Answer:
For α helices: a rigid, spring like structure around a central axis. form long, thin structures important transmembrane proteins.
For β sheets: keep their shape due to hydrogen bonds between adjacent polypeptide chains. flat zig-zag-like structure.
Step-by-step explanation:
There are two common structures found in proteins and they are β sheets and α helices . The α helices generally are characterized by their rigid, spring like structures around a central axis and they also form thin structures which is vital for transmembrane proteins. On the contrary, the β sheets can sustain their shape because of the presence of hydrogen bonds and they are usually flat with zigzag structure.