Lecture Flashcards: The Chemical Basis of Life (Biomolecules, Bonds, Water, and Origin of Life)

A comprehensive set of practice flashcards covering atoms, bonds, water properties, biomolecules, and origins of life based on the provided lecture notes.

What are the three forms of matter that occur in living organisms?

Solid, liquid, and gas.

What is the smallest functional unit of matter that forms all chemical substances and organisms?

Atom.

What does the nucleus of an atom contain?

Protons and neutrons.

What is the charge of an electron?

Negative.

What is the simplest atom in the world?

Hydrogen.

What is a chemical element?

A specific type of atom (e.g., hydrogen, nitrogen, oxygen).

Where are electrons located in an atom and what is their charge?

Outside the nucleus; negatively charged.

What makes up the nucleus of an atom?

Protons and neutrons.

What does the atomic number represent?

The number of protons in an atom.

What is atomic mass?

The mass of the atom's nucleus (protons + neutrons).

What is an orbital?

The region around the nucleus where an electron is most likely found; can hold up to 2 electrons.

What is an electron shell?

An energy level; outer electrons have higher energy.

For hydrogen, how many electron shells does it have?

One electron shell.

What do the periods (rows) of the periodic table indicate?

The number of electron shells (energy levels).

What does the periodic table cell indicate about an element?

The element's atomic number (number of protons).

What are the four major biomolecule classes?

Carbohydrates, proteins, lipids, nucleic acids.

What is a molecule?

Two or more atoms bonded together.

What is a compound?

A molecule composed of two or more different elements.

What is a covalent bond?

Electrons are shared between two nonmetals.

What is an ionic bond?

Electrons are transferred from a metal to a nonmetal, creating ions that attract.

What is an ion?

An atom or molecule with a net electric charge due to gain or loss of electrons.

What is electronegativity?

The ability of an atom to attract electrons in a bond.

What is a polar covalent bond?

A covalent bond in which electrons are shared unequally due to electronegativity differences.

Why is water a polar molecule?

Oxygen is more electronegative than hydrogen, pulling electrons toward oxygen.

What is the result of unequal sharing of electrons in a bond?

A polar molecule with partial positive and partial negative charges.

What determines polarity in molecules?

Electronegativity difference, leading to uneven electron density and partial charges.

How do polar and nonpolar molecules differ in solubility?

Polar molecules dissolve in polar solvents (like water); nonpolar molecules dissolve in nonpolar solvents.

Why do polar molecules generally have higher boiling and melting points than nonpolar molecules of similar size?

Due to stronger intermolecular forces (dipole interactions, hydrogen bonding) in polar molecules.

What causes hydrogen bonds in water?

Oxygen's higher electronegativity causes partial negative on O and partial positive on H, enabling H-bonding.

What is an ionic bond’s basic nature?

Electrostatic attraction between positively and negatively charged ions formed by electron transfer.

What happens in a chemical reaction in terms of bonds?

Bonds are broken and new bonds are formed, rearranging atoms.

What are solutes, solvents, and aqueous solutions?

Solute is dissolved; solvent is the dissolving medium; solution is the mixture; aqueous solutions have water as the solvent.

What is dehydration synthesis?

A reaction where a water molecule is removed to form a covalent bond between monomers.

What are monosaccharides?

Simple sugars (e.g., glucose); typically 3–6 carbon atoms; end with -ose; often ring-structured in solution.

What is a disaccharide?

Two monosaccharides linked by a dehydration synthesis (e.g., lactose, maltose, sucrose).

What is a polysaccharide?

A long chain of monosaccharides; may be branched or unbranched (e.g., starch, glycogen, cellulose).

What is the general carbohydrate formula and ratio?

(CH2O)n with a 1:2:1 ratio of C:H:O.

What are storage polysaccharides and structural polysaccharides?

Storage: starch (plants) and glycogen (animals); Structural: cellulose, hemicellulose, etc.

What is an amino acid?

The building block of proteins; central carbon with hydrogen, amino group, carboxyl group, and variable R group.

What makes some amino acids essential?

Essential amino acids cannot be synthesized by the body and must be obtained from diet (e.g., histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine).

What is hemoglobin and its function?

A protein that transports oxygen from the lungs to tissues and helps carry carbon dioxide back to the lungs.

What is a nucleotide composed of?

A phosphate group, a nitrogenous base, and a five-carbon sugar.

What are purine and pyrimidine bases?

Purines: adenine and guanine; Pyrimidines: cytosine, thymine (DNA), uracil (RNA).

What is ATP and its role?

Adenosine triphosphate; energy-carrying molecule with three phosphate groups.

What are nucleic acids?

Polymers of nucleotides; DNA and RNA.

What are the four major bases used in DNA and RNA?

DNA: adenine, thymine, cytosine, guanine; RNA: adenine, uracil, cytosine, guanine.

What is a fatty acid?

A long hydrocarbon chain with a terminal carboxyl group.

What is a saturated fatty acid?

No double bonds between carbon atoms; usually solid at room temperature; linear.

What is an unsaturated fatty acid?

One or more double bonds between carbon atoms; usually liquid at room temperature; kink in chain.

What is a phospholipid and its role in membranes?

A lipid with a glycerol backbone, a phosphate-containing head (polar) and two fatty acid tails (nonpolar); amphipathic and a major component of cell membranes.

What is the phospholipid bilayer arrangement in membranes?

Hydrophilic heads face outward toward water; hydrophobic tails face inward.

What roles do phospholipids play in membranes?

Provide membrane structure, fluidity, and selective permeability.

What is the origin-of-life four-stage hypothesis (overview)?

Stage 1: abiotic synthesis of organic monomers; Stage 2: polymerization into RNA/DNA and proteins; Stage 3: polymers enclosed in membranes; Stage 4: enclosed polymers acquire cellular properties.