Metabolism - General Flashcards by Katie Hutchins

what metabolism occurs in the mitochondria only?

FA oxidation (B-oxidation)
acetyl-coA production
TCA
oxidative phosphorylation

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what metabolism occurs in the cytoplasm only?

glycolysis
FA synthesis
HMP/PPP shunt
protein synthesis (rER)
steroid synthesis (sER)
cholesterol synthesis

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what metabolism occurs in both mitochondria and cytoplasm?

heme synthesis
urea cycle
gluconeogenesis

(HUGs take two)

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what is a kinase?

uses ATP to add high energy P onto substrate

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what is a phosphorylase?

adds Pi onto substrate without using ATP

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what is a phosphatase?

removes P group from substrate

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what is a dehydrogenase?

catalyzes redox reactions

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what is a hydroxylase?

adds OH group onto substrate

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what is a carboxylase?

transfers CO2 groups with help of biotin

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what is a mutase?

relocates a functional group within a molecule

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glycolysis: rate-limiting step and regulations of this step

PFK-1

(+) AMP; F-2,6-BP
(-) ATP; citrate

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gluconeogenesis: rate-limiting step and regulations of this step

F-1,6-bisphosphatase

(+) ATP; acetyl-coA
(-) AMP; F-2,6-BP

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TCA: rate-limiting step and regulations of this step

isocitrate DH

(+) ADP
(-) ATP; NADH

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Glycogenesis: rate-limiting step and regulations of this step

glycogen synthase

(+) G6P; insulin; cortisol
(-) epinephrine; glucagon

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glycogenolysis: rate-limiting step and regulations of this step

glycogen phosphorylase

(+) epinephrine; glucagon; AMP
(-) G6P; insulin; ATP

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HMP/PPP shunt: rate-limiting step and regulations of this step

G6PDH

(+) NADP+
(-) NADPH

de novo pyrimidine synthesis: rate-limiting step and regulations of this step

carbamoyl phosphate synthetase II (CPS II)

no regulators mentioned

de novo purine synthesis: rate-limiting step and regulations of this step

PRPP amidotransferase

(-) AMP; IMP; GMP

urea cycle: rate-limiting step and regulations of this step

carbamoyl phosphate synthetase I (CPS I)

+) NAG (N-acetylglutamate

FA synthesis: rate-limiting step and regulations of this step

acetyl-coA carboxylase (ACC)

(+) insulin; citrate
(-) glucagon; palmitoyl-coA

FA oxidation: rate-limiting step and regulations of this step

carnitine acyltransferase I

(-) malonyl-coA

ketogenesis: rate-limiting step and regulations of this step

HMG-coA synthase

no regulators mentioned

cholesterol synthesis: rate-limiting step and regulations of this step

HMG-coA reductase

+) insulin; thyroxine (T4
(-) glucagon; cholesterol

calories/g of food: carbs, fat, protein, alcohol

carbs: 4 kcal
fat: 9 kcal
protein: 4 kcal
alcohol: 7 kcal

what are the largest stores of energy in the average human?

fat (TGs)

BMI and cutoffs for different categories

body mass index = weight (kg)/height^2 (m) >30: obese < 18.5: underweight

essential amino acids: glucogenic, ketogenic, or both

glucogenic: Met, His, Val (sometimes Arg) ketogenic: Lys, Leu both: Ile, Thr, Trp, Phe

who should have a positive vs. negative N balance?

positive: kids, pregnant women negative: protein deficient diet, stress, burn victim

describe role of [citrate] in lipid/carb metabolism

high [citrate] -> activates ACC, inhibits citrate synthase (TCA), and inhibits PFK1 (glycolysis)

what does insulin release stimulate?

- increased glycogen synthesis - increased FA synthesis - increased TG synthesis - increased liver glycolysis

what does glucagon release stimulate?

- increased glycogenolysis - increased gluconeogenesis - increased lipolysis - decreased liver glycolysis

action of glucagon

acts through GPCR -> stimulates adenylate cyclase -> cAMP, protein kinase A

action of insulin

acts through membrane receptor Tyr kinase -> phosphorylates insulin receptor substrate (IRS-1), PI3K, PI-3,4,5-trisP, and protein kinase B

what does epinephrine release stimulate?

- increased glycogenolysis from liver and muscle - stimulates FA release from adipose - possible short term activation of gluconeogenesis

kwashiorkor vs. marasmus

kwashiorkor: - protein malnutrition - results from a protein deficient "MEAL" -> malnutrition, edema, anemia, liver (fatty) - child with swollen belly marasmus: - total calorie malnutrition - tissue and muscle wasting - loss of subQ fat

glucose transporters: where are the different isoforms located

GLUT1: RBC, blood-brain barrier (high affinity transporter) GLUT2: liver, kidney, pancreatic B cells (low affinity) GLUT3: brain neurons GLUT4: adipose, skeletal muscle, heart (INSULIN RESPONSIVE)