Chemistry and Biological Molecules

Flashcards covering general chemistry, water properties, chemical reactions, macromolecules, and nucleic acids from the lecture.

Atom

The basic structure that makes up everything, consisting of protons, neutrons, and electrons.

Ion

An atom that has gained or lost electrons, acquiring a net charge.

Electron Shells

Layered regions surrounding an atom's nucleus where electrons fill from inner to outer layers (inner holds $2$, next $2$ hold $8$), determining how the atom interacts with other atoms.

Ionic Bonds

Bonds formed between ions with opposite charges, which are weaker in the presence of water.

Covalent Bonds

Bonds formed when atoms share pairs of electrons that orbit the nuclei of both atoms; can be polar or nonpolar.

Hydrogen Bonds

Weak bonds formed when polar covalent bonds containing hydrogen attract to negative atoms, typically oxygen ($\text{O}$) and nitrogen ($\text{N}$).

Hydrophilic

A term describing polar molecules or substances that love water and interact well with it.

Dissociation

The process that occurs when ionic compounds are added to water, disrupting their ionic bonds.

Hydrophobic

A term describing non-polar molecules that do not interact well with water.

Cohesion

The property of water molecules attracting each other to form a united whole, such as slightly overfilling a glass with water without spilling.

Adhesion

The attraction between water and other molecules, such as water climbing a thin tube.

Mole

A quantitative unit equal to $6.02 \times 10^{23}$ atoms, molecules, or other entities.

Molarity (M)

A unit representing the concentration of a substance in a solution.

pH

A measure of the hydrogen ion concentration in a solution, defined as $\text{pH} = (-1)\,\log_{10}[\text{H}^+\text{ concentration}]$.

Chemical Reactions

Processes that occur when two or more atoms bond together to form molecules or when bonded atoms are broken apart.

Equilibrium

The state of balance between forward and reverse chemical reactions.

Monomers

Small repeating subunits that serve as the building blocks for polymers.

Polymers

Large molecules created by joining small repeating subunits known as monomers.

Condensation Reactions

Common chemical reactions that form a covalent bond between two molecules, release water, and require an input of energy.

Hydrolysis Reactions

Chemical reactions in which large organic molecules are broken down into subunits by adding water; functions as a condensation reaction in reverse without requiring energy input.

Carbohydrates

Biological molecules that provide energy to the body, characterized by a general formula of $\text{(CH}_2\text{O)}_n$ and a ratio of $2\text{H} + 1\text{O}$ for each $\text{C}$ atom.

Monosaccharides

The smallest carbohydrates and monomers for larger carbohydrates, classified by the number of carbon atoms and joined via covalent bonds.

Polysaccharides

Long chains of monosaccharides linked by glycosidic bonds, such as starch, glycogen, cellulose, and chitin.

Lipids

Organic molecules that are largely insoluble in water, lack a defined chemical formula or structure, and can lack a clear monomer.

Steroids

A type of lipid, such as cholesterol and related sterols, that are found in cell membranes.

Fatty Acids

Hydrocarbon chains containing $4$ to $36$ carbon atoms with a carboxyl group attached at the end.

Triacylglycerols

Animal fats and plant oils composed of one glycerol covalently attached to three fatty acids via condensation reactions; they are solid with no kinks and liquid with kinks.

Phospholipids

Major structural constituents of cell membranes consisting of two fatty acids attached to a glycerol molecule and a third carbon attached to a hydrophilic head group.

Amphipathic

Describing a molecule, such as a phospholipid, that possesses both hydrophobic and hydrophilic regions.

Amino Acids

The building blocks of proteins, structured around a central alpha carbon atom forming $4$ covalent bonds, which can serve as signal molecules or precursors for synthesis.

Proteins

Linear polymers of amino acids that serve as cellular structural building blocks, catalyze reactions as enzymes, assist immune responses, and drive movement.

Nucleotides

Structures containing a $5$-carbon sugar with a specific nitrogen-containing base attached to the other side of the sugar ring, which can undergo hydrolysis (e.g., ATP yielding ADP).

Nucleic Acids

Polymers of nucleotides, including DNA (built from four deoxyribonucleotides: Adenosine, Thymine, Cytosine, Guanosine) and RNA (built from ribonucleotides: Adenosine, Ribose, Cytosine, Guanosine).

Simple sugars

Monosaccharides or disaccharides that provide energy.

Complex carbohydrates

Polysaccharides that can provide energy or biological structure.

Cellulose

A complex carbohydrate that provides structure and is very difficult to break down into energy, with pretty much only certain bacteria able to break it down.

Chitin

A compound and complex carbohydrate that gives structure within the body.

Reducing sugars

Monomers or dimers, such as glucose or maltose, that possess an OH group.

Starch

A polysaccharide held together by strong covalent bonds forming long chains.

Triglycerides

Lipids, including fats and oils, that provide energy when broken down by the body.

Steroids

A type of lipid that includes different hormones within the body.

Phospholipids

Structural lipids containing a hydrophilic head and a hydrophobic tail that form cell membranes in the body.

Hydrophobic tail

The part of a phospholipid that repels or hides from water.

Hydrophilic head

The part of a phospholipid that, along with the hydrophobic tail, allows phospholipids to form membranes.

Membrane proteins

Structures embedded in lipid bilayers—such as channels and signal receptors—that mediate most interactions between cells.