BTL2 cheat sheet

First law of thermodynamics: ΔG = ΔH − TΔS; a reaction is spontaneous only when ΔG < 0 at constant temperature and pressure.

Michaelis-Menten: v = Vmax[S]/(Km + [S]); Km equals the substrate concentration at half-maximal velocity and is inversely related to substrate affinity.

Competitive inhibition raises apparent Km with unchanged Vmax; noncompetitive inhibition lowers Vmax with unchanged Km; uncompetitive lowers both.

ATP hydrolysis releases roughly 30.5 kJ/mol under standard conditions; coupled reactions use this to drive endergonic steps.

Fluid mosaic model: phospholipid bilayer with embedded integral proteins, peripheral proteins, cholesterol modulating fluidity, and glycoproteins facing the extracellular space.

Membrane transport decision rule: simple diffusion for small nonpolar molecules, facilitated diffusion for polar solutes down gradient, active transport against gradient requiring ATP.

Glycolysis yields net 2 ATP, 2 NADH, and 2 pyruvate per glucose; the citric acid cycle and oxidative phosphorylation add about 30-32 ATP in total.

Cell cycle checkpoints: G1/S (DNA integrity, size), G2/M (replication completion), and spindle assembly checkpoint before anaphase; failure drives genomic instability.

Central dogma: DNA is transcribed to RNA by RNA polymerase, and mRNA is translated to protein by ribosomes using the genetic code.

Base pairing rules: adenine pairs with thymine (uracil in RNA) via two hydrogen bonds; guanine pairs with cytosine via three hydrogen bonds.

DNA replication is semiconservative; DNA polymerase synthesizes only 5' to 3', so the lagging strand is made in Okazaki fragments.

PCR cycle: denaturation near 95 °C, primer annealing near 55-65 °C, extension near 72 °C by a thermostable DNA polymerase.

Mendelian ratios: monohybrid F2 gives 3:1 phenotype and 1:2:1 genotype; dihybrid F2 gives 9:3:3:1 when genes assort independently.

Restriction endonucleases cut palindromic recognition sequences; sticky ends enable ligation of insert into vector.

Mutations: silent changes the codon but not the amino acid, missense substitutes one amino acid, nonsense creates a stop codon, frameshift alters downstream reading frame.

Gram staining decision rule: crystal violet retained in thick peptidoglycan yields Gram-positive purple; thin peptidoglycan with outer membrane decolorizes and counterstains pink (Gram-negative).

Bacterial growth curve phases: lag, exponential (log), stationary, and death; generation time is calculated from log-phase doubling.

Antibody structure: two heavy and two light chains, variable regions forming the antigen-binding site, constant regions determining isotype (IgG, IgM, IgA, IgE, IgD).

Innate versus adaptive immunity: innate is fast, nonspecific, no memory; adaptive is slower, antigen-specific, and generates memory B and T cells.

Cellular immunity: CD8+ cytotoxic T cells kill infected cells via MHC class I; CD4+ helper T cells recognize MHC class II and activate B cells and macrophages.

Primary immune response produces mainly IgM first, then IgG; secondary response is faster, larger, and dominated by IgG due to memory cells.

Sterilization versus disinfection: sterilization destroys all microorganisms including endospores; disinfection reduces pathogens on inanimate surfaces without necessarily killing spores.

Viruses are obligate intracellular parasites lacking ribosomes; they replicate only inside host cells using host machinery and are classified by genome type (DNA or RNA).

Recombinant protein workflow: gene cloning into expression vector, transformation into host, selection, induction of expression, and purification.

Fed-batch versus batch versus continuous culture: fed-batch adds nutrients during the run to avoid substrate inhibition; continuous maintains steady-state growth with constant dilution.

Monod growth kinetics: μ = μmax·S/(Ks + S); Ks is the substrate concentration at half-maximal specific growth rate.

Bioreactor parameters: aeration and agitation control dissolved oxygen; temperature and pH are regulated to maintain optimal enzyme activity and product yield.

Chromatography sequence for protein purification: affinity capture, ion exchange intermediate, size exclusion or polishing; purity assessed by SDS-PAGE.

CRISPR-Cas9 genome editing requires a guide RNA complementary to the target and Cas9 nuclease creating a double-strand break repaired by NHEJ or homology-directed repair.

ELISA formats: direct, indirect, sandwich, and competitive; sandwich ELISA is most sensitive for antigen detection using two matched antibodies.

Scale-up rule: keep geometric similarity and match dimensionless parameters such as Reynolds number, oxygen transfer rate (kLa), and power per unit volume.