Bitcoin Question: Addresses & Exchanges

[3runhomer]

I'm knee deep in bitcoin...but still have some questions:

-Bitcoin are obviously tied to an address that can change as they move through transactions...what happens when they go to an exchange? Ex: If your bitcoins are in blockchain, and you then transfer them to an exchange using your exchange deposit address...and you do this a few times with a new deposit address each time...

Are the coins "dis-associated" with an address when they are at the exchange?

Is this why people say you can "wash" the coins by depositing at an exchange?

[3runhomer]

Let me try asking my question in another way:

Suppose you made 5 bitcoin withdrawals all to blockchain over a few months.

Let's say each one was for $1,000. So you currently have $5,000 in blockchain...with $1,000 in 5 different bitcoin addresses (you withdrew to a new/fresh/unused address for each payout).

Now you want to transfer to an exchange like Poloniex and convert your $5,000 to USD, and maybe do some trading...

You will have to do 5 different transfers ($1,000 each) to get all your money in the exchange (Poloniex).

Once you have made the 5 transfers, and all your funds are at the exchange...what "bitcoin address" are they currently tied to?

Or are they "disassociated" from addresses until you decide to move the funds again?