Comprehensive Biology Study Cards: Cell Biology, Biological Chemistry, Water, and Macromolecules

Vocabulary practice flashcards covering cellular organelles, microscopy, cell components, organic chemistry, carbon functional groups, water chemistry, and biological macromolecules.

Magnification

The ratio of an object's image size to its real size.

Resolution

The measure of image clarity, defined as the minimum distance between two distinguishable points.

Contrast

The visible differences in brightness between different parts of a specimen sample under a microscope.

Cell Fractionation

A cellular research technique where cells are broken up (homogenization) and spun in a centrifuge (differential centrifugation) to separate cellular components by size and density.

Prokaryotic Cell

A simpler cell lacking a true nucleus and membrane-bound organelles, where DNA is localized in a region called the nucleoid.

Eukaryotic Cell

A complex cell type characterized by housing its DNA within a membrane-enclosed nucleus and possessing distinct membrane-bound organelles.

Nuclear Envelope

A double membrane perforated by pores that encloses the nucleus and regulates the entry and exit of molecules in eukaryotic cells.

Nucleolus

A nonmembranous structure within the eukaryotic nucleus involved in the synthesis of ribosomal RNA (rRNA) and the production of ribosomes.

Chromatin

The complex of DNA and associated proteins found within eukaryotic cells that condenses to form individual chromosomes during cell division.

Smooth ER

A region of the endoplasmic reticulum lacking ribosomes that functions in lipid synthesis, drug and poison detoxification, and calcium ion storage.

Rough ER

A region of the endoplasmic reticulum studded with ribosomes that synthesizes proteins (especially glycoproteins), distributes transport vesicles, and acts as a membrane factory.

Golgi Apparatus

An organelle composed of flattened membranous sacs called cisternae that modifies, manufactures, sorts, and packages ER products into transport vesicles.

Lysosome

A membranous sac containing acidic hydrolases that functions as the major recycling center of the cell to digest macromolecules, damaged organelles, and cellular debris.

Peroxisome

A single-membrane oxidative organelle containing oxidases and catalase that detoxifies harmful molecules and breaks down fatty acids, producing hydrogen peroxide ($H_2O_2$) as a byproduct.

Endosymbiont Theory

The evolutionary theory stating that mitochondria and chloroplasts originated as prokaryotic cells engulfed by an ancestral eukaryotic cell.

Microtubules

Thick, hollow tubes made of tubulin that maintain cell shape, facilitate organelle and vesicle movement, and separate chromosomes during cell division.

Microfilaments

Thin fibers composed of a twisted double chain of actin involved in cell shape, muscle contraction, amoeboid motility, and cytoplasmic streaming.

Intermediate Filaments

Fibrous protein structures of intermediate diameter that provide structural stability, anchor the nucleus and organelles, and form the nuclear lamina.

Plasmodesmata

Cytoplasmic channels passing through plant cell walls that connect adjacent cell cytoplasms and permit the movement of water, solutes, and macromolecules.

Tight Junctions

Animal cell junctions where plasma membranes are pressed tightly together to form continuous seals preventing extracellular fluid leakage.

Desmosomes

Anchoring junctions in animal cells that fasten cells together into strong, continuous sheets.

Gap Junctions

Communicating junctions between adjacent animal cells consisting of membrane channels that allow cytoplasmic exchange of ions and small molecules.

Tetrahedral Geometry

The three-dimensional spatial arrangement formed when a central carbon atom creates four single covalent bonds with surrounding atoms.

Valence

The bonding capacity of an atom, equal to the number of covalent bonds the atom typically forms to complete its outer valence shell.

Hydrocarbons

Organic molecules consisting solely of carbon and hydrogen, which are nonpolar, hydrophobic, and store substantial chemical energy.

Structural Isomers

Molecules that share the same molecular formula but differ in the covalent arrangement of their carbon skeletons.

Cis-Trans Isomers

Geometric isomers resulting from the inflexibility of double bonds, where functional groups are located on the same side (cis) or opposite sides (trans) of the double bond.

Enantiomers

Isomers that are non-superimposable mirror images of each other due to an asymmetric carbon bonded to four different functional groups.

Hydroxyl Group

A polar functional group represented as $-OH$ that increases water solubility and participates in chemical reactions.

Carboxyl Group

An acidic functional group represented as $-COOH$ that donates $H^+$ and carries a negative charge at cellular pH.

Amino Group

A basic functional group represented as $-NH_2$ that accepts $H^+$ and carries a positive charge at cellular pH.

Adenosine Triphosphate (ATP)

An organic molecule composed of adenosine bound to three phosphate groups that acts as the main chemical energy currency of cells.

Cohesion

The property of water molecules sticking to one another via hydrogen bonding, enabling water transport against gravity in plants and high surface tension.

Adhesion

The attraction and clinging of water molecules to distinct hydrophilic substances, such as plant cell walls.

Surface Tension

A measure of how difficult it is to stretch or break the surface of a liquid, produced in water by strong inter-molecular hydrogen bonding.

Specific Heat

The amount of heat energy required to change the temperature of $1\,\text{g}$ of a substance by $1\,^\circ\text{C}$.

Evaporative Cooling

The reduction in temperature of a liquid's remaining surface as the highest-kinetic-energy molecules undergo vaporization into a gas.

Hydration Shell

The surrounding sphere of water molecules attracted to and oriented around an ion dissolved in an aqueous solution.

Hydrophilic

Having an affinity for water; describing polar or ionic molecules that readily interact with or dissolve in water.

Hydrophobic

Lacking an affinity for water; describing nonpolar molecules (such as oils and fats) that do not dissolve in or mix with water.

Molarity

A unit of concentration defined as the number of moles of solute dissolved per liter of solution ($\text{M}$).

Acid

A substance that increases the hydrogen ion ($H^+$) concentration of a solution, causing its pH to drop below $7$.

Base

A substance that decreases the hydrogen ion ($H^+$) concentration of a solution, causing its pH to rise above $7$.

Buffer

A system consisting of a weak acid and its conjugate base that resists drastic pH changes by accepting or donating $H^+$ ions.

Ocean Acidification

The process by which excess atmospheric carbon dioxide ($CO_2$) dissolves into oceans, forming carbonic acid and lowering seawater pH and carbonate ion ($CO_3^{2-}$) concentration.

Monosaccharide

The simplest carbohydrate monomer, typically having a molecular formula that is a multiple of $CH_2O$, such as glucose ($C_6H_{12}O_6$).

Aldose

A monosaccharide containing a carbonyl group located at the terminus of its carbon chain.

Ketose

A monosaccharide containing a carbonyl group positioned within its carbon chain.

Dehydration Reaction

A reaction in which two monomers become covalently bonded to each other with the simultaneous loss of a water molecule.

Hydrolysis

A chemical reaction that breaks the covalent bond between monomers in a polymer through the addition of a water molecule.

Glycosidic Linkage

A covalent bond formed between two monosaccharide units via a dehydration reaction.

Starch

A plant storage polysaccharide consisting entirely of glucose monomers linked by glycosidic bonds, occurring as amylose and amylopectin.

Glycogen

An extensively branched storage polysaccharide made of glucose monomers, stored predominantly in liver and muscle cells of animals.

Cellulose

A unbranched structural polysaccharide of $\beta$ glucose monomers that serves as the major structural component of plant cell walls.

Chitin

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

Primary Structure

The specific, linear sequence of amino acids in a protein chain running from the N-terminus to the C-terminus.

Secondary Structure

Local coils ($\alpha$ helix) and folds ($\beta$ pleated sheet) in a polypeptide chain stabilized by hydrogen bonds along the polypeptide backbone.

Tertiary Structure

The overall three-dimensional shape of a single polypeptide determined by side-chain (R group) interactions such as ionic bonds, hydrogen bonds, hydrophobic interactions, and disulfide bridges.

Quaternary Structure

The complex overall protein structure resulting from the assembly and interaction of multiple individual polypeptide subunits.

Denaturation

The process in which a protein loses its native shape and biological activity due to environmental disruption of weak chemical bonds, caused by extreme pH, temperature, or salt changes.

Transcription

The synthesis of messenger RNA (mRNA) from a complementary DNA template inside the nucleus.

Translation

The process in which ribosomes in the cytoplasm synthesize a polypeptide chain using the genetic code carried by an mRNA molecule.

Pyrimidines

Nitrogenous bases containing a single six-membered ring structure, specifically cytosine (C), thymine (T), and uracil (U).

Purines

Nitrogenous bases containing a six-membered ring fused to a five-membered ring, specifically adenine (A) and guanine (G).

Phosphodiester Bond

The covalent linkage connecting the $3'$ hydroxyl group of one nucleotide's sugar to the $5'$ phosphate group of the next nucleotide in a polynucleotide strand.

Antiparallel

The arrangement of the two sugar-phosphate strands in a DNA double helix, running side-by-side in opposite $5' \rightarrow 3'$ and $3' \rightarrow 5'$ directions.

Triacylglycerol

A fat molecule formed by joining three fatty acid tails to a single glycerol backbone via ester linkages.

Phospholipid

An amphipathic lipid consisting of two hydrophobic fatty acid tails and a hydrophilic phosphate-containing head attached to glycerol.

Steroid

A lipid characterized by a carbon skeleton composed of four fused rings, such as cholesterol.