BTL2 flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Michaelis-Menten equation

v = Vmax[S]/(Km + [S]). It describes enzyme velocity as a function of substrate concentration, with Vmax at saturation and Km at half-maximal velocity.

Gibbs free energy change

ΔG = ΔH − TΔS. A negative ΔG indicates a spontaneous (exergonic) reaction; a positive value indicates a nonspontaneous (endergonic) reaction requiring energy input.

Competitive inhibition kinetics

An inhibitor binds the enzyme active site, competing with substrate. Apparent Km increases while Vmax is unchanged, because high substrate can overcome inhibition.

Fluid mosaic model

Describes membranes as a phospholipid bilayer with embedded integral proteins, peripheral proteins, cholesterol, and glycoproteins, all able to move laterally within the membrane.

Net ATP from glycolysis

Per glucose molecule, glycolysis consumes 2 ATP and produces 4 ATP, giving a net gain of 2 ATP plus 2 NADH and 2 pyruvate molecules.

G2/M checkpoint

A cell cycle control point that verifies DNA replication is complete and damage is repaired before the cell enters mitosis, preventing propagation of mutations.

Semiconservative replication

Each new DNA double helix contains one original parental strand and one newly synthesized strand, as demonstrated by the Meselson-Stahl density gradient experiment.

PCR thermal cycling steps

Denaturation near 95 degrees Celsius separates strands, annealing near 55-65 degrees Celsius binds primers, and extension near 72 degrees Celsius lets thermostable polymerase synthesize DNA.

Dihybrid cross ratio

For two independently assorting heterozygous genes (AaBb x AaBb), the F2 phenotypic ratio is 9:3:3:1, reflecting independent assortment of alleles.

Nonsense mutation

A base substitution that converts a codon into a stop codon, causing premature termination of translation and usually producing a truncated, nonfunctional protein.

Frameshift mutation

Insertion or deletion of nucleotides not in multiples of three shifts the reading frame, altering all downstream codons and typically destroying protein function.

DNA polymerase directionality

DNA polymerase adds nucleotides only to the 3' end, so synthesis proceeds 5' to 3'. The lagging strand is synthesized discontinuously as Okazaki fragments later joined by ligase.

Restriction endonuclease function

Enzymes that recognize specific palindromic DNA sequences and cleave them, often producing sticky ends useful for inserting fragments into cloning vectors.

Gram stain principle

Gram-positive cells retain crystal violet due to thick peptidoglycan and appear purple; Gram-negative cells have thin peptidoglycan and an outer membrane, decolorize, and stain pink.

Bacterial growth curve phases

Lag phase precedes exponential (log) growth, then stationary phase balances growth and death, and finally death phase reduces viable cell numbers as nutrients deplete.

Antibody structure

Two heavy and two light chains linked by disulfide bonds; variable regions form the antigen-binding site, while constant regions define isotype and effector function.

Innate versus adaptive immunity

Innate immunity is rapid, nonspecific, and lacks memory; adaptive immunity is slower, antigen-specific, and produces memory B and T cells for faster secondary responses.

CD8 cytotoxic T cells

T lymphocytes recognizing antigen presented on MHC class I molecules; they kill virus-infected and tumor cells by releasing perforin and granzymes.

Primary versus secondary response

The primary response produces mainly IgM first, then IgG; the secondary response is faster, larger, and dominated by IgG due to memory B cells.

Sterilization versus disinfection

Sterilization destroys all microorganisms including endospores; disinfection reduces pathogenic organisms on surfaces but may not eliminate spores or all viruses.

Viral replication requirement

Viruses lack ribosomes and metabolic machinery, so they are obligate intracellular parasites that replicate only inside a host cell using host biosynthetic pathways.

Monod growth kinetics

μ = μmax·S/(Ks + S) relates specific growth rate to limiting substrate concentration; Ks is the substrate concentration supporting half-maximal growth rate.

Fed-batch culture

A bioprocess where nutrients are added during the run without removing culture fluid, avoiding substrate inhibition and extending product formation time.

CRISPR-Cas9 editing

A guide RNA directs Cas9 nuclease to a complementary target sequence, creating a double-strand break repaired by error-prone NHEJ or homology-directed repair.

Sandwich ELISA

An assay using a capture antibody bound to a plate and a detection antibody that binds a different epitope of the same antigen, giving high sensitivity.

Recombinant protein workflow

Cloning the gene into an expression vector, transforming a host cell, selecting transformants, inducing expression, and purifying the target protein by chromatography.

Dissolved oxygen control

In bioreactors, agitation and aeration rates are adjusted to keep dissolved oxygen above the critical level needed for microbial respiration and product formation.

Affinity chromatography

A purification method using a specific ligand immobilized on a resin to bind the target protein selectively, which is then eluted by changing buffer conditions.

kLa oxygen transfer coefficient

A volumetric mass transfer coefficient describing oxygen transfer from gas bubbles to liquid; it is matched during scale-up to preserve dissolved oxygen availability.

Transformation in cloning

Introduction of recombinant plasmid DNA into competent bacterial cells, often by heat shock or electroporation, followed by selection on antibiotic media.

SDS-PAGE protein analysis

Electrophoresis that denatures proteins with SDS, giving a uniform negative charge, so migration depends on molecular mass and purity can be assessed.

Enzyme-linked immunosorbent assay

An antibody-based assay detecting antigen or antibody through enzyme-linked colorimetric signal, available in direct, indirect, sandwich, and competitive formats.