The Chemistry of Life

Flashcards covering basic chemistry concepts, chemical bonds, energy, chemical reactions, water properties, acids, bases, salts, and the four major organic macromolecules (carbohydrates, lipids, proteins, and nucleic acids).

What is an atom?

The smallest unit of matter that still retains its original properties.

What are the three basic types of subatomic particles?

Protons, Neutrons, Electrons.

What is the maximum number of electrons the first electron shell can hold?

2.

What is the maximum number of electrons the second electron shell can hold?

8.

What is the outermost electron shell called?

The valence shell.

Why does an atom overall have no charge?

Because the number of positively charged protons equals the number of negatively charged electrons.

What is an element?

A substance composed of one or more identical atoms defined by their number of protons.

What does the atomic number represent?

The number of protons.

What does the mass number represent?

The number of protons + neutrons.

What is atomic weight?

The average mass of all isotopes weighted by their natural abundance.

What are radioisotopes?

Unstable isotopes that undergo radioactive decay to release energy and attain a more stable form.

What are radioisotopes used for in nuclear medicine?

As tracers and in radiation therapy.

What is a mixture?

Physically intermixing atoms of two or more elements where the mixing does NOT change the chemical nature of the atoms involved.

What are the three types of mixtures?

Suspensions, Colloids, Solutions.

What is a solute?

The substance that dissolves in a solution.

What is a solvent?

The substance in which the solute dissolves.

What is solubility?

The degree to which the solute dissolves in a solution.

What is concentration?

The amount of solute present in a solution; often stated as a percentage.

What are molecules?

Two or more atoms chemically bonded together.

What are compounds?

Two or more atoms from different elements that are bonded together.

What is the octet rule?

Atoms are most stable when they have 8 electrons in their valence shell.

What kind of atoms are inert or non-reactive?

Atoms with filled valence shells.

What are the two major types of chemical bonds?

Ionic and Covalent.

Between what types of elements do ionic bonds occur?

Metals and non-metals.

How do ionic bonds form?

As a result of the transfer of electrons from the metal to the nonmetal.

What is a cation?

An ion that develops a positive charge after losing an electron.

What is an anion?

An ion that develops a negative charge after gaining an electron.

Between what types of elements do covalent bonds form?

Non-metals.

What do covalent bonds involve?

Sharing of valence electrons to fulfill the duet or octet rule.

What is a nonpolar covalent bond?

A bond where electrons are equally shared.

What is a polar covalent bond?

A bond where electrons are shared unequally.

What is electronegativity?

The extent to which protons can attract electrons.

When do non-polar molecules occur?

When atoms sharing electrons are of the same element, the molecule is symmetrical, AND/OR the bond is between carbon and hydrogen.

When do polar molecules occur?

When the molecule contains two nonmetals with substantially different electronegativities.

What are hydrogen bonds?

Weak attractions between polar covalent compounds where electrons are neither transferred nor shared.

Why is the polarity of a molecule important?

It has a large impact on how it can be moved and transported across membranes and around the body ('Like dissolves like').

What is energy?

The capacity to do work.

What are the two classes of energy?

Potential energy (energy of position) and Kinetic energy (energy of motion).

What is chemical energy?

Energy inherent in all chemical bonds.

What are anabolic reactions?

Synthesis reactions (A + B AB).

What are catabolic reactions?

Decomposition reactions (AB A + B).

What is oxidation in a redox reaction?

When a reactant loses an electron.

What is reduction in a redox reaction?

When a reactant gains an electron.

What are endergonic reactions?

Reactions that require an input of energy greater than the energy of the reactants (products have more energy).

What are exergonic reactions?

Reactions that result in products with less energy than the reactants (energy is released).

What is activation energy?

The energy required to get all chemical reactions started.

How do enzymes increase reaction rates?

By reducing the activation energy.

What is the main characteristic of enzymes regarding their role in a reaction?

They are neither consumed nor altered in the reaction and do not change the nature of the reaction.

What are organic compounds broadly defined as?

Compounds containing carbon bonded to hydrogen.

What are inorganic compounds?

Compounds that generally do not contain carbon bonded to hydrogen (e.g., water, acids, bases, salts).

What percentage of the human body's mass does water make up?

50-65%.

What is surface tension?

The inward pulling of cohesive forces at the surface of the water.

What is heat capacity?

The amount of energy needed to increase the temperature of 1g of a substance by 1oC.

What are hydrophilic solutes?

Solutes that can dissolve in water (polar molecules & ions).

What are hydrophobic solutes?

Solutes that do not dissolve in water (non-polar molecules).

What does the pH scale measure?

The relative concentration of H+ in a solution.

What is an acid?

A substance that dissociates in water to form a hydrogen cation (H+) and an anion, increasing the concentration of H+ in the solution.

What is a base?

A substance that accepts H+ when added to a solution, decreasing the concentration of H+.

What is the normal pH range of the human body?

7.35-7.45.

What do buffers do?

Resist changes in pH.

What are electrolytes?

The resulting cations and anions when salts dissolve in water.

What are monomers?

Single subunits that can be combined to build larger structures.

What are polymers?

Larger structures that consist of many monomers linked together.

How are polymers formed from monomers?

By dehydration synthesis, linking them with a covalent bond.

How are polymers broken down into monomers?

By hydrolysis, where an atom of water is added to break the covalent bonds.

What is the monomer of carbohydrates?

Monosaccharides.

What are the main components of a triglyceride?

Glycerol and three fatty acids.

What is the monomer of proteins?

Amino acids.

What type of bond links amino acids together?

A peptide bond.

What are the four levels of protein structure?

Primary, Secondary, Tertiary, Quaternary.

What are the three components of a nucleotide?

A nitrogenous base, a pentose sugar, and a phosphate group.

What are the purine and pyrimidine bases found in nucleic acids?

Purines: Adenine (A), Guanine (G); Pyrimidines: Cytosine (C), Thymine (T) in DNA, Uracil (U) in RNA.

What is the primary function of ATP?

It is the main energy currency of the cell, releasing energy when bonds between phosphates are broken.