AP Biology Unit 1: Chemistry of Life

Vocabulary practice flashcards covering water properties, elements of life, macromolecules, carbohydrates, lipids, nucleic acids, and protein structures from AP Biology Grade 12 (Unit 1).

Covalent Bond

The type of chemical bond in which atoms share electrons.

Polarity

A condition in a covalently bonded molecule resulting from differences in atomic electronegativities that cause an unequal sharing of electrons.

Hydrogen Bond

A weak bond interaction between the negative and positive regions of two separate molecules.

Cohesion

The intermolecular attraction that occurs when two of the same molecules form hydrogen bonds with each other.

Adhesion

The intermolecular attraction that occurs when two different molecules form hydrogen bonds with each other.

Surface Tension

The property of water resulting from hydrogen bonds between water molecules at the surface of liquid water.

Emergent Properties (of Water)

Additional chemical behaviors demonstrated by water that arise from cohesion, adhesion, and surface tension.

Density Anomaly of Water

The property where water expands as it reaches $0^\circ\text{C}$ and freezes, causing solid ice to be less dense than liquid water because hydrogen bonds become more rigid and open below $4^\circ\text{C}$.

Law of Conservation of Energy

A physical law stating that energy cannot be created or destroyed, only transformed.

Carbon

An essential element used by living systems to build biological macromolecules, including carbohydrates, proteins, nucleic acids, and lipids.

Nitrogen

An essential element obtained from the environment that is used to build proteins and nucleic acids.

Phosphorus

An element absorbed from the environment used to construct nucleic acids and certain lipids.

Carbon Skeleton

A chain, ring, or branched structure formed by carbon atoms covalently bonding to other carbon atoms, to which other atoms attach.

Monomer

A chemical subunit with specific chemical properties used to create polymers.

Polymer

A macromolecule made up of many monomers connected by covalent bonds.

Dehydration Synthesis Reaction

A reaction used to create macromolecules where a hydrogen atom ($\text{H}$) and a hydroxide ($\text{OH}$) are removed from interacting monomers, forming a covalent bond between them and generating a molecule of water ($\text{H}_2\text{O}$) as a byproduct.

Hydrolysis Reaction

A reaction in which polymers are broken down into monomers as covalent bonds are cleaved by adding the subcomponents ($\text{H}$ and $\text{OH}$) of a hydrolyzed water molecule to different monomers.

Monosaccharide

A simple sugar containing one sugar subunit with attached hydroxides ($\text{OH}$) and hydrogen atoms ($\text{H}$), serving as the monomer for polysaccharides.

Polysaccharide

A complex carbohydrate macromolecule consisting of more than two sugar subunits connected by covalent bonds.

Glycogen

A complex branched glucose polymer that serves as the main storage form of glucose in animals and other vertebrates to provide quick energy when needed.

Cellulose

A linear carbohydrate polymer that functions as structural support and provides rigidity and strength in plant cell walls.

Amylopectin

A major component of starch in plants that features a branched structure configured for rapid glucose release.

Amylose

A major component of starch in plants that stores energy in long, unbranched chains of glucose.

Lipids

Nonpolar, hydrophobic biological molecules that lack true monomers and whose structure and function are derived from how their subcomponents are assembled.

Saturated Fatty Acid

A fatty acid hydrocarbon chain containing only single bonds between carbon atoms.

Unsaturated Fatty Acid

A fatty acid chain containing at least one double bond between carbon atoms, which results in a kink in the carbon chain.

Phospholipid

A lipid molecule composed of a hydrophilic head and a hydrophobic tail that groups together to form the lipid bilayer of plasma and cell membranes.

Steroids

Lipid hormones that support physiological functions including growth and development, energy metabolism, and homeostasis.

Cholesterol

A common steroid found in animal cell membranes that is essential for structural stability.

Nucleotide

The monomer subunit of nucleic acids, comprised of a 5-carbon sugar, a phosphate group, and a nitrogenous base.

Sugar-Phosphate Backbone

The alternating chain of sugar and phosphate groups in a nucleic acid strand formed by covalent bonds linking adjacent nucleotide monomers.

Antiparallel

The opposite orientation of the two complementary strands in a double-stranded DNA molecule, where one strand runs in a $5' \rightarrow 3'$ direction and the other runs in a $3' \rightarrow 5'$ direction.

DNA (Deoxyribonucleic Acid)

A nucleic acid polymer that contains deoxyribose sugar, the nitrogenous base thymine, and is typically double-stranded with antiparallel strands.

RNA (Ribonucleic Acid)

A nucleic acid polymer that contains ribose sugar, the nitrogenous base uracil, and is typically single-stranded.

Directionality of Nucleic Acid Synthesis

The biological principle that free nucleotides can only be covalently added to the $3'$ hydroxyl end of a growing nucleic acid strand.

Amino Acid

The protein monomer composed of a central carbon atom covalently bound to a hydrogen atom, an amino group ($-\text{NH}_2$), a carboxyl group ($-\text{COOH}$), and a variable $\text{R}$ group (side chain).

Peptide Bond

The covalent bond connecting amino acid monomers, formed between the carboxyl group ($-\text{COOH}$) of one amino acid and the amino group ($-\text{NH}_2$) of another.

Primary Structure (Protein)

The linear sequence of amino acids in a polypeptide chain held together by covalent peptide bonds.

Secondary Structure (Protein)

Local folding patterns of the polypeptide chain into elements such as alpha-helices and beta-sheets, stabilized by hydrogen bonding between atoms of the polypeptide backbone.

Tertiary Structure (Protein)

The overall 3D shape of a single protein that minimizes free energy, stabilized by hydrogen bonds, hydrophobic interactions, ionic interactions, or disulfide bridges between variable $\text{R}$ groups.

Quaternary Structure (Protein)

The structural level of a protein that arises from interactions and bonding between multiple polypeptide subunits.

Hemoglobin

A protein with quaternary structure composed of four polypeptide subunits, each containing an iron-containing heme group that binds to oxygen.