Astairway has 6 steps. is is a handrail required?

 if there are at least 4 risers (steps) in the stairway, standard railings or handrails depending on the width and type of stairway. If the stairway is less than 44 inches wide and is enclosed on both sides, only one handrail is required, and if one side is open, only a railing on the open side is required. If both sides are open, standard railings are required on both sides. A standard railing for stairways would be between 30 and 34 inches above the forward edge of each riser.

If the stairway is between 44 and 88 inches in width, a handrail is required on each enclosed side and a standard railing is required on each open side. Any stairway over 88 inches wide must also have an intermediate railing halfway across its width. A winding stairway must also have a handrail offset for any portion of the risers with less than 6 inches depth.

helicase, i think thats it

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products