is it possible to program an arduino with usb/ttl adapter i want to upload sketch into arduino uno using usb/ttl adapter.i tried searching for it, but found about programming arduino using another. can anyone help me.
The Arduino onboard USB to serial is connected to D0 (Rx) and D1 (Tx).

And without a USB connected to the Arduino you can use a USB/TTL adapter connected to D0 and D1 like this;

Arduino  - USB/TTL
Tx       - Rx
Rx       - Tx


And to get the Arduino inte "programming" mode:


Automatic way, if the USB/TTL have CTS, connect it to Arduinos reset pin.
Manual way, press the reset button when the Arduino IDE starts to upload the code.