Question About Jump Starting a Car?

My mom's car battery is dead and the car won't start. My car runs and has a working battery in it. If I give my mom's car a jump, would that have a negative consequence on my car's battery? like drain the voltage down or decrease the power in my battery? I ask because I'm nervous that if I give my mom a jump, my car won't start afterwards or am I just worrying about nothing? Any help is appreciated.

Suggestion:

For one jump you need not worry. Have your car running and charging your systems when you connect to her battery. Make sure you connect the same sides on each car – negative to negative, positive to positive.

Have you determined why her battery is dead? Someone leave the lights on? Or is it more serious such as a bad alternator? If you know the answer to that question then she'll know what her next move is. It might be to drive to a store that sells new batteries, a garage to replace the alternator, or just around the block to recharge her battery.