Proteins and Their Structure

To obtain the protein of interest from the source material while preserving its structure.

pH and temperature.

By summing the masses of the individual amino acids composing the protein.

<p>The tertiary structure of the protein determines its basic function.</p> Signup and view all the answers

<p>Precipitates are usually non-crystalline and impure, while crystals are pure and formed through temperature decreases.</p> Signup and view all the answers

<p>They help maintain pH and prevent the cleavage of proteins during the extraction process.</p> Signup and view all the answers

<p>Quaternary structure refers to the arrangement of multiple polypeptide chains, known as subunits, into a single protein macromolecule.</p> Signup and view all the answers

<p>Hemoglobin is an example; it consists of four subunits: two alpha and two beta subunits.</p> Signup and view all the answers

<p>Chromatography and electrophoresis.</p> Signup and view all the answers

<p>'Salting out' refers to the process of precipitating proteins by adding salts to reduce their solubility.</p> Signup and view all the answers

<p>Conformational changes are shifts between different structural forms of a protein, often induced by substrate binding.</p> Signup and view all the answers

<p>Controlled conditions prevent protein denaturation and ensure accurate study of their properties.</p> Signup and view all the answers

<p>Sample preparation helps prevent contamination, improves accuracy, and minimizes distortion of results.</p> Signup and view all the answers

<p>The first step is extraction, where a representative sample of the material is isolated from a larger source.</p> Signup and view all the answers

<p>Thermal vibrations cause proteins to undergo variations in structure, impacting their function.</p> Signup and view all the answers

<p>Assays identify the location of the protein of interest after fractionation during purification.</p> Signup and view all the answers

<p>The secondary structure of a protein is defined by the coiling or folding of the polypeptide chain, which forms structures like alpha helices and beta pleated sheets.</p> Signup and view all the answers

<p>An alpha helix structure forms through hydrogen bonding between the polypeptide chain, resembling a coiled spring.</p> Signup and view all the answers

<p>Beta pleated sheet structures are stabilized by hydrogen bonding between adjacent polypeptide units.</p> Signup and view all the answers

<p>The tertiary structure refers to the overall three-dimensional shape of a single protein molecule formed by the spatial relationship of its secondary structures.</p> Signup and view all the answers

<p>Hydrophobic interactions lead to the folding of a protein by positioning hydrophobic 'R' groups towards the protein's interior, away from the aqueous environment.</p> Signup and view all the answers

<p>Hydrogen bonds stabilize the tertiary structure by holding the protein in the shape established through hydrophobic interactions.</p> Signup and view all the answers

<p>A disulfide bridge is a covalent bond formed between the 'R' groups of cysteine amino acids, providing additional stability to the protein structure.</p> Signup and view all the answers

<p>Van der Waals forces contribute to protein stability through attractive and repulsive interactions that occur between polarized molecules.</p> Signup and view all the answers

<p>At its isoelectric point, the protein has no net charge, which reduces its interaction with water and decreases solubility.</p> Signup and view all the answers

<p>Low salt concentrations increase protein solubility, a process known as salting-in.</p> Signup and view all the answers

<p>Divalent ions, like magnesium chloride, are more effective at precipitating proteins than monovalent ions, such as sodium chloride.</p> Signup and view all the answers

<p>Ammonium sulfate is commonly used due to its high solubility, low toxicity, and protein-stabilizing properties.</p> Signup and view all the answers

<p>Centrifugation uses centrifugal force to separate components based on density, with denser particles forming a pellet at the bottom.</p> Signup and view all the answers

<p>Differential centrifugation allows for the separation of cellular fractions by performing multiple rounds of centrifugation at varying speeds.</p> Signup and view all the answers

<p>Dialysis involves placing a protein solution in a semi-permeable membrane to exchange solvent with a larger volume of buffered solution.</p> Signup and view all the answers

<p>High salt concentrations can remove water of hydration from protein molecules, leading to decreased solubility.</p> Signup and view all the answers

<p>The migration rate is influenced by the net charge, size and shape of the molecules, field strength, and the nature of the medium.</p> Signup and view all the answers

<p>The gel matrix serves as a porous medium that allows for the separation of biomolecules based on size and charge.</p> Signup and view all the answers

<p>Proteins can be visualized using silver stain or Coomassie Brilliant Blue dye.</p> Signup and view all the answers

<p>Paper electrophoresis separates amino acids or peptides based on their charge, with more highly charged species migrating further.</p> Signup and view all the answers

<p>The electric field creates a negative charge at one end and a positive charge at the other, pushing and pulling molecules through the gel.</p> Signup and view all the answers

<p>Larger molecules move more slowly through the gel, while smaller molecules move faster, leading to distinct bands.</p> Signup and view all the answers

<p>Nitrocellulose membranes allow for the transfer of proteins from the gel for probing with specific antibodies (Western Blot).</p> Signup and view all the answers

<p>The distinct bands formed are referred to as molecular bands or protein bands.</p> Signup and view all the answers

<p>To create varying sized mesh networks that can effectively separate proteins or small nucleic acids based on their size.</p> Signup and view all the answers

<p>Agarose has large pores due to its unbranched chains of uncharged carbohydrates, making it suitable for larger molecules.</p> Signup and view all the answers

<p>EMF applies an electric field that drives the charged molecules through the gel matrix at different rates based on their mass, charge, and shape.</p> Signup and view all the answers

<p>A high pH ensures that proteins carry a net-negative charge, promoting their movement towards the positive electrode.</p> Signup and view all the answers

<p>The stationary phase provides a stable medium that interacts differently with the components of the mixture, affecting their movement.</p> Signup and view all the answers

<p>Separation is influenced by molecular characteristics related to adsorption, partition, affinity, and differences in molecular weights.</p> Signup and view all the answers

<p>The stationary phase is composed of a solid phase or a layer of a liquid adsorbed on the surface of a solid support.</p> Signup and view all the answers

<p>Smaller molecules exhibit greater electrophoretic mobility than larger molecules with the same charge density.</p> Signup and view all the answers