Advertisement Upgrade to remove ads


Defined as anything that has mass and occupies space.


This subunit of an atom is found within the nucleus of the atom - and possesses a positive charge.


This subunit of an atom has no charge (electrically neutral) and is found within the nucleus of the atom.


This subunit of an atom possesses a negative charge - negligible mass - and is found orbiting the nucleus in shells (orbits).

Atomic Number

Defined as the number of protons found in the nucleus of a given atom.

Atomic Mass

This term is defined as the number of protons plus the number of neutrons found in the nucleus of an atom.


In an effort to become more stable - a sodium atom will lose an electron - and become one of these. (positive ion)


In an effort to become more stable - a chlorine atom will gain an electron - and thus become one of these. (negative ion)


This term refers to a variation of an atom that either gains or loses neutrons - rather than electrons - they are often used in medicine and research.

Ionic Bond

This type of chemical bond is formed when one atom gains an electron and the other loses an electron - this resulting molecule has a neutral charge.

Polar Covalent Bond

This type of bond is created when atoms share electrons - but not equally - creating both negatively and positively charged regions within the molecule - an example of this bond is found in water.

Hydrogen Bond

This type of chemical bond - although relatively weak and easily broken - helps to maintain the complex shape of large macromolecules like proteins.


Defined as a substance that releases (generates) hydrogen ions when it is dissolved in water.


Defined as a substance that releases (generates) hydroxide ions when it is dissolved in water.


If a substance is dissolved in water - and releases (generates) neither hydrogen nor hydroxide ions - it is one of these.


In a solution - this substance actually does the dissolving - water is an excellent example of one of these.


In a solution - this is the substance that is actually dissolved.


This term refers to a substance that works to keep our internal pH stable (within the homeostatic range) - it can either bond with hydrogen ions or release hydrogen ions to help prevent dramatic changes in pH.


A simple sugar (typically 6 carbons or less) - examples include glucose, fructose, and galactose.


These organic molecules are defined as short chains of two or more monosaccharides - examples include sucrose, lactose, and maltose.


These organic molecules are complex chains of hundreds - or even thousands of monosaccharides linked together - examples include amylose, cellulose, glycogen, and chitin.


This organic molecule - also referred to as a neutral fat - is comprised of one glycerol molecule and three fatty acids.

Saturated Fats

These lipids come from an animal source (butter, lard, bacon fat, etc.) - and exist as solids at room temperature.

Unsaturated Fats

These lipids are from plant sources (corn, peanut, safflower, oils, etc.) - and are liquids at room temperature.


In our bodies - bile is used to break large fats (lipids) into smaller pieces so that they can be digested - this is the term for that process.


This organic molecule is the major structural component of our cell membranes - it is comprised of hydrophilic heads of glycerol and hydrophobic tails of fatty acids.


Examples of this organic molecule are vitamin D, cholesterol, estrogen, and testosterone - complex lipids that have very important functions in our bodies.


This type of organic molecule is defined as a highly insoluble lipid - and acts as water repellent/insulator on the fur and feathers of animals/birds, and outer protective covering of many leaves and stems, and used in the construction of beehives.

Amino Acids

These molecules are the "building blocks" of all proteins - held together by numerous peptide bonds.

Peptide Bonds

This type of bond holds amino acids together in our proteins.


This term describes a process where a complex protein loses its shape (and usually its function) due to the breaking of its hydrogen bonds.


This term refers to the subunit (building block) of all nucleic acids - it is comprised of a five-carbon sugar, a phosphate group, and a nitrogen-containing base.


Adenosine Triphosphate - a very important nucleotide that is the main source of energy for our body's cells.


This type of nucleic acid - called Deoxyribonucleic Acid - is a double strand of nucleotides that forms the genetic material of our cells.


This type of nucleic acid - called Ribonucleic Acid - is comprised of a single strand and is responsible for directing the synthesis (production) of proteins in all of our cells.

Non-polar Covalent Bond

In this type of chemical bond - electrons are shared equally between two atoms - like in a molecule of oxygen gas - these are very strong bonds.

Properties of Water

■Highly polar molecule. ■Maintains body temperature. Absorbs and releases energy (heat) slowly. ■Has high surface tension (cohesion). ■Universal solvent. ■Involved in most reactions in the body - making it our most important inorganic molecule.

pH Scale

Ranges from 0 to 14. 0 most acidic. 14 most alkaline (basic). 7 is neutral. Human blood is between 7.35 - 7.45.


Monosaccharide: blood sugar - the main source of energy for most organisms.


Monosaccharide: fruit sugar.


Monosaccharide: milk sugar.


Disaccharide: table sugar from sugar cane or sugar beets (glucose + fructose).


Disaccharide: milk sugar (glucose + galactose).


Disaccharide: malt or grain sugar (glucose + glucose).


Polysaccharide: plant starch - stored energy source in plants.


Polysaccharide: indigestible fiber found commonly in plant cell walls - has a structural function.


Polysaccharide: animal starch (quick energy source stored in animal tissues) - most notably the liver and skeletal muscles.


Polysaccharide: insoluble, structural substance found in the exoskeletons of certain insects (arthropods) - very strong.

Lipids (The Fats)

■Insoluble in water - they are "non-polar" molecules. ■Mostly hydrocarbons. ■Form basic structures of animal cell membranes. ■Storage of energy (on average more than twice the energy of carbohydrates gram for gram). ■Provide insulation/protective function.

Adipose Cells

Human fat cells. Unlimited capacity to store fat.

20 Different Amino Acids

"12 non-essential" (liver can synthesize). "8 essential" (need in diet).

Protein Functions

■Act as enzymes - catalyze reactions in all organisms. ■Structure. ■Regulatory - controls cell activities (hormones). ■Transport - hemoglobin transports oxygen and carbon dioxide.

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again


Reload the page to try again!


Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording