Biology: Chapters 1 to 3 - Study of Life, Basic Chemistry, and Organic Molecules

Vocabulary practice flashcards based on Chapters 1-3 covering the study of life, basic chemistry principles, and biological macromolecules.

Evolution

The process by which populations of organisms change over time by passing genes for traits from one generation to another.

Scientific Method

A series of steps in which scientists make observations, ask questions, develop hypotheses, test those ideas with experiments, gather and analyze data, and draw conclusions.

Deductive Reasoning

A logical process that begins with supplied general information and draws specific conclusions based on that information.

Inductive Reasoning

A logical process that begins with specific observations and draws a general principle from them.

Hypothesis

A tentative explanation for observations that is consistent with well-established facts, testable, repeatable, and falsifiable.

Scientific Theory

An integrated explanation of some aspect of the natural world, based on several hypotheses supported by consistent results from many observations or experiments.

Cell Theory

The scientific theory stating that all living things are made of cells, and all cells come from pre-existing living cells.

Gene Theory

The scientific theory stating that traits and physical features are coded in genes made of DNA, which pass from parents to offspring.

Double-Blind Clinical Trials

A randomized study design where neither the patient nor the physician knows who receives the trial drug versus the placebo, minimizing bias.

Element

A substance that cannot be broken down into simpler substances by ordinary chemical reactions.

Atom

The smallest unit of an element that retains that element's chemical properties.

Atomic Number

The fixed number of protons in the nucleus of an atom, which determines its identity.

Atomic Mass Number

The total sum of the protons and neutrons in the nucleus of an atom.

Isotopes

Atoms of the same element that have varying numbers of neutrons.

Valence Shell

The outermost concentric electron shell of an atom containing the most energetic electrons.

Organic Compounds

Compounds containing carbon, usually covalently bonded to hydrogen, that typically originate from living organisms.

Covalent Bond

A chemical bond formed when atoms share electrons to fill each atom's valence shell.

Nonpolar Covalent Bond

A covalent bond in which electrons are shared equally between atoms.

Polar Covalent Bond

A covalent bond in which electrons are shared unequally between atoms, generating partial positive and negative charges.

Oxidation

A chemical process involving the loss of one or more electrons by an atom or molecule.

Reduction

A chemical process involving the gain of one or more electrons by an atom or molecule.

Cations

Positively charged ions formed when atoms with 1, 2, or 3 valence electrons lose electrons.

Anions

Negatively charged ions formed when atoms with 5, 6, or 7 valence electrons gain electrons.

Cohesion

The property of water molecules sticking to one another due to hydrogen bonding.

Adhesion

The ability of water to stick to other polar or charged substances.

Capillary Action

The tendency of water to move through narrow tubes against gravity through a combination of adhesion and cohesion.

Hydrophilic

Water-loving substances containing ionic or polar bonds that interact easily with water.

Hydrophobic

Water-fearing substances containing nonpolar bonds that do not dissolve in water and cluster together.

Acid

A substance that dissociates in solution to yield hydrogen ions ($\text{H}^+$) and an anion, acting as a proton donor.

Base

A substance that dissociates in solution to yield hydroxide ions ($\text{OH}^-$) and a cation, acting as a proton acceptor.

Isomers

Compounds with identical molecular formulas but different chemical structures and properties.

Enantiomers

Isomers that are non-superimposable mirror images of each other.

Dehydration Reaction

A chemical reaction in which monomers are covalently linked together into polymers by removing a water molecule ($\text{H}_2\text{O}$).

Hydrolysis Reaction

A chemical reaction in which polymers are degraded into monomers through the addition of a water molecule ($\text{H}_2\text{O}$).

Glycogen

An extensively branched energy storage polysaccharide made of glucose subunits stored in vertebrate liver and muscle cells.

Cellulose

An insoluble structural polysaccharide composed of glucose molecules that forms plant cell walls.

Triacylglycerol

A fat molecule consisting of glycerol joined to three fatty acids that serves as reserve fuel storage.

Saturated Fatty Acid

A fatty acid chain containing the maximum number of hydrogen atoms, with a straight shape that makes it solid at room temperature.

Unsaturated Fatty Acid

A fatty acid chain that includes one or more carbon-carbon double bonds, causing a kinked shape that keeps it liquid at room temperature.

Phospholipid

An amphipathic lipid molecule consisting of a hydrophilic head and two hydrophobic tails, functioning as a primary component of cell membranes.

Enzymes

Proteins that accelerate chemical reactions in living organisms.

Primary Structure

The specific sequence of amino acids in a polypeptide chain.

Secondary Structure

Polypeptide folding patterns resulting from hydrogen bonding along the backbone, such as an $\alpha$-helix or $\beta$-pleated sheet.

Tertiary Structure

The overall three-dimensional shape of a single polypeptide chain, determined by interactions among amino acid side chains (R groups).

Quaternary Structure

The overall protein structure resulting from interactions among multiple individual polypeptide chains.

Nucleotide

The fundamental monomer of nucleic acids, consisting of a five-carbon sugar, one or more phosphate groups, and a nitrogenous base.

Purines

Nitrogenous bases containing a double-ring structure, specifically adenine (A) and guanine (G).

Pyrimidines

Nitrogenous bases containing a single-ring structure, specifically cytosine (C), thymine (T), and uracil (U).

ATP (Adenosine Triphosphate)

The primary energy transfer molecule in all cells, composed of adenine, ribose, and three phosphate groups.