Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key

image

Play button

image

Play button

image

Progress

1/86

Click to flip

86 Cards in this Set

  • Front
  • Back
Any amphipathic phospholipid has a ____ and a ____.
-polar (hydrophilic) head
-nonpolar (hydrophobic) tail
automatically, if you add an amphipathic lipid to water, they will form a:
membrane with hydrophobic tails on the inside and hydrophilic heads on the outside (near the water)
Carbohydrate tails will be found on the ____ of membranes because ____.
-outside
-because they function as transport molecules
_____ is another lipid found in membranes.
Cholesterol
Cholesterol found within a membrane has a two fold purpose:
1. makes membrane more rigid if too fluid
2. makes membrane more fluid if too rigid
3 main components of cell membranes
1. amphipathic lipids
2. cholesterol
3. protein
Unsaturated lipids have ____ bonds and make membranes more ____ by ____.
-double bonds
-fluid
-by disrupting the structure
Heating up a membrane makes it more ____.
-fluid ("melts it")
Two important types of protiens:
1. Extrinsic (peripheral)
2. Intrinsic (integral)
Extrinsic Proteins
-sit on outside of membrane
-bound to membrane
-polar in order to bind to polar heads of membrane
When embedded deep within the hydrophobic tails of the membrane, INTRINSIC proteins undergo _____ interactions.
-hydrophobic
When part of the INTRINSIC protein is near the polar heads of the membrane, it undergoes _____ interactions.
-polar
Membranes in our cells are ____, meaning they are selective to a few different kinds of molecules.
-semi permeable
Why do molecules go through membranes?
-because there is an imbalance of molecules on either side of the membrane
Thermodynamically, it is favorable to go through the membrane from high concentration to low concentration.
Simple Diffusion
Sometimes, despite thermodynamically good conditions, a protein is needed to aid in the process of movement across a membrane.
Facilitated Diffusion
For both passive facilitated diffusion and passive simple diffusion, what are the energy requirements?
-no energy needed
-spontaneous event that does not require any outside energy
-energy is actually given off(exogonic
-along gradient
The movement of molecules through the membrane
Transport
Transport - proteins act as ____.
-ports
Types of Ports
1. uniport
2. coport
a) symport
b) antiport
Any amphipathic phospholipid has a ____ and a ____.
-polar (hydrophilic) head
-nonpolar (hydrophobic) tail
automatically, if you add an amphipathic lipid to water, they will form a:
membrane with hydrophobic tails on the inside and hydrophilic heads on the outside (near the water)
Carbohydrate tails will be found on the ____ of membranes because ____.
-outside
-because they function as transport molecules
_____ is another lipid found in membranes.
Cholesterol
Cholesterol found within a membrane has a two fold purpose:
1. makes membrane more rigid if too fluid
2. makes membrane more fluid if too rigid
Two Processes of Transport
1. Passive Transport
-no energy required
-gives off energy(exergonic)
-spontaneous event
-follows [ ] gradient (high to low)
2. Active Transport
-requires energy (endergonic)to move against [ ] gradient
Two Types of Passive Transport
a) Simple Diffusion
-follows [ ] gradient

b) Facilitated Diffusion
-involves a carrier protein
-still moves with [ ] gradient
Two Types of Active Diffusion
a) Primary
-energy used directly: Na/K pump

b) Secondary
-coupled to primary: glucose symport with Na ion driven by Na/K pump
Active Transport
-requires energy to move against a [ ] gradient
-presence of carrier protein
-involves pumps
-channel gated
Types of Channels
1. Voltate-gated
2. Ligand-gated (molecule-gated)
3. Pores
Steps of Primary Active Transport (Na-K Ion Pump)
1. ATP hydrolysis to ADP
2. Conformational change of membrane protein allows bound Na to exit cell
3. K binds to membrane protein
4.-Conformational change allows bound K to leave cell
-Hydrolysis of phosphate bound to protein
Net movement of pumping process
-transports 3 Na ions out of cell for ever 2 K ions transported into cell
-ie. 3 positive charges out and 2 negative charges in
-maintains cell potential (maintains voltage between sides)
There are sites on membrane protein for sodium to bind but they are only active when:
-a phosphate group is added to the acid group on the protein
-ie. phosphate activates sodium receptors
Secondary Active Transport
-energy is used in a secondary step
-you must have something undergoing a primary active transport first
Endocytosis
-process by which materials are brought into the cell when portions of a cell membrane are pinched off into the cell
Example of Endocytosis
-process by which LDL delivers cholesterol into the cell
-LDL receptors on cell membrane surface
-LDL binds
-cell membrane engulfs LDL & pushes it within cell
-LDL particle is broken down & releases contents (triglycerides) within cell
-cholesterol has gained access to inside of cell
Oversupply of cholesterol inhibits:
-synthesis of LDL receptor proteins on cell membrane surface
Exocytosis
-the process by which materials exit the cell by the pinching off of part of the cell membrane
Allosteric
-the property of multisubunit proteins such that a conformational change in one subunit induces a change in another subunit
Kinase
-an enzyme that transfers a phosphate group to some other molecule (it phosphorylates)
Receptor Proteins
-portion on outside of cell
-usually has a polysaccharide
-can recognize foreign molecule, bind to it and then do something to it
-must transmit info. from outside of cell to inside
-does this via change in conformation of cell
Enzyme
-on portion of receptor protein that is inside of cell
-when change in conformation occurs, the receptor protein directly activates the enzyme
Enzymes come in two flavors:
1. Active - phoshorylated
2. Inactive - not phosphorylated
G protein
-bound to portion of receptor protein that is on inside of cell
-always bound to receptor either in active (GTP) or inactive (GDP) form
Inactive form of G protein
-GDP = guanidine diphosphate
Active form of G protein
-GTP = guanidine triphosphate
-made upon phosphorylation of GDP
G protein can stimulate the production of another messenger:
-secondary messenger, which is inside the cell
-cAMP, IP3, DAG, Ca2++
Primary Receptor
-hormone that binds to receptor protein on outside of cell
Secondary Receptor
-hormone that binds to receptor on inside of cell
-directly stimulates another enzyme
Unique characteristic of the active form of G protein (GTP)
-it is its own enzyme
-it can shut itself off: the enzyme built into its own subunit hydrolyzes it to GDP to turn off signal transduction
Adenylate Cyclase
-produces secondary messenger, cAMP, when bound to G protein
Adenylate Cyclase is only active when:
-it is bound to G protein
cAMP
-a kinase
-has pairs of subunits: c & r
-causes phosphorylation of ATP to ADP
-
cAMP:
a) c subunit
b) r subunit
a) c subunit catalyzes
b) r subunit acts as receptors
phosphotase
-enzyme that helps dephosphorylate
kinase
-enzyme that helps phosphorylate
Activation of protein by replacement of GDP with GTP results in production of ___.
phospholipase
Calcium is bound to its own carrier protein:
-calmodulin: picks up calcium ion and transports it around
Holoenzyme
-total enzyme
Apoenzyme
-protein: active site, etc.
-an enzyme that consists of polypeptide chains alone
Coenzyme
-coreactant
-actual reactant
-prosthetic group or co-factor
Enzymes: Structure
1. Holoenzyme
2. Apoenzyme
3. Coenzyme
4. Metal ions
Metal Ions
-M++: usually co-factors, no heavy metals
Subdivisions of Coenzymes: two different states
a) prosthetic group - enzyme that is bound firmly to protein
b) cofactor - enzyme that is loosley bound to protein
Co-factors can be metal ions:
calcium, magnesium, manganese
What determines the rate of a chemical reaction?
1. Temperature
2. pH
3. Concentration of Enzyme
4. Concentration of Substrate
First Order Reaction Rates
-rate of reaction is directly related to concentration of reactants
Zero Order Reaction Rates
-rate of reaction is constant (plateau)
Plateau results from:
-the occurence of saturation
(hyperbolic curve)
Saturation
-the molecule cannot go any faster than rate at plateau
Induced Enzyme Concentration
-when concentration of enzyme in body is low, a signal sent to brain causes production of more enzyme and vice versa
Three things that must happen for two molecules to react:
1. collision
2. collisions must be of proper orientations
3. collisions must have sufficient energy to undergo bond making/breaking
Competitive Inhibition
-substrate & competitive inhibitor both fit into active site
-higher substrate [ ] to yield same rate as noncompetitive inhibition
-max. rate is the same
Noncompetitive Inhibition
-inhibitor does not fit into active site
-must bind somewhere else on molecule
Oxidation
-loss of protons (H+)
Reduction
-gain of protons (H+)
coenzyme A
-identify active form of co-A by sulfer group
-active form is also attached to fatty acid group
-sulfer reacts with a fatty acid to make acyl-coA
Dehydrogenases
-enzymes that can catalyze oxidation/reduction reactions
NAD+
-oxidized form
NADH
-reduced form
FAD+
-oxidized form
FADH
-reduced form
NAD removes ___ H ions at a time while FAD removes ___ H ions at a time.
-one
-two
FAD is used to remove:
-a double bond
-removing an H ion on each side of double bond
-lipid metabolism needs double bond formation
Molecule which has an "energetic" bond
ATP
ATP
-if you chop off a phosphate group, you get energy
-sometimes ATP gives off only one phosphate group but usually it gives off two