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

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

(69 cards)

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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
Types of enzymes / reactions: Oxidoreductase
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
26
Types of enzymes / reactions: Transferase
transfer functional group from one molecule to another Require energy Kinase - transfer a phosphate
27
Types of enzymes / reactions: Isomerase
catalyze isomerization, rearrangement
28
Types of enzymes / reactions: Hydrolase
break bonds by addition of H2O
29
Types of enzymes / reactions: Ligase
bond together 2 substrates
30
Types of enzymes / reactions: Lyase
add/remove grp from double bond (same as hydrolase but no H2O or ox/redoc)
31
Oxidoreductase Equation
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
Transferase Equation
A + BX → AX + B
33
Isomerase Equation
One substrate and one product One is converted to its isomer A → B Occurs in glycolysis: glucose-6-P → fructose-6-P
34
Hydrolase Equation
A + H2O → B + C
35
Ligase Equation
A + B = AB (like DNA 2 polymers coming into one strand by DNA ligase
36
Lyase Equation
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
At low substrate concentration,
the rate is directly proportional to the substrate concentration
38
With increasing substrate concentration,
the reaction rate slows
39
Rate of enzyme catalyzed reaction is dependent on the overall efficiency of the enzyme (depends on the enzyme's affinity for the substrate)
Rate at which they combine is the limiting factor | Occurs in enzyme substrate complex
40
Reaction rate reaches maxim when enzyme is saturated (active sites filled)
Reaction rate can increase again by increase enzyme concentration
41
Enzymes function best at body temperature
Rate decreases if below this temperature | Rate increase with increased temperature but will decrease once too high and protein denatures
42
Enzymes function best at pH of body fluid where they act
Rate will decrease if above or below this pH
43
Enzyme Regulation: Feedback
product of pathway effects earlier step
44
Enzyme Regulation: Inhibition
decreases enzyme activity
45
Enzyme Regulation: Allosteric
bind allosteric site and alter enzyme activity Positive - increase activity Negative - decrease activity
46
Enzyme Regulation: Covalent Modification
add or remove covalently bonded portion Zymogen - need part cleaved to be active Blood clotting factors
47
Enzyme Regulation: Genetic Control
hormones control the synthesis of enzymes until they are needed Example: lactase not synthesized til lactose is present
48
Reversible Enzyme Inhibition
inhibitor can leave restoring the enzymes activity
49
Irreversible Enzyme Inhibition
inhibitor remains permanently bound and enzyme is permanently inhabited
50
Competitive Enzyme Inhibition
inhibitor binds active site and prevents the substrate from binding Inhibitor looks like substrate
51
Noncompetitive Enzyme Inhibition
inhibitor binds allosteric site and substrate less likely to bind the enzyme
52
Noncompetitive inhibition (can/cannot) be overcome by increasing substrate concentration
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
Competitive inhibition (can/cannot) be overcome by increasing substrate concentration
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
No inhibition
rate increase with substrate concentration and reaches maximum when enzyme is saturated
55
Zymogens
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
Covalent modification
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
How covalent modification of the enzyme that catalyzes glycogen breakdown influences glucose levels
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
Vitamins are
Essential in trace amounts, must be consumed
59
Water soluble vitamins are vitamins _ and _
B and C
60
Water soluble vitamins
Can’t be stored, Can’t overdose because excreted in urine
61
Water sol vitamins: Important for coenzymes - help facilitate enzyme catalysis (important in redox reactions)
Coenzyme structure derived from these vitamins Ex: niacin and NAD+ Ex: riboflavin and FADH2
62
Fat soluble include _, _, _ and _
A, D, E, and K.
63
Fat soluble vitamins are stored __ _____ ______ and it is possible to _____.
stored in fat deposits | possible to overdose
64
Vitamin A
growth and development, eyesight, immune response
65
Vitamin D
calcium uptake
66
Vitamin E
antioxidant
67
Vitamin K
blood clotting/bone
68
NAD+
electron acceptor | Can be reduced to NADH
69
NADH
electron carrier, form of stored chemical energy Can be oxidized to produce ATP

Biochemistry (4 decks)

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