Chemistry of Life Study List Review

Flashcard practice set designed to review atoms, chemical bonding, water properties, pH and buffers, biomolecules, chemical reactions, and enzyme kinetics from the study list.

What is an atom?

An atom is the basic unit of matter and the fundamental building block of elements, consisting of a nucleus surrounded by electrons.

What are the three subatomic particles in an atom and their electric charges?

Protons carry a positive charge ($+1$), neutrons carry no charge (neutral, $0$), and electrons carry a negative charge ($-1$).

What is an element?

An element is a pure substance consisting of only one type of atom that cannot be broken down into simpler substances by chemical means.

How do elements chemically join to form compounds?

Elements join chemically through chemical bonding, where atoms gain, lose, or share valence electrons to achieve stability.

What is an ionic bond?

An ionic bond is a chemical bond formed when one or more electrons are transferred from one atom to another, creating oppositely charged ions that attract each other.

What is a covalent bond?

A covalent bond is a chemical bond formed when two atoms share one or more pairs of electrons.

What is a hydrogen bond?

A hydrogen bond is a weak electrostatic attraction between a slightly positive hydrogen atom of one polar molecule and a slightly negative atom of another molecule.

What causes the polarity of charges in a water molecule?

Water is polar because oxygen has a higher electronegativity than hydrogen, pulling shared electrons closer to oxygen and creating a partial negative charge ($\delta^-$) on oxygen and a partial positive charge ($\delta^+$) on hydrogen.

How do hydrogen bonds form between water molecules?

Hydrogen bonds form when the partial positive charge ($\delta^+$) on a hydrogen atom of one water molecule is attracted to the partial negative charge ($\delta^-$) on the oxygen atom of an adjacent water molecule.

What is cohesion?

Cohesion is the attraction between molecules of the same substance, such as water molecules sticking to other water molecules via hydrogen bonds.

What is adhesion?

Adhesion is the attraction between molecules of different substances, such as water molecules sticking to other non-water materials.

How does adhesion apply to water transport in plants?

Adhesion allows water molecules to stick to the vascular walls of plant xylem vessels, assisting cohesion in pulling water upward against gravity from roots to leaves.

What is water's high specific heat capacity, and why is it important?

High specific heat capacity means water requires a large amount of heat energy to raise its temperature, allowing living organisms and aquatic ecosystems to resist drastic temperature fluctuations.

Why is water referred to as a universal solvent?

Water is called a universal solvent because its polarity allows it to dissolve a wide variety of polar solutes and ionic compounds.

Why is water essential for cellular chemical reactions and life?

Water provides an aqueous environment for cellular transport and molecular collisions, and acts as a direct reactant or product in metabolic chemical reactions.

What does the pH scale measure?

The pH scale measures the relative concentration of hydrogen ions ($H^+$) in a solution to determine its acidity or basicity.

What is the numerical range of the pH scale?

The pH scale ranges from $0$ to $14$.

How are acidic, neutral, and basic substances classified on the pH scale?

Acidic substances have a pH less than $7$ ($\text{pH} < 7$), neutral substances have a pH equal to $7$ ($\text{pH} = 7$), and basic substances have a pH greater than $7$ ($\text{pH} > 7$).

What is an acid?

An acid is a compound that donates hydrogen ions ($H^+$) to a solution, resulting in a pH value below $7$.

What is a base?

A base is a compound that produces hydroxide ions ($OH^-$) or accepts hydrogen ions ($H^+$) in solution, resulting in a pH value above $7$.

What is the function of buffers in living organisms?

Buffers are weak acids or bases that minimize sharp changes in pH when strong acids or bases are added, maintaining homeostatic pH balance.

What is a monomer?

A monomer is a small molecular subunit that can chemically bind to other similar subunits to form a larger polymer.

What is a polymer?

A polymer is a large macromolecule constructed from many repeating monomer units joined together by covalent bonds.

Which elements compose carbohydrates?

Carbohydrates are composed of carbon ($C$), hydrogen ($H$), and oxygen ($O$).

What is the monomer of a carbohydrate?

The monomer of a carbohydrate is a monosaccharide, such as glucose.

What is the polymer of a carbohydrate?

The polymer of a carbohydrate is a polysaccharide, such as starch, glycogen, or cellulose.

How do plant cells and animal cells store excess carbohydrates?

Plant cells store excess carbohydrates as starch, whereas animal cells store excess carbohydrates as glycogen in liver and muscle tissue.

What are cellulose and starch, and what are their distinct roles in plants?

Starch is a carbohydrate storage polymer that plants break down for energy, while cellulose is a structural carbohydrate polymer that builds plant cell walls.

Which elements compose lipids?

Lipids are composed mainly of carbon ($C$), hydrogen ($H$), and oxygen ($O$).

What are the structural components of a triglyceride lipid?

A triglyceride consists of one glycerol backbone bonded to three fatty acid tails.

What are the primary functions of lipids in organisms?

Lipids function in long-term energy storage, body insulation, protective waterproofing, and building cell membranes.

What is the role of phospholipids in cell membrane structure?

Phospholipids assemble into a double layer (phospholipid bilayer) with hydrophobic tails inside and hydrophilic heads outside, providing a flexible, selectively permeable membrane barrier.

Which elements compose proteins?

Proteins are composed of carbon ($C$), hydrogen ($H$), oxygen ($O$), and nitrogen ($N$).

What is the monomer of a protein?

The monomer of a protein is an amino acid.

What type of chemical bond connects amino acids in a protein polymer?

Amino acids in a protein polymer are linked together by peptide bonds.

Why is a protein's 3D shape essential to its function?

A protein's unique shape determines its specific binding site and biological activity; if the shape changes, the protein loses its function.

Which elements compose nucleic acids?

Nucleic acids are composed of carbon ($C$), hydrogen ($H$), oxygen ($O$), nitrogen ($N$), and phosphorus ($P$).

What is the monomer of a nucleic acid?

The monomer of a nucleic acid is a nucleotide.

What are the two primary types of nucleic acids?

The two main nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

What is the primary function of DNA in a cell?

DNA stores and transmits genetic instructions required to build proteins and direct all cellular processes.

Where is DNA located in eukaryotic cells versus prokaryotic cells?

In eukaryotic cells, DNA is located inside a membrane-bound nucleus, whereas in prokaryotic cells, DNA is located in the cytoplasm in a nucleoid region.

In a chemical reaction, what are reactants and products?

Reactants are the starting substances that undergo chemical change, while products are the new substances created at the end of the reaction.

What is activation energy?

Activation energy is the minimum energy required to initiate a chemical reaction.

What is an enzyme, and to which group of biomolecules does it belong?

An enzyme is a biological catalyst that speeds up chemical reactions, and it belongs to the protein biomolecule group.

How do enzymes affect the activation energy of a chemical reaction?

Enzymes lower the activation energy barrier needed for a chemical reaction to start, accelerating reaction rates.

What is a catalyst?

A catalyst is any chemical agent that increases the rate of a reaction without being consumed or permanently altered in the process.

What is a substrate?

A substrate is the specific reactant molecule upon which an enzyme acts.

What is the active site of an enzyme?

The active site is the specific pocket or groove on an enzyme where substrate molecules bind and undergo a chemical reaction.

What is an enzyme-substrate complex?

An enzyme-substrate complex is a temporary intermediate bound state formed when a substrate molecule attaches to the active site of its enzyme.

What is the lock and key model of enzyme action?

The lock and key model states that an enzyme's active site and its substrate have rigid, perfectly complementary shapes that fit together precisely.

What is the induced fit model of enzyme action?

The induced fit model states that substrate binding causes the enzyme's active site to change shape slightly to bind the substrate more tightly around its bonds.

What are the four general steps of enzyme action?

1. Substrate binds to active site. 2. Enzyme-substrate complex forms. 3. Reaction is catalyzed to form products. 4. Products are released and the unchanged enzyme is reused.

How does temperature affect enzyme activity?

Enzyme activity increases with rising temperature up to an optimal level; beyond optimal heat, thermal motion breaks bonds and denatures the enzyme, dropping activity.

What is meant by an enzyme's optimal pH?

An enzyme's optimal pH is the specific pH level at which its catalytic activity and reaction rate are at maximum velocity.

What is denaturation?

Denaturation is a structural unfolding or shape alteration of a protein caused by extreme temperature, extreme pH, or chemical conditions.

What happens to a denatured enzyme's ability to catalyze a reaction?

A denatured enzyme loses the functional shape of its active site, preventing substrate binding and rendering the enzyme non-functional.

What is a competitive inhibitor?

A competitive inhibitor is a molecule that mimics the substrate shape and competes directly for binding at the enzyme's active site, blocking substrate entry.

What is a noncompetitive inhibitor?

A noncompetitive inhibitor binds to an enzyme at a site separate from the active site, changing the overall enzyme shape so the active site cannot process substrate.

How do substrate concentrations affect reaction rate, and why does the rate level off?

Increasing substrate concentration increases reaction rate until all active sites become fully saturated with substrate; once saturated, adding more substrate cannot increase reaction speed.

In John 6:35, to which biomolecule is Jesus compared when He calls Himself the Bread of Life?

Jesus is compared to bread, which represents carbohydrates—the primary biomolecule that provides physical energy to living organisms.