Chapter 2 Molecules of Life Practice Questions

Vocabulary flashcards covering atomic structure, chemical bonds, functional groups, biomolecules, and unique properties of water based on Chapter 2 practice questions.

Atomic Mass

The mass of an atom constituted by the combined number of protons plus neutrons.

Atomic Number

The number of protons in an atom, which also equals the number of electrons if the atom is neutral.

Isotopes

Elements with the same atomic number but different atomic mass, such as Carbon isotopes with atomic masses of 12, 13, and 14.

Sodium Ion ($\text{Na}^+$)

A cation derived from Sodium (atomic number 11) containing 11 protons and 10 electrons.

Valence Shell Electrons

Electrons located in the outermost shell that have the highest energy and determine an atom's chemical reactivity.

Polar Covalent Bond

A type of chemical bond formed within a single water molecule due to unequal sharing of electrons, creating partial positive and negative charges.

Hydrogen Bond

A weak chemical bond formed among water molecules that connects one water molecule to another water molecule.

Hydrophilic Molecules

Molecules that possess polarity (partial positive and negative charges) and can interact with water molecules.

Hydrophobic Molecules

Uncharged molecules containing non-polar covalent bonds, such as lipids, that cannot interact with water molecules.

Acidic Solution

A solution with a pH scale value below 7, such as $\text{HCl}$, $\text{H}_2\text{CO}_3$, or vinegar.

Basic Solution

A solution with a pH scale value above 7, such as $\text{NaOH}$.

Hydroxyl Group ($-\text{OH}$)

A polar functional group consisting of an oxygen and a hydrogen atom.

Methyl Group ($-\text{CH}_3$)

A non-polar functional group consisting of one carbon and three hydrogen atoms.

Phosphate Group ($-\text{PO}_4$)

A polar functional group found in nucleic acids and phospholipids.

Carboxyl Group ($-\text{COOH}$)

A polar functional group present in amino acids and fatty acids.

Amino Group ($-\text{NH}_2$)

A polar functional group present in amino acids.

Ionic Bond

A chemical bond formed between oppositely charged ions, such as $\text{Na}^+$ and $\text{Cl}^-$, which maintains the salt crystal structure.

Isomers

Molecules that share the same chemical formula (such as glucose and fructose, $\text{C}_6\text{H}_{12}\text{O}_6$) but have different structures and arrangements of functional groups.

Dehydration Reaction

A reaction that links monomeric subunits together to form polymers via the release of water.

Glycosidic Bond

The covalent bond that links monosaccharide monomers together to form carbohydrates.

Peptide Bond

The covalent bond that links amino acid monomers together to form proteins.

Phosphodiester Bond

The covalent bond linking nucleotides in DNA and RNA, formed between the $3'\,\text{OH}$ of the sugar of one nucleotide and the $5'\,\text{P}$ of the next nucleotide.

Storage Polysaccharides

Carbohydrate polymers used for energy storage, specifically starch in plants and glycogen in animals.

Amino Acid

The monomer subunit of proteins consisting of a carboxyl group ($-\text{COOH}$), an amino group ($-\text{NH}_2$), and a variable $\text{R}$ group that distinguishes the 20 different amino acids.

Nucleotide

The monomeric subunit of nucleic acids (DNA and RNA) composed of a phosphate group, a sugar, and a nitrogenous base.

Triacylglycerol

A lipid molecule consisting of a glycerol backbone connected to 3 fatty acid chains.

Phospholipid

A cell membrane lipid containing both hydrophilic components (phosphate group and glycerol) and hydrophobic components (two fatty acid chains attached to a glycerol backbone).

Saturated Fatty Acids

Fatty acids with longer tails that pack more tightly and have higher melting points compared to shorter-tail unsaturated fatty acids.

Cohesion and Adhesion

Unique properties of water responsible for liquid interactions, such as rain droplets sticking on a leaf surface.

High Surface Tension

A property of water resulting from hydrogen bonding that allows small organisms, such as spiders, to walk on a film of water.

Expansion of Water below $4\,^\circ\text{C}$

The phenomenon causing ice to have low density and float on liquid water.

High Specific Heat Capacity

A property of water that enables bodies of water to regulate the surrounding temperature in coastal regions.