The phrase "a single functioning unit" is correct and usable in written English.
It can be used to describe something that operates as one cohesive entity or system, often in technical or organizational contexts.
Example: "The new software update has improved the system's performance, allowing all components to work together as a single functioning unit."
Alternatives: "a unified operational entity" or "a cohesive working component".
Risk by its very nature threatens to hurt you, so when confronted by it your body and brain, under the influence of the stress response, unite as a single functioning unit.
It interesting to note that in addition to its enzymatic function, Erg28 has a unique role as an ER transmembrane protein that acts as a scaffold to tether other members of the ergosterol biosynthetic complex into a single functioning unit [ 34].
The DASH (Disability of Shoulder, Arm, and Hand questionnaire) (Hudak et al. 1996) aims to capture the patient's own perception of their upper extremity function as a single functional unit.
A species, furthermore, is composed of individuals, single functioning units identifiable as organisms.
I mean, look: here's the two biggest current-gen consoles, smashed together into a single, functioning (I assume) unit, learning to get along in harmony.
Building a single functioning prototype is not the same thing as building thousands of production units.
A leader who spends his or her career stuck in a single function or business unit will have an insular perspective that is a poor fit with the needs and challenges of the matrix.
Mr. Laurence, in his book "Dawn Over Zero" (Knopf, 1946), described how the nine men of the crew and the plane's maze of instruments had melded into a single smoothly functioning unit.
In most companies, executives rise through the ranks by specializing in a single function or dedicating themselves to specific business units.
Keep your features as small and compartmentalized as possible; that is, do not encapsulate all your functionality in one feature, but break it out into smaller units, each bundling a single function.
Your star talent can quickly become the property of a single business unit or function unless you have the processes and practices to ensure that these scarce resources are invested on behalf of your entire company, not just the division, business, geography, or function where they currently reside.
