Effect of Ascending an Ordinary Flight of Stairs on the Work of the Heart Observations on Normal Individuals and on Patients withCoronary Heart Disease By JAMESA. L. MATHERS,M.D.,HAROLD I. GRIFFEATH,M.D.,ROBERTL.LEVY,M.D., AND JOHNL. NICKERSON,PH.D.he blood pressure cuff andelectrocardiograplhic electrodes remained on the ex-tremities during the exercise to facilitate the speedof making the observations during the recovery period. All obstructions, such as closed doors andotherpersons, wereremoved fromthe path ofthesub-ject being tested.
Restriction enzymes, also known as restriction endonucleases, are enzymes that cut a DNA molecule at a particular place. They are essential tools for recombinant DNA technology. The enzyme scans a DNA molecule, looking for a particular sequence, usually of four to six nucleotides. Once it finds this recognition sequence, it stops and cuts the strands. This is known as enzyme digestion. On double stranded DNA the recognition sequence is on both strands, but runs in opposite directions.
Enzymes Examples. Special organic molecules called amino acids are used by living organisms to make proteins, and proteins are simply long chains of amino acids. Enzymes are special types of proteins also made from strings of amino acids. The enzyme's function is determined by the sequence and types of amino acids, and their shape. The functions of cells rely on these enzymes. The enzymes help produce and speed up the chemical reactions in cells. In short, the enzymes help cells get things done.