BIO 101 Exam 1 Study Guide Vocabulary

Flashcards based on BIO 101 Exam 1 Study Guide covering scientific thinking, basic chemistry, water properties, biomolecules, cell structures, organelles, cytoskeleton, membranes, and cell junctions.

Scientific theory

A well-tested explanation of natural phenomena supported by a large amount of evidence.

Scientific law

A description of an observed natural phenomenon that states what happens, whereas a theory explains how or why it happens.

Atom

The smallest unit of an element.

Element

A pure substance composed of only one type of atom.

Molecule

A structure formed when two or more atoms are chemically bonded together.

Atomic number

The total number of protons in the nucleus of an atom.

Mass number

The total sum of protons and neutrons in an atom's nucleus.

Isotope

Atoms of the same element that have the same number of protons but different numbers of neutrons.

Valence electrons

Electrons located in an atom's outermost electron shell that determine its chemical reactivity.

Ionic bond

A chemical bond formed when one or more electrons are transferred from a metal atom to a nonmetal atom.

Covalent bond

A chemical bond formed when atoms share one or more pairs of valence electrons.

Cation

A positively charged ion produced when an atom loses one or more electrons.

Anion

A negatively charged ion produced when an atom gains one or more electrons.

Hydrogen bond

A weak electrostatic attraction between a partially positive hydrogen atom and a nearby electronegative atom.

Electronegativity

A measure of an atom's ability to attract shared electrons within a chemical bond.

Polar covalent bond

A covalent bond in which shared electrons are pulled unequally toward the more electronegative atom, creating partial electrical charges.

Nonpolar covalent bond

A covalent bond in which electrons are shared equally between two atoms.

Cohesion

The property of water molecules sticking to other water molecules via hydrogen bonding.

Adhesion

The property of water molecules sticking to other polar or charged materials.

Capillary action

The upward movement of water through narrow spaces caused by adhesion pulling water along a surface and cohesion pulling other water molecules along.

High specific heat

The property of water requiring a large amount of energy to change its temperature due to hydrogen bonding.

Hydrophilic

Describing a polar or charged substance that is attracted to and readily interacts with water.

Hydrophobic

Describing a nonpolar substance that is repelled by and does not dissolve in water.

Buffer

A chemical system that resists sudden changes in $\text{pH}$ by accepting excess $\text{H}^+$ or releasing $\text{H}^+$ as needed.

Monomer

A small chemical subunit that serves as a building block for a larger polymer.

Polymer

A large molecule made of many repeating monomer subunits bonded together.

Dehydration synthesis

A chemical reaction that links monomers together to build polymers by removing a water molecule.

Hydrolysis

A chemical reaction that breaks down polymers into individual monomers by adding a water molecule.

Functional group

A specific arrangement of atoms attached to a carbon skeleton that confers distinct chemical properties to an organic molecule.

Hydroxyl group

A functional group represented by $\text{-OH}$.

Amino group

A functional group represented by $\text{-NH}_2$.

Carboxyl group

A functional group represented by $\text{-COOH}$.

Phosphate group

A functional group represented by $\text{-PO}_4$.

Monosaccharide

The monomer unit of carbohydrates consisting of a single simple sugar molecule.

Glycosidic bond

The covalent bond that joins monosaccharides together during dehydration synthesis.

Glycogen

A branched polysaccharide used for energy storage in animals.

Starch

A polysaccharide used for energy storage in plants.

Cellulose

A structural polysaccharide that forms the rigid cell wall of plant cells.

Chitin

A structural polysaccharide found in fungal cell walls and arthropod exoskeletons.

Peptidoglycan

A structural molecule composed of sugars and amino acids found in bacterial cell walls.

Triglyceride

A lipid composed of one glycerol molecule linked to three fatty acids that functions in long-term energy storage, insulation, and protection.

Saturated fatty acid

A fatty acid chain containing no $\text{C=C}$ double bonds, causing it to be straight and solid at room temperature.

Unsaturated fatty acid

A fatty acid chain containing one or more $\text{C=C}$ double bonds, which create bends or kinks preventing tight packing.

Phospholipid

An amphipathic lipid consisting of a hydrophilic phosphate head, glycerol, and two hydrophobic fatty-acid tails, forming the structural basis of cell membranes.

Amphipathic

Describing a molecule that possesses both a hydrophilic region and a hydrophobic region.

Amino acid

The monomer unit of proteins consisting of a central carbon, an amino group, a carboxyl group, a hydrogen atom, and a variable R-group.

Peptide bond

The covalent bond formed between two amino acids via dehydration synthesis.

Denaturation

The loss of a protein's natural three-dimensional shape and function caused by external stress such as extreme heat or $\text{pH}$.

Enzyme

A catalytic protein that speeds up chemical reactions without being permanently consumed by the reaction.

Prion

An infectious, misfolded protein that induces normal proteins of the same type to misfold abnormally.

Nucleotide

The monomer of nucleic acids composed of a five-carbon sugar, a phosphate group, and a nitrogenous base.

Phosphodiester bond

The covalent linkage that connects adjacent nucleotides along a nucleic acid backbone.

Antiparallel

The opposite structural orientation of double-stranded DNA, where one strand runs in the $5'\rightarrow 3'$ direction and the complementary strand runs $3'\rightarrow 5'$.

mRNA

Messenger RNA; a single-stranded RNA molecule that carries genetic instructions from DNA to a ribosome.

rRNA

Ribosomal RNA; RNA components that form part of the ribosome structure and catalyze protein synthesis.

tRNA

Transfer RNA; an RNA molecule that delivers specific amino acids to the ribosome during translation.

Ribozyme

An RNA molecule capable of functioning as a biological enzyme.

ATP

Adenosine triphosphate; the primary cellular energy currency that supplies immediate energy for cellular processes.

Nucleolus

A dense region inside the nucleus responsible for synthesizing rRNA and assembling ribosome subunits.

Rough ER

A network of folded membranes studded with ribosomes that synthesizes, modifies, and processes proteins and phospholipids.

Smooth ER

A network of folded membranes lacking ribosomes that synthesizes lipids and steroids, detoxifies chemicals, and stores calcium ions.

Golgi apparatus

An organelle composed of flattened membranous sacs that modifies, sorts, labels, packages, and ships proteins and lipids.

Lysosome

A membrane-bound organelle containing digestive enzymes that hydrolyze macromolecules, damaged cellular structures, and foreign material.

Peroxisome

An organelle that breaks down fatty acids and toxic substances, generating hydrogen peroxide ($\text{H}_2\text{O}_2$) and breaking it down with catalase.

Microtubules

Hollow cytoskeletal fibers made of tubulin proteins that serve as transport tracks, form the mitotic spindle, and construct cilia and flagella.

Centrosome

The principal microtubule-organizing center in eukaryotic cells that aids in forming the mitotic spindle during cell division.

Endosymbiotic theory

The theory proposing that eukaryotic organelles such as mitochondria and chloroplasts originated as free-living prokaryotes engulfed by an ancestral eukaryotic host cell.

Exocytosis

A form of bulk transport where an internal vesicle fuses with the plasma membrane to expel materials outside the cell.

Endocytosis

A form of bulk transport where the plasma membrane invaginates to engulf extracellular material into an intracellular vesicle.

Tight junctions

Intercellular junctions composed of claudins and occludins that form an impermeable seal between neighboring epithelial cells to prevent fluid leakage.

Gap junctions

Intercellular protein channels that allow direct diffusion of ions and small signaling molecules between adjacent animal cells.

Desmosomes

Strong anchoring cell junctions that rivet adjacent animal cells together, resisting mechanical tearing forces in tissues.

Plasmodesmata

Microscopic channels penetrating plant cell walls that connect the cytoplasm of neighboring plant cells for intercellular transport.

Apoplastic pathway

The route of water and solute movement through plant tissues exclusively via cell walls and extracellular spaces outside plasma membranes.

Symplastic pathway

The route of water and solute movement through plant tissues through the continuous cytoplasm of adjacent cells linked by plasmodesmata.