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ISBM > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

How does a catalyst effect Keq?

A

It doesn’t

  • Keq is a fixed ratio of [P]/[R]
  • cataylst only speeds up the rate of reaction to reach Keq faster
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2
Q

what factors changes in the velocity of a reactinon?

A
  1. prensence of a catalyst
  2. how saturable the system is
  3. the concentrations present (the more reactant present = a faster rate of conversion)
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3
Q

Why are enzymes/catalyst able to reduce the free energy of activation needed?

A
  • they have active sites taht set the stage for the rxn to occur
  • they put things closer together and form bonds that help push the rxn forward
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4
Q

viturally all enzymes are __

A

proteins

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5
Q

what happens to enzymes after they are used in a reaction they catalyze

A
  • they are not consumed, they are regenerated

- they do have a half life though and will degrade, but their half life is not influenced by their catalytic activity

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6
Q

6 types of enzyme classes

A
  1. Oxidoreductase
  2. Transferases
  3. Hydrolases
  4. Lyases
  5. Isomerases
  6. Ligases
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7
Q

what enzyme class?
has an extra electron and acts as our reduced compound. The enzyme transfers the e- from the reactant substance to our oxidized product which now becomes reduced

A

Oxidoreductases

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8
Q

what enzyme class?

Transfer a group on one molecule onto another molecule

A

transferases

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9
Q

what enzyme class?

Connect two separate molecules via a covalent linkage

A

ligases

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10
Q

what enzyme class?

These remove groups from molecules and connects the groups together

A

Lyases

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11
Q

what enzyme class?

isomer means different form of a molecule- just flip flops positions

A

isomerases

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12
Q

what enzyme class?
we are loaded with these. They introduce water into a reaction which splits a covalent linkage and an H to one and an OH to the other

A

hydrolases

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13
Q

an example of a covalent modification to an enzyme

A
  1. phosphorylation/ dephosphorylation

* they are reversible and can activate/inhibit

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14
Q

an example of a non-covalent modication of an enzyme

A

a conformational change is the enzyme due to association with another substance
- a change in enzyme/conformation may inhibit or activate

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15
Q

what is a cofactor

A

a non-protein component needed by an enzyme to carry out its catalytic activity

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16
Q

examples of cofactors

A
  • metal ions

- organic molecules (coenzymes)** do not have enzymatic activity

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17
Q

examples of coenzymes

A

NAD, FAD, coenzyme A

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18
Q

Mg2+ is an important cofactor for what?

A

reactions that require ATP will always have magnesium

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19
Q

what are/is the cofactors for:
Hexokinase
Glucose-6-phosphate

A

Mg2+

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20
Q

what are/is the cofactors for pyruvate kinase

A

Mg2+

K+

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21
Q

what are/is the cofactors for Glutathione peroxidase?

A

Se

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22
Q

what is the cofactor important in redox reactions

A

NAD

-carry electrons and H+ atoms

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23
Q

a specific domain within the protein enzyme where a specific reaction is favorable

A

active site

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24
Q

where does catalytic activity happen?

A

the active site

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25
Q

why are side chains on AA important for catalytic activity

A
  • active site is formed by R side chains

- the side chain must exist in an acidic or basic form

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26
Q

substrate complements the active site, no change in form

example?

A

lock and key fit
ex. Acetylcholine and enzyme (AchE’s active site become covalently bound)
and chymotrypsin

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27
Q

substrate alters enzymatic structure

example?

A

induced fit

  • change in enzyme and substrate form
    ex. hexokinase
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28
Q

function of acetylcholinesterase

A

used to cleave acetylcholine at neuromuscular jxn so it no longer acts on post-synaptic cells

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29
Q

what happens when acetyl choline diffuses inot the active site of acetylcholinesterase?

A

we get an electrostatic attraction due the N+ and anionic site

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30
Q

how does temperature effect an enzyme

A
  • at temp rises, enzymatic activity will first increase
  • then reaches a temp where it no long can handle the temp and activity will decrease (marked by loss of 3D structure of the enzyme)
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31
Q

where are most enzymes?

A

in intracellular fluid space

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32
Q

factors that effect enzymes?

A
  1. temp
  2. pH
  3. [S]
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33
Q

how does pH effect the enzyme

A

it effects the active site (can protonate the active site)

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34
Q

proteolytic enzymes and pH

A

they are not as effected by pH because they have an anionic site that can take on a H+

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35
Q

enzymes that perform the same activity even though they have different protein structures

A

isozymes

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36
Q

what are desciptors of enzyme activity

A
  1. Km

2. Vmax

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37
Q

concentration of substrate it takes to get to move at 1/2 max velocity

A

Km

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38
Q

the rate of reaction is dependent on what?

A

[S]

as we increase [S] the initial rate of reation will increase (steeper slope)

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39
Q

the rate (velocity) of the reaction is the product of ___

A

k2 (ES)

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40
Q

Km is an indicator for __

A

an enzymes affinity for its substrate

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41
Q

the lower the Km the ___ its affinity for its substrate

A

greater

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42
Q

what are allosteric enzymes?

A

a subset of enzymes that are involved in the control and regulation of biological processes

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43
Q

what type of enzymes do not follow Michaelis-Meton kinteics and why?

A

allosteric enzymes

  • bc they have multiple places for substrate to bind and thier affinity for the substrate changes as other places bind (have a sigmoidal relationsip w/ respect to substrate concentration)
  • have active sites and at least 1 regulatory site that will bind a modulator
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44
Q

examples of competitie inhibition

A

Myasthenia gravis

  • acetyl-choline receptors are attacked, therefore diminishing number of receptors
  • try inhibiting acetylcholinesterase w/ competiive inhibitor to increase concentration of acetyl choline to see if symptoms improve
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45
Q

inhibitor can interact w/ both active ES and non-occupied enzyme

A

non-competitive inhibitor

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46
Q

what effect does the presence of a non-competitve inhibitor have upon enzymatic activity

A

lower Vmax and Km stays the same

  • affinity of the substrate is unchanged
  • shifts graph down
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47
Q

These Enzymes do Not Belong in ECF- indicative of disease. They are intracellular enzymes BUT they do in fact enter - a function of the mass of tissue and rate of synthesis & TISSUE DAMAGE

A

plasma enzymes useful in diagnosis

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48
Q

these agents associate w/ the active site OR associate with a site other than the active site. They just diffuse in and out of place

A

reversible inhibitors

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49
Q

in this form of inhibition, the inhibitor bears a structure similar to the usual substrate and will associate w/ an empty active site rendering the enzyme incapable of carrying out catalytic activity

A

competitive inhibition

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50
Q

what effect does the presence of a competitve inhibitor have upon enzymatic activity

A

Vmax is unchanged and Km increases

-increasing [S] can out compete the inihibitor and shift the graph to the right

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51
Q

the allosteric interaction of AMP with PFK leads to a ___ Km and ____ affinity for substrate. Note the ___ the AMP the ___ the adenylate charge (cells energy)

A

lower Km
greater
higher
lower

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52
Q

regulation mechanisms for phosphorylase

A
  1. phosphorylation
  2. allosteric alteration
    * both cause increase in enzyme velocity (mixed regulatory effects)
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53
Q

glucogons main activity

A

raise glucose levels in the plasma by stimulating breakout of glycogen

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54
Q

exogenous regulation of enzymes

A

pharmaceutical inhibition

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55
Q

mechanisms of inhibition of enzymatic activity

A
  1. reversible– non-covalent binding of a compound w/ the enzyme **More common
  2. irreversible– covalent binding of the inhibitor to the active site where the addition of a substance wipes out the enzyme
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56
Q

enzymes regulated by phosphorylation

A

enzymes of:

  1. carbohydrate metabolism
  2. lipid metabolism
  3. AA metabolism
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57
Q

___ is regulated via hormonal activity while __ is not due to the environment of cell

A

covalent modificaiton is regulated via hormonal activity

-non-covalent isn’t–> just inside the cell

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58
Q

feedback inhibition where the end product of the pathway allosterically inhibits the enzyme that created it

A

non-covalent modification

allosteric modifaction

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59
Q

allosteric modification can ___ Km

A

increase or decrease Km (acting as an inhibitor)

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60
Q

this enzyme is the most important regulatory step in glycolosis

A

phosphofuctokinase (PFK)

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61
Q

fxn of kinases

A

phosphorylates things into active form
-often by taking -P from ATP
ATP –> ADP

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62
Q

fxn of phosphatase

A

de-phosphorylates things into inactive form

-usually with help of H2O (hydrolysis)

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63
Q

fxn of phosphorylase

A
  • clips away gylcogen removing glucose-1-phosphate residues for use in the glycolytic pathway
  • maintains glucose levels in a narrow range
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64
Q

as levels of AMP increases, what happens to the activity of unphosphorylated phosphorlyase?

A

activity increases

-phosphorylated form operates at 90% with zeo AMP (HUGE TURN ON**)

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65
Q

what happens to Vmax and Km with phosphorylated phosphorylase?

A

Vmax stays the same but KM of phosphorylated form is way less

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66
Q

___ is an endogenous regulator of all enzyme activity

-hyperbolic relationships

A

[S]

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67
Q

4 types of mechanisms that regulate enzymatic activity

A
  1. irreversibly (proteolytic cleavage)
  2. covalently (phosphoyrlation, acetylation, adenylation)
  3. non-covalently (allosteric modifcation)
  4. combination of covalent and non-covalent
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68
Q

examples of irreversible enzymes

A

digestive enzymes, coagulation enzymes

thrombin, clotting factors, plasminogen, pepsin, typrsin

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69
Q

what AA residues become phosphorylated

A

serine, threonine, tyrosine, histidine

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70
Q

how does penicillin inhibit some enzymes

A

by altering the activity of enzymes that are involved in forming cell walls (therefore ineffective in killing microbes that don’t have cell walls like human cells)

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71
Q

what determines “normal” serum concentrations?

and

A

function of:

  1. rate of entry
  2. rate of removal of the enzyme in the ECF

**there are age specific ranges

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72
Q

Factors that affect the amount of enzymes in tissues/ rate of entry into blood?

A
  1. rate of synthesis

2. mass of the tissue (as cell membranes break, IC contents become EC contents and affects the rate of enzymes)

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73
Q

factors that effect the rate of removal of enzymes

A
  1. degradation (clearance via pepitases and proteases)

2. inactivition with inhibitory factors

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74
Q

what causes normal variations in serum concentrations

A
  1. age- During periods of human growth, different normal values may exist for plasma enzymes
    ex. alkaline phosphatase is an enzyme in cells that make up bone- osteoplasts. The presence of this enzyme in plasma is a marker for bone degradation. However, if this is found in a growing child it is totally normal and expected- so the normal range for children is much higher
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75
Q

Why make use of plasma enzyme activity?

A
  1. to ID location of cellular/organ damage
  2. to determine the extent of damage
  3. to provide prognostic information (follow enzyme levels over time)

PROBLEM: enzymes may come from multiple tissues

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76
Q

how do we improve tissue localization

A
  1. measure the activity of other enzymes (CK, LDH, AST)
  2. measure isozymes (enzymes that are molecularly distinct but do the same activity, ex. CK, LDH have tissue specific distributions)
  3. conduct serial measurements (activities in plasma may vary with time– never measure just 1 value, always measure as a function of time)
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77
Q 
Creatine Kinase (CK) exists as a dimer of brain and/or muscle derived subunits:
where do the following originate:
CK-MM
CK-MB
CK-BB
A

CK-MM: skeletal and cardiac muscle
CK-MB: cardiac muscle** can ID cardiac degradation
CK-BB: brain, smooth muscle of GI, urinary tract

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78
Q

locations of lactate dehydrogenase isozyme:

LDH-1 and 2

A

LDH-1 and 2 are found in myocardium, RBCs and the brain so they help to localize but not pinpoint! but at least they aren’t in skeletal

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79
Q

locations of lactate dehydrogenase isozymes
LDH 3
LDH 4
LDH 5

A

LDH 3- found in brain and kidney
LDH 4- found in liver, kidney, skeletal muscle, brain
LDH 5- found in liver, kidney, skeletal muscle

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80
Q

what lactate dehydrongenase isozymes are found in the liver

A

liver- LDH4 and LDH5

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81
Q

what lactate dehydrongenase isozymes are found in the brain

A

LDH 1, LDH2, LDH3, LDH4

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82
Q

what lactate dehydrongenase isozymes are found in the kidney

A

Kidney- LDH3, LDH4, LDH5

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83
Q

what are cardiac enzymes

A 
CK
CK-MB
lactate dehydrogenase
Troponins I or T** not enzymes but tissue specific protein
ALT, AST
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84
Q

liver specific enzymes

A

aminotranserases: ALT, AST
GGT (fairly specific for assessing liver activity in terms of cholestasis and alcohol abuse, ie. elevated w/ alchol abuse)

*AST and ALT are found in liver and myocardium (a ratio helps us: more ALT means problem in liver, more AST means problem in heart)

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85
Q

pancrease specific enzymes

A

amylase, lipase

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86
Q

muscle specific enzymes

A

CK

87
Q

prostate specific enzymes

A

acid phosphatase, PSA

88
Q

function of plasma proteins and an example of each

A
  1. transport (thyroxin-binding globulin:TH)
  2. humoral immunity (immunoglobulins)
  3. maintence of oncotic pressure (all proteins*** specifically albumin)
  4. enzymes (renin, clotting factors)
  5. protease inhibitors (alpha-antitrypsin)
  6. buffering- AA side chains (all proteins**)
89
Q

what is the most important force in dictating fluid movement

A

oncotic pressure

90
Q

energy yielding nutrients (carbs, fats, proteins)—-> energy poor end products (H2O, CO2, NH3)

A

catabolism rxn
(oxidative, exergonic)
*energy chemical energy

91
Q

precursor molecules (AA, sugars, FA, nitrogenous bases)——> cell macromolecules (proteins, polysaccharides, lipids, nucleic acids)

A

anabolism rxn
(reductive, endergonic
*energy consuming

92
Q

Oxidative rxns yield ____

A

yield chemical energy in form of ATP and NADH that is used for reducing power
and heat loss

93
Q

NADP+ —-> NADPH

A

catabolism (reduced fuel to oxidized product)

94
Q

NADPH —–> NADP+

A

anabolism (oxidized precursor to reduced biosynthetic product)

95
Q

loss of electrons from one substance to another

A

oxidation

96
Q

6 metabolic strategies

A
  1. oxidative/exergonic rxns
  2. reductive/endergonic rxns
  3. induction: levels of proteins rising (stimulatory)
  4. Repression: enzyme population diminishing
  5. Catabolism: oxidative metabolism/degradation
  6. Anabolism: synthetic activity or building up
97
Q

more H atoms =

A

more reduced (fully saturated with H atoms)

98
Q

more O atoms=

A

more oxidized

99
Q

is ethane (CH3-CH3) more or less reduced than ethanol (CH3-CH2-OH)

A

ethane is more reduced (more H atoms), ethanol is more oxidized (more O atoms)

100
Q

what is the fully oxize form of ethane? (CH3-CH3)

A

carbon dixoides
O=C=O
*no electrons can be removed

101
Q

NAD vs NADP

A

NAD: used metabolically in oxidative metabolism a cofactor on oxidavtive side of things
NADP: serves as a source of elections, when its in its reduced form, in anabolic pathways
NADP (reduced) NAD+ (oxidized)

102
Q

precursor to riboflavin- water soluble vitamin we need

A

Flavin Adenine Dinucleotide (FADH2)

103
Q

FAD vs FADH2

A

FAD: oxidized form, FADH2: reduced form

*FAD is capable of accepting 2 electrons

104
Q

describe the oxidation of ethanol

A
  • oxidized in the liver 1st by alchol dehydrogenase and yields an aldehyde
  • the electrons we stripped from ethyl alcohol go onto NADH+ to make NADH
105
Q

what contributes to the adenylate pool?

A

ATP, ADP, AMP

  • cAMP does not, but when it is de-cyclized to AMP it can contribute
  • *ATP is typically the most dominant member
106
Q

an adenylate charge of 1 means

A

full charge all ATP

**the closer to 1 means the more metabolically charged and more capable of participating in metabolic rxns

107
Q

an adenylate charge of less than 1 means

A

increase in ADP or AMP relative to ATP

108
Q

reactions that are anabolic/synthetic. Using our oxidized precursors and generating reduced end products we want/need

A

Utilization

109
Q

oxidative reactions that produce reducing power chemical NRG with NADH, FADH2

A

replenshing

110
Q

what happens to the relative rate of replenshing/oxidative/catabolic and the adenylate energy charge approaches 1

A

relative rate decreases

111
Q

what happens to the relative rate of utilization/reductive/anabolic and the adenylate energy charge approaches 1

A

relative rate increases

112
Q

Adenylate charge is typically maintained around ____, which means what in relation to catabolic and anabolic rxns

A

maintained around 0.93 (ATP dominant)

-anabolic rxn is dominant

113
Q

are all catabolic rxns oxidzative

A

no!

ex. glycolysis

114
Q

if AC is low we see…..

A

cells are oxidizing, we are replenishing, anabolic acitivity drops
**At any AC both processes are going on but varying degrees! NOT off or on but up and down

115
Q

As AC increases….

A

there is more ATP and more charged cell

116
Q

what is Gibbs free energy and what is its importance

A
  • the amount of free energy used or gained during a reaction

- helps us to predict the probability of a reaction occurring

117
Q

a positive delta-G predicts what

A

the overall predominance of a substrate in a bidirectional rxn
(not a favorable rxn to occur spontaneouslty)– requires energy

118
Q

a negative delta-G predicts

A

the formation of product (we gain energy, so it is likely to occur spontaneously)

119
Q

what is the relationship between delta-G and Keq

A

inversely related

- the higher the positive delta G, the lower the Keq

120
Q

when Keq = 1 what does delta G equal?

A

0 (no free energy related)

-when Keq=1, there is no drive to form products or reactants–> they exists together equally

121
Q

if Keq >1 this means…

A
  • delta G is negative

- spontaneous reaction is likely to occur (product formation is favored)

122
Q

if Keq

A
  • delta-G is poisitive

- rxn will most likely not occur spontaneously (product formation is not favored)

123
Q

how can a rxn occur if spontaneous action is not favored

A

coupling rxns

  • delta G’s are additive
  • coupling rxns DO NOT change Keq!! (would still occur sponatneously w/o it would just take a very long time)
124
Q

how do we transport ammonia in our bodies?

A

we couple ATP hydrolysis with the formation of glutamine from glutamate—> phosphate group transfer drives glutamine synthesis
(attachment of NH3+ is not favorable bc it costs energy, but we are willing to spend our ATP we we don’t get harmed)

125
Q

reciprocal regulation

A

-by stimulating one path, you inhibit another (when you enhance a step to favor product formation, you inhibt the reverse rxn so you don’t waste energy/ATP

126
Q

whats the most common way of reciprocal regulation?

A

allosertic regulation of key control enzymes for the 2 pathways

  • So the molecule that allosterically “turns up” one pathway also “turns down” the other.
  • Essentially it alters Km’s so that the binding for substrate of these enzymes is turned up or down.
127
Q

how are the glycolysis and gluconeogensis pathways regulated

A

reciprocal regulation

128
Q

what are the key control points in glycolysis and gluconeogensis regulation

A

in the beginning

  1. Glucose—-> G6P
  2. pyruvate—-> phsophoenolpyruvate
129
Q

reciprocal regulation of the glycolysis and gluconeogenesis pathway is related to adenylate energy change.
When there is low AC, we activate….
when there is high ACE we active..

A

low AC= activate rate-controlling step in glycolysis and enhance glycolysis

high AC= gluconeogensis is stimulated (when ATP levels remain sufficienctly high)

130
Q

too much glucose present means what state is present

A

hyperosmotic state

131
Q

___ and ___ depend on gluocse for their source of generating useful energy/ATP

A

RBCs and the brain

  • CNS uses the most glucose
  • *GLUT transporters move glucose depending on their concentrations
132
Q

where does gluconeogenesis occur

A

the liver

133
Q

what happens when you eat huge carbohydrate meals intermittently

A
  • you will experience high glucose levels followed by dips below normal
  • the body sees the high levels and works to use/store the glucose but then goes too far and dips below normal glucose levels
  • organs attempt to bring glucose back up to normal and liver undergoes gluconeogensis
134
Q

what happens with extracellular glucose drops with intermittent eating in regards to tissue use, net liver uptake, absorption, and kidney filtration rate

A
  • tissue use decreases (starts producing glucose)
  • net liver uptake decreases
  • decrease in absorbtion
  • kidney filtration rate decreases
135
Q

why is it important to fast when getting your blood drawn

A

plasma [glucose] spikes after eating, then drops below normal, and eventually restores
*could look abnormal

136
Q

change in insulin is driven by what

A

glucose change
**we see a similar pattern in insulin change and glucose change— spike after eating, then drops below normal, then stabilizes

137
Q

what is the relationship between glucose/ insulin and glucagon

A

inversely related

as glucose/insulin increases, glucagon decreases

138
Q

a high insulin:glucagon ratio favors

A

insulin

139
Q

a low insulin: glucagon ratio favors

A

glucagon

**ratio NEVER decreases to 0

140
Q 
which can cross the cell membrane?
insulin
glucagon
epinephrine
cortisol
TH
A

Can cross: cortisol and TH bc they are lipophilc

CANNOT: insulin, glucagon, and epinephrine
*epi is charged therefore cannot cross

141
Q

what 3 tissues does insulin have a impact on their metabolic activity?

A
  1. Liver (least sensitive)
  2. Fat
  3. Muscles
142
Q

what are insulins affect in the liver? (4)

A
  1. promotes uptake of AA to increase protein synthesis
  2. inhibits gluconeogensis (by inhibiting FBPase 1’s activites
  3. actives PPP1 which promotes glycolysis
  4. promotes glycogen storage
143
Q

How does insulin promote glycogen storage?

A
  • it activates PPP1 by,
    1. de- phosphorylating glycogen synthase making it more active and
    2. de-phosphorylating phosphatase a rendering it less active b form
144
Q

increase glucose in the liver allows the liver to make ___

A

use glucose to make FA to store energy in adipocytes

-FA are incorporated into LDLs that will be released from the liver and sent into the plasma

145
Q

what are VLDLs

A

transporters

-transport FA into adipocytes and plasma

146
Q

what are insulins affect in skeletal muscle? (3)

A
  1. stimulates increase in GLUT4 transporters, which increase glucose uptake
  2. increases metabolic activity by increasing degree of glucose oxidation/catabolism
  3. increases uptake of AA to produce more protein
147
Q

what are insulins affect on adipocytes? (4)

A
  1. stimulates increase in GLUT4 transporters, which increase glucose uptake
  2. increases metabolic activity by increasing degree of glucose oxidation/catabolism
  3. stimulates formation of triglycerides (the storage form of FA)
  4. inhibits liberation of FA from triglycerides (in otherwords, inhibits metabolism of triglycerides into FA)
148
Q

what is glucose metabolized into in adipocytes? and then what is that product used for

A

metabolized into acetyl CoA, which is used to make FA in a process called “de novo lipogensis”

149
Q

What is the major source of FA?

A

Liver

-although adipocytes also produce FA

150
Q

what are insulins effects on GLUT4 transporters

A

-cause GLUT4 transporters that are in cytoplasmic pools to move to the membrane in skeletal muscle and adipocytes

151
Q

How does insulin promote glucose uptake in fat and skeletal muscle?

A

by causing GLUT4 transporters to migrate to fat and skeletal muscle membranes, which allos for more net flux of glucose into the cells

152
Q

what tissues does glucagon impact their metabolic activity

A
  1. Liver
  2. Adipocytes
    * *NOT skeletal muscle bc there are no glucagon receptors
153
Q

when does the pancreas release glucagon

A

when blood sugar/glucose levels fall too low

154
Q

How does glucagon effect the liver?

A
  1. promotes gluconeogensis
  2. increases uptake of AA to be used in gluconeogensis
  3. inhibits FA production for storage
155
Q

in the liver: glycogen favors

A
  1. gylcogen breakdown

2. gluconeogensis

156
Q

How does glucagon effect adipocytes?

A
  1. Stimulates the liberation of FA from triglycerides (increase FA presence in the plasma)
157
Q

A number that reflects the amount of CO2 produced in the metabolism of a particular type of fuel relative to the amount of oxygen that is consumed in that metabolic pathway

A

respiratory quotient

158
Q

Tissues using pure carbohydrate will have an RQ

A

1

*brain and RBCs will always have this

159
Q

Tissues using fatty acids to yield acetyl CoA has a RQ

A

0.7

160
Q

Tissues using amino acids have an RQ of roughly

A

0.8

161
Q

why won’t glucose levels ever drop to 0?

A

bc the brain needs glucose to function, so we make it (in liver) even though the metabolic cost is huge
-brain utilization will decrease with glucose fasting and switch to using keto-acids for energy

162
Q

during a fasting state, what does our fuel use look like

A
  • increase in FA utilization for fuel
  • increase in production and utilization of ketoacids for fuel
  • *drops RQ to around 0.7
163
Q

what ONLY uses gluoce (will not switch to using ketoacids or FA in a glucose fasting state)

A

RBCs

164
Q

where are ketones made and how?

A
  • made in the liver
  • generated from Acetyl CoA
  • Acetyl CoA is used to make acetoacetate and B hydroxybutyrate (ketone bodies) which diffuse out
165
Q

acetyl CoA is derived from what

A

oxidation of FA

166
Q

increased levels of acetoacetate and B hydroxybutyrate cause what

A

decrease in pH

167
Q

how does the CNS use ketone bodies?

A

by changing them back to acetyl CoA and put them through the krebb cycle to make more energy

168
Q

how does acetoacetate form B-hydroxybutyrate

A

acetoacetate is reduced by NADH

169
Q

how is lactate acid used to produce more energy

A
  • lactate is taken up by liver
  • liver oxidizes it to pyruvate, and uses it to make glucose
  • *metabolically expensive, but must be done for the brain and RBCs
170
Q

what is the fxn of epinephrine in regards to glucose homeostasis?

A

mobilizes fuel during acute stress

  • stimulates glucose production from glycogen
  • stimulates FA release in adipose tissue
171
Q

what is the fxn of cortisol in regards to glucose homeostasis?

A

provides for changing requirements over the long-term

  • stimulates AA mobilization from muscle protein
  • stimulates gluconeogenesis
  • stimulates FA release from adipose tissue
172
Q

fxns of insulin in regards to glucose homeostasis

A
  • promotes fuel storage after a meal

- promotes growth

173
Q

epinephrines effects on skeletal muscle

A

stimulates breakdown of muscle glycogen storage to pyruvate and lactate (which leaves the cell and enters liver to be used in gluconeogensis

174
Q

epinephrines effects on metabolic activity is similar to

A

glucagons

175
Q

how does cortisol effect metabolic activity

A

rather than directly stimulating the regulation of enzymatic activity within a pathway, it drives a change in the amount of molecular machinery available for these cells to use

176
Q

insulin is regulated via what kind of receptor

A

tyrosine kinase
-binding of 2 insulins triggers phosphorylation of tyrosine kinase, which results in a kinase cascade which changes expression of mRNA

177
Q

what is the environment of a cell when ligand is not bound to surface receptors compared to when ligands are bound?

A
  • unbound: low [cytosolic cAMP] or Ca2+

- Bound: high [cytosolic cAMP] or Ca2+

178
Q

5 general characteristics of hormone receptors

A
  1. they are proteins
  2. they are specific for their ligand
  3. they are saturable
  4. they show high affinity for the ligand
  5. Kinetics of ligand association vary
179
Q

as [ligand binding] increases what happens to the rate of cellular response ____

A

also increases

180
Q

Kd shows what

A
  • shows the affinity a receptor has for its ligand
  • is the concentration of hormone that is responsible for driving the occupancy of receptor to the 50% level
  • inversely related to Ka
181
Q

[H] x [R] / [HR]

A

Kd- the tendency for dissociation

182
Q

physiological response kd compared to ligand to the receptor

A

The physiologic response has a MUCH LOWER Kd than the ligand to receptor.

183
Q

our normal Kd will drive cellular responsiveness to ___ even though only ___ of receptors are bound at the Kd

A

our normal Kd will actually drive cellular responsiveness to 80% even though only 50% of receptors are bound at the Kd

184
Q

Magnitude of physiologic effect

A

power

185
Q

which has the greatest and least power in regardles to adenylate cyclase:
epinephrine, isoproterenol, or norepinephrine

A

isoprotereol has greatest power

*norepinephrine is least powerful

186
Q

Concentration required to elicit an effect whether it is maximal or not.

A

potency

187
Q

it reflects the affinity of the hormone and receptor

A

potency

188
Q

which is the most potent in regards to adenylate cyclase:

epinephrine, isoproterenol, or norepinephrine

A

isoproterenol

189
Q

the relationship between potency and kd

A

most potent= lowest kd

190
Q

low kd indicates

A

high affinity a receptor has for its ligand

191
Q

Substances which associate with a receptor and promote a specific response. These can be endogenous or pharmacologic

A

agonist

192
Q

Substances that associate with a receptor and promote no response. Pharmacologic

A

antagonist

193
Q

substances produced intracellularly in response to cell surface hormonal stimulation

A

secondary messengers

194
Q

This is a product of ATP, the substrate used by the enzyme adenylate cyclase.

A

cAMP

195
Q

This is a product of guanylate cyclase- a different enzymatic activity.

A

cGMP

196
Q

how to inhibit cAMP production

A
  1. slow down cAMP production- when alpha subunit of G protein converts GTP to GDP, therefore it turns itself off and rebinds to beta/gamma subunits (increases km)
  2. Terminating cAMP- PDE convert cAMP to AMP (no longer activates PKA)
197
Q

examples of PDE inhibitors

A

caffiene

theophylline

198
Q

this is a G protein that enhances phospholipase C

A

Gq

199
Q

describe the Gq cascade

A
  1. hormone binds to receptor (ie. angiotensin)
  2. activate phospholipase C
  3. phospholipase C metabolizes PIP2
  4. produces DG and IP3
    DG- activates PKC
    IP3- travels to receptors on ER, bind, release Ca2+, bind to calmodulin
200
Q

what are the roles of calmodulin

A
  1. smooth muscle contraction
  2. Exocytosis (neurotransmitter release)
  3. activation of cAMP PDE
201
Q

what receptors can autophosphorylate when hormone is bound

A

tyrosine kinase receptors

ex. insulin as hormone (need 2 binding)

202
Q

where are the alpha subunits for tyrosine kinase receptors and G protein receptors

A

tyrosine kinase- extracellular space

G protein receptors- intracellular space

203
Q

what is the net reaction of glycolysis

A

glucose + 2NAD+ + 2ADP + 2Pi —-> 2 pyruvate + 2 NADH + 2H+ + 2 ATP + 2 H20

204
Q

significance of phosphorylating glucose with hexokinase

A
  • glucose is now phosphorylated and cannot leave the cell (not a substrate for GLUT4 rececptors anymore bc it is now polar and charged)
  • molecule is now more active (more likely move to the next step)
205
Q

what enzymes phosphorylate glucose

A

hexokinase

glucokinase

206
Q

what is the effect of high AMP, ADP, and ATP on PFK1

A

high ADP and AMP–> lowers km = positive allosteric influence

high ATP–> increases km = negative allosteric influence

207
Q

positive modifiers of pyruvate kinase (PK)

A
  1. F16BP

2. PEP

208
Q

negative modifiers of pyruate kinase

A
  1. ATP
  2. Citrate
  3. Acetyl-CoA
  4. PKA** (phosphorylates PK and decreases its activity)
209
Q

why is the production of lactic acid crucial

A

it frees up the cofactor (NAD+) so that it can be recycled back into glycolysis to keep it going

210
Q

where is glycogen predomently produced?

A

liver and skeletal muscle

*7% of wet weight of liver

211
Q

uses of GDP glucose (4)

A
  1. Glycogen storage
  2. glycosylation of proteins (all membrane proteins are glycosylated as are other proteins. UDP glucose is a substrate for transferases (enzymes) that will transfer the glucose portion of the UDP glucose onto the reactive side chain of suitable Amino Acids= glycosylation)
  3. Used in the syntheses of lactose
  4. increase solubility of other substances
212
Q

a deficiency in uridylytransferase- this leads to a back up of galactose 1P, and galactose levels rise. this leads to hypoglycemia, suppresses gluconeogenesis, suppresses Amino acid uptake. Kids present FTT

A

classic form of galactosemia

213
Q

a deficiency in galactokinase. this is less frequent. we will see an accumulation of galactose happening bc we can’t phosphorylate it.

A

non-traditional galactosemia

214
Q

Galactose is used to produce galactatol which diffuses into the lens and leads to osmotic draw causing

A

cataracts
(polyol pathway)
typically in non-traditional galactose

ISBM (8 decks)

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