Why are proteins called amphoteric?

Related questions

1. What do you mean by Zwitter ion in amino acids?
2. How does the sequence of amino acids affect the structure and function of proteins?
3. What are the acidic and basic properties of amino acid?
4. Why do amino acids dissolve in water?
5. Why are amino acids soluble in water?
6. How does a zwitterion form?
7. What is the role of amino acids in protein synthesis?
8. Are amino acids made of DNA?
9. How do properties of amino acids affect the function of proteins?
10. What is the purpose of the R groups of the amino acids?

Tags

1. #field
2. #nature
3. #charges
4. #react
5. #electric
6. #groups
7. #hence
8. #basic
9. #amphoteric
10. #positive
11. #alkalies
12. #carry
13. #acids
14. #acidic
15. #solution
16. #salts
17. #towards
18. #cathode
19. #compounds
20. #amino
21. #contain