Biology 230: Chapters 1-5 Comprehensive Vocabulary Flashcards

A complete set of vocabulary flashcards covering fundamental terms in cell biology, chemistry, energy, protein structure, and chromatin architecture across Chapters 1-5.

Gene expression

The process of using information in a gene to produce its functional product, commonly a protein.

Genome

The complete sequence of nucleotides contained in an organism's DNA, representing its entire genetic information.

Resolution

The minimum distance by which two objects can be separated and still be distinguished as individual structures in microscopy.

Transmission Electron Microscopy (TEM)

A type of electron microscopy in which electrons pass through a thin specimen, best used for viewing internal cell ultrastructure.

Scanning Electron Microscopy (SEM)

A type of electron microscopy in which electrons scan the surface of a specimen, best used for producing detailed 3D surface topography views.

Endosymbiotic theory

The evolutionary theory proposing that mitochondria and chloroplasts originated from ancient prokaryotic cells that were engulfed by an ancestral host cell.

Model organism

An organism selected for intensive scientific study because research on it teaches general biological principles that apply to other organisms.

Homologous genes

Genes in different species or within an organism that share similar sequences because of common evolutionary origin.

Polar covalent bond

A covalent bond formed when electrons are shared unequally between atoms due to differences in electronegativity, creating partial electrical charges.

Ionic bond

A bond formed through the complete transfer of electrons from one atom to another, producing oppositely charged ions held together by electrostatic attraction.

Hydrogen bond

A weak noncovalent attraction between a partially positive hydrogen atom associated with a polar covalent molecule and a partially negative atom in another molecule.

Amphipathic

Describing a molecule that possesses both distinct hydrophilic (water-loving) and hydrophobic (water-fearing) regions.

Saturated fatty acid

A fatty acid with a hydrocarbon tail containing no carbon-carbon double bonds, allowing the molecules to pack tightly together.

Unsaturated fatty acid

A fatty acid with a hydrocarbon tail containing one or more carbon-carbon double bonds, creating kinks that prevent tight molecular packing.

Peptide bond

The covalent bond connecting the carboxyl group of one amino acid to the amino group of the next in a polypeptide chain.

Metabolism

The sum total of all chemical reactions occurring within a cell.

Catabolism

Metabolic pathways that break down larger food molecules into smaller ones, often releasing energy captured by activated carriers.

Anabolism

Metabolic pathways that build larger, complex cellular molecules from smaller precursors, requiring energy input.

Free energy ($\Delta G$)

The amount of energy in a system available to do work; a negative $\Delta G$ indicates an energetically favorable, spontaneous reaction.

Activation energy

The threshold energy barrier that must be overcome by colliding molecules before a chemical reaction can proceed.

Enzyme

A protein catalyst that speeds up chemical reactions by lowering activation energy without altering the overall $\Delta G$ or being consumed in the reaction.

Activated carrier

A small molecule that temporarily stores energy or chemical groups in a transferrable form to drive unfavorable cellular reactions.

Oxidation

The loss of electrons or electron density by an atom or molecule during a chemical reaction.

Reduction

The gain of electrons or electron density by an atom or molecule during a chemical reaction.

Primary structure

The exact linear sequence and order of amino acids comprising a polypeptide chain.

Secondary structure

Local folded structures formed within a polypeptide chain, specifically $\alpha$-helices and $\beta$-sheets, stabilized by hydrogen bonds between backbone groups.

Tertiary structure

The complete three-dimensional shape of a single folded polypeptide chain.

Quaternary structure

The complex protein structure formed by the assembly of multiple individual polypeptide chains or subunits.

Protein domain

A distinct, compact segment of a protein that can fold independently into a stable structure and often carries out a specific function.

Denaturation

The loss or unfolding of a protein's native three-dimensional conformation, caused by environmental stress such as altered temperature or pH, resulting in loss of function.

Chaperone

A specialized protein that helps other polypeptide chains fold into their correct, stable conformations without becoming part of the final structure.

Allosteric regulation

A regulatory mechanism where a molecule binds to a protein at a site other than the active site, inducing a conformational change that alters protein activity.

Phosphodiester bond

The covalent bond linking the $3'$ hydroxyl group of one sugar to the $5'$ phosphate group of the next nucleotide in a nucleic acid strand.

Antiparallel

The structural arrangement of two complementary strands in a DNA double helix running side-by-side but oriented in opposite chemical directions ($5'$ to $3'$ versus $3'$ to $5'$).

Chromatin

The complex of DNA and associated packaging proteins, predominantly histones, that makes up eukaryotic chromosomes.

Nucleosome

The basic repeating structural unit of chromatin, consisting of a segment of DNA wrapped around a protein core of eight histone proteins.

Histone octamer

The eight-protein complex at the core of a nucleosome, composed of two copies each of histones H2A, H2B, H3, and H4.

Centromere

A specialized, constricted region of a chromosome that attaches to spindle microtubules via the kinetochore to direct chromosome segregation during cell division.

Telomere

A repetitive DNA sequence at the end of a linear eukaryotic chromosome that protects the chromosome end from degradation and mistreatment as damaged DNA.

Euchromatin

A relatively decondensed, open form of eukaryotic chromatin that is accessible to nuclear proteins and active for gene expression.

Heterochromatin

Highly condensed, tightly packed eukaryotic chromatin that is transcriptionally inactive and resistant to DNA-binding proteins.

Chromatin remodeling complex

An enzyme complex that uses energy from ATP hydrolysis to alter nucleosome position or structure, regulating DNA accessibility for transcription, repair, and replication.