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BIO 202 > Chapter 7 > Flashcards

Chapter 7 Flashcards

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Biology 101 flashcards
1
Q

Plasma membrane

A

-boundary that separates living cell from surroundings
-controls traffic in and out of cell
-selective permeability-allows some substances to cross easier than others
-choosing what to pass= fundamental to life

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2
Q

Phospholipids

A

-most abundant lipid in plasma membrane
-amphipathic molecules- contain hydrophobic and hydrophilic regions

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3
Q

Fluid mosaic model

A

-membrane is a fluid structure with mosaic of proteins embedded in it
-freeze fracture studies support-splits membrane down middle of phospholipid bilayer

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4
Q

Sandwich model

A

-phospholipid bilayer lies between two layers of proteins
-problems with placement of membrane proteins which has hydrophilic and hydrophobic regions

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5
Q

Interactions that hold membrane molecules in place

A

-relatively weak hydrophobic interactions
-adjacent phospholipids switch positions, large membrane proteins may drift within layer but move slower

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6
Q

Fluidity

A

-influenced by components of membrane
-rich in un saturated fatty acids=more fluid than with saturated fatty acids
-membranes need to be fluid to work properly
-types of lipids determines temp membrane solidifies

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7
Q

Cholesterol

A

-different effects on membrane fluidity at different temps
-warm temps=restrains movement of phospholipids
-cool temps=membranes switch from fluid to solid state

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8
Q

Variations in lipid composition

A

-adaptations to specific environmental conditions
-ability to change lipid composition has evolved in organisms that live where temps vary

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9
Q

Membrane

A

collage of different proteins embedded in fluid matrix of lipid bilayer
-have unique collections of proteins

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10
Q

Protein

A

determine most of membranes specific functions

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11
Q

Peripheral proteins

A

bound to surface of the membrane

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12
Q

Integral proteins

A

penetrate the hydrophobic core
-hydrophobic regions consist of one or more stretches of non polar amino acids coiled into alpha helices

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13
Q

Transmembrane proteins

A

integral proteins that span the membrane

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14
Q

Major functions of membrane proteins

A

-transport
-enzymatic activity
-signal transduction (hormonal messages)
-cell cell recognition (allow proteins ro attach cells together)
-intercellular joining (joining with gap or tight junctions_
-attachment to cytoskeleton and extracellular matrix (maintain shape and stabilize location of proteins)

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15
Q

Cell cell recognition

A

-recognize each other by binding to surface molecules on extracellular surface of plasma membrane
-important in sorting and organizing of cells into tissues and organs
-basis for rejection of foreign cells

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16
Q

Glycolipids

A

membrane carbohydrates covalently bonded to lipids

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17
Q

Glyocproteins

A

membrane carbohydrates covalently bonded to proteins

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18
Q

Membrane built by

A

er and Golgi apparatus
-asymmetrical distribution of proteins, lipids and carbohydrates determined when built

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19
Q

What can pass through membrane rapidly

A

-hydrophobic (non polar) molecules (hydrocarbons, co2, o2) can dissolve in lipid bilayer and pass rapidly

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20
Q

What cannot cross membrane easily

A

polar molecules (sugars) and surrounding shells of water do not cross easily

21
Q

Transport proteins

A

-allow passage of hydrophilic substances across the membrane
-specific for substance it moves

22
Q

Channel proteins

A

-transport proteins have a hydrophobic channel that molecules or ion can use as a channel
-aquaporins-channel proteins that facilitate passage of water

23
Q

Carrier proteins

A

-transport proteins that bind to molecules and change shape to shuttle them across membrane

24
Q

Diffusion

A

tendency for molecules to spread out evenly into available space
-each molecule is random, diffusion of population of molecules is directional
-diffuse down their concentration gradient
-passive transport because no energy needed to happen

25
Q

Dynamic equilibrium

A

as many molecules cross the membrane in one direction as in the other

26
Q

Concentration gradient

A

region along which the density of a chemical substance increases or decreases
-no work done, no atp used to move substances down

27
Q

Osmosis

A

diffusion of water across selectively permeable membrane
-water diffuses across membrane from region of lower solute concentration to region of higher solute concentration until concentration is equal on both sides

28
Q

Tonicity

A

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

29
Q

Isotonic solution

A

solute concentration is the same as inside the cell, no net water movement across plasma membrane

30
Q

Hypertonic solution

A

solute concentration is greater than inside the cell, cell loses water

31
Q

Hypotonic solution

A

solute concentration is less than inside the cell, cell gains water

32
Q

Cell walls

A

help maintain water balance
-in hypotonic solution, wall swells and is now firm
-isotonic-no movement of water, wall is limp, wilting
-hypertonic- lose water, membrane pulls away from wall-plasmolysis

33
Q

Osmoregulation

A

control of solute concentrations and water balance
-necessary adaptation for life

34
Q

Facilitated diffusion

A

-transport proteins speed passive movement of molecules across membrane
-channel proteins provide corridors that allow specific molecule or ion to move across membrane

35
Q

Ion channels

A

-channel protein that open or close in response to stimulus

36
Q

Aquaporins

A

-channel proteins for facilitated diffusion of water

37
Q

Active transport

A

-moves substances against concentration gradient
-requires energy, ate
-performed by specific proteins in membranes
-allows cells to maintain concentration gradients
-sodium potassium pump

38
Q

Sodium potassium pump

A

-active transport
-K+ high inside cells and low outside
-Na+ low inside high outside
-uses a lot of bodies energy

39
Q

Membrane potential

A

-voltage difference across membrane
-cytoplasm -
-extracellular +
-created by differences in distribution of positive and negative ions across membrane

40
Q

Electrochemical gradient

A

-two forces that drive diffusion of ions across membrane
-chemical force-ions concentration gradient and
-electrical force-effect of membrane potential on ions movement

41
Q

Electrogenic pump

A

-transport protein that generates voltage across a membrane
-ex sodium potassium pump
-help store energy that can be used for cellular work

42
Q

Cotransport

A

-occurs when active transport of solute indirectly drives transport of other solutes

43
Q

Bulk transport

A

-small molecules enter or leave cell through lipid bilayer or transport proteins
-large molecules cross membrane in bulk via vesicles
-requires energy
-endocytosis and exocytosis

44
Q

Exocytosis

A

-transport vesicles migrate to membrane, fuse with it and release contents

45
Q

Endocytosis

A

-cell takes in macromolecules by forming vesicles from plasma membrane
-reversal of exocytosis involving different proteins
-3 types- phagocytosis, pinocytosis, receptor mediated endocytosis

46
Q

Phagocytosis

A

-cellular eating
-cell engulfs a particle in a vacuole
-vacuole fuses with lysosome to digest the particle

47
Q

Pinocytosis

A

-cellular drinking
-molecules taken up when extracellular fluid is gulped into tiny vesicles

48
Q

Receptor mediated endocytosis

A

-binding of ligands to receptors trigger vesicle formation

49
Q

Ligand

A

any molecule that binds specifically to a receptor site of another molecule

BIO 202 (10 decks)

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