I don't think Bittrex have a private key however you can add a 2fa on your Bittrex account to make sure you hold the private key on your account. Oh and by the way, Bittrex is the same as Poloniex, it is an exchange website for coins.
You don't control your private key regardless of whether you have 2-Factor-Authentication enabled on Bittrex. That's because the private key is not yours.
In order to have exclusive control of private keys, one needs to use an offline, hardware or paper wallet.
wow so many replies. thanks everyone !
the amount is nothing, only bought a very small amount from localbitcoin and moved to bittrex as a test case so it went well.
now, have to check how to buy altcoins with it and move/store it to a paper wallet.
once I understand how this entire chain works, then am going to invest a little bit more in the crypto. doesn't make any sense that one should invest a lot before understanding how the mechanisms related to crypto work.
so, i'll now try to move it to a paper wallet. hope bittrex doesn't charge me for withdrawing(?) it...
Bittrex does have withdrawal fees which can fluctuate depending on the Bitcoin network's mempool size, which affects the fee market.