Study Guide: Carbohydrates, Lipids, Amino Acids, Proteins, and Nucleic Acids

Chapter 13: Carbohydrates

Monosaccharides and Classification

Carbohydrates are essential biomolecules that serve as energy sources and structural components in living organisms. Understanding their classification and properties is fundamental in GOB Chemistry.

• Monosaccharides: The simplest carbohydrates, such as glucose, galactose, and fructose. They are classified by the number of carbon atoms and the type of carbonyl group (aldose or ketose).

• Disaccharides and Polysaccharides: Formed by linking monosaccharides via glycosidic bonds. Examples include sucrose (disaccharide) and starch (polysaccharide).

• D- and L- Isomers: Carbohydrates can exist as stereoisomers. D-isomers are most common in nature.

• Haworth Projections: A way to represent the cyclic structure of monosaccharides.

Example: Glucose is a D-aldose monosaccharide, while fructose is a D-ketose.

Additional info: You should be able to distinguish between D- and L- forms and recognize the difference between an aldose (aldehyde group) and a ketose (ketone group).

Chapter 14: Carboxylic Acids, Esters, Amines, and Amides

Functional Groups and Reactions

This chapter focuses on the identification and properties of carboxylic acids and their derivatives, as well as amines and amides.

• Carboxylic Acids: Organic acids containing the carboxyl group (-COOH). They are weak acids and participate in hydrogen bonding.

• Esters: Derived from carboxylic acids and alcohols. Commonly found in fats and oils.

• Amines: Organic compounds derived from ammonia (NH3), classified as primary, secondary, or tertiary based on the number of organic groups attached to the nitrogen.

• Amides: Formed from the reaction of carboxylic acids and amines.

• Reactions: Know the basic reactions for formation and hydrolysis of esters, amides, and the classification of amines.

Example: The hydrolysis of an ester produces a carboxylic acid and an alcohol.

Chapter 15: Lipids

Classification and Properties

Lipids are a diverse group of hydrophobic biomolecules, including fats, oils, phospholipids, and steroids. They are important for energy storage, membrane structure, and signaling.

• Saturated vs. Unsaturated Fatty Acids: Saturated fatty acids have no double bonds; unsaturated fatty acids have one or more double bonds.

• Triglycerides: Formed from glycerol and three fatty acids. Main form of energy storage in animals.

• Phospholipids: Major component of cell membranes, containing a phosphate group.

• Steroids: Lipids with a characteristic four-ring structure (e.g., cholesterol).

Type	Structure	Function
Triglyceride	Glycerol + 3 fatty acids	Energy storage
Phospholipid	Glycerol + 2 fatty acids + phosphate	Membrane structure
Steroid	Four fused rings	Hormones, membrane component

Additional info: Be able to identify the differences between these lipid types based on their structure and function.

Chapter 16: Amino Acids and Proteins

Structure and Function

Amino acids are the building blocks of proteins, which perform a vast array of functions in the body. Understanding their structure and how they form proteins is essential.

• Amino Acids: There are 20 standard amino acids, each with a unique side chain (R group). They can be classified as polar, non-polar, acidic, or basic.

• Protein Structure: Proteins have four levels of structure:

  • Primary: Sequence of amino acids

  • Secondary: Alpha helices and beta sheets (hydrogen bonding)

  • Tertiary: 3D folding due to side chain interactions

  • Quaternary: Multiple polypeptide chains

• Denaturation: Loss of protein structure due to heat, pH changes, or chemicals.

• Enzyme Inhibition: Know the difference between competitive, noncompetitive, and irreversible inhibitors.

Inhibitor Type	Binding Site	Effect
Competitive	Active site	Blocks substrate
Noncompetitive	Allosteric site	Changes enzyme shape
Irreversible	Covalent modification	Permanently inactivates enzyme

Example: Hemoglobin is a protein with quaternary structure, composed of multiple polypeptide chains.

Chapter 17: Nucleic Acids

Structure and Function of DNA and RNA

Nucleic acids store and transmit genetic information. DNA and RNA are polymers of nucleotides, each consisting of a sugar, phosphate, and nitrogenous base.

• Nucleotides: Composed of a nitrogenous base (purine or pyrimidine), a five-carbon sugar (ribose or deoxyribose), and a phosphate group.

• Purines: Adenine (A) and Guanine (G); Pyrimidines: Cytosine (C), Thymine (T), and Uracil (U).

• DNA vs. RNA: DNA contains deoxyribose and thymine; RNA contains ribose and uracil.

• Base Pairing: In DNA, A pairs with T, and G pairs with C via hydrogen bonds.

• Central Dogma: DNA is transcribed to RNA, which is translated into protein.

• Replication: DNA copies itself before cell division.

Process	Description
Replication	DNA makes a copy of itself
Transcription	DNA is used to synthesize RNA
Translation	RNA is used to synthesize protein

Example: During DNA replication, the enzyme DNA polymerase synthesizes a new strand complementary to the template strand.