BTL2 key terms

A ten-step cytoplasmic pathway that splits one glucose molecule into two pyruvate molecules, releasing a small amount of ATP and NADH. It functions whether or not oxygen is present.

The process in which electrons carried by NADH and FADH2 pass along the inner mitochondrial membrane chain, pumping protons to drive ATP synthase. It produces most cellular ATP in aerobic cells.

The combined electrical and chemical gradient of protons across a membrane. Cells use this stored energy to power ATP synthesis, transport, and rotation of bacterial flagella.

The movement of protons down their gradient through a membrane protein channel, coupling that flow to ATP production. It links electron transport to energy storage in cells and organelles.

A folded membrane network inside eukaryotic cells. Rough regions studded with ribosomes fold and modify new proteins, while smooth regions synthesize lipids and store calcium ions.

A stack of flattened membrane sacs that receives proteins and lipids from the endoplasmic reticulum, modifies them, sorts them, and packages them into vesicles for delivery elsewhere.

The budding, movement, and fusion of small membrane-bound carriers that shuttle cargo between organelles and the plasma membrane. Coat proteins and SNARE complexes govern specificity of each delivery step.

The inward folding of the plasma membrane to capture extracellular material into vesicles. Cells use it for nutrient uptake, receptor recycling, and immune sampling of their surroundings.

A form of endocytosis in which a cell engulfs large particles such as bacteria into a vesicle. Immune cells called phagocytes use it to destroy and clear invading microbes.

An acidic membrane-bound organelle packed with hydrolytic enzymes. It digests material delivered by endocytosis and breaks down worn-out cellular components during recycling.

A self-digestion process in which cells enclose damaged organelles or proteins in double-membrane vesicles and deliver them to lysosomes for breakdown and reuse of building blocks.

A dynamic network of actin filaments, microtubules, and intermediate filaments. It gives cells shape and mechanical support, enables movement, and organizes transport of organelles and chromosomes.

The division of a eukaryotic nucleus that distributes duplicated chromosomes into two daughter nuclei. It is followed by cytokinesis and maintains the chromosome number between generations.

A control point where the cell verifies that prior events are complete and accurate before continuing. Damage or errors halt progression, allowing repair or triggering programmed cell death.

A programmed, orderly form of cell death in which the cell shrinks, fragments, and is cleared without inflammation. It shapes tissues during development and removes damaged or infected cells.

The synthesis of an RNA copy from a DNA template by RNA polymerase. In eukaryotes the transcript is processed and exported before it directs protein production.

The process in which ribosomes read messenger RNA codons and assemble the corresponding amino acid chain. Transfer RNAs deliver each amino acid according to codon-anticodon pairing.

A DNA region upstream of a gene where RNA polymerase and regulatory proteins bind to start transcription. Its sequence and bound factors determine when and how strongly a gene is expressed.

A cluster of genes transcribed together from one shared promoter in prokaryotes. Regulatory proteins and small molecules switch the whole unit on or off in response to conditions.

A regulatory protein that binds a DNA operator site and blocks transcription of an operon or gene. Its binding is often controlled by a small molecule such as a sugar or end product.

A sequence of three nucleotides in messenger RNA that specifies one amino acid or a stop signal. The genetic code maps sixty-four codons onto twenty standard amino acids.

An insertion or deletion that changes the number of nucleotides by an amount not divisible by three. Every downstream codon is read differently, usually destroying protein function.

A change of a single nucleotide in DNA, such as a substitution. It may be silent, alter one amino acid, create a premature stop codon, or affect splicing and regulation.

A small circular DNA molecule that replicates independently of the main bacterial chromosome. Plasmids often carry accessory genes, including antibiotic resistance, and serve as cloning vectors.

A bacterial protein that cuts DNA at a specific recognition sequence. Researchers use these enzymes to cleave DNA predictably during cloning and to map and analyze fragments.

The joining of two DNA fragments by forming phosphodiester bonds between their ends. DNA ligase seals nicks in cloning and repair, producing a continuous recombinant molecule.

A technique that repeatedly copies a target DNA region using primers, a thermostable polymerase, and cycles of heating and cooling. It amplifies small samples into large detectable quantities.

A short single-stranded nucleic acid that provides a starting point for a polymerase. In PCR, two primers flank the target and define the boundaries of the amplified product.

A separation method in which charged molecules migrate through a gel under an electric field. Smaller fragments travel farther, allowing size-based analysis of DNA, RNA, or proteins.

A procedure in which separated DNA fragments are transferred from a gel to a membrane and detected with a labeled probe. It identifies specific sequences among many fragments.

The uptake of free DNA from the environment by a bacterial cell, which may then express newly acquired genes. In the laboratory it also means introducing plasmid DNA into competent cells.

A bacterial cell made able to take up external DNA, often by chemical treatment or an electric pulse. Competence is essential for routine cloning and library construction.

The direct transfer of DNA between bacteria through a connecting tube called a pilus. It spreads plasmids, including those carrying antibiotic resistance genes, across bacterial populations.

The transfer of bacterial DNA from one cell to another by a bacteriophage. The virus accidentally packages host DNA and injects it into a new recipient cell.

A virus that infects bacteria by attaching to the cell surface and injecting its genetic material. It may replicate and burst the host or integrate quietly into the host genome.

A viral life cycle in which a phage genome integrates into the bacterial chromosome and is copied along with it. The dormant virus can later switch to active replication and burst the cell.

A rigid polymer of sugar chains cross-linked by short peptides that forms the bacterial cell wall. Its synthesis is the target of penicillin and other cell-wall antibiotics.

A differential staining method that separates bacteria into two groups based on cell wall structure. Thick-walled cells retain the primary dye and appear purple; thin-walled cells appear pink.

The ability of a microbe to survive and grow despite exposure to a drug that would normally inhibit or kill it. It can arise by mutation or by acquiring resistance genes from other organisms.

A Y-shaped protein produced by B cells that binds a specific molecular target called an antigen. Binding can neutralize the target or recruit immune cells and complement proteins to destroy it.

Any molecule that the immune system recognizes and can respond against. Proteins and polysaccharides on pathogen surfaces commonly serve as antigens that trigger antibody production.

An antibody preparation in which every molecule derives from one identical B-cell clone and binds the same epitope. Such reagents are used in diagnostics, research, and targeted therapy.

A fused cell formed by joining an antibody-producing B cell with an immortal myeloma cell. The hybrid divides indefinitely and secretes one specific antibody, enabling continuous monoclonal production.

A vessel in which living cells or enzymes carry out a desired biological reaction under controlled conditions. Temperature, pH, oxygen, and mixing are regulated to maximize product yield.

A cultivation strategy in which nutrients are added gradually during the run without removing culture fluid. It sustains growth and product formation while avoiding excessive substrate inhibition.

The series of steps after cultivation that recover, concentrate, and purify a product to required quality. It includes cell disruption, filtration, chromatography, and formulation.

A separation technique in which molecules travel through a stationary phase at different rates according to properties such as charge, size, or binding affinity. It is central to purifying biological products.

The study of how reaction rate depends on substrate concentration, enzyme amount, and conditions. Parameters such as maximum velocity and the Michaelis constant describe and compare enzyme behavior.

Control of a protein's activity by a molecule binding at a site distinct from the active site. Binding shifts the protein between active and inactive shapes, tuning pathway flux.