Molecules of Cells - Principles of Biology I

A compilation of essential terms and definitions from the lecture notes on the molecules of cells, designed to assist students in reviewing key vocabulary for their exam.

Molecule

A group of atoms bonded together, representing the smallest fundamental unit of a chemical compound.

Trans fats

Artificial fats made by adding hydrogen atoms to liquid vegetable oils, associated with negative health effects.

Matter

Anything that has mass and takes up space.

Element

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

Molecule

Substances made of two or more different atoms.

Atomic Structure

The arrangement of protons, neutrons, and electrons in an atom.

Proton

A positively charged subatomic particle found in the nucleus of an atom.

Neutron

An uncharged subatomic particle found in the nucleus of an atom.

Electron

A negatively charged subatomic particle that orbits around the nucleus of an atom.

Atomic Mass

The total mass of an atom, calculated as the sum of protons and neutrons.

Atomic Number

The number of protons in an atom's nucleus.

Periodic Table

A tabular arrangement of the chemical elements, organized by their atomic number.

Isotope

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

Radiation

Energy released from radioactive isotopes in the form of subatomic particles.

Electrons

Subatomic particles that are responsible for forming chemical bonds.

Chemical Bonds

Forces holding atoms together in a molecule.

Ionic Bond

A chemical bond formed through the transfer of electrons from one atom to another.

Covalent Bond

A chemical bond formed by the sharing of electrons between atoms.

Hydrogen Bond

A weak attraction between a slightly positive hydrogen atom and a slightly negative atom.

pH Scale

A scale that measures how acidic or basic a solution is.

Acid

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

Base

A substance that accepts hydrogen ions or releases hydroxide ions (OH-) in a solution.

Buffer

A chemical that helps maintain a stable pH in a solution.

Organic Molecule

Molecules that contain both carbon and hydrogen.

Carbohydrates

Organic compounds made of carbon, hydrogen, and oxygen, serving as energy sources.

Proteins

Large molecules composed of one or more chains of amino acids.

Lipids

Fats and oils that are hydrophobic and serve as energy storage.

Nucleic Acids

Polymers of nucleotides, including DNA and RNA.

DNA

Deoxyribonucleic acid; the carrier of genetic information.

RNA

Ribonucleic acid; plays a role in protein synthesis.

Triglyceride

A type of lipid made of glycerol and three fatty acids.

Polysaccharides

Long chains of monosaccharides that serve as energy stores.

Hydrophilic

Substances that attract water, usually polar molecules.

Hydrophobic

Substances that do not attract water, usually nonpolar molecules.

Monomer

A simple molecule that can join together to form polymers.

Polymer

A large molecule made up of repeated subunits called monomers.

Peptide Bond

The bond formed between amino acids in a protein.

Denaturation

The process in which proteins lose their structure and functionality due to environmental changes.

Dehydration Reaction

A chemical reaction that involves the loss of a water molecule when forming a bond.

Hydrolysis Reaction

A chemical reaction that breaks down a compound by adding water.

Amino Acid

The building block of proteins, consisting of an amine group, a carboxyl group, and an R group.

Saturated Fat

A type of fat in which all carbon atoms are connected by single bonds, solid at room temperature.

Unsaturated Fat

A type of fat that contains one or more double bonds, liquid at room temperature.

Phospholipid

A lipid molecule composed of glycerol, two fatty acids, and a phosphate group, crucial for cell membranes.

Steroid

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

Cholesterol

A type of steroid that is a component of cell membranes and a precursor for other steroids.

Gene

A segment of DNA that codes for a protein or a functional RNA.

Chromosome

A structure that carries genetic information, composed of DNA and proteins.

Genetic Code

The set of rules by which information encoded in genetic material is translated into proteins.

Transcription

The process of copying a segment of DNA into RNA.

Translation

The process by which ribosomes synthesize proteins using the mRNA template.

Enzyme

A protein that acts as a catalyst to accelerate chemical reactions.

Substrate

The reactant on which an enzyme works.

Active Site

The specific region of an enzyme where the substrate binds.

Inhibitor

A substance that decreases or prevents the action of an enzyme.

Catalyst

A substance that increases the rate of a chemical reaction without being consumed.

Metabolism

The total of all chemical reactions that occur within a living organism.

Homeostasis

The regulation of internal conditions in an organism to maintain a stable environment.

Ecosystem

A community of living organisms and their physical environment interacting as a system.

Biodiversity

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

Cell Theory

The theory that all living things are composed of cells, which are the basic units of life.

Prokaryotic Cell

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

Eukaryotic Cell

A cell that contains a nucleus and membrane-bound organelles.

Cell Membrane

The semipermeable membrane surrounding the cytoplasm of a cell.

Cytoplasm

The material within a living cell, excluding the nucleus.

Nucleus

The membrane-bound organelle that contains the cell's DNA.

Organelle

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

Ribosome

The cellular structure where protein synthesis occurs.

Mitochondria

The organelle responsible for producing energy in the form of ATP.

Chloroplast

The organelle where photosynthesis occurs in plant cells.

Endoplasmic Reticulum

An organelle involved in protein and lipid synthesis.

Golgi Apparatus

An organelle that modifies, sorts, and packages proteins for secretion.

Vesicle

A small membrane-bound sac that transports substances within a cell.

Lysosome

An organelle that contains digestive enzymes to break down waste.

Peroxisome

An organelle that breaks down fatty acids and detoxifies harmful substances.

Centrosome

An organelle that organizes microtubules and is critical during cell division.

Cytoskeleton

A network of fibers that provides structural support to the cell.

Flagella

Long, whip-like structures that aid in cell movement.

Cilia

Short hair-like structures that assist in cell movement and sensing the environment.

Stem Cells

Undifferentiated cells with the potential to develop into different cell types.

Tissue

A group of similar cells that work together to perform a specific function.

Organ

A collection of tissues that work together to perform a specific function.

Organ System

A group of organs that work together to perform complex functions.

Organism

An individual living entity made up of one or more cells.

Population

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

Community

All the populations of different species that live and interact in a particular area.

Biome

A large geographic biotic unit, a major community of plants and animals with similar life forms.

Biomass

The total mass of living matter within a given area.

Trophic Level

Each level in a food chain or food web.

Producer

An organism that can make its own food, typically through photosynthesis.

Consumer

An organism that consumes other organisms for energy.

Decomposer

An organism that breaks down dead matter and recycles nutrients.

Carbon Cycle

The series of processes by which carbon compounds are interconverted in the environment.

Nitrogen Cycle

The process by which nitrogen is converted between its various chemical forms.

Water Cycle

The continuous movement of water on, above, and below the surface of the Earth.

Eutrophication

The process by which water bodies become enriched with nutrients, often leading to excessive growth of algae.

Climate Change

Long-term alteration in temperature and typical weather patterns in a place.

Sustainable Development

Development that meets the needs of the present without compromising the ability of future generations to meet their own needs.

Ecological Footprint

A measure of human demand on the Earth's ecosystems.

Endangered Species

A species that is at risk of extinction.