intracellular Joining
6) Attachment to the cytoskeleton and extracellular matrix (ECM)

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21
Q

Transport

A

a protein that spans the membrane may provide a hydrophilic channel across the membrane that is selective for a particular solute

  • can change shape or use ATP
  • to get into the cell
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22
Q

Enzymatic activity

A

a protein in the membrane may be an enzyme with its active site exposed to substances in the adjacent solution

  • can carry out sequential steps of metabolic pathway
  • can control what they do

i. e. proteins in mitochondria will affect different
- can localize proteins
- improves efficiency

23
Q

Signal Transduction

A

a membrane protein may bind an external messenger (signal) that causes a message to be sent inside of the cell

  • function as a receptor
  • lock and key
  • i.e. endorphine and pain response
24
Q

Cell-Cell Recognition

A

some glycoproteins serve as identification tags that are specifically recognized by other cells, facilitating cell-cell recognition

  • cell circular and move around the body
  • or adjacent cells in tissues
  • use proteins to associate with other proteins to determine if adjacent cells are a part of that organism
  • “handshake”
    i. e. foreign vs. immune cell
25
Q

?Intracellular Joining

A

membrane proteins of adjacent cells may hook together in various kinds of junctions, such as gap junctions or tight junctions

  • i.e. gap or tight junctions
  • protein rich regions of cells
  • hold/anchor cells together
26
Q

?Attachment to the cytoskeleton and extracellular matrix (ECM)

A

-attach to tissue

27
Q

?Membrane have …

A

distinct inside and outside faces that affects the movement of proteins synthesized in the endomembrane system
-eukaryotic cells

28
Q

?Membrane proteins and lipids from the ER and Golgi apparatus are …

A
  • transported in membrane’s vesicles that may fuse with the plasma membrane to release their cargo
  • inside of the Golgi or ER will be produced on the outside of the plasma membrane
  • i.e phagocytosis: produced on outside now becomes the inside
29
Q

Hydrophobic molecules

A

lipid soluble and can pass through the membrane rapidly

30
Q

Polar molecules

A

do no cross the membrane rapidly
-transport proteins allow passage of hydrophilic substances across the membrane

  • utilize proteins that provide passageways
  • different channels
31
Q

Passive Transport

A

diffusion of a substance across a membrane with no energy investment
-no ATP (directly) needed

32
Q

Diffusion

A

-the tendency for molecules of any substance to spread out evenly into the available space
-from [high] to [low]
(until equilibrium is reached)
-type of passive transport

-substances diffuse down their concentration gradient, the difference in concentration of a substance from one area to another to the point of equilibrium

33
Q

Osmosis

A

the movement of water across a semipermeable membrane and is affected by the concentration gradient of dissolved substances

  • move from area of higher free water concentration to an area of lower free water concentration
  • type of passive transport
34
Q

Tonicity

A

the ability of a solution to cause a cell to gain or lose water and has great impact on cells without walls

35
Q

Isotonic

A
  • the concentration of solutes in the same as it is inside the cell
  • no net movement of water
36
Q

Hypertonic

A
  • the concentration of solutes outside is greater than it is inside the cell
  • cell will lose water or shrink

-solutes higher outside the cell –> cause shrinking

37
Q

Hypotonic

A
  • the concentration of solutes is less than it is inside the cell
  • cell will gain water or swell

-solutes higher inside the cell –> draw liquid in –> cause bursting (lysed)

38
Q

animals and other organisms without right cell walls living in hypertonic or hypotonic environments must have special adaptations such as

A

transport proteins for osmoregulation

39
Q

Osmoregulation

A

-movement of bulk water across the membrane

40
Q

Aquaporin

A
  • channel protein, involved in water movement
  • find in intestines, on skin (cells), move water in and out of did fern location
  • move water quickly

-can move water in both directions

41
Q

in Facilitated Diffusion

A

transport proteins speed the movement of molecules across the plasma membrane

42
Q

Transport or channel proteins

A
  • work on one or two specific types of proteins
  • different types
  • provide corridors that allow a specific mo
43
Q

Carrier protein

A
  • facilitate movement of molecules through membranes
  • undergo a subtle change in shape that translocates or moves the solute-binding site across the membrane
  • change shape when bind to protein they are binding to (conformational change)
  • shape change, allow to drop off molecule on inside
  • [high] to [low]

-i.e. glucose transporters

44
Q

Active Transport

A

uses energy, usually in the form of ATP to move solutes against their concentration gradient ( [low] to [high] )
-molecules are pumped against gradient, that’s why they need ATP

45
Q

Sodium-potassium pump

A

one type of active transport system

  • co-transporter
  • moves two things at once
  • uses ATP
46
Q

Membrane Potential

A
  • the voltage difference across a membrane
  • type of active transport
  • create a “battery”
47
Q

Electrochemical gradient

A
  • caused by the concentration electrical gradient of ions across a membrane
  • a charge differential across the membrane
48
Q

Electrogenic pump

A
  • a transport protein that generates the voltage across a membrane
  • create reservoir (storage area) for different types of molecules of highly concentrated molecules (protons, H+)
49
Q

Bulk transport of large molecules (or large amounts) move …

A

ACROSS the plasma membrane occurs
-NOT THROUGH the membrane

done by…
exocytosis and endocytosis
-movement into and out of the cell

50
Q

Exocytosis

A

transport vesicles migrate to the plasma membrane, fuse with it, and release their contents outside the cell

i. e. cell produces something and releases (proteins) outside of the cell
i. e. beta lets-secrete insulin

51
Q

Endocytosis

A

the cell takes in macromolecules by forming new vesicles from the plasma membrane

i.e. phagocytosis (cell eating)-bring in solid of some type (food, macromolecule, whole organism, bacteria)
white blood cell (immune cell)-to eat bacteria/viruses and break them down

i.e. pinocytosis (cell drinking)-liquids

52
Q

receptor-mediated endocytosis

A

-bring in proteins from plasma membrane

  • constantly recycling and feeding out new vesicles
  • make cell membrane roughly the same size
  • control behavior of cell
  • i.e. endorphines and morphine
  • receptor on protein of cell
53
Q

3 primary types of endocytosis

A

1) phagocytosis
2) pinocytosis
3) receptor-mediated endocytosis

General Biology I E2 (5 decks)

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