All of these must pass through the cell membrane. Transport may occur by diffusion and osmosis across the membrane. It can also occur when a vescicle attaches to the cell membrane from the inside and then opens to form a pocket, expelling its contents to the outside. This may be called exocytosis.ll of these must pass through the cell membrane. Transport may occur by diffusion and osmosis across the membrane. It can also occur when a vescicle attaches to the cell membrane from the inside and then opens to form a pocket, expelling its contents to the outside. This may be called exocytosis.
Many enzymes that occur in certain tissues are found in blood plasma at higher levels when the cancer involves that tissue. Enzymes are usually measured by determining the rate at which they convert a substrate to an end product, while most tumor markers of other types are measured by a test called an immunoassay.
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.