16 Questions
Which end of a polypeptide chain contains the residue with a free α-amino group?
Left end
How are amino acids classified based on polarity?
Into four groups based on the presence of charge on the 'R' group.
What are the two most common types of secondary structures in proteins?
α helix and β pleated sheet
In Fischer projection, how can you differentiate between D and L amino acids?
By observing the position of the amino group in relation to the carboxyl group.
What does secondary structure in proteins refer to?
Local folded structures within a polypeptide due to backbone interactions
What forces are NOT listed in the text as controlling protein structure?
Covalent Bonds
What does quaternary structure in proteins refer to?
Association of different polypeptide chains held by non-covalent forces
How are non-polar amino acids characterized?
Neutral with no charge on the 'R' group and hydrophobic.
Which type of protein is Hemoglobin classified as based on its quaternary structure?
Hetero-oligomeric protein
What distinguishes polar amino acids with positive charge from other amino acids?
Presence of more amino groups compared to carboxyl groups.
Which type of proteins help maintain cell shape by providing a scaffolding or framework?
Fibrous proteins
What is the net effect of alterations in the biological, chemical, and physical properties of a protein?
Protein denaturation
What is the major nitrogenous waste product in the body?
Urea
Where are amino acids absorbed after the completion of protein digestion?
Small intestine
Which enzymes are responsible for dividing proteins into short peptides during digestion?
Trypsin, chymotrypsin, and elastase
What happens to proteins in the body to give rise to nitrogenous waste products?
They are metabolized to form urea
Study Notes
Amino Acids and Polypeptide Chains
- The N-terminal end of a polypeptide chain contains the residue with a free α-amino group.
Amino Acid Classification
- Amino acids are classified based on polarity as non-polar, polar uncharged, and polar charged.
Secondary Structures in Proteins
- The two most common types of secondary structures in proteins are α-helices and β-pleated sheets.
Fischer Projection
- In Fischer projection, D and L amino acids can be differentiated based on the orientation of the hydrogen atom attached to the α-carbon atom.
Protein Structure
- Secondary structure in proteins refers to the specific 3D arrangement of amino acids in a polypeptide chain.
- Quaternary structure in proteins refers to the arrangement of multiple polypeptide chains (subunits) in a protein.
Non-Polar Amino Acids
- Non-polar amino acids are characterized by their hydrophobic (water-repelling) nature.
Protein Classification
- Hemoglobin is classified as a tetramer based on its quaternary structure, consisting of four subunits.
Polar Amino Acids
- Polar amino acids with a positive charge are distinguished from other amino acids by the presence of a positive charge.
Cytoskeleton Proteins
- Cytoskeletal proteins help maintain cell shape by providing a scaffolding or framework.
Protein Alterations
- Alterations in the biological, chemical, and physical properties of a protein can result in a net effect on its function.
Nitrogenous Waste Products
- The major nitrogenous waste product in the body is urea.
Amino Acid Absorption
- Amino acids are absorbed in the small intestine after the completion of protein digestion.
Digestive Enzymes
- Proteolytic enzymes, such as pepsin and trypsin, are responsible for dividing proteins into short peptides during digestion.
Nitrogenous Waste Formation
- Proteins in the body are broken down to form nitrogenous waste products, such as urea, which is excreted by the kidneys.
Test your knowledge on protein quaternary structure and the forces that control it, including hydrogen bonding, hydrophobic forces, electrostatic forces, and Van der Waals forces. Explore the different types of proteins and their classifications.
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