The process in which a transformation is induced in the topological structure of a double-stranded DNA helix, resulting in a change in linking number.

Any process that decreases the rate, frequency, or extent of ribonuclease activity, catalysis of the hydrolysis of phosphodiester bonds in chains of RNA.

The process in which a transformation is induced in the topological structure of a double-stranded DNA helix, resulting in a change in linking number.

The process in which interchain hydrogen bonds between two strands of DNA are broken or 'melted', generating unpaired template strands for DNA replication.

The part of the cytoplasm that does not contain organelles but which does contain other particulate matter, such as protein complexes.

The rigid or semi-rigid envelope lying outside the cell membrane of plant, fungal, most prokaryotic cells and some protozoan parasites, maintaining their shape and protecting them from osmotic lysis. In plants it is made of cellulose and, often, lignin; in fungi it is composed largely of polysaccharides; in bacteria it is composed of peptidoglycan; in protozoan parasites such as Giardia species, it's made of carbohydrates and proteins.

The part of the cytoplasm that does not contain organelles but which does contain other particulate matter, such as protein complexes.

The membrane surrounding a cell that separates the cell from its external environment. It consists of a phospholipid bilayer and associated proteins.