Cytology and Biochemistry Lecture Review

Comprehensive vocabulary flashcards covering biochemistry basics, enzyme kinetics, cell structure, metabolism, and photosynthesis based on the cytology lecture notes.

Acid dissociation constant ($K_a$)

A quantitative measure of the strength of an acid in solution, defined by the equilibrium expression $K_a = \frac{[A^-][H_3O^+]}{[HA]}$.

Henderson-Hasselbalch equation

An equation used to estimate the pH of a buffer solution: $pH = pK_a + \log\frac{[A^-]}{[HA]}$.

Vitamin B12 (Cobalamin)

A water-soluble vitamin involved in red blood cell production; deficiency leads to pernicious anemia.

Vitamin K

A fat-soluble vitamin involved in the conversion of prothrombin to thrombin for blood clotting; deficiency causes acquired hemophilia.

Epimer

Stereoisomers that differ in the arrangement of atoms at only one specific chiral center.

Anomer

Isomers that differ in configuration specifically at the hemiacetal or hemiketal carbon.

Trehalose

A non-reducing disaccharide composed of two $\alpha$-glucose units linked by an $\alpha$-1,1-glycosidic bond.

Peptidoglycan

A structural polysaccharide in bacterial cell walls composed of Mur2Ac and GlcNAc joined by $\beta$-1,4-glycosidic bonds.

Benedict's reaction

A test for reducing sugars where aldehydes are oxidized to carboxylic acids while $CuSO_4$ is reduced to $Cu_2O$, resulting in a yellow-red color change.

Ninhydrin reaction

A chemical test used to detect amino acids by reacting with their $\alpha$-amino group to form Ruhemann's purple.

Phospholipase C (PLC)

A phospholipase enzyme that cleaves the bond between the glycerol carbon 3 ($sn-3$) and the phosphate oxygen.

Cholesterol

A major structural component of animal cell membranes that stabilizes the membrane, reduces fluidity, and serves as a precursor for steroid synthesis.

Alpha-helix ($\alpha$-helix)

A secondary protein structure stabilized by hydrogen bonds between peptide groups, typically completing one turn every $3.6$ amino acid residues.

Chaperones (Chaperonins)

Proteins such as hsp70 and hsp60 that assist in the proper folding of other proteins to reach their thermodynamically stable state.

SDS-PAGE

An electrophoresis technique that separates proteins primarily by molecular weight by coating them with SDS to provide a uniform negative charge and using reducing agents like DTT to break disulfide bonds.

Sanger method

A method for N-terminal amino acid analysis using FDNB (1-fluoro-2,4-dinitrobenzene) to label the amino terminal.

Cofactor

Non-protein components such as metal ions or coenzymes required for an enzyme to achieve its full catalytic activity.

Activation energy

The minimum energy required for a substance to reach the transition state and undergo a chemical reaction.

Michaelis constant ($K_m$)

The substrate concentration at which the reaction velocity is half of $V_{max}$; it often reflects the affinity between the enzyme and substrate.

Competitive inhibitor

A type of reversible inhibitor that competes with the substrate for the active site, resulting in an increased $K_m$ while $V_{max}$ remains unchanged.

Differential centrifugation

A method of separating cell components based on size and density by varying centrifugal force and time.

Lipid raft

Microdomains in the lipid bilayer enriched with cholesterol and sphingolipids that have low fluidity and facilitate cell signaling.

Flippase (P-type ATPase)

An enzyme that facilitates the translocation of lipids from the outer leaflet to the inner leaflet of the biological membrane.

Intermediate filaments

Cytoskeletal fibers with a diameter of $8-12\,mm$ and a rope-like structure that provide high tensile strength and mechanical support to cells.

Kinesin

A motor protein that typically moves organelles or vesicles along microtubules from the negative ($-$) end toward the positive ($$+\,$) end.

Rubisco

An enzyme that catalyzes both the carboxylation and oxygenation of RuBP; it is composed of 8 large subunits (encoded by chloroplast DNA) and 8 small subunits (encoded by nuclear DNA).

C4 cycle

A photosynthetic pathway that spatially separates initial carbon fixation (in mesophyll cells via PEPC) and the Calvin cycle (in bundle sheath cells) to minimize photorespiration.

PFK-1 (Phosphofructokinase-1)

A key regulatory enzyme in glycolysis that is inhibited by high levels of ATP and citrate, and activated by AMP, ADP, and fructose-2,6-bisphosphate.

Ubiquitin-proteasome system

An ATP-dependent cytosolic degradation system that selectively breaks down target proteins tagged with ubiquitin.

LDL (Low-Density Lipoprotein)

A lipoprotein specialized in transporting cholesterol to peripheral tissues by binding to ApoB-100 receptors.