General Biology: Cell Biology, Macromolecules, and Metabolism

Comprehensive vocabulary flashcards covering macromolecule functional groups, chemical bonds, cellular organelles, membrane transport mechanisms, thermodynamics, and enzyme kinetics.

Functional group

Group of atoms that gives a molecule its unique chemical personality and properties.

Hydroxyl group

($-\text{OH}$) in compounds such as alcohols and sugars.

Carboxyl group

($-\text{COOH}$) in fatty acids and amino acids.

Amino group

($-\text{NH}_2$) in amino acids.

Phosphate group

($-\text{PO}_4$) in ATP and DNA/RNA nucleotides.

Dehydration synthesis

joins smaller molecules together by removing water, building larger molecules/polymers.

Hydrolysis

breaks molecules apart by adding water.

Disaccharides

Carbohydrates formed from two monosaccharides, ex. lactose and maltose.

Polysaccharides

Carbohydrate polymers that provide energy storage or structural support, ex. starch and glycogen.

Triglyceride

lipid made of $1$ glycerol and $3$ fatty acids.

Saturated fat

lipid that has no $\text{C=C}$ double bonds, straight fatty acid chains, solid at room temperature.

Unsaturated fat

A lipid with one or more $\text{C=C}$ double bonds that introduce bends/kinks into its fatty acid chains, making it usually liquid at room temperature.

Phospholipid

A molecule with a hydrophilic head and hydrophobic tails that forms the bilayer of cell membranes.

Secondary protein structure

Local folding patterns in a polypeptide such as an alpha helix or beta-pleated sheet.

Tertiary protein structure

The overall 3-D shape of a single polypeptide, exemplified by myoglobin.

Quaternary protein structure

A protein structure consisting of multiple polypeptide chains, exemplified by hemoglobin.

Denaturation

The disruption of interactions that maintain a protein's structure and active-site shape, often caused by high temperature or extreme pH.

Nucleotide

The building block of nucleic acids consisting of a phosphate group, a $5$-carbon sugar, and a nitrogenous base.

Glycosidic bond

The covalent linkage present between sugar units in carbohydrates.

Ester bond

The chemical linkage present in lipids connecting glycerol to fatty acids.

Peptide bond

The covalent bond that links amino acids together in proteins.

Phosphodiester bond

The chemical bond that links nucleotides together in a polynucleotide chain.

Nucleus

A large, usually round organelle surrounded by a double membrane with pores and chromatin; stores DNA and controls cell activities.

Ribosomes

Very small structures made of rRNA and proteins, either free in the cytoplasm or attached to rough ER, that make proteins.

Rough ER

A network of flattened membrane sacs studded with ribosomes that makes and processes proteins, especially for secretion or membranes.

Smooth ER

A network of membrane tubules without ribosomes that synthesizes lipids, detoxifies substances, and stores calcium.

Golgi apparatus

A stack of flattened membrane sacs called cisternae that modifies, sorts, packages, and ships proteins and lipids.

Lysosomes

Small membrane-bound sacs containing digestive enzymes that break down waste, old organelles, and large molecules.

Peroxisomes

Small membrane-bound sacs containing oxidative enzymes that break down fatty acids, detoxify harmful substances, and break down hydrogen peroxide.

Vacuoles

Membrane-bound storage sacs that store water, ions, nutrients, pigments, and wastes, and help maintain pressure in plant cells.

Mitochondrion

A double-membrane organelle with an inner membrane folded into cristae and a matrix that produces ATP through cellular respiration.

Chloroplast

A double-membrane organelle containing internal thylakoids stacked into grana and chlorophyll that performs photosynthesis.

Microtubules

The largest cytoskeletal fibers; hollow tubes made of tubulin that maintain cell shape, move organelles, separate chromosomes, and form cilia and flagella.

Microfilaments

Thin solid fibers made mainly of actin that assist in cell movement, muscle contraction, cell shape, and support of microvilli.

Intermediate filaments

Rope-like protein fibers intermediate in size between microfilaments and microtubules that provide mechanical strength and stabilize cells.

Centrioles

Cylindrical organelles made of $9$ groups of $3$ microtubules that help organize microtubules during cell division.

Cilia

Short, numerous hair-like projections containing a $9 + 2$ microtubule arrangement that move the cell or move material across the cell surface.

Flagella

Long, whip-like projections with a $9 + 2$ microtubule arrangement that propel cells, such as sperm.

Microvilli

Short, nonmoving plasma membrane folds supported by actin microfilaments that increase surface area for absorption.

Endomembrane system

A cellular system consisting of the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles, and plasma membrane.

Fluid mosaic model

A model of membrane structure describing it as fluid because lipids and proteins move laterally, and mosaic due to embedded proteins, cholesterol, and carbohydrates.

Hypotonic solution

A solution with a lower solute concentration outside the cell relative to inside, causing water to enter and potentially lyse an animal cell.

Isotonic solution

A solution with equal effective solute concentration inside and outside the cell, resulting in no net water movement.

Hypertonic solution

A solution with a higher solute concentration outside the cell, causing water to move out of the cell.

Sodium-potassium pump

An active transport mechanism that uses ATP to move $3\,\text{Na}$ out of the cell and $2\,\text{K}$ into the cell.

Cotransport

A transport process where the movement of one substance down its gradient provides the energy to transport another substance (e.g., sodium-glucose cotransporter).

Phagocytosis

A form of endocytosis known as 'cell eating' in which a cell engulfs large particles, such as a macrophage engulfing bacteria.

Pinocytosis

A form of endocytosis known as 'cell drinking' in which a cell takes in extracellular fluid and dissolved substances.

Receptor-mediated endocytosis

A selective form of endocytosis where specific target molecules bind to membrane receptors before being internalized, such as LDL cholesterol uptake.

Exocytosis

The fusion of an intracellular vesicle with the plasma membrane to release its contents outside the cell, such as neurotransmitters or hormones.

Catabolism

A metabolic pathway that breaks down complex molecules into simpler ones and generally releases free energy.

Anabolism

A metabolic pathway that builds complex molecules from simpler ones and requires energy input.

First law of thermodynamics

The principle stating that energy cannot be created or destroyed, only transferred or transformed.

Second law of thermodynamics

The principle stating that every energy transfer increases the entropy/disorder of the universe and disperses usable energy, often as heat.

Cofactor

A nonprotein helper substance required for enzyme function, which can be an inorganic ion such as $\text{Mg}^{2+}$ or $\text{Zn}^{2+}$.

Coenzyme

An organic molecule that assists enzyme activity, such as NAD, FAD, and CoQ.

Competitive inhibitor

A molecule that binds directly to an enzyme's active site, competing with the substrate; its effect can often be overcome by increasing substrate concentration.

Noncompetitive inhibitor

An inhibitor that binds to an allosteric site rather than the active site, altering enzyme function; its inhibition cannot be overcome by increasing substrate concentration.

Emergent property

A property that arises through the cooperative action of lower-level components, such as a heart pumping blood while a single cardiac muscle cell cannot.

Homologous structures

Structures with similar anatomical features resulting from common ancestry despite differing functions, such as human arms, whale flippers, and bat wings.

Hydrogen bond

A weak attraction between a partially positive hydrogen atom and an electronegative atom like oxygen or nitrogen.

Acid

A substance that increases $\text{H}$ concentration and has a pH below $7$.

Base

A substance that decreases $\text{H}$ concentration or accepts $\text{H}$, having a pH above $7$.

Simple diffusion

Direct movement of molecules like $\text{O}_2$ and $\text{CO}_2$ across the membrane down their concentration gradient without transport proteins.

Facilitated diffusion

The passive movement of substances down their concentration gradient assisted by transport proteins such as channels or carriers.

Osmosis

The diffusion of water across a selectively permeable membrane.

Aquaporins

Membrane channel proteins that facilitate the rapid passage of water molecules across cell membranes.

Active transport

The movement of substances against their concentration or electrochemical gradient, requiring energy input.