75 terms

BIO201 - Chapter 2

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Acid
A molecule that is capable of releasing a hydrogen ion.
Adenosine triphosphate (ATP)
Nucleotide consisting of adenosine bonded to three phosphate groups; it is the principal immediate-energy source for prokaryotic and eukaryotic cells.
Alpha (α) helix
One possible secondary structure of polypeptides, in which the backbone of the chain forms a spiral (i.e., helical) conformation.
Amide bond
The chemical bond that forms between carboxylic acids and amines (or acidic and amino functional groups) while producing a molecule of water.
Amphipathic
The biologically important property of a molecule having both hydrophobic and hydrophilic regions.
Anion
An ionized atom or molecule with a net negative charge.
Base
Any molecule that is capable of accepting a hydrogen ion.
Beta (β) pleated sheet
One possible secondary structure of a polypeptide, in which several β-strands lie parallel to each other, creating the conformation of a sheet.
Beta (β) strand
One possible secondary structure of a polypeptide, in which the backbone of the chain assumes a folded (or pleated) conformation.
Biochemicals
Compounds synthesized by living organisms.
Buffers
Compounds that can interact with either free hydrogen or hydroxyl ions, minimizing a change in pH.
Carbohydrates (Glycans)
Organic molecules including simple sugars (monosaccharides) and multisaccharide polymers, which largely serve as energy-storage and structural compounds in cells.
Cation
An ionized atom or molecule with an extra positive charge.
Cellulose
Unbranched glucose polymer with β(1→4) linkages that assembles into cables and serves as a principal structural element of plant cell walls.
Conformation
The three-dimensional arrangement of the atoms within a molecule, often important in understanding the biological activity of proteins and other molecules in a living cell.
Conformational change
A predictable movement within a molecule that is associated with biological activity.
Covalent bond
The type of chemical bond in which electron pairs are shared between two atoms.
Denaturation
Separation of the DNA double helix into its two component strands.
Deoxyribonucleic acid (DNA)
A double-stranded nucleic acid composed of two polymeric chains of deoxyribose-containing nucleotides. The genetic material of all cellular organisms DNA may be duplicated as in DNA replication (13) and produced in large quantities of a specific segment as in DNA cloning.
Disulfide bridge
Forms between two cysteines that are distant from one another in the polypeptide backbone or in two separate polypeptides. They help stabilize the intricate shapes of proteins.
Domain
A region within a protein (or RNA) that folds and functions in a semi-independent manner.
Electronegative atom
The atom with the greater attractive force; the atom that can capture the major share of electrons of a covalent bond.
Ester bond
The chemical bond that forms between carboxylic acids and alcohols (or acidic and alcoholic functional groups) while producing a molecule of water.
Families
Groupings of proteins that have arisen from a single ancestral gene that underwent a series of duplications and subsequent modifications during the course of evolution.
Fats
Molecules consisting of a glycerol backbone linked by ester bonds to three fatty acids, also termed triacylglycerols.
Fatty acid
Long, unbranched hydrocarbon chain with a single carboxylic acid group at one end.
Fibrous protein
One with a tertiary structure that is greatly elongated, resembling a fiber.
Free radical
Highly reactive atom or molecule that contains a single unpaired electron.
Functional groups
Functional groups
Particular groupings of atoms that tend to act as a unit, often affecting the chemical and physical behavior of the larger organic molecules to which they belong.
Globular protein
One with a tertiary structure that is compact, resembling a globe.
Glycogen
Highly branched glucose polymer that serves as readily available chemical energy in most animal cells.
Glycosaminoglycans (GAGs)
A group of highly acidic polysaccharides with the structure of —A—B—A—B—, where A and B represent two different sugars.
Glycosidic bond
The chemical bond that forms between sugar molecules.
Guanosine triphosphate (GTP)
A nucleotide of great importance in cellular activities. It binds to a variety of proteins (called G proteins) and acts as a switch to turn on their activities.
Heat shock response
Activation of the expression of a diverse array of genes in response to temperature elevation. The products of these genes, including molecular chaperones, help the organism recover from the damaging effects of elevated temperature.
Hydrogen bond
The weak, attractive interaction between a hydrogen atom covalently bonded to an electronegative atom (thus, with a partial positive charge) and a second electronegative atom.
Hydrophilic
The tendency of polar molecules to interact with surrounding water molecules, which are also polar; derived from "water loving."
Hydrophobic interaction
The tendency of nonpolar molecules to aggregate so as to minimize their collective interaction with surrounding polar water molecules; derived from "water fearing."
Ion
An atom or molecule with a net positive or negative charge because it has lost or gained one or more electrons during a chemical reaction.
Ionic bond
A noncovalent bond occurring between oppositely charged ions, also called a salt bridge.
Isoforms
Different versions of a protein. Isoforms may be encoded by separate, closely related genes, or formed as splice variants by alternative splicing from a single gene.
Macromolecules
Large, highly organized molecules crucial to the structure and function of cells; divided into polysaccharides, certain lipids, proteins, and nucleic acids.
Metabolic intermediate
A compound produced during one step of a metabolic pathway.
Metabolic pathway
A series of chemical reactions that results in the synthesis of an end product important to cellular function.
Molecular chaperones
Various families of proteins whose role is to assist the folding and assembly of proteins by preventing undesirable interactions.
Multiprotein complex
The interaction of more than one complete protein to form a larger, functional complex.
Noncovalent bond
A relatively weak chemical bond based on attractive forces between oppositely charged regions within a molecule or between two nearby molecules.
Nonpolar molecules
Molecules whose covalent bonds have a nearly symmetric distribution of charge because the component atoms have approximately the same electronegativities.
Oils
Fats that are liquid at room temperature.
Oligosaccharides
Small chains composed of sugars covalently attached to lipids and proteins; they distinguish one type of cell from another and help mediate interactions of a cell with its surroundings.
Peptide bond
The chemical bond linking amino acids in a protein, which forms when the carboxyl group of one amino acid reacts with the amino group of a second amino acid.
pH
The standard measure of relative acidity, it mathematically equals −log[H+].
Polar molecules
Molecules with an uneven distribution of charge because the component atoms of various bonds have greatly different electronegativities.
Polypeptide chain
A long, continuous unbranched polymer formed by amino acids joined to one another by covalent peptide bonds.
Polysaccharide
A polymer of sugar units joined by glycosidic bonds.
Posttranslational modifications (PTMs)
Alterations to the side chains of the 20 basic amino acids after their incorporation into a polypeptide chain.
Proteome
The entire inventory of proteins in a particular organism, cell type, or organelle.
Proteomics
Expanding field of protein biochemistry that performs large-scale studies on diverse mixtures of proteins.
Purine
A class of nitrogenous base found in nucleotides that has a double-ring structure, including adenine and guanine, which are found in both DNA and RNA.
Pyrimidine
A class of nitrogenous base found in nucleotides that has a single-ring structure, including cytosine and thymine, which are found in DNA, and cytosine and uracil, which are found in RNA.
Quaternary structure
The three-dimensional organization of a protein that consists of more than one polypeptide chain, or subunit.
Ribonucleic acid (RNA)
A single-stranded nucleic acid composed of a polymeric chain of ribose-containing nucleotides.
Ribozyme
An RNA molecule that functions as a catalyst in cellular reactions.
Saturated fatty acids
Those lacking double bonds between carbons.
Self-assembly
The property of proteins (or other structures) to assume the correct (native) conformation based on the chemical behavior dictated by the amino acid sequence.
side chain or R group
The defining functional group of an amino acid, which can range from a single hydrogen to complex polar or non-polar units in the 20 amino acids most commonly found in cells.
Site-directed mutagenesis
A research technique to modify a gene in a predetermined way so as to produce a protein with a specifically altered amino acid sequence.
Specificity
The property of selective interaction between components of a cell that is basic to life.
Starch
Mixture of two glucose polymers, amylose and amylopectin, that serves as readily available chemical energy in most plant cells.
Subunit
A polypeptide chain that associates with other chains (subunits) to form a complete protein or protein complex.
Triacylglycerols
Polymers consisting of a glycerol backbone linked by ester bonds to three fatty acids, commonly called fats.
Unsaturated fatty acids
Those having one or more double bonds between carbon atoms.
Van der Waals force
A weak attractive force due to transient asymmetries of charge within adjacent atoms or molecules.
X-ray crystallography (X-ray diffraction)
A technique that bombards protein crystals with a thin beam of X-rays of a single (monochromatic) wavelength. The radiation that is diffracted by the electrons of the protein atoms strikes a photographic plate or sensor. The diffraction pattern produced by the crystal is determined by the structure within the protein.
Guanosine triphosphate (GTP)
A nucleotide of great importance in cellular activities. It binds to a variety of proteins (called G proteins) and acts as a switch to turn on their activities.