Chapter 03: The Chemical Building Blocks of Life

A complete set of review flashcards covering Chapter 3: The Chemical Building Blocks of Life, including carbon structures, carbohydrates, nucleic acids, proteins, and lipids.

What were the key results of the cell-free fermentation experiment conducted with yeast extract?

Fermentation occurred and produced $CO_2$ when fermentable substrates like cane sugar and glucose were added, but no $CO_2$ was produced with nonfermentable substrates like lactose and mannose.

What type of stereoisomers are shown in this diagram, characterized by non-superimposable mirror images around a chiral carbon?

Enantiomers

According to the functional groups chart, which group has the structural formula $-S-H$ and is found in proteins?

Sulfhydryl

How many covalent bonds can a single carbon atom form with other atoms?

Up to $4$ covalent bonds.

What is the structural distinction between structural isomers and stereoisomers?

Structural isomers differ in the actual structure of their carbon skeleton, whereas stereoisomers have the same carbon skeleton but differ in how attached groups are spatially arranged.

What is the difference between dehydration synthesis and hydrolysis?

Dehydration synthesis joins monomers into polymers by removing a water molecule, while hydrolysis breaks down polymers into monomers by adding a water molecule.

What is the general empirical formula for carbohydrates?

$$(CH_2O)_n$$

How are fructose and galactose chemically related to glucose?

Fructose is a structural isomer of glucose, whereas galactose is a stereoisomer of glucose.

Which polysaccharides serve as primary energy storage molecules in plants and animals?

Plants use starch for energy storage, while animals use glycogen.

Which structural polysaccharides are found in plant cell walls and arthropod exoskeletons/fungi?

Plants use cellulose in their cell walls, while arthropods and fungi use chitin.

What are the three chemical components that make up a nucleotide monomer?

A $5\text{-carbon}$ sugar, a phosphate group, and a nitrogenous base.

Which nitrogenous bases belong to the purine class and which belong to the pyrimidine class?

Purines include adenine and guanine, while pyrimidines include cytosine, thymine, and uracil.

What are the structural differences between DNA and RNA regarding their sugar components and pyrimidine bases?

DNA contains deoxyribose sugar and thymine, whereas RNA contains ribose sugar and uracil.

What type of bond connects individual nucleotides into a nucleic acid polymer chain?

Phosphodiester bonds

What are the seven major biological functions performed by proteins?

Enzyme catalysis, defense, transport, support, motion, regulation, and storage.

What four functional groups or atoms are attached to the central carbon atom of an amino acid?

An amino group ($-NH_2$), a carboxyl group ($-COOH$), a single hydrogen atom ($-H$), and a variable R group.

In the levels of protein structure, which level is characterized by regular patterns such as the \text{\beta-pleated sheet} and \text{\textalpha-helix}?

Secondary structure

What is the difference between a protein motif and a protein domain?

A motif is a common arrangement or combination of secondary structures, whereas a domain is a distinct functional unit within a protein structure.

What role do chaperone proteins play, and what hereditary disorder is linked to improper protein folding?

Chaperone proteins assist in the correct folding of proteins; deficiencies in proper folding are implicated in cystic fibrosis.

What process causes a protein to lose its three-dimensional structure and function, and what environmental factors trigger it?

Denaturation, which is triggered by changes in pH, temperature, or ionic concentration.

What was the main conclusion of the ribonuclease folding experiment?

The amino acid sequence (primary structure) contains all necessary information for a protein to fold into its thermodynamically stable native structure.

How do saturated fats differ from unsaturated fats in terms of chemical bonds and physical state?

Saturated fats contain no double bonds between carbon atoms and have higher melting points (animal origin), whereas unsaturated fats contain one or more double bonds and have lower melting points (plant origin).

Which component of a phospholipid molecule forms the polar hydrophilic head, and which forms the nonpolar hydrophobic tails?

The polar head consists of glycerol, phosphate, and choline, while the nonpolar tails consist of two fatty acid chains.

How are phospholipids arranged in a micelle when placed in water?

Their hydrophilic heads point outward toward the water, while their hydrophobic tails point inward away from the water.