Chapter 2: Atoms, Elements, and Organic Compounds

These flashcards cover the vocabulary and key concepts of Chapter 2, including basic atomic structure, chemical bonds, water properties, metabolic reactions, and the four major classes of organic molecules.

element

Makes up matter; each has a different number of subatomic particles.

atom

The basic building block that makes up elements.

neutron

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

proton

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

electron

A negatively charged subatomic particle.

isotope

An element containing a different number of neutrons than normal; it may be radioactive due to an unstable nucleus.

ion

An element that contains unequal numbers of protons and electrons, resulting in an unstable outer shell.

molecule

Contains two or more bonded atoms; it is the smallest part of a compound.

organic compound

A compound that contains carbon.

inorganic compound

A compound that does not contain carbon (e.g., $H_2O$).

ionic bond

A bond formed by the transfer of electrons between ions.

covalent bond

A bond formed by the sharing of electron pairs.

hydrogen bond

A weak bond involving hydrogen; in terms of strength, covalent > ionic > hydrogen.

exergonic reaction

A reaction that releases energy and is usually catabolic.

catabolic

A breakdown or decomposition reaction, such as the breakdown of glycogen into glucose.

endergonic reaction

A reaction that requires energy input.

anabolic

A synthesis reaction, such as the bonding of glucose monomers into glycogen.

hydrophilic

A substance that dissolves in water; described as water-loving.

hydrophobic

A substance that does not dissolve in water; described as water-fearing.

high heat capacity

A property of water indicating it does not change its temperature rapidly.

high heat of vaporization

A property of water that allows for cooling of the body through the evaporation of sweat.

Properties of Water

1. serves as a solvent

2. saves as a reactant or product in reactions

3. has a high heat capacity

4. has a high heat of vaporization

solvent

water in living organisms; dissolves solutes

Solute

dissolves in a solvent

Examples of a solvent

salt and glucose

acidic pH

$6.9$ or less; a solution containing more $H^+$ ions than $OH^-$ ions.

neutral pH

A pH value of exactly $7.0$.

basic pH

$7.1$ or more; a solution containing more $OH^-$ ions than $H^+$ ions.

salt

An inorganic compound that dissociates into anions and cations (e.g., $KCl$).

buffer

A substance that weakens strong acids and strong bases, such as the carbonic acid-bicarbonate buffer in blood.

monosaccharide

A simple sugar and the monomer of carbohydrates.

disaccharide

Consists of two linked monosaccharides, such as sucrose, maltose, or lactose.

polysaccharide

A long chain (polymer) of many linked simple sugars.

triglyceride

A lipid that contains three fatty acids.

saturated fat

A fat that lacks double bonds in its fatty acid chains (e.g., lard, butter, coconut oil).

polyunsaturated fat

A fat that contains two or more double bonds (e.g., soybean oil, canola oil).

essential fatty acids

Fatty acids humans must receive in their diets: linoleic acid (omega-3) and linolenic acid (omega-6).

phospholipid

Contains two fatty acid chains, glycerol, and a phosphate group; it is used to form cell membrane bilayers.

steroid

A lipid containing four rings of carbon atoms, such as cholesterol and sex hormones.

eicosanoid

A lipid derived from arachidonic acid containing $20$ carbons, including prostaglandins and thromboxanes.

protein

A polypeptide made of a chain of amino acids.

primary structure

The unique, one-dimensional sequence of amino acids in a polypeptide chain.

secondary structure

The twisting or folding of a polypeptide chain into a 2D alpha helix or pleated sheet, stabilized by hydrogen bonds.

tertiary structure

The 3D globular shape of a polypeptide chain held together by intramolecular bonds.

quaternary structure

A functional protein structure formed when two or more globular polypeptide chains combine.

Structural Protein

Actin and myosin in muscle

enzyme

A biological catalyst that speeds up a reaction by holding reactants in an active site.

denaturation

The unravelling of a protein's 3D structure due to extremes of temperature or pH, leading to loss of function.

Antibody

Defends against invaders

Hormone

Chemical messenger

nucleic acid

A chain of nucleotides.

nucleotide

The building block of nucleic acids consisting of a sugar, a phosphate group, and a nucleotide base.

DNA

A double-stranded helix containing deoxyribose sugar, phosphate groups, and the bases A, C, T, and G.

RNA

A nucleic acid containing ribose sugar and the base U in place of T.

mRNA

Messenger RNA; codes for protein.

rRNA

ribosomal RNA; makes up ribosome subunits

tRNA

transfer RNA; carries amino acids to the ribosome.

ATP

Adenosine triphosphate; contains adenosine plus three phosphate groups and is formed by phosphorylation to provide energy.