Element
Substance that cannot be broken down to other substances by chemical reactions
Compound
Substance containing 2 or more elements combined
Trace Elements
Elements required by an organism in very small quantities
Proton
Positively charged subatomic particle
Neutron
Neutrally charged subatomic particle
Electron
Negatively charged subatomic particle
Atomic Number
Number of protons in an atom
Atomic Mass
Sum of neutrons and protons in an atom
Isotope
Atoms with the same number of protons but different number of neutrons
Potential Energy
Energy that is stored due to position or structure
Valence Shell
Outermost electron shell with electron capacity (2,8,8)
Valence Electron
Electrons in the outermost shell of an atom
Valence Number
Number of unpaired electrons in the outer shell
Electronegativity
Atom's attraction for electrons
Nonpolar
Equal sharing of electrons in a covalent bond
Polar
Unequal sharing of electrons in a covalent bond
Ionic bond
Bond formed by transfer of electrons between atoms
Anion
Negatively charged ion
Cation
Positively charged ion
Hydrogen bonds
Weak attractions between polar molecules
Equilibrium
State where forward and reverse reactions occur at the same rate
Hydrophobic
Substances that repel water
Hydrophilic
Substances that attract water
Hydrocarbons
Molecules composed of carbon-hydrogen chains
Hydroxyl
Functional group (-OH) found in alcohols
Carbonyl
Functional group (-C=O) found in sugars
Carboxyl
Functional group (-COOH) found in carboxylic acids
Amino
Functional group (-NH2) found in amines
Sulfhydryl
Functional group (-SH) found in thiols
Phosphate
Functional group (-OPO3) found in phosphates
Polymer
Long molecule made of repeating monomers
Monomer
Building block of a polymer
Dehydration synthesis
Process that joins monomers by removing water
Hydrolysis
Process that breaks polymers by adding water
Polypeptides
Chains of amino acids forming proteins
Peptide Bonds
Bonds between amino acids in a polypeptide
Primary Structure
Sequence of amino acids in a protein
Secondary Structure
Coils and folds in a protein due to hydrogen bonding
Tertiary Structure
Overall 3D shape of a protein
Quaternary Structure
Structure formed by multiple protein subunits
Chaperonins
Proteins that assist in protein folding
Protein Denaturation
Loss of protein's shape and function
Monosaccharides
Simple sugars with CH2O formula
Carbohydrates
Molecules containing sugars and their polymers
Disaccharides
Double sugars like sucrose
Starch
Plant energy storage polysaccharide
Glycogen
Animal energy storage polysaccharide
Cellulose
Polysaccharide used in plant cell walls
Lipids
Hydrophobic molecules including fats
Fats (triacylglycerol)
Glycerol and fatty acids linked by ester bonds
G1 Checkpoint
Decision point in the cell cycle where the cell can proceed to divide, enter G0 phase, or stop
MPF (M phase promoting factor)
Cyclin CDK complex that triggers cell passage past the G2 checkpoint
Growth Factor
Protein released by cells triggering other cells to divide
Density Dependent Inhibition
Mechanism where crowded cells stop dividing
Anchorage Dependence
Requirement for cells to be attached to divide
Transformation (cancer)
Process where a single cell becomes a cancer cell
Tumor
Mass of cells originating from a transformed cell
Benign Tumor
Non-invasive tumor remaining in the original site
Malignant Tumor
Invasive tumor impairing healthy tissue, leading to cancer
Metastasis
Spread of cancer cells to other body parts
Radiation
Targeted cancer treatment
Chemotherapy
Treatment using toxic drugs targeting rapidly dividing cells
Gene
DNA segment coding for a specific trait
Haploid Cell
Cell with one set of chromosomes
Diploid Cell
Cell with two sets of chromosomes
Sex Chromosomes
Chromosome pair #23 determining sex
Autosomes
Chromosomes pairs #1-#22 excluding sex chromosomes
Homologous Chromosomes
Chromosome pairs with genes for the same traits
Interphase (meiosis)
Phase where DNA replication occurs
Meiosis 1
Division of diploid cells into two haploid cells with double chromosomes
Meiosis 2
Division of haploid cells into four haploid cells with single chromosomes
Crossing Over
Exchange of genetic material between non-sister chromatids
Independent Assortment of Chromosomes
Random distribution of chromosomes into gametes
Random Fertilization
Fusion of gametes leading to over 70 trillion possible zygotes
Parasitism
Relationship where the parasite benefits by getting nourishment from the host, which is harmed
Autotroph
Organism that produces its own food by capturing physical or chemical energy
Protosynthetic Autotroph
Autotrophs that use light to produce food
Chemosynthetic Autotroph
Autotrophs that use energy from chemical reactions to make food
Heterotroph
Organism that obtains energy from other organisms
Biodiversity
The variety of species present in an ecosystem
Keystone Species
Species that have a significant impact due to their ecological niche, not their abundance
Invasive Species
Species that cause ecological or economic harm in a new environment where they are not native
Trophic Cascade
Effect where changes in one part of a trophic pyramid influence other, sometimes unrelated parts
Succession
Process where the structure of a biological community changes over time
Primary succession
Colonization of newly exposed rock for the first time
Secondary succession
Recolonization of an area with living things after a disturbance
Primary productivity
Rate at which autotrophs produce organic compounds
Gross Primary productivity
Total amount of organic compounds produced
Net Primary productivity
Amount of organic compounds remaining after plants use what they need
Trophic efficiency
Percentage of biomass/energy transferred from one trophic level to the next (about 10%)
Nitrogen fixation
Conversion of N2 to nitrogen compounds
Saturated Fats
all single bonds, maximum hydrogens, linear (solid at room temperature) (source: animal fats)
Unsaturated Fats
At least 1 double bond, less than maximum hydrogens, bent (liquid at room temperature) (source: plants and fish oils)
Phospholipids
one phosphate, on glycerol, two fatty acids (polar head and nonpolar tail)
Cholesterol
helps with membrane stability (not too fluid, not too viscous)
Amphipathic Molecule
has both a hydrophobic and hydrophilic region
Selective Permeability
some substances are allowed to cross the membrane; others are not
Membrane Fluidity
held together by hydrophobic interactions
Integral Proteins
extend into the hydrophobic interactions
Transmembrane Proteins
Cross the entire membrane