Biochemistry Exam 2

Front 1

Any amphipathic phospholipid has a ____ and a ____.

Back 1

-polar (hydrophilic) head
-nonpolar (hydrophobic) tail

Front 2

automatically, if you add an amphipathic lipid to water, they will form a:

Back 2

membrane with hydrophobic tails on the inside and hydrophilic heads on the outside (near the water)

Front 3

Carbohydrate tails will be found on the ____ of membranes because ____.

Back 3

-outside
-because they function as transport molecules

Front 4

_____ is another lipid found in membranes.

Back 4

Cholesterol

Front 5

Cholesterol found within a membrane has a two fold purpose:

Back 5

1. makes membrane more rigid if too fluid
2. makes membrane more fluid if too rigid

Front 6

3 main components of cell membranes

Back 6

1. amphipathic lipids
2. cholesterol
3. protein

Front 7

Unsaturated lipids have ____ bonds and make membranes more ____ by ____.

Back 7

-double bonds
-fluid
-by disrupting the structure

Front 8

Heating up a membrane makes it more ____.

Back 8

-fluid ("melts it")

Front 9

Two important types of protiens:

Back 9

1. Extrinsic (peripheral)
2. Intrinsic (integral)

Front 10

Extrinsic Proteins

Back 10

-sit on outside of membrane
-bound to membrane
-polar in order to bind to polar heads of membrane

Front 11

When embedded deep within the hydrophobic tails of the membrane, INTRINSIC proteins undergo _____ interactions.

Back 11

-hydrophobic

Front 12

When part of the INTRINSIC protein is near the polar heads of the membrane, it undergoes _____ interactions.

Back 12

-polar

Front 13

Membranes in our cells are ____, meaning they are selective to a few different kinds of molecules.

Back 13

-semi permeable

Front 14

Why do molecules go through membranes?

Back 14

-because there is an imbalance of molecules on either side of the membrane

Front 15

Thermodynamically, it is favorable to go through the membrane from high concentration to low concentration.

Back 15

Simple Diffusion

Front 16

Sometimes, despite thermodynamically good conditions, a protein is needed to aid in the process of movement across a membrane.

Back 16

Facilitated Diffusion

Front 17

For both passive facilitated diffusion and passive simple diffusion, what are the energy requirements?

Back 17

-no energy needed
-spontaneous event that does not require any outside energy
-energy is actually given off(exogonic
-along gradient

Front 18

The movement of molecules through the membrane

Back 18

Transport

Front 19

Transport - proteins act as ____.

Back 19

-ports

Front 20

Types of Ports

Back 20

1. uniport
2. coport
a) symport
b) antiport

Front 21

Any amphipathic phospholipid has a ____ and a ____.

Back 21

-polar (hydrophilic) head
-nonpolar (hydrophobic) tail

Front 22

automatically, if you add an amphipathic lipid to water, they will form a:

Back 22

membrane with hydrophobic tails on the inside and hydrophilic heads on the outside (near the water)

Front 23

Carbohydrate tails will be found on the ____ of membranes because ____.

Back 23

-outside
-because they function as transport molecules

Front 24

_____ is another lipid found in membranes.

Back 24

Cholesterol

Front 25

Cholesterol found within a membrane has a two fold purpose:

Back 25

1. makes membrane more rigid if too fluid
2. makes membrane more fluid if too rigid

Front 26

Two Processes of Transport

Back 26

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

Front 27

Two Types of Passive Transport

Back 27

a) Simple Diffusion
-follows [ ] gradient

b) Facilitated Diffusion
-involves a carrier protein
-still moves with [ ] gradient

Front 28

Two Types of Active Diffusion

Back 28

a) Primary
-energy used directly: Na/K pump

b) Secondary
-coupled to primary: glucose symport with Na ion driven by Na/K pump

Front 29

Active Transport

Back 29

-requires energy to move against a [ ] gradient
-presence of carrier protein
-involves pumps
-channel gated

Front 30

Types of Channels

Back 30

1. Voltate-gated
2. Ligand-gated (molecule-gated)
3. Pores

Front 31

Steps of Primary Active Transport (Na-K Ion Pump)

Back 31

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

Front 32

Net movement of pumping process

Back 32

-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)

Front 33

There are sites on membrane protein for sodium to bind but they are only active when:

Back 33

-a phosphate group is added to the acid group on the protein
-ie. phosphate activates sodium receptors

Front 34

Secondary Active Transport

Back 34

-energy is used in a secondary step
-you must have something undergoing a primary active transport first

Front 35

Endocytosis

Back 35

-process by which materials are brought into the cell when portions of a cell membrane are pinched off into the cell

Front 36

Example of Endocytosis

Back 36

-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

Front 37

Oversupply of cholesterol inhibits:

Back 37

-synthesis of LDL receptor proteins on cell membrane surface

Front 38

Exocytosis

Back 38

-the process by which materials exit the cell by the pinching off of part of the cell membrane

Front 39

Allosteric

Back 39

-the property of multisubunit proteins such that a conformational change in one subunit induces a change in another subunit

Front 40

Kinase

Back 40

-an enzyme that transfers a phosphate group to some other molecule (it phosphorylates)

Front 41

Receptor Proteins

Back 41

-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

Front 42

Enzyme

Back 42

-on portion of receptor protein that is inside of cell
-when change in conformation occurs, the receptor protein directly activates the enzyme

Front 43

Enzymes come in two flavors:

Back 43

1. Active - phoshorylated
2. Inactive - not phosphorylated

Front 44

G protein

Back 44

-bound to portion of receptor protein that is on inside of cell
-always bound to receptor either in active (GTP) or inactive (GDP) form

Front 45

Inactive form of G protein

Back 45

-GDP = guanidine diphosphate

Front 46

Active form of G protein

Back 46

-GTP = guanidine triphosphate
-made upon phosphorylation of GDP

Front 47

G protein can stimulate the production of another messenger:

Back 47

-secondary messenger, which is inside the cell
-cAMP, IP3, DAG, Ca2++

Front 48

Primary Receptor

Back 48

-hormone that binds to receptor protein on outside of cell

Front 49

Secondary Receptor

Back 49

-hormone that binds to receptor on inside of cell
-directly stimulates another enzyme

Front 50

Unique characteristic of the active form of G protein (GTP)

Back 50

-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

Front 51

Adenylate Cyclase

Back 51

-produces secondary messenger, cAMP, when bound to G protein

Front 52

Adenylate Cyclase is only active when:

Back 52

-it is bound to G protein

Front 53

cAMP

Back 53

-a kinase
-has pairs of subunits: c & r
-causes phosphorylation of ATP to ADP
-

Front 54

cAMP:
a) c subunit
b) r subunit

Back 54

a) c subunit catalyzes
b) r subunit acts as receptors

Front 55

phosphotase

Back 55

-enzyme that helps dephosphorylate

Front 56

kinase

Back 56

-enzyme that helps phosphorylate

Front 57

Activation of protein by replacement of GDP with GTP results in production of ___.

Back 57

phospholipase

Front 58

Calcium is bound to its own carrier protein:

Back 58

-calmodulin: picks up calcium ion and transports it around

Front 59

Holoenzyme

Back 59

-total enzyme

Front 60

Apoenzyme

Back 60

-protein: active site, etc.
-an enzyme that consists of polypeptide chains alone

Front 61

Coenzyme

Back 61

-coreactant
-actual reactant
-prosthetic group or co-factor

Front 62

Enzymes: Structure

Back 62

1. Holoenzyme
2. Apoenzyme
3. Coenzyme
4. Metal ions

Front 63

Metal Ions

Back 63

-M++: usually co-factors, no heavy metals

Front 64

Subdivisions of Coenzymes: two different states

Back 64

a) prosthetic group - enzyme that is bound firmly to protein
b) cofactor - enzyme that is loosley bound to protein

Front 65

Co-factors can be metal ions:

Back 65

calcium, magnesium, manganese

Front 66

What determines the rate of a chemical reaction?

Back 66

1. Temperature
2. pH
3. Concentration of Enzyme
4. Concentration of Substrate

Front 67

First Order Reaction Rates

Back 67

-rate of reaction is directly related to concentration of reactants

Front 68

Zero Order Reaction Rates

Back 68

-rate of reaction is constant (plateau)

Front 69

Plateau results from:

Back 69

-the occurence of saturation
(hyperbolic curve)

Front 70

Saturation

Back 70

-the molecule cannot go any faster than rate at plateau

Front 71

Induced Enzyme Concentration

Back 71

-when concentration of enzyme in body is low, a signal sent to brain causes production of more enzyme and vice versa

Front 72

Three things that must happen for two molecules to react:

Back 72

1. collision
2. collisions must be of proper orientations
3. collisions must have sufficient energy to undergo bond making/breaking

Front 73

Competitive Inhibition

Back 73

-substrate & competitive inhibitor both fit into active site
-higher substrate [ ] to yield same rate as noncompetitive inhibition
-max. rate is the same

Front 74

Noncompetitive Inhibition

Back 74

-inhibitor does not fit into active site
-must bind somewhere else on molecule

Front 75

Oxidation

Back 75

-loss of protons (H+)

Front 76

Reduction

Back 76

-gain of protons (H+)

Front 77

coenzyme A

Back 77

-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

Front 78

Dehydrogenases

Back 78

-enzymes that can catalyze oxidation/reduction reactions

Front 79

NAD+

Back 79

-oxidized form

Front 80

NADH

Back 80

-reduced form

Front 81

FAD+

Back 81

-oxidized form

Front 82

FADH

Back 82

-reduced form

Front 83

NAD removes ___ H ions at a time while FAD removes ___ H ions at a time.

Back 83

-one
-two

Front 84

FAD is used to remove:

Back 84

-a double bond
-removing an H ion on each side of double bond
-lipid metabolism needs double bond formation

Front 85

Molecule which has an "energetic" bond

Back 85

ATP

Front 86

ATP

Back 86

-if you chop off a phosphate group, you get energy
-sometimes ATP gives off only one phosphate group but usually it gives off two