DAT terms

Academic Average (AA)

The mean score from Biology, General Chemistry, Organic Chemistry, Reading Comprehension, and Quantitative Reasoning — a primary dental school admissions metric

Activation Energy (Ea)

The minimum energy required for a chemical reaction to proceed. Catalysts lower this energy without being consumed.

Active Transport

Movement of molecules across a cell membrane against a concentration gradient, requiring ATP.

Allele

One of two or more alternative forms of a gene at the same chromosomal locus. May be dominant or recessive

Aufbau Principle

The rule that electrons fill atomic orbitals in order of increasing energy, used to write ground-state electron configuration

Buffer Solution

A solution resisting pH changes when small amounts of acid or base are added; contains a weak acid and it conjugate base

Cell cycle

The ordered sequence a cell undergoes to grow and divide: Interphase (G1, S, G2) followed by Mitosis and Cytokinesis

Colligative Properties

Solution properties depending on solute particle count not identity — include boiling point elevation and freezing point depression

Combustion Reaction

A reaction of a hydrocarbon with oxygen producing CO₂, water, and heat. Always exothermic

Crossing over

Exchange of genetic material between homologous chromosomes during Meiosis I, increasing genetic diversity

DENTPIN

Dental Personal Identifier Number issued by the ADA. Required to register for the DAT

Dimensional Analysis

A problem-solving method using unit conversion factors to ensure correct units throughout a calculation

DNA Replication

The process of copying DNA before cell division using helicase, DNA, polymerase, and ligase. Occurs during S phase

Dominant Allele

An allele whose trait is expressed when only one copy is present in heterozygote. Denoted by capital letter

Enantiomers

Non-superimposable mirror-image stereoisomers that rotate plane-polarized light in opposite directions

Entropy (S)

A measure of disorder in a system. Spontaneous processes generally increase this (S > 0)

Equilibrium Constant (K)

The ratio of product to reactant concentrations at equilibrium, each raised to its stoichiometric coefficient

Functional Group

An atom group determining a molecules’ characertistic reactions

Genetic Drift

Random changes in allele frequencies, especially significant in small populations. Includes bottleneck and founder effect.

Gibbs Free Energy (G)

Determines spontaneity: G = H - TS. Negative = spontaneous ; positive = non-spontaneous; zero = equilibrium

Hardy-Weinberg Equilibrium

Allele frequencies remain constant absent evolutionary forces: mutation, selection, migration, drift, or non-random mating

Hess’s Law

Total enthalpy change is path-independent — the same whether a reaction occurs in one or multiple steps

Heterozygous

Having two different alleles for a gene (Aa). the dominant allele is typically expressed in the phenotype

Homozygous

Having two identical alleles for a gene (AA or aa), determining dominant or recessive expression

Keyhole Test

A PAT subtest requiring identification of which opening a 3D object can pass through without rotation

Le Chatelier’s Principle

A disturbed equilibrium system shifts to counteract the disturbance and restore equilibrium

Limiting Reactant

The reactant completely consumed in a reaction, determining the maximum product yield

Meisosis

Cell division producing four haploid gametes through two rounds of division (I and II)

Mitosis

Cell division producing two genetically identical diploid daughter cells. Phase: Prophase, Metaphase, Anaphase, Telophase

Molarity (M)

Concentration in moles of solute per liter of solution — the most common unit in DAT chemistry problems.

Mole

The SI unit equal to 6.022 × 10²³ particles (Avogadro’s number). Links mass, volume, and particle count

Natural Selection

the mechanism where organism with favorable heritable traits survive and reproduce more successfully

Nucleotide

The monomer of DNA and RNA: a phosphate group, five-carbon sugar, and nitrogenous base

Osmosis

Passive water movement across a semipermeable membrane from low to high solute concentration

Oxidation

Loss of electrons during a reaction. Always paired with reduction in redox reactions (OIL RIG)

PAT

Perceptual Ability Test — a DAT section with 90 questions in 60 minutes assessing spatial reasoning and visualization

pH

Logarithmic hydrogen ion concentration scale

Phenotype

The observable physical expression of an organism’s genotypes, influenced by both genetics and environment.

PCR

Polymerase Chain Reaction — a laboratory technique to rapidly amplify specific DNA segments using thermal cycles

Prometric

The testing company that administers the DAT at test centers on behalf of the ADA

Punnett Square

A grid diagram predicting offspring genotype probabilities from a genetic cross between two parents

Quantitative Reasoning (QR)

DAT section covering algebra, probability, statics, geometry, and applied math — 40 questions in 45 minutes

Rate law

Relates rate to reactant concentrations: Rate = k[A]^x[B]^y. Orders are determined experimentally

Recessive Allele

An allele expressed only in homozygous recessive individuals (aa). Denoted by lowercase letter

Resonance Structures

Multiple Lewis structures for a molecule when a single structure cannot fully depict electron distribution

Solubility Product (Ksp)

Equilibrium constant for a sparingly soluble salt: product of dissolved ion concentrations in saturated solution.

Stereoisomers

Molecules with identical connectivity but different spatial arrangements. Includes enantiomers and diastereomers.

Stoichiometry

Calculation of reactant and product quantities using mole ratios from balanced chemical equations

SN1 Reaction

unimolecular nucleophilic substitution via carbocation intermediate. Favored by tertiary substrates and polar protic solvents

SN2 reaction

Bimolecular nucleophilic substitution in once converted step with inversion of configuration. Favored by primary substrate

Survey of Natural Sciences

Largest DAT section: 100 question in 90 minutes

Thermodynamics

Study of energy changes in chemical and physical processes. Key quantities: enthalpy (H), entropy (S), Gibbs free energy (G)

Transcription

Synthesis of RNA from a DNA template in the nucleus — the first step of gene expression.

Translation

Protein synthesis at the ribosome using mRNA as a template; tRNA brings amino acids matching each codon

Valence Electrons

Electrons in an atom’s outermost shell that participate in chemicals bonding and determine reactivity.