Intro to Biology, Chemistry, Macromolecules, and Cell Structure: Key Concepts for Test 1

Biology

The scientific study of life.

Homeostasis

The ability of an organism to maintain a stable internal environment.

Atom

The basic unit of a chemical element.

Molecule

A group of atoms bonded together.

Macromolecule

A large molecule composed of smaller subunits, such as proteins, nucleic acids, carbohydrates, and lipids.

Organelle

A specialized subunit within a cell that has a specific function.

Cell

The smallest unit of life that can function independently.

Prokaryote

A unicellular organism that lacks a nucleus and membrane-bound organelles.

Eukaryote

An organism whose cells contain a nucleus and membrane-bound organelles.

Tissues

Groups of similar cells that perform a specific function.

Organs

Structures composed of different types of tissues that work together to perform specific functions.

Organ systems

Groups of organs that work together to perform complex functions.

Organisms

Individual living entities that can react to stimuli, reproduce, grow, and maintain homeostasis.

Population

A group of individuals of the same species living in a specific area.

Community

All the different populations that live together in an area.

Ecosystem

A biological community of interacting organisms and their physical environment.

Biosphere

The global sum of all ecosystems; the zone of life on Earth.

Biodiversity

The variety of life in the world or in a particular habitat or ecosystem.

Genetic Diversity

The total number of genetic characteristics in the genetic makeup of a species.

Species diversity

The number of different species and the abundance of each species within a given area.

Ecosystem Diversity

The variety of ecosystems in a given place.

Phylogeny

The evolutionary history and relationship among individuals or groups of organisms.

Taxonomy

The science of classification of living organisms.

Domain

The highest taxonomic rank in the hierarchical biological classification system.

Kingdom

A taxonomic rank below domain and above phylum.

Phylum

A taxonomic rank below kingdom and above class.

Class

A taxonomic rank below phylum and above order.

Order

A taxonomic rank below class and above family.

Family

A taxonomic rank below order and above genus.

Genus

A taxonomic rank below family and above species.

Species

The basic unit of biological classification, a group of organisms capable of interbreeding.

Taxon

A group of one or more populations of an organism or organisms.

Hypothesis

A proposed explanation for a phenomenon, to be tested.

Dependent variable

The variable that is measured in an experiment.

Independent variable

The variable that is manipulated in an experiment.

Positive Control

A group in an experiment that receives a treatment with a known result.

Negative Control

A group in an experiment that does not receive the treatment and is used as a benchmark.

Matter

Anything that has mass and takes up space.

Elements

Pure substances that cannot be broken down into simpler substances.

Atoms

The smallest unit of an element.

Atomic Number

The number of protons in the nucleus of an atom.

Atomic Mass

The weighted average mass of an element's isotopes.

Isotope

Atoms of the same element with different numbers of neutrons.

Octet Rule

The principle that atoms tend to bond in such a way that they have eight electrons in their valence shell.

Valence shell

The outermost shell of an atom, containing the valence electrons.

Chemical Bond

The lasting attraction between atoms that enables the formation of chemical compounds.

Molecules

Groups of two or more atoms bonded together.

Ions

Atoms or molecules that have a net electric charge due to the loss or gain of one or more electrons.

Cations

Positively charged ions.

Anions

Negatively charged ions.

Polar covalent bond

A type of chemical bond where a pair of electrons is unequally shared between two atoms.

Non-polar covalent bond

A type of chemical bond where two atoms share a pair of electrons equally.

Ionic bond

A type of chemical bond formed through the electrostatic attraction between oppositely charged ions.

Hydrogen bond

A weak bond between two molecules resulting from an electrostatic attraction.

Functional group

A specific group of atoms within a molecule that is responsible for a characteristic of that molecule.

Acid

A substance that donates protons (H+) in a solution.

Base

A substance that accepts protons (H+) in a solution.

pH scale

A scale used to specify the acidity or basicity of an aqueous solution.

Buffer

A solution that resists changes in pH when an acid or base is added.

Chemical Reaction

A process that leads to the transformation of one set of chemical substances to another.

Reactants

The starting materials in a chemical reaction.

Products

The substances formed as a result of a chemical reaction.

Compounds

Substances formed when two or more elements are chemically bonded together.

Equilibrium

The state in which the concentrations of reactants and products remain constant over time.

Anabolic and Catabolic reactions

Anabolic reactions build molecules, while catabolic reactions break them down.

Enzyme

A protein that acts as a catalyst to speed up a chemical reaction.

1st law of thermodynamics

Energy cannot be created or destroyed, only transformed.

2nd law of thermodynamics

In any energy transfer, there will always be a loss of energy in the form of heat.

entropy

A measure of the disorder or randomness in a system.

Proteins

Large biomolecules made up of amino acids that perform a variety of functions.

Amino Acids

The building blocks of proteins.

Peptide bond

The bond formed between two amino acids.

Primary structure

The sequence of amino acids in a protein.

Secondary structure

The folding or coiling of the polypeptide chain into a specific shape.

Alpha helix

A common secondary structure in proteins characterized by a right-handed coil.

Beta pleat

A secondary structure in proteins that consists of beta strands connected by hydrogen bonds.

Tertiary structure

The overall three-dimensional shape of a polypeptide.

Disulfide bond

A covalent bond formed between the sulfur atoms of two cysteine amino acids.

Quaternary Structure

The arrangement of multiple polypeptide chains in a protein.

Denaturation

The process in which proteins lose their structure and function due to external stress.

Chaperone

A protein that assists in the folding of other proteins.

Lipids

A diverse group of hydrophobic molecules including fats, oils, and steroids.

Fatty acids

Carboxylic acids with long hydrocarbon tails.

Saturated

Fatty acids with no double bonds between carbon atoms.

Unsaturated

Fatty acids that contain one or more double bonds.

Cis-fatty acid

An unsaturated fatty acid where the hydrogen atoms are on the same side of the double bond.

Trans-fatty acid

An unsaturated fatty acid where the hydrogen atoms are on opposite sides of the double bond.

Wax

A type of lipid that is hydrophobic and used for protection.

Phospholipid

A lipid molecule that is a major component of cell membranes.

Polar head

The hydrophilic part of a phospholipid.

Non-polar tail

The hydrophobic part of a phospholipid.

Amphipathic

Molecules that have both hydrophilic and hydrophobic parts.

Steroids

Lipids characterized by a carbon skeleton consisting of four fused rings.

Cholesterol

A type of steroid that is an essential component of cell membranes.

Carbohydrates

Organic compounds made of carbon, hydrogen, and oxygen, typically in a 1:2:1 ratio.

Monosaccharide

The simplest form of carbohydrates, consisting of a single sugar unit.

Glycosidic bond

The bond formed between two monosaccharides.

Dissaccharide

A carbohydrate formed from two monosaccharides.

Polysaccharide

A carbohydrate composed of many monosaccharides.

Starch

A storage polysaccharide in plants.