Biological Concepts Review

A collection of vocabulary flashcards covering key biological concepts and terminology.

Anaphase

The stage of mitosis and meiosis II during which sister chromatids separate and move to opposite poles of the cell.

Aneuploidy

A condition in which a cell or organism has an abnormal number of chromosomes.

Anticodon

A sequence of three nucleotides in a tRNA molecule that is complementary to a codon in mRNA.

Aquaporin

A channel protein in the plasma membrane that facilitates the diffusion of water (osmosis).

Autophagy

A cellular process of self-eating, involving the degradation of damaged or unnecessary cellular components within lysosomes.

Buffer

A solution that minimizes changes in pH when small amounts of acid or base are added.

Carbohydrate

A biological macromolecule consisting of carbon, hydrogen, and oxygen atoms, often in a ratio of 1:2:1; includes sugars and polysaccharides.

Cell Cycle

The series of events that a eukaryotic cell goes through from its formation until it divides.

Cellular Respiration

The process by which cells break down glucose and other organic molecules in the presence of oxygen to produce ATP.

Chromosome

A thread-like structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

Codon

A sequence of three nucleotides in mRNA that specifies a particular amino acid or a stop signal during translation.

Competitive Inhibition

A type of enzyme inhibition where the inhibitor binds to the active site, blocking substrate binding.

Cytokinesis

The division of the cytoplasm to form two separate daughter cells after mitosis or meiosis.

Dehydration Synthesis

A chemical reaction in which two molecules are joined together with the removal of a water molecule.

Denaturation

The process by which a protein loses its native shape due to the disruption of weak chemical bonds and interactions, leading to loss of function.

Diffusion

The movement of a substance from an area of high concentration to an area of low concentration.

Diploid (2n)

A cell containing two sets of chromosomes, one set inherited from each parent.

Dimerize

To combine to form a dimer, which is a molecule consisting of two identical or similar subunits.

DNA (Deoxyribonucleic Acid)

A double-stranded nucleic acid molecule that carries the genetic information.

Endocytosis

The process by which cells take in substances from the extracellular fluid by forming vesicles from the plasma membrane.

Endoplasmic Reticulum (ER)

An extensive network of membranes in eukaryotic cells, involved in protein and lipid synthesis. Rough ER has ribosomes attached, while smooth ER does not.

Enzyme

A protein that acts as a biological catalyst, speeding up chemical reactions without being consumed in the process.

Exocytosis

The process by which cells release substances to the extracellular fluid by the fusion of vesicles with the plasma membrane.

Facilitated Diffusion

The diffusion of a substance across a membrane with the help of membrane proteins (e.g., channel proteins or carrier proteins).

Feedback Inhibition

A type of metabolic regulation where the end product of a metabolic pathway inhibits an earlier step in the pathway.

Fluid Mosaic Model

The currently accepted model of the plasma membrane structure, depicting it as a fluid phospholipid bilayer with embedded and attached proteins.

Gene

A unit of heredity that carries the instructions for a specific trait or protein; a specific sequence of nucleotides in DNA.

Genome

The entire set of genetic material in an organism or cell.

Gibbs Free Energy (ΔG)

A thermodynamic quantity that measures the amount of energy in a system available to do useful work at constant temperature and pressure; predicts the spontaneity of a reaction.

Glycolysis

The initial stage of cellular respiration, occurring in the cytoplasm, in which glucose is broken down into two molecules of pyruvate.

Golgi Apparatus

An organelle in eukaryotic cells consisting of flattened membranous sacs (cisternae) involved in modifying, sorting, and packaging proteins and lipids for secretion or delivery to other organelles.

Haploid (1n)

A cell containing only one set of chromosomes.

Hydrolysis

A chemical reaction in which a molecule is cleaved into two smaller molecules by the addition of a water molecule.

Hydrophilic

Having an affinity for water; polar or charged molecules that dissolve readily in water.

Hydrophobic

Lacking an affinity for water; nonpolar molecules that do not dissolve readily in water.

Hydrogen Bond

A weak noncovalent interaction between a hydrogen atom that is covalently bonded to an electronegative atom and another electronegative atom.

Hypertonic

A solution with a higher concentration of solutes compared to another solution (e.g., the inside of a cell).

Hypotonic

A solution with a lower concentration of solutes compared to another solution (e.g., the inside of a cell).

Independent Assortment

The principle that alleles of different genes segregate independently of one another during gamete formation.

Interphase

The phase of the cell cycle between cell divisions, during which the cell grows and replicates its DNA.

Isomers

Compounds with the same molecular formula but different structural arrangements of atoms.

Isotonic

A solution with the same concentration of solutes compared to another solution (e.g., the inside of a cell), resulting in no net movement of water.

Karyotype

A display of the chromosome pairs of a cell arranged by size and shape.

Ligand

A molecule that binds specifically to a receptor protein, triggering a cellular response.

Lipid

A diverse group of hydrophobic biological macromolecules, including fats, phospholipids, and steroids.

Locus

The specific location of a gene on a chromosome.

Lysosome

A membrane-bound organelle in eukaryotic cells containing hydrolytic enzymes that break down waste materials and cellular debris.

Meiosis

A type of cell division that reduces the number of chromosomes by half, producing four haploid gametes from a diploid parent cell.

Messenger RNA (mRNA)

A type of RNA molecule that carries the genetic information from DNA to the ribosomes for protein synthesis.

Metaphase

The stage of mitosis and meiosis II during which chromosomes line up at the metaphase plate.

Mitochondria

Membrane-bound organelles in eukaryotic cells that are the primary sites of cellular respiration and ATP production.

Mitosis

A type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth.

Monosaccharide

A simple sugar molecule; the monomer of polysaccharides.

Monosomic

Having only one copy of a particular chromosome in an otherwise diploid cell (2n-1).

Mutation

A change in the nucleotide sequence of DNA.

Noncompetitive Inhibition

A type of enzyme inhibition where the inhibitor binds to a site other than the active site, causing a conformational change in the enzyme that reduces its activity.

Nondisjunction

The failure of homologous chromosomes or sister chromatids to separate properly during meiosis.

Nucleic Acid

A biological macromolecule (DNA or RNA) consisting of nucleotide monomers linked by phosphodiester bonds.

Nucleotide

The monomer of nucleic acids, consisting of a sugar, a phosphate group, and a nitrogenous base.

Nucleus

The central organelle in eukaryotic cells that contains the cell's DNA.

Osmolarity

The concentration of osmotically active solutes in a solution.

Osmosis

The movement of water across a selectively permeable membrane from a region of higher water concentration to a region of lower water concentration.

Passive Transport

The movement of substances across a cell membrane without the input of energy.

Peptide Bond

The covalent bond that joins two amino acids together in a polypeptide chain.

Phospholipid

A lipid molecule with a hydrophilic head (phosphate group and glycerol) and two hydrophobic fatty acid tails; the main component of cell membranes.

pH

A measure of the hydrogen ion concentration in a solution; a scale from 0 to 14, where 7 is neutral, values below 7 are acidic, and values above 7 are basic.

Polymer

A large molecule consisting of many similar or identical monomers linked together by covalent bonds.

Polypeptide

A polymer of amino acids linked together by peptide bonds.

Polysaccharide

A carbohydrate polymer consisting of many monosaccharides linked together.

Primary Structure (Protein)

The linear sequence of amino acids in a polypeptide chain.

Protein

A biological macromolecule consisting of one or more polypeptide chains folded into a specific three-dimensional structure; plays diverse roles in the cell.

Quaternary Structure (Protein)

The association of two or more polypeptide chains (subunits) to form a functional protein.

Receptor Tyrosine Kinase (RTK)

A type of cell-surface receptor that has enzymatic activity; ligand binding leads to receptor dimerization and autophosphorylation, initiating signaling pathways.

Ribonucleic Acid (RNA)

A single-stranded nucleic acid molecule that plays various roles in protein synthesis and gene regulation.

Ribosome

A complex of RNA and proteins that is the site of protein synthesis.

Secondary Structure (Protein)

Localized, repetitive folding patterns in a polypeptide chain, such as the alpha helix and beta sheet, stabilized by hydrogen bonds.

Signal Peptide

A short amino acid sequence at the N-terminus of a polypeptide that directs it to the endoplasmic reticulum or other specific locations.

Signal Recognition Particle (SRP)

A protein-RNA complex that binds to a signal peptide on a growing polypeptide and escorts the ribosome to the endoplasmic reticulum.

Steroid

A type of lipid characterized by a carbon skeleton consisting of four fused rings.

Substrate

The reactant on which an enzyme acts.

Telophase

The final stage of mitosis and meiosis I and II, in which the chromosomes reach the poles and nuclear envelopes reform.

Tertiary Structure (Protein)

The overall three-dimensional shape of a polypeptide chain, resulting from interactions between the side chains of amino acids.

Tonicity

The ability of a surrounding solution to cause a cell to gain or lose water.

Transcription

The process by which the genetic information in DNA is copied into a complementary RNA sequence.

Transfer RNA (tRNA)

A type of RNA molecule that brings amino acids to the ribosome during protein synthesis, matching its anticodon to a codon in mRNA.

Translation

The process by which the genetic information encoded in mRNA is used to synthesize a polypeptide chain at the ribosomes.

Trisomic

Having three copies of a particular chromosome in an otherwise diploid cell (2n+1).

Tyrosine Kinase

An enzyme that catalyzes the transfer of a phosphate group from ATP to a tyrosine residue in a protein.

Valence Electrons

The electrons in the outermost shell of an atom, which are involved in chemical bonding.

Van der Waals Interactions

Weak, short-range attractions between molecules due to temporary fluctuations in electron distribution.

Vesicle

A small membrane-bound sac in the cytoplasm of eukaryotic cells used for transport and storage.

Wobble

The flexible base pairing that can occur between the third base of a codon and the corresponding base of an anticodon.

Zygote

A diploid cell resulting from the fusion of two haploid gametes (sperm and ovum).

Genes, Alleles, Loci

Understand the definitions of gene, allele, and locus.

Mendelian Genetics

Understand the basic principles of Mendelian inheritance, including the law of segregation and the law of independent assortment.

Energy Transformation

Understand basic concepts of energy (kinetic vs. potential, thermal, chemical, etc.) and the laws of thermodynamics. Understand the concept of Gibbs free energy (ΔG) and its relationship to spontaneous reactions.

Enzymes

Understand the role of enzymes as biological catalysts, enzyme structure (active site), enzyme specificity, and factors affecting enzyme activity (temperature, pH, inhibitors). Distinguish between competitive and noncompetitive inhibition, allosteric regulation, and feedback inhibition.

Cellular Respiration

Understand the overall process of cellular respiration and the roles of glycolysis, the citric acid cycle, and oxidative phosphorylation in ATP production. Understand the location of these processes within the cell (cytosol and mitochondria).

Tyrosine Kinase Receptors (TKRs)

Understand the basic mechanism of TKR signaling, including ligand binding and dimerization. Contrast with GPCR signaling.

Steroid Hormone Receptors

Understand the mechanism of intracellular steroid hormone receptor signaling, including receptor location and gene expression regulation.