AP Biology Unit 1: Chemistry of Life Vocabulary

active site

a region on an enzyme that binds to a substrate during a reaction

allosteric site

The place on an enzyme where a molecule that is not a substrate may bind, thus changing the shape of the enzyme and influencing its ability to be active

amino acid

monomer of protein

amphipathic

having both a hydrophilic region and a hydrophobic region

carbohydrate

compound made up of carbon, hydrogen, and oxygen atoms; major source of energy for living organisms

carbon

element that makes up living things; forms many bonds

catalyst

substance that speeds up the rate of a chemical reaction

denaturation

A process in which a protein unravels, losing its specific structure and hence function; can be caused by changes in pH or salt concentration or by high temperature. Also refers to the separation of the two strands of the DNA double helix, caused by similar factors.

dissacharide

A molecule made of two monosaccharides.

hydrogen bond

Attraction between a slightly positive hydrogen atom and a slightly negative atom.

hydrophilic

Attracted to water

hydrophobic

Having an aversion to water; tending to coalesce and form droplets in water.

ion

A charged atom

lipid

macromolecule made mostly from carbon and hydrogen atoms; includes fats, oils, and waxes

macromolecule

A very large organic molecule composed of many smaller molecules

monomer

A simple compound whose molecules can join together to form polymers

monosaccharide

A single sugar molecule such as glucose or fructose, the simplest type of sugar.

nonpolar molecule

molecule that shares electrons equally and does not have oppositely charged ends

nucleic acid

macromolecule containing hydrogen, oxygen, nitrogen, carbon, and phosphorus

nucleotide

monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base

organic molecule

A molecule containing carbon that is a part of or produced by living systems.

peptide bond

The chemical bond that forms between the carboxyl group of one amino acid and the amino group of another amino acid

polar molecule

molecule with an unequal distribution of charge, resulting in the molecule having a positive end and a negative end

polymer

A long molecule consisting of many similar or identical monomers linked together.

protein

A three dimensional polymer made of monomers of amino acids.

substrate

A specific reactant acted upon by an enzyme

cohesion

Attraction between molecules of the same substance

adhesion

An attraction between molecules of different substances

surface tension

the cohesive force at the surface of a body of liquid that prevents the molecules from separating

specific heat

The amount of energy required to raise the temperature of 1 gram of a substance by 1 degree Celcius

dehydration synthesis

A chemical reaction in which two molecules are bonded together with the removal of a water molecule.

hydrolysis

A chemical process that splits a molecule by adding water.

polysaccharide

Carbohydrates that are made up of more than two monosaccharides

elements in carbohydrates

CHO in a 1:2:1 ratio

elements in lipids

CHO

elements in proteins

CHON

elements in nucleic acids

CHONP

saturated fatty acids

have the maximum number of hydrogen atoms possible and no double bonds

unsaturated fatty acids

A fatty acid possessing one or more double bonds between the carbons in the hydrocarbon tail. Such bonding reduces the number of hydrogen atoms attached to the carbon skeleton.

R group

a functional group that defines a particular amino acid and gives it special properties.

protein primary structure

amino acid sequence

protein secondary structure

alpha helix and beta pleated sheet formed by hydrogen bonds between atoms of the polypeptide backbone

pyrimidines

Cytosine and Thymine; nitrogen bases containing one ring

purines

Adenine and Guanine; nitrogen bases containing a double-ring structure

noncompetitive inhibitor

A substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing its conformation so that it no longer binds to the substrate.

competitive inhibitor

A substance that reduces the activity of an enzyme by entering the active site in place of the substrate whose structure it mimics.