Biochemistry and Cell Structure Practice Flashcards

Flashcards testing vocabulary and definitions of chemical reactions, energy types, enzymes, inorganic and organic biomolecules, and basic cell structures based on lecture notes.

Metabolism

Collectively, all the chemical reactions that occur in the body.

Potential energy

Energy that is stored, ready to be released and used to do work.

Kinetic energy

Energy in motion; work is being done.

Chemical energy

A form of potential energy stored within the chemical bonds of a substance.

Electrical energy

Energy resulting from the movement of charged particles or ions.

Mechanical energy

Energy directly transferred from one object to another, involved in moving matter.

Endergonic reaction

A chemical reaction that requires energy from another source to proceed, resulting in products that contain more energy than the reactants.

Exergonic reaction

A chemical reaction in which excess energy stored in the reactants is released, resulting in products that contain less energy than the reactants.

Catabolic reaction

A decomposition reaction in which larger substances are broken down into smaller ones ($AB \rightarrow A + B$).

Synthesis reaction

An anabolic reaction in which atoms or molecules combine to form larger, more complex molecules ($A + B \rightarrow AB$).

Exchange reaction

A chemical reaction in which one or more atoms from reactants are exchanged for one another ($AB + CD \rightarrow AD + BC$).

Oxidation-reduction reaction

A special exchange reaction where electrons and energy are transferred; the reactant that loses electrons is oxidized and the reactant that gains electrons is reduced.

Activation energy ($E_a$)

The energy required for all chemical reactions to occur by getting the reactants to the transition state.

Catalyst

A substance that increases the rate of a chemical reaction by lowering the activation energy without being permanently altered or becoming part of the product.

Enzyme

A biological catalyst that speeds up chemical reactions by lowering the activation energy without altering the reactants or products.

Active site

A specific region on an enzyme where substrate molecules bind.

Substrate

A specific substance or reactant that binds to the active site of an enzyme.

Organic compound

A compound containing carbon bonded to hydrogen, characterized by covalent bonds.

Inorganic compound

A compound that does not contain carbon bonded to hydrogen.

Hydrophilic

Referring to solutes with partial or complete charges (ionic or polar covalent bonds) that are able to dissolve in water.

Hydrophobic

Referring to uncharged, nonpolar covalent molecules or compounds that lack charged ends and will not dissolve in water.

Acid

A hydrogen ion ($H^+$) or proton donor that splits into an $H^+$ and an anion in solution, increasing the $H^+$ concentration.

Base

A hydrogen ion ($H^+$) acceptor that splits into cation and anion components, where the negatively charged anion binds free $H^+$ to decrease the solution's $H^+$ concentration.

pH scale

A scale from $0$ to $14$ representing the negative logarithm of a solution's hydrogen ion concentration ($-\log[H^+]$).

Buffer

A chemical system consisting of a weak acid and its conjugate base that resists changes in pH when small amounts of acids or bases are added to a solution.

Salt

A compound composed of a metal cation and a nonmetal anion held together by ionic bonds that dissociates into its ionic components in water.

Electrolyte

Cations and anions in solution resulting from dissolved salts, acids, or bases that conduct an electric current in water.

Monomer

A single subunit that can be combined with others to build larger structures.

Polymer

A large structure consisting of many monomers linked together.

Dehydration synthesis

An anabolic chemical reaction in which two molecules are covalently bonded together by removing a water molecule.

Hydrolysis reaction

A catabolic chemical reaction in which a water molecule is added to break covalent bonds, separating a polymer into its monomers.

Monosaccharide

The simple sugar monomer of carbohydrates, typically composed of 3 to 7 carbon atoms.

Isomer

Compounds that have the same molecular formula but a different arrangement of their atoms.

Disaccharide

A carbohydrate compound formed via dehydration synthesis joining two monosaccharides together by a polar covalent bond.

Polysaccharide

A complex carbohydrate polymer composed of long, branching chains of monosaccharides joined by covalent bonds.

Fatty acid

A basic lipid monomer consisting of a hydrocarbon chain bonded to a carboxylic acid group ($-\text{COOH}$).

Triglyceride

A neutral fat polymer formed by linking three fatty acids to a glycerol molecule via dehydration synthesis.

Saturated fat

A triglyceride containing fatty acid chains with no double bonds between carbon atoms, allowing the straight chains to pack tightly as a solid at room temperature.

Unsaturated fat

A triglyceride containing one or more double bonds in its fatty acid chains, causing kinks that prevent tight packing and forming a liquid at room temperature.

Phospholipid

An amphiphilic lipid containing a glycerol attached to two nonpolar fatty acid tails and a polar phosphate group.

Amphiphilic

Describing a molecule that contains both polar (hydrophilic) and nonpolar (hydrophobic) regions.

Steroid

A nonpolar lipid class sharing a four-ring hydrocarbon structure called the steroid nucleus.

Amino acid

The monomer of proteins, featuring a central carbon atom bonded to an amino group ($-\text{NH}_2$), a carboxylic acid group ($-\text{COOH}$), a hydrogen atom, and a variable R group.

Peptide bond

A covalent bond formed between amino acids to create a polypeptide chain.

Primary structure

The linear amino acid sequence bound by peptide bonds in a polypeptide chain.

Secondary structure

The folding or bending pattern of a polypeptide chain (such as an ̑\alpha-helix or ̑\beta-pleated sheet) caused by hydrogen bonds between amino acids.

Tertiary structure

The final three-dimensional shape that a polypeptide chain assumes after folding, stabilized by R group interactions.

Quaternary structure

The structural level of a protein formed by the assembly of two or more individual polypeptide chains.

Nucleotide

The monomer of nucleic acids, consisting of a nitrogenous base, a pentose sugar, and a phosphate group.

Purines

Nitrogenous bases containing a double hydrocarbon ring structure, specifically adenine (A) and guanine (G).

Pyrimidines

Nitrogenous bases containing a single hydrocarbon ring structure, specifically cytosine (C), uracil (U), and thymine (T).

Complementary base pairing

The specific hydrogen bonding pattern between opposite nitrogenous bases in DNA, where adenine bonds to thymine ($\text{A}-\text{T}$) and cytosine bonds to guanine ($\text{C}-\text{G}$).

Adenosine Triphosphate (ATP)

A nucleotide that serves as the body's primary source of chemical energy to drive cellular processes.

Plasma membrane

The cell's outer boundary that controls what enters and leaves the cell and participates in cell signaling, recognition, and attachment.

Cytoplasm

The area inside the cell between the plasma membrane and nucleus, containing the cytosol, organelles, and cytoskeleton.

Nucleus

The cellular organelle that contains most of the cell's DNA and serves as its genetic control center.

Cytosol

The fluid portion of the cytoplasm consisting primarily of water with dissolved ions, proteins, and nutrients.

Organelles

Specialized structures within a cell that perform specific functions necessary for the cell's survival and activity.

Fluid mosaic model

A model describing the plasma membrane as a flexible, dynamic phospholipid bilayer containing laterally moving proteins, cholesterol, and carbohydrates.