Protein Structures and Functions Quiz

A substance that increases the concentration of hydronium ions (H3O+) in solution.

A substance that accepts an electron pair from another molecule, often described as an electron acceptor.

A substance that donates a proton (H+) to another molecule.

A substance that increases the concentration of hydroxide ions (OH-) in solution.

A substance that donates an electron pair to another molecule, often described as an electron donor.

A substance that accepts a proton (H+) from another molecule.

The hydrogen nucleus (H+) is a subatomic particle that readily combines with water molecules to form hydronium ions (H3O+).

Electrolytes that dissociate completely in solution.

Electrolytes that only partially dissociate in solution, reaching an equilibrium between dissociated and undissociated forms.

The equilibrium between the undissociated and dissociated forms of a weak electrolyte, consisting of the protonated form (HA) and the unprotonated form (A-).

Hemoglobin (Hb) binds and releases hydrogen ions (H+) and carbon dioxide (CO2) to help regulate blood acidity (pH).

This buffer system primarily affects the intracellular fluid and urine pH but also contributes to blood pH. It involves the equilibrium between dihydrogen phosphate (H2PO4-) and monohydrogen phosphate (HPO42-).

Proteins like albumin can accept or release H+ ions based on pH changes, acting as a buffer in blood.

Carbon dioxide (CO2) produced during cellular respiration is transported in the blood and forms carbonic acid (H2CO3) which can release H+ ions, impacting blood pH.

When blood becomes acidic, HPO42- combines with H+ to form H2PO4-, reducing acidity. When blood is basic, H2PO4- releases H+ to increase acidity, striving for a balanced pH.

This refers to the process where RBC's transport bicarbonate (HCO3-) out in exchange for chloride (Cl-) to maintain electrostatic balance.

Hb binds CO2 to form carboxyhaemoglobin, which is transported to the lungs for exhalation.

Proteins like albumin can contribute by accepting H+ when blood is acidic or releasing H+ when blood is basic.

A structural motif in proteins where polypeptide chains run alongside each other, forming a sheet-like structure. The side chains alternate above and below the plane of the sheet, allowing interactions with other molecules or protein regions.

The sequential arrangement of amino acids linked together in a polypeptide chain, determined by the genetic code.

Hydrogen bonds form between the carbonyl oxygen of one strand and the amide hydrogen of an adjacent strand in a beta-sheet, stabilizing the structure.

The unique sequence of amino acids in a protein determines its specific shape, folding pattern, and ultimately its biological function.

A fibrous protein found in spider silk, composed of beta-sheets.

A fibrous protein associated with Alzheimer's disease, composed of beta-sheets.

A globular protein, like antibodies, that has a beta-sheet core within its structure.

Non-polar side chains in beta-sheets can interact with each other through hydrophobic interactions, contributing to the stability of the structure, particularly when the beta-sheet is buried within the protein core.

The carbonic acid-bicarbonate buffer system helps maintain blood pH within a narrow range. It involves the reversible reaction between carbon dioxide (CO₂), carbonic acid (H₂CO₃), and bicarbonate ions (HCO₃⁻).

Carbonic anhydrase is an enzyme found in red blood cells that speeds up the reaction between CO₂ and water, forming carbonic acid (H₂CO₃).

Although H₂CO₃ is largely dissociated at physiological pH, it is constantly replenished by the hydration of CO₂ in the body, maintained by a dynamic equilibrium.

The effective buffering capacity of the bicarbonate system is not solely determined by the pKa of H₂CO₃ alone, but by the combined equilibria involving CO₂ and HCO₃⁻.

The ratio of HCO₃⁻ to H₂CO₃ in the blood is approximately 20:1, maintaining strong resistance to pH changes.

Dissolved CO₂ acts as a 'reservoir' for the bicarbonate buffer system, maintaining equilibrium with gaseous CO₂ in the lungs.

The respiratory rate can be adjusted through hyperventilation (increased breathing) or hypoventilation (decreased breathing) to regulate the CO₂ concentration in the body, thereby influencing the pH of the blood.

The dissociation of HCO₃⁻ to carbonate (CO₃²⁻) is negligible at physiological pH due to its high pKa (9.8). This ensures that the bicarbonate buffering system operates within its optimal range.

A change in the DNA sequence that can alter the amino acid sequence of a protein.

A variation in DNA sequence that occurs in at least 1% of a population and usually doesn't cause disease.

Changes in amino acid sequence that significantly alter protein function. Typically involve substitutions of amino acids with vastly different properties.

Changes in a gene's DNA that cause premature termination of protein synthesis. Often result in non-functional or truncated proteins.

A genetic disorder caused by a single nucleotide change in the HBB gene, resulting in the substitution of glutamic acid with valine at position 6 of the beta-globin chain.

A genetic disorder caused by mutations in the CFTR gene, leading to impaired chloride ion transport and thick, sticky mucus buildup in the lungs and digestive system.

A genetic disorder characterized by progressive muscle weakness and wasting caused by mutations in the DMD gene, resulting in the absence of functional dystrophin.

An amino acid substitution in a protein that can significantly alter its function, often leading to disease.

A protein that lacks its essential non-protein components (prosthetic groups), rendering it inactive.

The functional form of a protein, containing its complete polypeptide chain and all non-protein groups (prosthetic groups) required for activity.

Non-protein molecules that associate with proteins, often essential for their activity.

A type of polymorphism involving a single nucleotide change in the DNA sequence.

Variations in the number of copies of a particular gene or DNA segment.