AP Biology Unit 1: Chemistry of Life

Flashcard study set for AP Biology Unit 1: Chemistry of Life, covering water properties, elements of life, macromolecules, carbohydrates, lipids, nucleic acids, and protein structures.

What causes water molecules to exhibit polarity?

Water has polarity because of the formation of polar covalent bonds between hydrogen and oxygen within water molecules.

How does water's high specific heat capacity support living organisms?

Water's high specific heat capacity allows for the maintenance of homeostatic body temperature within living organisms.

What biological function is enabled by water's high heat of vaporization?

It allows for evaporative cooling of the surrounding environment, enabling living organisms to maintain their body temperature.

Which water properties result directly from hydrogen bonding between adjacent polar water molecules?

Cohesion, adhesion, and surface tension.

Which three elements are most prevalent in building biological molecules such as carbohydrates, proteins, lipids, and nucleic acids?

Carbon, hydrogen, and oxygen.

In which major biological macromolecule is sulfur specifically used?

Sulfur is used in the building of proteins.

Which element is required to build both phospholipids and nucleic acids?

Phosphorus.

Which element is used alongside carbon, hydrogen, oxygen, and phosphorus in the building of nucleic acids?

Nitrogen.

How does a hydrolysis reaction break down polymers into monomers?

Water is added to the covalent bond between monomers. A hydrogen ion from the water molecule is added to one monomer, and a hydroxyl group is added to the other monomer, cleaving the bond.

What happens during a dehydration synthesis reaction?

Two smaller molecules are joined together by covalent bonding. A hydrogen ion is removed from one monomer and a hydroxyl group is removed from the other, causing the loss of a water molecule equivalent.

What is polymerization?

The connection of many monomers together through chemical bonding (such as dehydration synthesis).

What are the monomers and polymers of carbohydrates?

Monosaccharides (simple sugars) are the monomers that connect via covalent bonds to form polysaccharides (complex carbohydrates).

What are three illustrative examples of carbohydrate polymers?

Cellulose, starch, and glycogen.

What is the structural difference between saturated and unsaturated fatty acids?

Saturated fatty acids contain only single bonds between carbon atoms. Unsaturated fatty acids contain at least one double bond between carbon atoms, which causes the carbon chain to kink.

How does the degree of double bonds in a lipid affect its state at room temperature?

The more double bonds in a fatty acid tail, the more unsaturated the lipid becomes, making it more liquid at room temperature.

What biological functions do fats serve in organisms?

Fats provide energy storage, support cell function, and can provide insulation to help keep mammals warm.

What biological role do steroid hormones play?

Steroids are hormones that support physiological functions including growth and development, energy metabolism, and homeostasis.

What structural role does cholesterol serve in animal cell membranes?

Cholesterol provides essential structural stability to animal cell membranes.

What structure do phospholipids form in biological membranes?

Phospholipids group together to form the lipid bilayers found in plasma and cell membranes.

What are the three structural components of a nucleotide?

A five-carbon sugar (deoxyribose or ribose), a phosphate, and a nitrogenous base (adenine, thymine, guanine, cytosine, or uracil).

During nucleic acid synthesis, to which end of the growing strand are new nucleotides added?

Nucleotides are added to the $3'$ (three prime) hydroxyl end of the growing strand.

What is the structural orientation and base-pairing rules of DNA?

DNA is an antiparallel double helix with strands in opposite $5'$ to $3'$ orientation. Adenine pairs with thymine ($\text{A-T}$) and cytosine pairs with guanine ($\text{C-G}$) via hydrogen bonds.

What three structural differences distinguish DNA from RNA?

1. DNA contains deoxyribose, RNA contains ribose. 2. DNA contains thymine (where RNA contains uracil, pairing $\text{A-U}$). 3. DNA is typically double-stranded, while RNA is typically single-stranded.

Which functional groups react to form a peptide bond in a protein?

A covalent (peptide) bond forms between the carboxyl group ($-\text{COOH}$) of one amino acid and the amine group ($-\text{NH}_2$) of the next amino acid.

What structural components surround the central carbon atom of an amino acid?

A hydrogen atom, a carboxyl group, an amine group, and a variable R group.

What three chemical properties categorize the variable R group of an amino acid?

Hydrophobic/nonpolar, hydrophilic/polar, or ionic.

What determines the primary structure of a protein?

The specific sequence of amino acids in the polypeptide chain.

What interactions form the secondary structure of a protein, and what shapes result?

Hydrogen bonding between atoms of the polypeptide backbone forms secondary structures such as alpha-helices and beta-pleated sheets.

What interactions stabilize the three-dimensional tertiary structure of a protein?

Hydrogen bonds, hydrophobic interactions, ionic interactions, or disulfide bridges.

How is the quaternary structure of a protein defined?

Quaternary structure arises from interactions between multiple polypeptide chains.