UNIT ONE

Biology

The study of living things.

Darwin's Theory of Evolution

The core concept of biology that explains the diversity of life and the common features shared by all living things.

Biological Diversity

The variety of life on Earth, which is divided into three domains (Bacteria, Archaea, Eukarya) and three multicellular kingdoms (Fungi, Plantae, Animalia).

Fundamental Properties of Life

Cellular organization, energy utilization, homeostasis, growth, development, and reproduction, and heredity are the fundamental properties shared by all living things.

Hierarchical Organization

Living things are organized into levels, including the cellular level, organismal level, population level, and ecosystem level.

The Nature of Science

Science aims to understand the natural world through observation and reasoning, and it is based on the fundamental nature of the universe that has not changed since its inception.

Descriptive Science

Science that involves making observations and forming hypotheses that are experimentally testable.

Logical Reasoning

Two types of logical reasoning used in science:deductive reasoning and inductive reasoning.

Hypothesis-Driven Science

Science that involves making and testing predictions based on hypotheses.

Hypothesis

A possible explanation for an observation that generates testable predictions and can be supported or rejected through experiments.

Hypothesis Testing

The process of designing and conducting experiments to test hypotheses.

Scientific Theories

Proposed explanations for natural phenomena that are based on general principles, supported by scientific reasoning and experimental evidence.

Cell Theory

The theory that states that cells are the smallest unit of life, all living things are made of cells, and life comes from pre-existing life.

Reductionism

The approach of breaking down complex processes into simpler parts to understand them.

Systems Biology

The approach that examines the whole of a system as well as the workings of its parts.

Science as a Social Construct

The process of scientific research, publication, and review by other scientists.

Evolution

The theory that explains the unity and diversity of life, stating that all organisms today descended from a common ancestor and that advantageous traits are selected for through natural selection.

Evidence Supporting Darwin's Theory

Fossil record, comparative anatomy, and molecular evidence that support the theory of evolution.

Five Concepts that Unify Biology

Life is subject to chemical and physical laws, structure determines function, living systems transform energy and matter, living systems depend on information transactions, and evolution explains the unity and diversity of life.

Atoms

The basic building blocks of matter, composed of protons, neutrons, and electrons.

Atomic Number

The number of protons in an atom, which determines its identity as an element.

Atomic Mass

The sum of protons and neutrons in an atom.

Electrons

Negatively charged particles that orbit the nucleus of an atom.

Isotopes

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

Electron Arrangement

The number and arrangement of electrons in their orbitals, which determines the chemical behavior of an atom.

Chemical Bonds

The forces that hold atoms together in molecules or compounds.

Ionic Bonds

Formed by the attraction of oppositely charged ions.

Covalent Bonds

Formed when atoms share two or more valence electrons.

Hydrogen Bonds

Weak bonds formed between a hydrogen atom and an electronegative atom in a different molecule.

Water

The single most outstanding chemical property of water is its ability to form hydrogen bonds, which gives it unique properties such as high specific heat, high heat of vaporization, and the ability to dissolve polar molecules and ions.

[H+]

The concentration of hydrogen ions in a solution, measured in moles per liter (mol/L).

Neutral

A solution with a [H+] of 10^-7 mol/L, considered neither acidic nor basic.

pH

The negative logarithm of the hydrogen ion concentration of a solution, used to measure acidity or alkalinity.

Acid

Any substance that dissociates in water to increase the [H+] and lower the pH of the solution.

Base

A substance that combines with H+ dissolved in water, lowering the [H+] and raising the pH of the solution.

Buffers

Substances that resist changes in pH by releasing or absorbing hydrogen ions when acids or bases are added.

Biological buffers

Pairs of molecules, one acid and one base, that help maintain a relatively constant [H+] in biological systems.

Carbon

The framework of biological molecules, primarily bonded to carbon, oxygen, sulfur, nitrogen, phosphorus, or hydrogen.

Isomers

Molecules with the same molecular or empirical formula but different structural or stereochemical arrangements.

Macromolecules

Four general classes of large biological molecules:carbohydrates, proteins, nucleic acids, and lipids.

Carbohydrates

Molecules with a 1:2:1 ratio of carbon, hydrogen, and oxygen, often used as energy storage molecules.

Monosaccharides

The simplest carbohydrates, including glucose, fructose, and galactose.

Disaccharides

Two monosaccharides linked together by dehydration synthesis, such as sucrose, lactose, and maltose.

Polysaccharides

Long chains of monosaccharides linked through dehydration synthesis, used for energy storage or structural support.

Proteins

Biological macromolecules with diverse functions, including enzyme catalysis, defense, transport, support, motion, regulation, and storage.

Amino acids

The monomers of proteins, composed of a central carbon atom, amino group, carboxyl group, hydrogen, and variable R group.

R Groups

The variable side chains of amino acids that determine their chemical properties.

Protein structure

The shape of a protein, including primary, secondary, tertiary, and quaternary structures.

Nucleic acids

Polymers composed of nucleotides, including DNA and RNA, which store and transmit genetic information.

DNA

A double helix structure composed of deoxyribose sugar, phosphate, and nitrogenous bases (adenine, guanine, cytosine, thymine).

RNA

Usually single-stranded, composed of ribose sugar, phosphate, and nitrogenous bases (adenine, guanine, cytosine, uracil).

Lipids

Hydrophobic molecules, including fats, oils, waxes, and steroids, with high proportions of nonpolar C-H bonds.

Fats

Triglycerides composed of glycerol and three fatty acids, used for energy storage.

Phospholipids

Composed of glycerol, two fatty acids, and a phosphate group, forming biological membranes.

Other lipids

Terpenes found in biological pigments, such as chlorophyll, and steroids involved in membrane structure and hormone signaling.