UIC BIOS 222 Exam 1 All Terms

Cell

The basic unit of all life on Earth and the smallest entity that can be considered alive.

Cell biology

The study of how these basic units of life work.

DNA (deoxyribonucleic acid)

A macromolecule composed of two antiparallel and complementary chains of deoxynucleotides.

Centromere

A region of a nuclear structure to which the kinetochore forms and to which microtubules attach during mitosis.

Chromosome

A long genetic macromolecule that encodes some or all of the instructions for cellular function within its sequence of nucleotides. In eukaryotes they are usually linear, and in prokaryotes they are usually circular.

Golgi apparatus (Golgi)

A set of lipid membrane enclosed, flattened sacs called cisternae that receives proteins from the endoplasmic reticulum (ER), sorts them, and then packages them in vesicles to be delivered to their final destination.

Microscope

An instrument used for viewing very small objects.

ATP synthase

A protein complex that produces adenosine triphosphate from ADP and Pi using the mechanical energy of a spinning turbine powered by proton flow across the inner mitochondrial membrane.

Mitochondria (singular: mitochondrion)

Organelles found in eukaryotic cells that evolved from independent proteobacteria to extract potential chemical energy from carbohydrates and lipids and package it into bite-size packets of chemical currency.

Cristae (singular: crista)

Sheet- and tube-like infoldings of the inner mitochondrial membrane that significantly increase its surface area while maintaining a relatively small intermembrane volume.

Bacteria

One of the three domains of life on Earth consisting of single-celled organisms with a peptidoglycan cell wall.

Archaea

One of the three domains of life on Earth consisting of single-celled organisms known for residing in extreme environments.

Eukarya

One of the three domains of life on Earth containing membrane-bound organelles; members may be single-celled or multicellular.

Eukaryote

An organism whose cells possess a nucleus and other lipid membrane-bound organelles.

Abiogenesis

The evolution of life from nonliving material.

Single-celled organism

An entity that is composed of only one individual living unit as opposed to forms composed of many.

Eukaryotic cell

An individual living unit possessing a nucleus and membrane-bound organelles, existing independently or as part of a larger tissue.

Lipid membrane

A barrier composed of two fatty layers that separates two aqueous solutions.

Prokaryote

An organism that belongs to either Bacteria or Archaea, characterized by being exclusively unicellular and lacking a nucleus and other internal compartments.

Cell wall

A rigid outer layer surrounding the plasma barrier that functions to shape, protect, and provide resistance to osmotic pressure; usually composed of polysaccharides.

Polysaccharide

A macromolecule composed of many carbohydrate molecules linked together.

Peptidoglycan

A complex sugar-and-peptide polymer used to form the protective outer layer of most bacterial species.

Gram-positive bacteria

Organisms that stain purple when exposed to a specific dye because their thick peptidoglycan layer is exposed on the outside.

Gram-negative bacteria

Organisms that stain red when exposed to a specific dye because their peptidoglycan layer is concealed by an outer lipid barrier.

Genome

All of the collective chromosomes within an organism, with the exception of mitochondrial and perhaps chloroplast genetic material.

Nucleoid

A region in the center of an organism lacking a nucleus where the circular genetic material is localized.

Multicellular organism

A complex living entity composed of many specialized units functioning together.

Cytoskeleton

A network of structural proteins (F-actin filaments, intermediate filaments, and microtubules) that acts as an internal framework, shapes the boundary, and serves as tracks for cargo transport.

Morphological diversity

The variation in shape, structure, size, color, and overall appearance between different objects, cells, or organisms.

Functional diversity

The variation in biological roles, activities, and tasks carried out between different molecules, organelles, or organisms.

Intracellular

Located or occurring within the interior boundary of a living unit.

Ion

A single atom carrying a net electrical charge due to the loss or gain of electrons.

Light microscope

An instrument that uses visible wavelengths of illumination to view very small specimens.

Fluorescence microscope

An instrument that uses ultraviolet radiation to excite specific dye molecules within a specimen.

Electron microscope

An instrument that directs beams of high-energy charged particles to visualize structural differences in density.

Ultraviolet (UV) light

Short-wavelength electromagnetic radiation used as the excitation source for viewing fluorescently tagged samples.

Confocal microscope

An advanced optical device that captures images of a specimen across multiple vertical focal planes to assemble a three-dimensional model.

Transmission electron microscopy (TEM)

An imaging technique where charged subatomic particles pass through a thinly sliced sample to map internal density variations in two dimensions.

Scanning electron microscopy (SEM)

An imaging technique where charged subatomic particles deflect off the surface of a specimen to produce a three-dimensional representation of external topography.

Surface topography

The external three-dimensional contours, relief, and shape of an object.

Cryogenic electron microscopy (cryo-EM)

A high-resolution visualization method where rapidly frozen samples are imaged from multiple angles to reconstruct three-dimensional macromolecular architectures.

Nuclear magnetic resonance (NMR)

The use of magnetic fields to indirectly determine the exact spatial coordinates of specific atomic centers within a specimen.

X-ray crystallography

A technique that directs high-energy electromagnetic rays at an ordered molecular lattice to produce an atomic-resolution structural model.

Diffraction pattern

The array of constructive and destructive scattering spots produced when electromagnetic beams strike an ordered atomic crystal.

Subatomic particle

The fundamental components—protons, neutrons, and electrons—that make up all elements.

Organic molecule

In biology, any chemical compound containing carbon, with a few simple exceptions such as carbon dioxide.

Inorganic molecule

A chemical compound that lacks carbon atoms.

Functional side group

An atom or cluster of atoms attached to a carbon backbone that determines specific chemical properties and reactivity.

Hydroxyl

A side moiety consisting of an oxygen atom covalently linked to a hydrogen atom.

Methyl

A side moiety consisting of a single carbon atom bonded to three hydrogen atoms.

Carboxyl (carboxylic acid)

A side moiety consisting of a carbon atom double-bonded to an oxygen atom and single-bonded to an -OH group.

Carbonyl

A side moiety consisting of a carbon atom sharing a double covalent bond with an oxygen atom.

Phosphoryl (phosphate)

A side moiety consisting of a central phosphorus atom bonded to several oxygen atoms, one of which is double-bonded.

Amino

A side moiety consisting of a nitrogen atom covalently bonded to two hydrogen atoms.

Thiol (sulfhydryl)

A side moiety consisting of a sulfur atom bonded to a hydrogen atom.

Hydrophilic

Readily dissolving in or interacting with aqueous solutions due to a high presence of polar or electrically charged bonds.

Amphipathic

Possessing distinct regions that are polar and water-soluble as well as regions that are nonpolar and water-insoluble.

Hydrophobic

Lacking affinity for water and failing to dissolve in aqueous solutions due to nonpolar characteristics.

Monomer

A single building-block subunit capable of joining covalently with others to build larger chains.

Polymer

A large chainlike structure formed by covalently linking many smaller repeating chemical subunits together.

Carbohydrate

A biological class of hydrated carbon molecules with the formula (CH2O)n, serving as fuel and structural polymers.

Isomers

Two distinct chemical compounds that share the exact same formula of elements but differ in spatial connectivity or atomic arrangement.

Optical isomers

Molecules that are non-superimposable mirror reflections of one another, distinguished as D- and L-forms.

Nucleotide

A building block comprising a nitrogen-rich ring, a five-carbon sugar, and one or more terminal phosphate moieties.

Ribose

A five-carbon sugar containing hydroxyl groups on both the 2' and 3' carbons, found in RNA.

Ribonucleotide

A subunit containing a 2'-hydroxylated pentose sugar, a nitrogen-rich base, and phosphates.

Deoxyribose

A five-carbon sugar lacking an oxygen atom at the 2' position, found in DNA.

Deoxyribonucleotide

A subunit containing a 2'-deoxygenated pentose sugar, a nitrogen-rich base, and phosphates.

Nitrogenous base

An aromatic carbon-and-nitrogen ring structure that projects from the sugar moiety of genetic building blocks.

Nucleoside

A unit formed strictly by a nitrogen-rich ring linked to a five-carbon pentose, lacking any attached phosphates.

Pyrimidine

A single six-membered aromatic ring containing nitrogen, such as cytosine, thymine, or uracil.

Purine

A fused double-ring aromatic structure containing nitrogen, such as adenine or guanine.

Adenosine (A)

A purine-containing subunit featuring the aromatic base adenine attached to a pentose sugar.

Guanosine (G)

A purine-containing subunit featuring the aromatic base guanine attached to a pentose sugar.

Cytidine (C)

A pyrimidine-containing subunit featuring the aromatic base cytosine attached to a pentose sugar.

Thymidine (T)

A pyrimidine-containing subunit featuring the aromatic base thymine attached to a deoxyribose sugar.

Uridine (U)

A pyrimidine-containing subunit featuring the aromatic base uracil attached to a ribose sugar.

Phosphoanhydride bond

The high-energy linkage connecting adjacent phosphate groups in energy-storage molecules.

Adenosine triphosphate (ATP)

A purine ribonucleotide bearing three phosphate groups that transfers energy via hydrolysis to drive work.

Guanosine triphosphate (GTP)

A purine ribonucleotide bearing three phosphate groups whose hydrolysis governs molecular timing mechanisms.

Amino acid

A monomer built around a central alpha-carbon bonded to an NH2 group, a COOH group, a hydrogen, and an R group.

Lipid

An amphipathic molecule composed largely of carbon and hydrogen that aggregates non-covalently in water.

Phospholipid

A membrane constituent featuring a polar head group linked via a three-carbon connector to two hydrophobic hydrocarbon tails.

Glycerol

A three-carbon polyol that serves as the backbone linking the polar head to fatty acyl chains.

Cholesterol

A sterol composed of four hydrocarbon rings coupled to a small polar hydroxyl head.

Macromolecule

A very large polymer (such as a protein, polysaccharide, or nucleic acid) composed of hundreds or thousands of covalently linked atoms.

Polymerization

The biochemical process of covalently joining individual monomeric units end-to-end to generate large chains.

Condensation reaction

A chemical synthesis joining two molecules through the net elimination and production of a single water molecule.

Monosaccharide

A single sugar molecule that cannot be hydrolyzed into simpler carbohydrate units.

Disaccharide

A carbohydrate formed by covalently joining two simple sugar rings together.

Oligosaccharide

A short chain containing a few (typically between three and a couple dozen) linked sugar units.

Polysaccharide

A complex macromolecule constructed from extensive linear or branched assemblies of monosaccharides.

Glycosidic bond

The covalent linkage formed between the hydroxyl groups of adjacent sugars accompanied by water release.

Glycogen

A highly branched polysaccharide used by animal cells to store glucose for energetic needs.

Starch

A polysaccharide storage polymer synthesized by plant cells to reserve chemical energy.

Cellulose

An unbranched polysaccharide composed of glucose chains that provides structural rigidity to plant cell walls.

Glycocalyx

A sugar-rich exterior surface coating formed by oligosaccharide chains linked to membrane proteins and lipids.

Base pair

Two opposing nucleotides from antiparallel strands linked internally across a double helix by non-covalent hydrogen bonds.

Hydrogen bond (interaction)

An electrostatic attraction between a partially positive hydrogen atom and an electronegative partner with a partial negative charge.

Complementary base pairing

The specific hydrogen-bonding alignment between purines and pyrimidines, notably A with T and G with C.