If you earn 120 credits in college, which is pretty typical unless you have a ton of AP credit, you will have the possibility of earning 480 grade points. If Physics I is 4 credits, and you earned a C rather than an A, you lost 8 grade points out of the 480 that are possible. That is less than 1.7% of your GPA. It is a little more of a hit within your science GPA but if you do well in biology, chemistry, organic chem, and math, that one lower grade is not the end of the world.