Structure and function of proteins Flashcards
(23 cards)
What are the biological functions of proteins?
Proteins perform various biological functions including enzymatic activity, structural support, transport, and regulation of biochemical processes.
Proteins are essential for cell structure and function, and they play a role in nearly every biological process.
How are biogenic amino acids classified?
Biogenic amino acids are classified according to the structure of their radicals and polarity at pH=7.
This classification helps in understanding their biochemical roles and interactions.
What are atypical amino acids?
Atypical amino acids are those that do not fit into the standard classification of the 20 amino acids commonly found in proteins.
Examples include selenocysteine and pyrrolysine.
Define oligopeptides, polypeptides, and proteins.
Oligopeptides are short chains of amino acids (2-20), polypeptides are longer chains (21-50), and proteins are large, complex molecules made of one or more polypeptides.
Proteins can consist of hundreds or thousands of amino acids.
What are hetero-, iso- and alloproteins?
Heteroproteins contain non-amino acid components, homoproteins consist solely of amino acids, and alloproteins are proteins that can exist in multiple forms.
The classification is based on composition and functionality.
What is the primary structure of a protein molecule?
The primary structure of a protein molecule refers to the linear sequence of amino acids.
This sequence determines the protein’s properties and function.
What is the conformation of a protein?
Conformation refers to the three-dimensional shape of a protein, which is crucial for its function.
The conformation is influenced by the sequence of amino acids and chemical interactions.
What are the types of secondary structures in proteins?
The two main types of secondary structures are α-helices and β-sheets.
These structures are formed by hydrogen bonding between the backbone of the polypeptide chain.
What are disordered regions in a polypeptide chain?
Disordered regions are segments of a polypeptide that do not adopt a stable secondary or tertiary structure.
These regions can be important for protein function and interaction.
Define supersecondary structure.
Supersecondary structure refers to specific combinations of secondary structures, such as motifs and domains.
These structures contribute to the overall shape and function of the protein.
What is the tertiary structure of proteins?
The tertiary structure is the overall three-dimensional shape of a single polypeptide chain, formed by interactions among the side chains.
It includes various types of interactions such as hydrogen bonds, ionic bonds, and hydrophobic interactions.
What are globular and fibrillar proteins?
Globular proteins are spherical and soluble, while fibrillar proteins are elongated and provide structural support.
These structural differences relate to their functions in biological systems.
What is the quaternary structure of proteins?
Quaternary structure refers to the assembly of multiple polypeptide chains into a functional protein complex.
Hemoglobin is a classic example of a protein with quaternary structure.
What mechanisms maintain protein conformation?
Protein conformation is maintained through various chemical interactions, including hydrogen bonds, ionic bonds, hydrophobic interactions, and disulfide bridges.
These interactions help stabilize the protein’s three-dimensional shape.
What is denaturation and renaturation?
Denaturation is the process by which a protein loses its native structure, while renaturation is the process of regaining that structure.
Denaturation can be caused by factors like heat, pH changes, and chemicals.
What is the relationship between protein structure and biological function?
The structure of a protein is directly related to its function; changes in structure can lead to loss of function.
This principle is fundamental in biochemistry and molecular biology.
What are defects in receptors?
Defects in receptors can lead to diseases such as familial hypercholesterolemia and Diabetes insipidus.
These conditions are often due to mutations affecting receptor function.
What are conformational diseases?
Conformational diseases are disorders caused by misfolded proteins, such as Alzheimer’s disease, prion disease, and cystic fibrosis.
These diseases often involve aggregation of misfolded proteins.
What are point mutations?
Point mutations are changes in a single nucleotide in the DNA sequence, which can lead to diseases such as sickle cell anemia.
These mutations can alter the amino acid sequence of proteins.
What are defects in post-translational modification of proteins?
Defects in post-translational modifications can lead to conditions such as glycated hemoglobin and scurvy.
These modifications are crucial for the proper function of many proteins.
What are the charge properties of proteins?
The charge properties of proteins depend on the pH and the ionization state of their amino acid side chains.
This affects protein solubility and interaction with other molecules.
What methods are used for isolation and purification of proteins?
Methods include 1D and 2D electrophoresis, Western blot analysis, chromatographic analysis, and mass spectral analysis.
These techniques are essential for studying protein structure and function.
What analytical approaches are used for structural studies of proteins?
Analytical approaches include X-ray structural analysis, circular dichroism, and NMR analysis.
These methods provide insights into protein conformation and dynamics.
