Protein Electrophoresis (lab 4) Flashcards
What are proteins?
- They are molecular machines that get things done at the cellular level
- Different proteins have different functions
- Polymers of amino acids that are linked to peptide bonds (theres only 20 different amino acids but proteins contain an average of 300 amino acids)
What is Electrophoresis?
- One major way to identify & separate proteins
- Depends on net electrical charge of protein, & relevant to size & shape of protein
What groups do proteins always have?
- Atleast one Carboxyl group (carboxy terminus)
- Atleast one amino group (amino terminus)
What are the different charges a protein can have?
- It’s due to the nature of R groups & amino acids
- 3 categories for R groups Non-polar, polar, ionic
What are the amino acids with ionic R groups?
- Aspartic acid
- Glutamic acid
- Lysine
- Arginine
- Histidine
What happens when the enviormental pH is high?
-Carboxyl group donates proton to OH- ions
What happens when the environmental pH is low?
- Protons H+ are abundant in the medium surrounding protein
- Negatively charged carboxyl group may gain proton H+ = net zero charge
How does the net charge of a protein change?
- The lower the pH the more positively charged it’ll be
- The higher the pH the more negatively charged it’ll be
- At a pH in between= isoelectric point= no net charge
What is the purpose of the lab?
-Determine how changes in the environmental pH affect the electrical charge of a protein, (Will it gain a positive charge, negative charge or be neutral)
What are the independent variables?
-pH
What is the dependent variable
-Net electrical charge of the protein
What is the net charge of aspartic acid protein in a low environmental pH?
+1
What is the net charge of aspartic acid-rich protein in a high environmental pH?
-3
What is the net charge of lysine-rich protein in a low environmental pH?
+3
What is the net charge of a lysine-rich protein in a high environmental pH?
-1
