06/30/2025 Notes

Vocabulary flashcards summarizing major concepts, molecules, and processes from the lecture notes on post-translational modifications, metabolism, hormones, and carbohydrate chemistry.

Phosphorylation

Post-translational addition of a phosphate (PO₄³⁻) group—usually to Serine, Threonine, or Tyrosine—acting as a molecular on/off switch.

Protein Kinase

Enzyme that transfers a phosphate from ATP to a specific amino-acid residue on a target protein.

Dephosphorylation

Removal of a phosphate group from a protein, reversing phosphorylation effects.

Phosphatase

Enzyme that hydrolyzes phosphate groups off proteins or small molecules.

N-terminus Charge

+1 formal charge at physiological pH due to the free amino group of a peptide.

C-terminus Charge

−1 formal charge at physiological pH because of the free carboxylate group of a peptide.

N-linked Glycosylation

Attachment of sugar chains to the amide nitrogen of Asparagine, affecting folding, stability, and cell recognition.

O-linked Glycosylation

Attachment of sugar chains to the hydroxyl oxygen of Serine or Threonine residues.

Ubiquitination

Covalent addition of ubiquitin to Lysine residues, marking proteins for proteasomal degradation.

Acetylation

Replacement of an amino-group hydrogen with an acetyl group; example: histone acetylation that opens chromatin for transcription.

Methylation (DNA)

Addition of a methyl group to cytosine bases, condensing chromatin and silencing gene expression.

Disulfide Bond

Covalent linkage between two Cysteine residues, stabilizing protein tertiary structure.

Cytochromes

Heme-containing proteins that participate in electron transport and redox reactions (e.g., mitochondrial ETC).

Cytochrome P450

Liver enzyme family that metabolizes drugs via oxidation reactions.

Anabolic Pathway

Energy-requiring process that builds complex molecules from simpler ones (e.g., fatty-acid synthesis).

Catabolic Pathway

Energy-releasing breakdown of complex molecules into simpler units (e.g., glycolysis).

Fatty-Acid Synthesis

anabolic conversion of acetyl-CoA (exported as citrate) into long-chain fatty acids. Synthesis occurs in cytoplasm, acetyl-CoA is produced in Mitochondria

Acetyl-CoA

Two-carbon metabolic intermediate that enters the Krebs cycle and serves as a building block for lipids.

Malonyl-CoA

Synthesized from acetyl- CoA, just add CO2. Serves as the primary carbon donor in fatty acid synthesis

Basal Metabolic Rate (BMR)

Minimum energy expenditure required to maintain vital functions at rest; generally higher in obese individuals because of greater mass.

Leptin

Adipose-derived hormone that suppresses appetite and signals adequate energy stores.

Ghrelin

Stomach-derived hormone that stimulates hunger, especially during fasting.

32P Label

Radioactive phosphorus isotope used to track DNA or RNA via their phosphate backbones.

35S Label

Radioactive sulfur isotope used to trace proteins via methionine and cysteine residues.

Bohr Effect

Decreased hemoglobin affinity for O₂ at low pH, high CO₂, or high temperature—facilitating O₂ release to active tissues.

Start Codon (AUG)

mRNA codon that signals initiation of translation and encodes Methionine.

Stop Codons (UAA, UAG, UGA)

mRNA codons that signal termination of translation; nicknames: UAA ‘U Are Away,’ UAG ‘U Go Away,’ UGA ‘U G(o) Away’.

Insulin

β-cell pancreatic hormone that lowers blood glucose by promoting cellular uptake and storage.

Glucagon

α-cell pancreatic hormone that raises blood glucose by stimulating glycogenolysis and gluconeogenesis.

Monosaccharide

Single carbohydrate unit classified by carbon number (triose, tetrose, pentose, hexose).

Aldose

Monosaccharide containing an aldehyde group (e.g., glucose).

Ketose

Monosaccharide containing a ketone group (e.g., fructose).

D- vs. L-Sugar

Configuration determined by the chiral carbon furthest from the carbonyl; D = R (clockwise), L = S (counter-clockwise) in Fischer projections.

Hemiacetal Formation

Cyclization of an aldose when an internal alcohol attacks the carbonyl, producing a new anomeric carbon.

Hemiketal Formation

Cyclization of a ketose via internal alcohol attack on the ketone carbonyl.

Anomeric Carbon

New stereocenter created during sugar cyclization; determines α (trans) or β (cis) orientation of the ring hydroxyl.

Reducing Sugar

Carbohydrate with a free anomeric carbon (free aldehyde or ketone) capable of acting as a reducing agent (positive Tollens or Benedicts test).

Non-Reducing Sugar

Sugar whose anomeric carbons are locked in glycosidic bonds and cannot reduce oxidizing agents.

Glycosidic Bond

–O– linkage formed when a hemiacetal/hemiketal reacts with another hydroxyl group, joining monosaccharides.