General Biology Exam 1 Study Guide: Cells, Chemistry, Water, and Biomolecules

Study Guide - Smart Notes

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The cell is the fundamental unit of life. All living organisms are composed of one or more cells, and all cells arise from pre-existing cells.

Cell: The smallest structural and functional unit of an organism, typically microscopic and consisting of cytoplasm and a nucleus enclosed in a membrane.
Cell Theory: States that all living things are composed of cells, and all cells come from other cells.
Genetic Code: The set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins by living cells.
Organization of Genetic Material: Genetic material is organized into chromosomes, which are composed of DNA and associated proteins.

Charles Darwin observed that species vary over time and space, and that genetic variation is essential for evolution by natural selection.

Genetic Variation: Differences in DNA sequences among individuals, leading to diversity within a population.
Example: Variation in beak shapes among Galápagos finches.

The scientific method is a systematic approach to inquiry based on observation, hypothesis formation, experimentation, and analysis.

Scientific Method: Steps include observation, question, hypothesis, prediction, experiment, and conclusion.
Scientific Hypothesis: A testable statement that explains an observation or answers a scientific question.

All matter is composed of atoms, which combine to form elements and compounds essential for life.

Atom: The basic unit of a chemical element, consisting of protons, neutrons, and electrons.
Atomic Number: The number of protons in an atom's nucleus.
Atomic Mass: The total mass of protons and neutrons in an atom.
Compound: A substance formed when two or more elements are chemically bonded together.

The behavior of atoms is determined by the arrangement of electrons, especially those in the outermost shell (valence electrons).

Electron Shells: Energy levels where electrons are found; the outermost shell determines chemical reactivity.
Valence: The number of electrons an atom needs to gain, lose, or share to fill its outer shell.
Ion: An atom or molecule with a net electric charge due to the loss or gain of electrons.
Hydrogen Ion (H+): A proton released when a hydrogen atom loses its electron; important in acid-base chemistry.
Net Charge: The overall charge of an atom or molecule after accounting for all protons and electrons.
Mass of Subatomic Particles: Protons and neutrons have approximately 1 atomic mass unit (amu) each; electrons have negligible mass.

Atoms form chemical bonds to achieve stable electron configurations.

Covalent Bond: A chemical bond formed by the sharing of electron pairs between atoms.
Polar Covalent Bond: A covalent bond in which electrons are shared unequally, resulting in partial charges on atoms.

Water is a polar molecule, allowing it to form hydrogen bonds and exhibit unique physical and chemical properties essential for life.

Polarity of Water: Water has a partial positive charge on hydrogen atoms and a partial negative charge on oxygen, making it polar.
Hydrogen Bonding: Weak bonds between the hydrogen atom of one water molecule and the oxygen atom of another.
Cohesion: The attraction between water molecules due to hydrogen bonding.
Surface Tension: The measure of how difficult it is to stretch or break the surface of a liquid; water has high surface tension.
Specific Heat: The amount of heat required to raise the temperature of 1 gram of a substance by 1°C. Water has a high specific heat, helping to stabilize temperatures.
Density of Ice vs. Liquid Water: Ice is less dense than liquid water due to the arrangement of hydrogen bonds, causing ice to float.
Effect of CO2 in Water: CO2 dissolves in water to form carbonic acid, affecting pH and aquatic life.

Carbon's unique bonding properties allow it to form a wide variety of complex organic molecules essential for life.

Carbon Valence: Carbon has four valence electrons, allowing it to form four covalent bonds with other atoms.
Characteristics of Organic Molecules: Organic molecules contain carbon and hydrogen, often with oxygen, nitrogen, and other elements.
Role of Carbon Atoms: Carbon forms the backbone of organic molecules, enabling the diversity of life.
Hydrophobic Substances: Molecules that do not interact well with water, often nonpolar (e.g., oils, fats).
Representation of Alcohol: Alcohols contain a hydroxyl group (-OH) attached to a carbon atom.
Hydroxyl Group: A functional group consisting of an oxygen atom bonded to a hydrogen atom (-OH).
Isomers: Molecules with the same molecular formula but different structures and properties.

Biological macromolecules are large molecules essential for life, built from smaller subunits and characterized by specific functional groups.

Functional Groups in Amino Acids: Amino acids contain an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom, and a variable R group attached to a central carbon.
Dehydration Reactions: Chemical reactions that join monomers by removing a water molecule.
Hydrolysis: The breakdown of polymers into monomers by adding water.
Aldose Sugar: A monosaccharide with an aldehyde group (e.g., glucose).
Ketose Sugar: A monosaccharide with a ketone group (e.g., fructose).
Polysaccharides: Large carbohydrates formed by the linkage of many monosaccharides (e.g., starch, glycogen, cellulose).
Role of Glycogen: Glycogen is a storage polysaccharide in animals, primarily found in the liver and muscles.

Type	Functional Group	Example
Aldose	Aldehyde (-CHO)	Glucose
Ketose	Ketone (C=O)	Fructose

Functional Group	Structure	Role
Amino	-NH2	Acts as a base; found in amino acids
Carboxyl	-COOH	Acts as an acid; found in amino acids
Hydroxyl	-OH	Increases solubility in water; found in alcohols

Additional info: Some content and definitions have been expanded for clarity and completeness based on standard General Biology curriculum.