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Biochemistry > Membrane Structure and Function, Enzymes (14-17) > Flashcards

Membrane Structure and Function, Enzymes (14-17) Flashcards

1
Q

Functions of membrane proteins (4)

A

Transport
Enzyme Activity
Signal transduction
Cell-cell recognition

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2
Q

Functions of membrane proteins: TRANSPORT

A

control movement of molecules through membrane

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3
Q

Functions of membrane proteins: ENZYME ACTIVITY

A

enzymes that function on lipid substrates

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4
Q

Functions of membrane proteins: SIGNAL TRANSDUCTION

A

bind chemical signals like hormones and cause a biochemical change within the cell

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5
Q

Functions of membrane proteins: CELL-CELL RECOG

A

interact with neighbors and extracellular components

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6
Q

Definitions of types of membrane transport: PASSIVE transport

A

move down concentration gradient (high to low), does not require energy, polar and charged molecules require integral membrane protein

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7
Q

Type of Passive Transport: Simple Diffusion

A

small nonpolar molecules

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8
Q

Type of Passive Transport: Facilitated Diffusion

A

use of integral membrane protein for polar/charged molecules
Channel - pore
Carrier - bind and change conformation
Transporter

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9
Q

Definitions of types of membrane transport

ACTIVE transport

A

requires energy from ATP hydrolysis to move up the concentration gradient (low to high)

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10
Q

Channel Protein

A

Hydrophilic pore across lipid bilayer
Highly selective based on size of pore and amino acid residues lining the pore
Can be open or closed in response to signals
Example: aquaporin - water specific channel

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11
Q

Carrier Protein

A 
Binds the molecule they transport
Undergoes conformational change to expose the bound molecule to the other side
Example: GLUT transporter
Binds glucose (polar) outside of cell
Conformational change
Release glucose inside cell
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12
Q

active transport by Na+/K+ pump key features:
Na+ (high/low) (inside/outside cell)
K+ (high/low) (inside/outside cell)

A

Na+ high outside cell

K+ high inside cell

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13
Q

Na+/K+ pump uses energy from ___ _______ to move molecules against/up their concentration gradient

A

ATP hydrolysis

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14
Q

Na+/K+ Pump Step By Step (y’all just watch a video or something this is a lot)

A

Binding pocket open to inside cell (cytosol)
3 Na+ bind
Pump binds ATP and phosphate is attached
Conformational change so binding pocket face outside of cell
Reduced affinity for Na+ causes it to be released outside the cell
Phosphorylated pump has increased affinity for K+ so 2 K+ bind
Phosphate is cleaved
Protein returns to original conformation facing the inside of cell and K+ is released

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15
Q

cAMP role

A

cAMP initiates pathways (activates glycogen phosphorylase) to release glucose from glycogen stores to provide fuel for muscles

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16
Q

** for “ex of receptors and cell signal, insulin and glucose and epinephrine and degradation of glycogen”

A

look at the study guide

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17
Q

How acetylcholine transmits a nerve signal

A

ACh is a neurotransmitter that controls skeletal muscle

ACh crosses a synapse and binds receptors on the postsynaptic neuron

Results in change in permeability or ions on the postsynaptic neuron which initiates a nerve impulse

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18
Q

What is an enzyme and why is it specific?

A

Enzyme is a protein that catalyzes a biochemical reaction

Specific for substrate, reaction, and type of reaction based on the geometry and chemical complementarity of the the active site and substrate

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19
Q

Enzymes are good catalysts because (4)

A

Proximity effect
Orientation effect
Catalytic effect
Energy effect

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20
Q

Proximity effect

A
  • bring substrate and active site close together
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21
Q

Orientation effect

A
  • hold substrate at exact distance needed for catalysis
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22
Q

Catalytic effect

A
  • provide acidic, basic, or other groups necessary for catalysis
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23
Q

Energy effect

A
  • lower energy barrier by weakening substrate bonds
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24
Q

Six types of enzymes, reactions they catalyze (BE ABLE TO RECOGNIZE - she has hard examples on the problem sets)

A

-

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25
Q

Types of enzymes / reactions: Oxidoreductase

A

catalyze redox reaction
Usually add or remove O or H
Can involve NAD+ reduced to NADH

Require coenzymes that are reduced or oxidized as the substrate is oxidized or reduced

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26
Q

Types of enzymes / reactions: Transferase

A

transfer functional group from one molecule to another
Require energy
Kinase - transfer a phosphate

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27
Q

Types of enzymes / reactions: Isomerase

A

catalyze isomerization, rearrangement

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28
Q

Types of enzymes / reactions: Hydrolase

A

break bonds by addition of H2O

29
Q

Types of enzymes / reactions: Ligase

A

bond together 2 substrates

30
Q

Types of enzymes / reactions: Lyase

A

add/remove grp from double bond (same as hydrolase but no H2O or ox/redoc)

31
Q

Oxidoreductase Equation

A

Transfer electrons from molecule A to B or B to A
A + B: → or ← A: + B

Ex: pyruvate + NADH → ← lactic acid + NAD+
Performed by lactate dehydrogenase

32
Q

Transferase Equation

A

A + BX → AX + B

33
Q

Isomerase Equation

A

One substrate and one product
One is converted to its isomer
A → B
Occurs in glycolysis: glucose-6-P → fructose-6-P

34
Q

Hydrolase Equation

A

A + H2O → B + C

35
Q

Ligase Equation

A

A + B = AB

(like DNA 2 polymers coming into one strand by DNA ligase

36
Q

Lyase Equation

A

A → B + C

In order to accomplish their goals, lyase generate either a double bond or a ring structure in a molecule between two atoms

37
Q

At low substrate concentration,

A

the rate is directly proportional to the substrate concentration

38
Q

With increasing substrate concentration,

A

the reaction rate slows

39
Q

Rate of enzyme catalyzed reaction is dependent on the overall efficiency of the enzyme (depends on the enzyme’s affinity for the substrate)

A

Rate at which they combine is the limiting factor

Occurs in enzyme substrate complex

40
Q

Reaction rate reaches maxim when enzyme is saturated (active sites filled)

A

Reaction rate can increase again by increase enzyme concentration

41
Q

Enzymes function best at body temperature

A

Rate decreases if below this temperature

Rate increase with increased temperature but will decrease once too high and protein denatures

42
Q

Enzymes function best at pH of body fluid where they act

A

Rate will decrease if above or below this pH

43
Q

Enzyme Regulation: Feedback

A

product of pathway effects earlier step

44
Q

Enzyme Regulation: Inhibition

A

decreases enzyme activity

45
Q

Enzyme Regulation: Allosteric

A

bind allosteric site and alter enzyme activity
Positive - increase activity
Negative - decrease activity

46
Q

Enzyme Regulation: Covalent Modification

A

add or remove covalently bonded portion
Zymogen - need part cleaved to be active
Blood clotting factors

47
Q

Enzyme Regulation: Genetic Control

A

hormones control the synthesis of enzymes until they are needed
Example: lactase not synthesized til lactose is present

48
Q

Reversible Enzyme Inhibition

A

inhibitor can leave restoring the enzymes activity

49
Q

Irreversible Enzyme Inhibition

A

inhibitor remains permanently bound and enzyme is permanently inhabited

50
Q

Competitive Enzyme Inhibition

A

inhibitor binds active site and prevents the substrate from binding
Inhibitor looks like substrate

51
Q

Noncompetitive Enzyme Inhibition

A

inhibitor binds allosteric site and substrate less likely to bind the enzyme

52
Q

Noncompetitive inhibition (can/cannot) be overcome by increasing substrate concentration

A

CANNOT. since the inhibitor binds a site different from the active site (they are not competing)

A noncompetitive inhibitor will slow the reaction rate and it will not be able to reach the maximum

53
Q

Competitive inhibition (can/cannot) be overcome by increasing substrate concentration

A

CAN.

Increasing the substrate concentration makes it more likely to bind the active site than the inhibitor

A competitive inhibitor will slow the reaction rate but it is still able to reach the maximum

54
Q

No inhibition

A

rate increase with substrate concentration and reaches maximum when enzyme is saturated

55
Q

Zymogens

A

enzymes synthesized in an inactive form, not activated till they are needed
Activation requires chemical reaction to cleave part of the molecule (covalent modification)
Ex: enzymes that digest proteins or act as blood clotting factors

56
Q

Covalent modification

A

add or remove a covalently bonded portion of an enzyme in order to activate it when it is needed
Ex: phosphorylation - addition of a phosphate by kinase to activate an enzyme

57
Q

How covalent modification of the enzyme that catalyzes glycogen breakdown influences glucose levels

A

Phosphorylation by kinase

Glycogen phosphorylase becomes more active when phosphorylated

Glycogen phosphorylase breaks down glycogen stores to release glucose to be used by muscles

58
Q

Vitamins are

A

Essential in trace amounts, must be consumed

59
Q

Water soluble vitamins are vitamins _ and _

A

B and C

60
Q

Water soluble vitamins

A

Can’t be stored, Can’t overdose because excreted in urine

61
Q

Water sol vitamins: Important for coenzymes - help facilitate enzyme catalysis (important in redox reactions)

A

Coenzyme structure derived from these vitamins
Ex: niacin and NAD+
Ex: riboflavin and FADH2

62
Q

Fat soluble include _, _, _ and _

A

A, D, E, and K.

63
Q

Fat soluble vitamins are stored __ _____ ______ and it is possible to _____.

A

stored in fat deposits

possible to overdose

64
Q

Vitamin A

A

growth and development, eyesight, immune response

65
Q

Vitamin D

A

calcium uptake

66
Q

Vitamin E

A

antioxidant

67
Q

Vitamin K

A

blood clotting/bone

68
Q

NAD+

A

electron acceptor

Can be reduced to NADH

69
Q

NADH

A

electron carrier, form of stored chemical energy

Can be oxidized to produce ATP

Biochemistry (4 decks)

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