Yes you can and it's the better way when you have low capital. You can choose between ETH, LTC or even TRX for high speed transactions. Some exchange, for example Binance doesn't require any minumum deposit but does requires minimum trade value (0.001 BTC). If your capital in bitcoin is less than that amount then you can't make any trades. But buying altcoins instead enables you to sell if you find the prices juicy.