Biology: Macromolecules and Cell Structure Review

Vocabulary flashcards covering key definitions for biological macromolecules (carbohydrates, lipids, proteins, nucleic acids) and cell anatomy/organelles from Chapter 5 and Chapter 6 lecture notes.

Polymer

A long molecule consisting of many similar or identical building blocks linked by covalent bonds.

Monomer

The repeating unit that serves as a building block of a polymer.

Dehydration reaction

A chemical reaction in which two molecules become covalently bonded to each other through the loss of a water molecule.

Hydrolysis

A chemical reaction that breaks bonds between two molecules by the addition of water, disassembling polymers into monomers.

Monosaccharide

The simplest carbohydrate, serving as a monomer for disaccharides and polysaccharides, with a molecular formula that is generally a multiple of $\text{CH}_2\text{O}$.

Glycosidic linkage

A covalent bond formed between two monosaccharides by a dehydration reaction.

Starch

A storage polysaccharide in plants consisting entirely of glucose monomers linked by glycosidic bonds.

Glycogen

An extensively branched glucose storage polysaccharide found in animal liver and muscle cells.

Cellulose

A structural polysaccharide that is a major component of tough plant cell walls, consisting of unbranched glucose polymers joined by distinct glycosidic linkages.

Triacylglycerol

A lipid consisting of three fatty acids linked to one glycerol molecule by ester linkages; also called a fat or triglyceride.

Saturated fatty acid

A fatty acid in which all carbons in the hydrocarbon tail are connected by single bonds, maximizing the number of hydrogen atoms attached.

Unsaturated fatty acid

A fatty acid possessing one or more double bonds between carbons in the hydrocarbon tail, reducing the number of attached hydrogen atoms.

Phospholipid

A lipid composed of glycerol attached to two fatty acids and a phosphate group, possessing hydrophobic hydrocarbon tails and a hydrophilic head.

Steroid

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

Amino acid

An organic molecule possessing both a carboxyl and an amino group, serving as the monomer of polypeptides and proteins.

Peptide bond

The covalent bond between the carboxyl group of one amino acid and the amino group of another, formed by a dehydration reaction.

Primary structure

The unique level of protein structure consisting of the linear sequence of specific amino acids.

Secondary structure

Regions of repetitive coiling or folding in a polypeptide backbone due to hydrogen bonding between backbone constituents, such as an $\alpha$ helix or $\beta$ pleated sheet.

Tertiary structure

The overall three-dimensional shape of a polypeptide resulting from interactions between the side chains (R groups) of amino acids.

Quaternary structure

The overall protein structure resulting from the aggregation of two or more polypeptide subunits.

Denaturation

A process in which a protein loses its native shape and biological function due to disruption of weak chemical bonds caused by changes in pH, salt concentration, or temperature.

Nucleotide

The building block of a nucleic acid, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and one or more phosphate groups.

Pyrimidine

A family of nitrogenous bases characterized by a six-membered ring, including cytosine (C), thymine (T), and uracil (U).

Purine

A family of nitrogenous bases characterized by a six-membered ring fused to a five-membered ring, including adenine (A) and guanine (G).

Antiparallel

Referring to the arrangement of the sugar-phosphate backbones in a DNA double helix, which run in opposite $5' \rightarrow 3'$ directions.

Magnification

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

Resolution

The measure of image clarity, defined as the minimum distance two distinguishable points can be separated and still be distinguished.

Prokaryotic cell

A type of cell lacking a membrane-enclosed nucleus and membrane-bound organelles, with DNA located in an unbound region called the nucleoid.

Eukaryotic cell

A type of cell with a membrane-enclosed nucleus containing DNA and distinct membrane-bound organelles located in the cytoplasm.

Nuclear envelope

A double membrane that encloses the nucleus, separating its contents from the cytoplasm and perforated by nuclear pores.

Nucleolus

A specialized structure in the nucleus consisting of chromosomal regions and proteins, functioning as the site of ribosomal RNA (rRNA) synthesis.

Smooth ER

The portion of the endoplasmic reticulum that lacks ribosomes on its outer surface and synthesizes lipids, metabolizes carbohydrates, detoxifies drugs, and stores calcium ions.

Rough ER

The portion of the endoplasmic reticulum studded with ribosomes that synthesizes membrane proteins and secretes glycoproteins.

Golgi apparatus

An organelle consisting of stacks of flat membranous sacs (cisternae) that modify, store, and route products of the endoplasmic reticulum.

Lysosome

A membrane-enclosed sac of hydrolytic enzymes found in eukaryotic cells that digests macromolecules, engulfed food particles, or cellular debris.

Phagocytosis

A type of endocytosis in which large particulate substances or small organisms are engulfed by a cell and packaged into a food vacuole.

Autophagy

A recycling process in which lysosomes use hydrolytic enzymes to break down and recycle the cell's own damaged organelles and macromolecules.

Endosymbiont theory

The theory stating that mitochondria and plastids originated as prokaryotic cells engulfed by an ancestral eukaryotic cell, which then evolved into a single organism.

Cristae

Infoldings of the inner membrane of a mitochondrion that house electron transport chains and molecules involved in ATP synthesis.

Thylakoid

A flattened, membranous sac inside a chloroplast that contains chlorophyll and forms stacks called grana.

Peroxisome

A specialized metabolic organelle bounded by a single membrane that contains enzymes transferring hydrogen atoms from substrates to oxygen, producing hydrogen peroxide.

Microtubule

A hollow rod composed of tubulin proteins that forms part of the cytoskeleton, maintaining cell shape, guiding organelle transport, and separating chromosomes during division.

Centrosome

A structure present in animal cells that functions as a microtubule-organizing center, containing two centrioles.

Microfilament

A solid rod composed of actin proteins in the cytoplasm, forming part of the cytoskeleton and functioning in tension resistance and cellular movement.

Intermediate filament

A component of the cytoskeleton including keratin proteins that provides permanent structural support for cell shape and fixes organelle positions.

Plasmodesmata

Open channels through plant cell walls that connect adjacent cells' cytoplasm, allowing water, small solutes, and certain molecules to pass through.

Tight junction

A cell junction in animal epithelial tissue that forms a continuous seal around cells to prevent leakage of extracellular fluid.

Desmosome

A type of intercellular junction in animal cells that functions like a rivet, fastening cells together into strong structural sheets.

Gap junction

A type of intercellular junction in animal cells consisting of membrane proteins surrounding a pore that allows ions, sugars, and amino acids to pass between adjacent cells.