Primary Structure of Protein quiz #1 Flashcards
Primary Structure of Protein quiz #1
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What is the primary structure of a protein?
The primary structure of a protein is the specific sequence and composition of amino acid residues linked together by peptide bonds in a polypeptide chain. How are amino acids referred to once they are incorporated into a polypeptide chain?
Once incorporated into a polypeptide chain, amino acids are referred to as amino acid residues. What is the difference between amino acid composition and sequence in the context of primary protein structure?
Amino acid composition refers to the types and quantities of amino acids present, while sequence refers to the exact order of amino acid residues from the N-terminal to the C-terminal end. From which end to which end is the amino acid sequence of a protein always read?
The amino acid sequence of a protein is always read from the N-terminal end (free amino group) to the C-terminal end (free carboxyl group). What functional groups are present at the N-terminal and C-terminal ends of a polypeptide chain?
The N-terminal end has a free amino group, and the C-terminal end has a free carboxyl group. Why do internal amino acid residues in a polypeptide not have free amino or carboxyl groups?
Internal amino acid residues lack free amino or carboxyl groups because these groups are involved in peptide bond formation, which links the residues together. How does a change in the amino acid composition or sequence affect the primary structure of a protein?
A change in either the composition or sequence of amino acids alters the primary structure of a protein. Why is the primary structure of a protein important for its overall function?
The primary structure determines the protein's overall shape and function by dictating the higher levels of structure: secondary, tertiary, and quaternary. What type of bond links amino acids together in a polypeptide chain?
Amino acids are linked together by peptide bonds in a polypeptide chain. What happens to the ionizability of the amino and carboxyl groups when amino acids form peptide bonds?
When amino acids form peptide bonds, their amino and carboxyl groups lose their ionizability except at the terminal ends. Do all proteins have a quaternary structure? Explain.
No, not all proteins have a quaternary structure; some function as single polypeptide chains without assembling into multi-chain complexes. What is meant by the term 'residue' in the context of protein structure?
A 'residue' refers to an amino acid that has been incorporated into a polypeptide chain via peptide bonds. How does the primary structure influence the secondary, tertiary, and quaternary structures of a protein?
The primary structure dictates the folding and interactions that lead to the formation of secondary, tertiary, and quaternary structures. What is the consequence of altering the primary structure of a protein?
Altering the primary structure can change the protein's higher-order structures and potentially its function.
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