Enzyme Regulation and the Molecular Basis of Inheritance

Vocabulary flashcards covering enzyme mechanics, allosteric regulation, feedback inhibition, and the historical discoveries leading to the double-helix model of DNA.

Enzyme

A catalyst composed of protein or RNA that accelerates a chemical reaction by lowering the activation energy required for the reaction to occur.

Activation Energy

The minimal amount of energy required for a chemical reaction to take place.

Allosteric Regulation

A regulatory mechanism in which a regulatory molecule binds to a specific regulatory site on an enzyme, altering the shape and function at another site on the protein.

Catalytically Active Shape

The structural conformation of an enzyme in which it efficiently speeds up its designated reaction, stabilized by the binding of an activator molecule.

Catalytically Inactive Shape

The structural conformation of an enzyme in which active sites cannot bind substrate or accelerate the reaction, stabilized by an inhibitor molecule.

Cooperativity

A form of allosteric regulation in a multi-subunit enzyme where substrate binding to one active site changes the shape of the remaining subunits, making it easier for substrate to bind to the other active sites.

Feedback Inhibition

A cellular control mechanism in which the end product of a metabolic pathway binds to and inhibits an early enzyme in the pathway, stopping the overproduction of unneeded molecules.

Gene

A unit of inheritance or heredity composed of DNA that is transmitted from parents to offspring.

Chromosome

A compacted cellular structure composed of DNA and proteins upon which genes are physically located.

Pathogen

An organism that causes disease and can cause death in an infected host.

Transformation

A change in an organism's genotype and phenotype resulting from the uptake and assimilation of external, foreign DNA.

Bacteriophage

A virus that infects bacterial cells by injecting its genetic material into them.

Virus

A nonliving particle made of genetic material (DNA or RNA) enclosed in an outer coat typically consisting of protein.

Nucleotide

The monomer building block of DNA, consisting of a nitrogenous base, a sugar, and one or more phosphate functional groups.

Chargaff's Rules

Two rules stating that DNA base composition varies between species, and that within any species, the number of adenine bases equals thymine ($A = T$) and cytosine bases equals guanine ($C = G$).

Photo 51

An X-ray crystallography image produced by Rosalind Franklin's laboratory that provided critical structural evidence revealing the double-helical structure and dimensions of DNA.

Antiparallel

The structural arrangement in double-stranded DNA where the two sugar-phosphate backbones run in opposite directions relative to one another.