Chapter 2: The Molecules of Cells - Proteins and Nucleic Acids

Vocabulary flashcards covering Sections 2.7 (Proteins) and 2.8 (Nucleic Acids) from Chapter 2 of BC Biology 12.

Amino Acid

The building block monomer of proteins, consisting of a central carbon atom bonded to an amino group, a carboxyl group, a hydrogen atom, and a variable R group.

Enzyme

A category of proteins that act as biological catalysts to speed up chemical reactions in cells.

Polypeptide

A polymer composed of amino acids joined together in a chain by peptide bonds.

Peptide Bond

A polar covalent bond linking amino acids together in a polypeptide chain, formed through a dehydration reaction between an amino group and an acidic carboxyl group.

Primary Structure

The level of protein structure defined by its own particular linear sequence of amino acids.

Secondary Structure

The level of protein structure created by hydrogen bonding between amino acids, commonly forming an alpha ($\alpha$) helix or a beta ($\beta$) pleated sheet.

Tertiary Structure

The three-dimensional shape of a single polypeptide chain formed by bending and twisting, held together by covalent, ionic, and hydrogen bonds between R groups (including disulfide linkages $S-S$).

Quaternary Structure

The level of protein structure that occurs when two or more polypeptide chains join together to form a single protein.

Denatured

The state of a protein that has undergone an irreversible change in shape, causing it to lose its activity or remain only partially active.

Nucleic Acid

A polymer made of nucleotide monomers that stores genetic information and, with RNA, specifies protein synthesis.

Nucleotide

The monomer component of nucleic acids, consisting of a phosphate group, a pentose sugar, and a nitrogen-containing base.

DNA (Deoxyribonucleic Acid)

A double-stranded nucleic acid containing deoxyribose sugar and adenine, thymine, guanine, and cytosine bases, which serves as the genetic material for cell replication and protein synthesis.

RNA (Ribonucleic Acid)

A single-stranded nucleic acid containing ribose sugar and adenine, uracil, guanine, and cytosine bases, which works with DNA to specify protein synthesis.

Double Helix

The structure formed by two strands of DNA twisted about each other, held together by hydrogen bonding between complementary base pairs.

Complementary Base Pairing

The specific hydrogen bonding arrangement in DNA where cytosine (C) pairs with guanine (G) and thymine (T) pairs with adenine (A).

ATP (Adenosine Triphosphate)

An unstable nucleotide with high potential energy that serves as the energy currency of cells for chemical, transport, and mechanical work.

ADP (Adenosine Diphosphate)

A lower-energy, more stable molecule formed when ATP undergoes hydrolysis to release a phosphate group and energy.

ATP Cycle

The continuous process in which ATP is broken down into ADP and inorganic phosphate ($P_i$) to release energy for metabolic work, and regenerated from ADP and $P_i$ using energy input from processes like cellular respiration.