Bio Exam 130

Atoms

Smallest unit of an element with its chemical properties; building block of all matter.

Molecules & Macromolecules

Atoms bond to form molecules; macromolecules are large polymers (carbs, proteins, nucleic acids).

Cells

Simplest unit of life; surrounded by a membrane containing molecules/macromolecules.

Tissues

Group of similar cells associated together to perform a specific function.

Organs

Two or more tissue types working together to perform a specific function.

Organ Systems

Groups of organs interacting to perform major body functions.

Organism

An individual living thing belonging to a specific species.

Population

Group of organisms of the same species living in the same environment.

Community

Assemblage of populations of different species living together in an area.

Ecosystem

Biological community interacting with its non-living physical environment.

Biosphere

All places on Earth where living organisms exist.

Evolution

Diversity of life changes over time via mutation, natural selection, and genetic exchange.

Structure and Function

Basic structural units define function ("structure determines function").

Energy and Matter

Systems acquire energy/matter from the environment for chemical pathways.

Systems Biology

Study of how complex interactions between parts create emergent properties.

Biological Evolution

Heritable change in a population from generation to generation.

Mutation

Heritable change in DNA; can be beneficial, harmful, or neutral.

Vertical Descent

Traits passed down parent-to-offspring lineage; beneficial mutations accumulate via Natural Selection.

Horizontal Gene Transfer

Direct transfer of genes between different species or non-offspring.

Genome

Complete set of DNA in an organism; stores info and drives evolution.

Proteome

Entire set of proteins a cell or organism produces.

Taxonomy

Grouping and classifying species based on evolutionary history.

Domains of Life

Bacteria (simple prokaryotes), Archaea (extreme prokaryotes), Eukarya (complex eukaryotic cells).

Taxonomic Hierarchy

Domain -> Supergroup -> Kingdom -> Phylum -> Class -> Order -> Family -> Genus -> Species.

Binomial Nomenclature

Unique 2-part scientific name: Genus (capitalized) + species descriptor (lowercase).

Model Organisms

Organisms studied extensively so results apply broadly (e.g., E. coli, fruit flies, mice).

Hypothesis

Proposed explanation for an observation; must be testable and falsifiable.

Theory

Broad explanation backed by extensive evidence that allows verified predictions.

Controlled Experiment

Compares a baseline control group against an experimental group with one variable changed.

Carbohydrates Formula

Cn(H2O)n containing carbon, hydrogen, and oxygen with hydroxyl (-OH) groups.

Monosaccharides

Single sugars including pentoses (ribose, deoxyribose) and hexoses (glucose).

Glucose Isomers

Alpha-glucose vs. beta-glucose (based on hydroxyl orientation) and D-glucose vs. L-glucose enantiomers.

Disaccharides

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

Storage Polysaccharides

Starch (plants) and Glycogen (animals/muscles) made of alpha-glucose polymers.

Structural Polysaccharides

Cellulose (plant cell walls), Chitin (fungi/insects), and Peptidoglycan (bacteria).

Lipids

Nonpolar, hydrophobic organic molecules insoluble in water.

Triglycerides

Fats and oils made of 1 glycerol + 3 fatty acids linked by ester bonds for long-term energy storage.

Saturated vs. Unsaturated Fats

Saturated fats have no double bonds (solid); unsaturated fats have C=C double bonds (liquid).

Trans Fats

Artificially hydrogenated unsaturated fats containing trans double bonds; linked to cardiovascular risk.

Phospholipids

Amphipathic molecules with a hydrophilic phosphate head and 2 hydrophobic fatty acid tails; form cell membranes.

Steroids

Lipids with four fused carbon rings used for membrane stability and hormone signaling (e.g., cholesterol, estrogen, testosterone).

Waxes

Complex nonpolar lipids secreted onto surfaces to prevent water loss.

Proteins

Functional units composed of one or more folded polypeptide chains made of amino acid monomers.

Amino Acid Structure

Central carbon bonded to an amino group (-NH2), carboxyl group (-COOH), hydrogen, and variable R-group.

Protein Functions

Enzymes, cell signaling, motor movement, structural support, membrane transport, and gene regulation.

Protein Structures

Primary (amino acid sequence), Secondary (alpha-helices/beta-sheets), Tertiary (overall 3D shape), Quaternary (multi-subunit complex).

Protein Denaturation

Loss of a protein's 3D structure and function due to heat, pH, or chemical stress.

Nucleic Acids

Polymers of nucleotide monomers (5-carbon sugar, phosphate, nitrogenous base) that store and express genetic code.

DNA vs. RNA

DNA (double-stranded, deoxyribose, stores genes) vs. RNA (single-stranded, ribose, translates DNA to protein).

Nitrogenous Bases

Purines (Adenine, Guanine) and Pyrimidines (Cytosine, Thymine in DNA, Uracil in RNA).

Phosphodiester Bond

Covalent bond linking the sugar of one nucleotide to the phosphate group of the next.

Passive Transport

Movement down a concentration gradient (high to low) without energy.

Simple Diffusion

Direct passage of solutes across the phospholipid bilayer.

Facilitated Diffusion

Movement across a membrane assisted by a transmembrane channel or transport protein.

Active Transport

Movement against a concentration gradient (low to high), requiring transport proteins and energy (ATP).

Bilayer Permeability Factors

Favors smaller size, nonpolar (hydrophobic) polarity, non-charged, and higher solute concentrations.

Permeability Hierarchy

Gases/small nonpolar > small uncharged polar > large polar (sugars) > charged ions & macromolecules.

Chemical Gradient

Difference in solute concentration across a membrane.

Electrochemical Gradient

Dual gradient containing both solute concentration and net charge differences across a membrane.

Osmosis

Movement of water across a membrane from hypotonic (lower solute) to hypertonic (higher solute) regions.

Isotonic Solution

Equal solute concentrations inside and outside the cell; no net water movement.

Hypertonic Solution

Higher solute concentration outside; causes animal cells to shrink (crenation) and plant cells to undergo plasmolysis.

Hypotonic Solution

Lower solute concentration outside; causes animal cells to swell/burst (osmotic lysis) and plant cells to maintain turgor pressure.

Contractile Vacuoles

Adaptation in freshwater organisms (e.g., Paramecium) to pump out excess water entering from hypotonic environments.

Membrane Channels

Transmembrane proteins forming open passageways for direct, rapid facilitated diffusion.

Gated Channels

Channels regulated to open/close via ligand binding or electrical signals.

Aquaporins

Specialized transmembrane channel proteins that facilitate rapid water diffusion via osmosis (discovered by Peter Agre).

Transporters

Proteins that undergo conformational changes to move solutes (Uniporters, Symporters, Antiporters).

Primary Active Transport

Direct use of energy (typically ATP hydrolysis) by a pump to move solutes against a concentration gradient.

Secondary Active Transport

Uses a pre-existing ion gradient established by primary transport to drive active transport of a second solute.

Na+/K+-ATPase Pump

Electrogenic antiporter pumping 3 Na+ out and 2 K+ in per ATP hydrolyzed, generating a net negative cytosolic charge.

E1 Conformation

Na+/K+ pump state with high affinity for cytosolic Na+; binding triggers ATP hydrolysis and phosphorylation.

E2 Conformation

Na+/K+ pump state with high affinity for extracellular K+; binding triggers dephosphorylation and returns pump to E1.

Monomer

monomer = simplest unit of a macromolecule

4 Essential Macromolecules

• Carbs

• Lipids

• Amino Acids

• Nucleic Acids

Monomer —> polymer

dehydration reaction

What determines characteristic of an Amino Acid

R groups