Medical Biochemistry Final Exam Flashcards

core metabolic pathways

glycolysis, gluconeogenesis, fatty acid metabolism, citric acid cycle, oxidative phosphorylation

glycolysis

degrades glucose into 2 pyruvate molecules and 2 ATP

gluconeogenesis

process of synthesizing glucose

fatty acid metabolism

synthesis converts acetyl-CoA to malonyl-CoA, while degradation (beta oxidation) breaks down fatty acids into acetyl-CoA

oxidative phosphorylation

couples the oxidation of the coenzymes to phosphorylate ADP, creating ATP

metabolism common intermediates

pyruvate, acetyl-CoA

citric acid cycle

oxidizes acetyl-CoA into CO2+H2O, producing reduced NADH+FADH2

acetyl-CoA

central degradation product of glucose, fatty acids, and ketogenic amino acids. it can be oxidized for energy or used to synthesize fatty acids and ketone bodies

pyruvate

end product of glycolysis and degradation of glucogenic amino acids. it can be converted into acetyl-CoA, used in gluconeogenesis, or used for amino acid synthesis

hormonal control of tissues

insulin, glucagon, epinephrine

glucagon

has no effect on muscles, increases triglyceride hydrolysis in adipose tissue, and increases glyconeogenesis as well as gluconeogenesis in the liver

insulin

increases glucose uptake and glycogen synthesis in muscles, increases glucose uptake and fatty acid synthesis in adipose tissue, and increases glycogen/fatty acid synthesis while decreasing gluconeogenesis in the liver

epinephrine

increases glyconeogenesis in muscles, increases triglyceride hydrolysis in adipose tissue, and increases glyconeogenesis and gluconeogenesis in the liver

function of carbohydrate

provide energy, supply carbon for cellular components, store chemical energy (as glycogen), and serve as structural components

carbohydrate isomerism

they exist as mirror images/enantiomers, designamted as D/right or L/left based on orientation of the -OH group on the chiral carbon furthest from the carbonyl group.

what do humans mainly metabolize

D-glucose

monosaccharides

simplest sugars classified by carbon count, 3-triose, 4-tetrose, 5-pentose, 6-hexose. they are further categorized as aldoses/aldehyde group or ketoses (ketone group)

cyclization

monosaccharides form stable cyclic structures, pyranose=6-membered, furanose=5-membered. the new chiral center is the anomeric carbon, the alpha form has the -OH pointing down, while the beta from has it pointing up

key sugars

fructose, glucose, galactose, ribose/deoxyribose

glucose

most important sugar for metabolism

galactose

found in lactose, differs from glucose at carbon #4

fructose

sweetest common sugar and major ketohexose

ribose/deoxyribose

use in DNA and RNA

disaccharides

2 units linked by glycosidic linkage

examples of disaccharides

maltose, lactose, sugar

polysaccharides

long chains of glucose units. starch, glycogen, cellulose

starch

polysaccharide; energy storage in plants

glycogen

polysaccharide; energy storage in animal liver and muscles

cellulose

polysaccharide; structural component of plant cell walls, people are unable to digest it, but it serves as a dietary fiber

lipids

hydrophobic molecules used for energy storage and structures, they are split into saponifiable and nonsaponifiable

saponifiable

contain esters and can by hydrolyzed

nonsaponifiable

can’t be hydrolyzed

fatty acids

long-chain carboxylic acids the form micelles in water, unsaturated fatty acids and essential fatty acids

unsaturated fatty acids

contain double bond, usually cis, creating kinks that lower their melting points, making them liquids (oils) at room temperature

essential fatty acid

linoleic and linolenic acid must be obtained from the diet

triglycerides

storage forms of fats and oil, they undergo hydrolysis (via lipases) or saponification (witha base to make soap)

hydrogenation

converts liquids oils into solids fats but can produce unhealthy trans fatty acids

membrane lipids

include phosphoglycerides, sphingomyelins, and cholesterol. these form a bilayer where unsaturated chains increase membrane fluidity

cholesterol

precursor for bile salts, sex hormones, and vitamin D

hormones

cortisol increases glucose/glycogen and acts as an anti-imflammatory. aldosterone regulates ion and water balance

prostaglandins

regulate reproduction, blood clotting, and inflammation

what do most drugs target?

proteins (enzymes or receptors)

binding affinity

measured by the dissociation constant (Kd); a lower Kd indicates a stronger interaction

potency

measured by IC50 (50% inhibition) or EC50 (50% biological response)

IC50

represents the concentration of a drug or substance required to achieve 50% inhibition of a target's activity, used when a drug is designed to block or reduce the function of a specific protein, such as an enzyme or receptor

EC50

refers to the concentration of a ligand (drug) needed to elicit 50% of a biological response, measures the concentration required to reach half of the maximum possible effect or response

drug disposition (ADME)

absorption, distribution, metabolism, excretion

lipinski’s rules

predict poor oral absorption a drug has: molecular weight >500g/mol, more than 5 H-bond donors, more than 10 H-bond acceptors, a partition coefficient (membrane solubility) > 5

drug discovery

identify a target, develop an assay, and deter structure-activity relationship (SAR)

Preclinical

testing in animals for pharmacokinetics (PK) safety and toxicity before FDA approval for human trials

clinical trial - phase 1

small group of healthy volunteers; checks for safety and tolerability

clinical trial - phase 2

small group of patients; tests for efficacy and dosage

clinical trial - phase 3

large scale trials (1,000+ patients) for statistical significance and economic analysis

clinical trial - phase 4

post marketing surveillance to find rare or long-term side effects

commercial reality

drug development is high risk; only about 1 in 50 projects reach the market; patents typically last 20 years, after which generic competitors can enter the market