Describe how the computing profession is structured by job functions?

Answer 1

The computing profession tends to be project oriented - a software company often has units separated by what program they're working on at a given time.

A typical organization will have:
Executives for similar business units (see Microsoft's executive list: http://www.microsoft.com/presspass/exec/default.mspx?group=A-D )
An application lead - usually a senior programmer or project manager

Programmers/Coders: most organizations will combine software design and implementation in the same unit, some do not.
Team leads - senior programmer, who also may deal with clients.
Senior programmers
Programmers

Quality Assurance - may or may not have programming experience, depending on the organization. QA includes both software testing and ensuring that the application meets the stated requirements:
QA lead
QA analysts

Help Desk/Customer Service: Some organizations combine these positions, others do not. Typically, smaller units will combine them, whereas larger units will split them up so they can put their best analysts on the help desk, and entry level people in customer service. Customer service may handle things like password resets, account questions, billing, etc. Help Desk will handle actual application issues.
Help Desk manager/lead
Help Desk Analyst
Customer Service manager/lead
Customer Service Analyst