Biology Chapter: Proteins and Amino Acids Quiz

Large molecules found in living organisms, composed of repeating units called monomers.

A type of biomolecule composed of amino acids linked together.

The basic building block of proteins. There are 20 standard amino acids.

The chemical bond that links amino acids together to form proteins.

A sequence of amino acids linked by peptide bonds.

The specific order of amino acids in a protein.

The three-dimensional shape of a protein.

The ability of proteins to perform specific functions due to their unique structure.

A chain of amino acids that is longer than a tripeptide, but shorter than a polypeptide. Typically contains between 3 and 10 amino acids.

A chain of amino acids that is longer than an oligopeptide. Typically contains more than 10 amino acids.

Proteins composed of two or more polypeptide chains associated noncovalently.

Proteins that contain a non-amino acid component in addition to their amino acid sequence.

Proteins that remain structurally similar to their natural state, retaining their original amino acid composition and molecular conformation.

Proteins formed as intermediates during the breakdown of larger proteins, such as during digestion.

A protein with a spiral structure, stabilized by hydrogen bonds between amide hydrogens and carbonyl oxygens of peptide bonds.

A protein with a zigzag structure formed by hydrogen bonds between polypeptide chains, often containing polar and small residues.

The linear sequence of amino acids in a protein, joined by covalent peptide bonds.

The three-dimensional arrangement of the polypeptide backbone, including alpha helices and beta sheets.

The overall three-dimensional shape of a protein, determined by the interactions between amino acid side chains.

The arrangement of multiple polypeptide chains (subunits) in a protein complex.

Proteins that accelerate biochemical reactions by lowering activation energy

Proteins that bind and transport molecules within the body.

A type of protein that binds to oxygen in muscle cells, delivering it to myocytes for energy production.

Proteins found embedded within cell membranes, playing roles in transport, signaling, and anchoring.

Proteins that lack a fixed three-dimensional structure and adopt different conformations based on their environment.

Proteins with a long, extended structure, often providing structural support or forming fibers.

The most abundant protein in the human body, found in connective tissues, providing strength and flexibility.

The loss of a protein's three-dimensional structure, often leading to loss of function.

A group of diseases caused by the accumulation of misfolded proteins in amyloid fibers, leading to tissue damage.

Amino acids have a central carbon atom, called the α-carbon, to which four different groups are attached: a carboxyl group (-COOH), an amino group (-NH2), a hydrogen atom (-H), and a side chain or R group (-R).

Differences in amino acid side chains (R groups) are responsible for the unique properties of each amino acid, such as their polarity, size, and charge.

The α-carbon is a chiral center, meaning it has four different groups attached, making it asymmetric. This leads to two possible stereoisomers: L-isomers and D-isomers. Only L-isomers are typically found in proteins.

Enantiomers are stereoisomers that are nonsuperposable mirror images of each other. This means they have the same chemical formula, but their atoms are arranged differently in space.

Amino acids are classified into five main groups based on the properties of their R groups. These groups include nonpolar aliphatic, aromatic, polar uncharged, positively charged (basic), and negatively charged (acidic).

Nonpolar, aliphatic R groups are hydrophobic (water-insoluble). They tend to cluster together inside proteins, contributing to protein structure stability through the hydrophobic effect.

Aromatic R groups contain aromatic rings, making them relatively nonpolar and hydrophobic. They contribute to the hydrophobic effect and can also participate in hydrogen bonding.

Polar, uncharged R groups are hydrophilic (water-soluble) due to their ability to form hydrogen bonds with water. This group includes serine, threonine, cysteine, asparagine, and glutamine.

Positively charged (basic) R groups have a net positive charge at pH 7.0. This group includes lysine, arginine, and histidine, each with a distinctive positively charged side chain.

Negatively charged (acidic) R groups have a net negative charge at pH 7.0. This group includes aspartate and glutamate, each with an extra carboxyl group.

A zwitterion is an ion that contains both a positive and a negative charge. Amino acids exist as zwitterions at neutral pH, with the amino group protonated and the carboxyl group deprotonated.

Amino acids are polymerized to form polypeptides and proteins through condensation reactions. This involves removing a water molecule to form a peptide bond between the carboxyl group of one amino acid and the amino group of another.

The sequence of amino acids in a protein is called the primary structure. This sequence determines the protein's shape and function.

Proteins fold into three-dimensional structures, determined by interactions between amino acid side chains. These structures include secondary, tertiary, and quaternary structure.

Proteins are essential components of all living organisms. They participate in a wide range of biological processes, such as catalyzing reactions, transporting molecules, and providing structural support.

A genetic disorder caused by defects in the cystic fibrosis transmembrane conductance regulator (CFTR) protein, leading to impaired salt and water balance in the lungs and other tissues.

A group of neurodegenerative diseases caused by the accumulation of misfolded proteins in the brain, leading to cell damage and dysfunction.

Amino acids that the body cannot synthesize and must be obtained from the diet.

Amino acids that the body can synthesize from other molecules.

Amino acids that are normally non-essential but may become essential during certain periods of growth, development, or illness.

A genetic disorder caused by a mutation in the phenylalanine hydroxylase enzyme, leading to the accumulation of phenylalanine in the body.

A measure of the protein's digestibility and its amino acid profile, indicating how efficiently the protein can be utilized by the body.

The recommended daily intake of protein for adults, based on factors like age, activity level, and health status.