Unit 1 The Chemistry of Life

Matter

anything that takes up space and has mass

Element

a substance that cannot be broken down into other substances by chemical reactions

Compound

a substance consisting of two or more different elements combined in a fixed ratio

Essential elements

of the 92 naturally occurring elements 20-25% are essential to survive and reproduce. Carbon, Hydrogen, Oxygen, Phosphorous, Nitrogen make up 96% of living matter

Trace elements

of the 92 naturally occurring elements, these are required by an organism in very small quantities

Octet rule

elements will gain, lose, or share electrons to complete their valence shell and become stable (like noble gases)

Valence shell

outermost layer of electrons in an atom

Chemical Bonds

an attraction between two atoms, resulting from the sharing or transferring of valence electrons

Electronegativity

the measure of an atom’s ability to attract electrons to itself

Covalent bonds

when two or more atoms share electrons (usually between two nonmetals)

Nonpolar covalent

electrons are shared equally between two atoms

Polar covalent

electrons are not shared equally between two atoms

Ionic bonds

the attraction between oppositely charged atoms (ions)

Cation

positively charged ion

Anion

negatively charged ion

Hydrogen bonds

the partially positive hydrogen atom in one polar covalent molecule will be attracted to an electronegative atom in another polar covalent molecule

Intermolecular bond

bond that forms between molecules

Polarity

polar covalent bonds created by unequal sharing of electrons between oxygen and hydrogen within the molecule of water

Cohesion

attraction of molecules for other molecules of the same kind (H₂O to H₂O)

Surface tension

the result of cohesive forces among liquid molecules, creating a layer that resists external force

Adhesion

the attraction to other molecules that are polar or have charge (H₂O to other molecules)

Capillary Action

the upward movement of water due to the forces of cohesion, adhesion, and surface tension

High Specific Heat

H₂O resists changes in temperature

High heat of vaporization

Water requires a large amount of energy to evaporate due to strong hydrogen bonds

Evaporative cooling

as water molecules evaporate, the surface they evaporate from gets cooler

Density (floating ice)

as water solidifies it expands and becomes less dense

Solvent

dissolving agent in a solution

pH

a measure of how acidic or basic (alkaline) a solution is, logarithmic scale

Acid

substance that releases hydrogen ions (H+) when dissolved in water

Base

substance that accepts H+ or releases hydroxide ions (OH-) when dissolved in water

Buffer

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

Organic chemistry

the study of compounds with covalently bonded carbon

Organic compounds

compounds that contain carbon and hydrogen

Hydrocarbons

organic molecules consisting only of carbon and hydrogen

Functional groups

chemical groups attached to the carbon skeleton that participate in chemical reactions

Polymers

chain like macromolecules of similar or identical repeating units that are covalently bonded together

Monomers

the repeating units that make up polymers

Dehydration reaction

bonds two monomers with the loss of H₂O

Hydrolysis

breaks the bonds in a polymer by adding H₂O

Carbohydrates

organic compounds made of carbon, hydrogen, and oxygen that serve as a major energy source for living organisms

Monosaccharides

simple sugars

Disaccharides

two monosaccharides joined together by covalent bonds

Polysaccharides

polymer with many sugars joined via dehydration reactions

Starch

allows plants to store excess glucose

Glycogen

allows animals to store excess glucose in liver and muscle cells

Cellulose

tough substance that forms plant cell walls

Chitin

forms exoskeleton of arthropods

Proteins

macromolecules made of amino acids that perform a variety of functions in living organisms, contains carbon, hydrogen, oxygen, nitrogen and sulphur

Polypeptides

chains of amino acids that make up proteins and can fold into functional structures

• One end is a free amino group (N-terminus)

• One end is a free carboxyl group (C-terminus)

Amino acids

monomer of proteins

Antibody

help protect the body from disease

Enzyme

carry out chemical reactions or assist in creating new molecules

Messenger

transmit signals (ie hormones)

Structural

provide structure and support

Transport/storage

bind to and carry small atoms and molecules through the body

Primary structure

the specific sequence of amino acids in a peptide chain

Secondary structure

the local folded structures that form within a polypeptide due to hydrogen bonding between amino acid backbones

• 𝛃 pleated sheets

• 𝛂 helices

Tertiary structure

the overall three-dimensional shape of a protein formed by the interactions between the side chains of amino acids

Quaternary structure

the structure formed when two or more polypeptide chains interact to form a functional protein

Nucleic acids

macromolecules that store and transmit genetic information, primarily DNA and RNA

Nucleotides

monomer of nucleic acids

RNA

a type of nucleic acid that plays a crucial role in coding, decoding, regulation, and expression of genes

DNA

a nucleic acid that carries the genetic instructions for life and is composed of two strands forming a double helix

Lipids

a group of hydrophobic biomolecules that include fats, oils, and steroids, playing key roles in energy storage and cellular structure

Saturated fatty acid

no double bonds between carbons in the carbon chain

Unsaturated fatty acid

contains one or more double carbon bonds

Glycerol

classified as an alcohol (hydroxyl groups)

Fatty acids

long carbon chains (carboxyl group at one end)

Steroids

a class of lipid molecules characterized by a core structure of four carbon rings, play important roles in cell membrane structure and as signaling molecules in the body,