BIOL 3301 - Complete Cell Biology Flashcards

Vocabulary flashcards generated from BIOL 3301 lecture materials covering Module 1 (Introduction to Cells), Module 2 (Molecules & Membranes), and Chapter 3 (Bioenergetics & Metabolism).

Cell

The basic unit of all living organisms and the essential building block of life.

Cell Physiology

The study of how living cells maintain internal order, communicate with each other and the environment, convert substrates into energy, make molecular building blocks, and how cell molecules, structures, cell fate, and health are connected.

Central Dogma of Molecular Biology

The core framework of molecular biology stating that genetic information flows from DNA to RNA to protein ($\text{DNA} \rightarrow \text{RNA} \rightarrow \text{Protein}$).

ATP

Adenosine triphosphate; the major molecule cells use to provide usable metabolic energy for cellular processes.

Prokaryotic Cells

Simpler, usually smaller cells that lack a true nucleus and membrane-bound organelles, containing circular DNA located in the nucleoid region.

Eukaryotic Cells

Structurally complex, generally larger cells that contain a true nucleus, internal membranes, membrane-bound organelles, and linear DNA strands.

Endosymbiosis

An evolutionary process where an ancestral cell engulfed bacteria, which eventually evolved into specialized internal organelles such as mitochondria and chloroplasts.

Model Organism

An organism studied in the laboratory to understand biological processes that can apply to other organisms, including humans.

Comparative Genomics

The process of comparing genetic information between different organisms to investigate structural and functional similarities and differences.

In Vivo

Experimental procedures or biological processes that take place inside a living organism.

In Vitro

Experimental procedures performed outside an intact living organism ("in glass"), such as using cells grown under laboratory conditions.

HeLa Cells

The first immortal human cell line, established in 1951 at Johns Hopkins Hospital from cervical-tumor tissue taken from Henrietta Lacks.

Resolution

The ability of a microscopic imaging system to distinguish two neighboring objects as distinct and separate objects.

Light Microscopy

A microscopy technique using visible light passing through a specimen that can resolve biological details down to about $0.2\,\mu\text{m}$.

Fluorescence Microscopy

A microscopy technique that uses a fluorescent dye to label specific molecules; the dye absorbs one wavelength of light and emits a different wavelength.

Confocal Microscopy

A specialized microscopy method that combines images at different depths of focus to create a sharper image through image deconvolution.

Transmission Electron Microscopy (TEM)

A microscopy method that sends electrons through a thin specimen to produce a 2D image with resolution as small as about $1\,\text{nm}$.

Scanning Electron Microscopy (SEM)

A microscopy technique that scans the surface of a sample with electrons to produce a 3D surface view with about $3\text{--}20\,\text{nm}$ resolution.

Covalent Bond

A strong chemical bond formed when two atoms share a pair of electrons.

Nonpolar Covalent Bond

A covalent bond in which two atoms share electrons equally, creating relatively hydrophobic molecules.

Polar Covalent Bond

A covalent bond in which electrons are shared unequally due to differences in atomic electronegativity, creating distinct positive and negative poles.

Ionic Bond

A noncovalent interaction resulting from the complete transfer of an electron to a more electronegative atom, producing oppositely charged ions.

Cation

A positively charged ion.

Anion

A negatively charged ion.

Hydrogen Bond

A noncovalent interaction involving a partially positive hydrogen atom and a negatively charged oxygen or nitrogen atom on another molecule.

Hydrophobic Interactions

Associations between nonpolar molecules driven by the exclusion of water; critical for protein folding and lipid-bilayer formation.

Van der Waals Interactions

Very weak temporary interactions that occur between any atoms when they come into close proximity.

Polymer

A large organic macromolecule composed of smaller repeating molecular units called monomers.

Monosaccharide

A carbohydrate monomer containing one sugar unit, such as glucose or fructose.

Disaccharide

A carbohydrate composed of two linked monosaccharide monomers, such as sucrose or lactose.

Polysaccharide

A complex carbohydrate polymer containing three or more monosaccharide monomers, such as starch or glycogen.

Condensation Synthesis

A chemical reaction that joins two monomers together by removing one molecule of water; also known as dehydration synthesis.

Hydrolysis

A chemical reaction that cleaves bonds between joined monomers by adding a molecule of water.

Triglyceride

A lipid composed of three fatty acids attached to one glycerol molecule; stored in adipose tissue for long-term energy.

Fatty Acid

A hydrophobic carbon chain bonded to hydrogens with a terminal acidic carboxyl group ($\text{-COOH}$).

Saturated Fatty Acid

A fatty acid whose carbon chain contains only single covalent bonds and is fully saturated with hydrogen atoms.

Unsaturated Fatty Acid

A fatty acid containing at least one carbon-carbon double bond within its hydrocarbon chain.

Phospholipid

An amphipathic lipid consisting of two fatty-acid tails, glycerol, and a negatively charged phosphate group; the main structural component of cell membranes.

Sphingomyelin

The only nonglycerol-based phospholipid component of cell membranes listed in the lectures.

Steroids

Lipids characterized by a four-carbon-ring structure that act as signaling molecules and help regulate membrane fluidity.

Cholesterol

The major steroid in human cells that regulates membrane fluidity and serves as a structural precursor for steroid hormones.

Nucleotide

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

Nucleoside

A nucleic-acid subunit consisting of a nitrogenous base bonded to a 5-carbon sugar, without a phosphate group.

Peptide Bond

The covalent bond linking amino acids together in a polypeptide chain, formed through a condensation reaction.

Primary Structure

The specific linear sequence of amino acids in a polypeptide chain.

Secondary Structure

Local folding pattern in a protein stabilized by noncovalent interactions, predominantly forming $\alpha$-helices and $\beta$-sheets.

Tertiary Structure

The overall three-dimensional shape of a single polypeptide chain resulting from interactions among helices, sheets, and loops.

Quaternary Structure

The spatial organization and interaction of a protein composed of two or more polypeptide subunits.

Enzyme

A specialized protein that acts as a biological catalyst to accelerate chemical reactions without being permanently altered or altering chemical equilibrium.

Substrate

The specific reactant molecule that binds to an enzyme and undergoes catalysis.

Active Site

The region on an enzyme containing substrate-binding and catalytic sites where chemical conversion occurs.

Coenzyme

A small organic molecule (such as $\text{NADH}$) that participates in enzymatic reactions by carrying chemical groups or electrons between substrates.

Feedback Inhibition

A mechanism of metabolic control in which the final product of a pathway inhibits an upstream enzyme in that same pathway.

Allosteric Regulation

Regulation of enzyme activity caused by the binding of a regulatory molecule to an allosteric site separate from the active site.

Phosphorylation

A reversible covalent modification involving the addition of a phosphate group to a protein, altering its conformation and activity.

Amphipathic

Describing a molecule that possesses both a hydrophilic (water-attracting) region and a hydrophobic (water-repelling) region.

Fluid Mosaic Model

A structural model describing biological membranes as dynamic two-dimensional fluids composed of a mosaic of phospholipids, proteins, cholesterol, and glycolipids.

Integral Membrane Protein

A protein directly embedded within the hydrophobic core of the phospholipid bilayer.

Transmembrane Protein

An integral membrane protein that spans across the entire lipid bilayer, contacting both intracellular and extracellular environments.

Peripheral Membrane Protein

A protein indirectly associated with the membrane, typically attached to an integral membrane protein or polar lipid head on one side.

$\beta$-barrel

A transmembrane protein structure formed when $\beta$-sheets roll into a cylinder, creating a channel across the membrane.

Catabolism

Metabolic pathways that break down larger complex molecules into smaller ones, generally releasing usable energy like $\text{ATP}$.

Anabolism

Metabolic pathways that construct complex cellular molecules from simpler building blocks, requiring energy input.

First Law of Thermodynamics

The law of conservation of energy stating that energy cannot be created or destroyed, only converted from one form to another.

Second Law of Thermodynamics

The thermodynamic law stating that any isolated system or the universe spontaneously tends toward greater disorder (entropy).

Entropy

A mathematical and physical measure of the degree of disorder or randomness in a system.

Free Energy ($G$)

The portion of a system's total energy that is available to perform chemical or cellular work.

Exergonic Reaction

A reaction that releases free energy ($\Delta G < 0$) and proceeds spontaneously.

Endergonic Reaction

A nonspontaneous chemical reaction that requires energy input ($\Delta G > 0$) to proceed.

Reaction Coupling

The process of driving an energetically unfavorable endergonic reaction by combining it with an energetically favorable exergonic reaction.

Activated Carriers

Molecules such as $\text{ATP}$, $\text{NADH}$, $\text{NADPH}$, and $\text{FADH}_2$ that temporarily store and transport high-energy electrons or chemical groups during metabolism.

Substrate-Level Phosphorylation

The direct transfer of a phosphate group from a phosphorylated metabolic intermediate to $\text{ADP}$ to form $\text{ATP}$.

Oxidative Phosphorylation

The synthesis of $\text{ATP}$ driven by an $\text{H}^+$ gradient across the inner mitochondrial membrane via chemiosmosis and $\text{ATP}$ synthase.

Glycolysis

An anaerobic metabolic pathway in the cytosol that breaks down one 6-carbon glucose molecule into two 3-carbon pyruvate molecules, generating net $2\,\text{ATP}$ and $2\,\text{NADH}$.

Phosphofructokinase (PFK)

The key rate-limiting regulatory enzyme in Step 3 of glycolysis, allosterically inhibited by $\text{ATP}$ and activated by $\text{AMP}$.

Citric Acid Cycle

A mitochondrial matrix pathway that oxidizes acetyl-$\text{CoA}$ to regenerate oxaloacetate, capturing energy as $\text{GTP}$, $\text{NADH}$, and $\text{FADH}_2$.

Chemiosmosis

The movement of hydrogen ions ($\text{H}^+$) down an electrochemical gradient across a membrane to drive the enzymatic synthesis of $\text{ATP}$ by $\text{ATP}$ synthase.

Gluconeogenesis

An energy-requiring pathway used to synthesize new glucose molecules, consuming $4\,\text{ATP}$ and $2\,\text{GTP}$ per glucose produced.

Lipolysis

The metabolic breakdown of stored triacylglycerols into glycerol and free fatty acids by lipases.

Lipogenesis

The metabolic formation of new triglycerides for storage from excess metabolic intermediates.

Photosynthesis

The metabolic process in chloroplasts that utilizes sunlight energy, water, and $\text{CO}_2$ to create organic sugars and release oxygen ($\text{O}_2$).

Photosystem

A multiprotein complex embedded in the thylakoid membrane containing light-harvesting antenna chlorophylls and a central reaction center.

Rubisco

The primary enzyme that catalyzes carbon fixation during the photosynthetic dark reactions to convert $\text{CO}_2$ into organic molecules.