Introduction to Biology: Key Terms and Concepts 4

A comprehensive set of vocabulary flashcards covering core biology concepts from the notes, including cell types, biomolecules, genetics, evolution, and cell structure/function.

Biology

The scientific study of life, including the structure, function, growth, origin, evolution, and distribution of living organisms.

Seven characteristics of life

Order, reproduction, growth and development, energy processing, regulation, response to the environment, and evolutionary adaptation.

Prokaryotic cell

A small, simple cell lacking a membrane-bound nucleus or organelles; DNA is in a nucleoid region and the cell is usually unicellular.

Eukaryotic cell

A larger, more complex cell with a membrane-bound nucleus and membrane-bound organelles; can be unicellular or multicellular.

Homeostasis

Regulation of a stable internal environment (e.g., temperature, pH, nutrient balance) despite external changes.

Metabolism

All chemical reactions in a living organism that enable energy capture, transformation, and use.

Emergent properties

New properties that arise at higher levels of organization due to interactions among components.

Taxonomy

Science of classifying, describing, and naming organisms; includes eight taxonomic ranks.

Domain (three domains of life)

The highest taxonomic rank: Bacteria, Archaea, and Eukarya.

Central dogma

DNA stores genetic information; transcription makes RNA; translation uses RNA to synthesize proteins.

Evolution

Core theme of biology; the process by which life changes over time, leading to unity and diversity.

Natural selection

Process by which organisms with advantageous traits are more likely to survive and reproduce, passing traits to offspring.

Unity and diversity of life

Life is unified by common ancestry and diversified by adaptation and evolution.

Energy flow in ecosystems

Energy from the sun flows through producers to consumers and exits as heat; matter cycles within ecosystems.

Scientific method

A systematic approach: observe, question, hypothesize, test, analyze, conclude, and share results.

Observation

Careful, detailed noting of phenomena that lead to questions and hypotheses.

Hypothesis

A testable, educated guess about a natural phenomenon.

Independent variable

The factor deliberately changed in an experiment.

Dependent variable

The factor measured to assess the effect of the independent variable.

Negative feedback

Regulation in which the output reduces the initial stimulus to maintain homeostasis.

Positive feedback

Regulation in which the end product speeds up its own production; less common in biology.

DNA

Deoxyribonucleic acid; stores genetic information; typically double-stranded; composed of nucleotides.

RNA

Ribonucleic acid; usually single-stranded; plays a key role in transcription and translation; uses ribose and uracil.

Transcription

Process of copying a DNA sequence into an RNA molecule, occurs in the nucleus.

Translation

Process of synthesizing a protein from an mRNA template at the ribosome.

Nucleotide

Monomer of nucleic acids; consists of a sugar, a phosphate group, and a nitrogenous base.

Monomer vs polymer

Monomer is a building block; polymers are long chains formed by linking monomers.

Monosaccharide

A single sugar unit (e.g., glucose); general formula CnH2nOn; building block of carbohydrates.

Disaccharide

Two monosaccharides linked by a glycosidic bond (e.g., maltose, sucrose, lactose).

Polysaccharide

Long chains of monosaccharides; examples include starch, glycogen, cellulose, and chitin.

Glycosidic bond

Bond between carbohydrate monomers; can be alpha or beta, affecting structure and digestibility.

Alpha vs beta glycosidic linkages

Alpha linkages (down) vs. beta linkages (up); determine digestibility and properties (e.g., starch vs cellulose).

Isomers (glucose vs fructose)

Same molecular formula (C6H12O6) but different arrangement of atoms, giving different properties.

Lipids

A diverse class of hydrophobic biomolecules largely composed of carbon and hydrogen; not polymers; include fats, phospholipids, and steroids.

Triglyceride

Fat formed from glycerol and three fatty acids; primary energy-storage lipid in animals and plants.

Phospholipid

Glycerol + two fatty acids + a phosphate group; forms the phospholipid bilayer of cell membranes; amphipathic.

Cholesterol

A steroid lipid; component of animal cell membranes; precursor to steroid hormones.

Fatty acid saturation

Saturated fats have no double bonds; unsaturated fats have one or more; cis double bonds create kinks.

Phospholipid bilayer

Two-layered cell membrane with hydrophilic heads outward and hydrophobic tails inward; forms barrier and membrane structure.

Proteins

Large, diverse molecules made of amino acids; perform numerous functions (enzymes, transport, antibodies, hormones, receptors, structural roles).

Amino acids

Monomers of proteins; contain an amino group, a carboxyl group, a hydrogen, and an R group; 20 different side chains.

Peptide bond

Covalent bond formed by a dehydration reaction linking the carboxyl group of one amino acid to the amino group of the next.

Protein structure levels

Primary: amino acid sequence; Secondary: alpha helices and beta sheets; Tertiary: 3D shape from R-group interactions; Quaternary: two or more polypeptides forming a functional protein.

Enzyme

Biological catalyst, typically a protein, that speeds up chemical reactions.

Nucleic acids (DNA vs RNA)

DNA stores hereditary information; RNA participates in protein synthesis; DNA is usually double-stranded, RNA single-stranded.

Base pairing (DNA/RNA)

DNA: A with T, C with G; RNA: A with U, C with G; hydrogen-bonded pairs stabilize structures.

Phosphodiester bonds

Covalent bonds that link nucleotides in a nucleic acid’s backbone, directionality 5′ to 3′.

Polarity in nucleic acids

Nucleic acids have directionality (5′ end and 3′ end) determined by the sugar-phosphate backbone.

Water properties (polarity, solvent)

Water is a polar molecule; high polarity enables dissolving many substances; acts as a versatile solvent.

Cohesion, adhesion, surface tension

Cohesion: water molecules attract; adhesion: water to other surfaces; surface tension at air-water interface.

Water’s heat properties

High specific heat and high heat of vaporization; helps stabilize temperature in organisms and environments.

pH, acids, bases, buffers

pH measures hydrogen ion concentration; acids increase H+, bases decrease; buffers stabilize pH.

Glycoproteins & glycolipids

Carbohydrates attached to proteins or lipids on cell surfaces; important for cell recognition and signaling.

Endomembrane system

Interconnected membrane-bound organelles (nucleus, ER, Golgi, lysosomes, vesicles) involved in synthesis, processing, and transport.

Rough vs smooth ER

Rough ER has ribosomes and synthesizes secretory/membrane proteins; smooth ER makes lipids and processes toxins.

Golgi apparatus

Modifies, sorts, and ships proteins and lipids produced by the ER for secretion or delivery to organelles.

Lysosome

Digestive compartment containing hydrolases that break down ingested substances and damaged organelles.

Vacuole

Membrane-bound vesicle; plant cells have a large central vacuole for storage and growth.

Mitochondria

Powerhouse of the cell; site of cellular respiration; produces ATP; contains own DNA and ribosomes.

Chloroplasts

Sites of photosynthesis in plants and algae; convert light energy to chemical energy; contain their own DNA and ribosomes.

Cytoskeleton

Network of protein filaments (microfilaments, intermediate filaments, microtubules) that support cell shape, enable movement, and organize organelles.

Microtubules, microfilaments, intermediate filaments

Three cytoskeletal components with distinct roles: microtubules for transport and division, microfilaments for shape and movement, intermediate filaments for support.

Plasmodesmata

Plant cell connections that allow transport and communication between adjacent cells through channels in cell walls.

Extracellular matrix (ECM)

Animal cell network of glycoproteins (e.g., collagen) that supports, anchors cells, and mediates signaling via integrins.

Cell junctions (tight, desmosomes, gap)

Tight junctions seal cells into sheets; desmosomes anchor cells; gap junctions allow direct cytoplasmic exchange between cells.

Plant cell wall

Rigid layer of cellulose outside the plasma membrane; provides structural support and protection; plasmodesmata connect plant cells.

Endosymbiotic theory

Mitochondria and chloroplasts originated as free-living prokaryotes that were engulfed by early eukaryotic cells.

Evidence for endosymbiosis

Mitochondria and chloroplasts have their own circular DNA and ribosomes and double membranes, similar to bacteria.

Prokaryotes vs eukaryotes

Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have a nucleus and organelles; size and complexity differ.

DNA replication (concept)

Before cell division, DNA is replicated to provide identical genetic information to daughter cells.

RNA world hypothesis

Idea that early life used RNA for both genetic information and catalysis before DNA and proteins became dominant.

Hydrolysis vs dehydration synthesis

Hydrolysis splits polymers with water; dehydration synthesis forms polymers by removing water to join monomers.

Isotopes

Atoms of the same element with different numbers of neutrons, affecting mass and nuclear properties.

Ions

Atoms with a net electric charge due to loss or gain of electrons (cations and anions).

Radiometric dating (Carbon-14)

Dating method using radioactive decay (e.g., C-14 with a half-life ~5730 years) to estimate age of biological samples.

Proteins as enzymes

Proteins that act as biological catalysts to accelerate chemical reactions.

Amino acid properties (R groups)

Amino acids differ by their side chain (R group), which determines polarity, charge, and interactions.

Three domains vs kingdoms (summary)

Domains: Bacteria, Archaea, Eukarya; kingdoms include Bacteria, Archaea, Protista, Plantae, Fungi, Animalia.

Cell theory (three parts)

All living things are composed of cells; cells are the basic units of life; new cells arise from pre-existing cells.