Ch.5 study guide

Hydrolysis and Condensation Reactions

Definitions and Connections

Hydrolysis and condensation are two fundamental chemical reactions involved in the synthesis and breakdown of biological macromolecules.

• Condensation (Dehydration Synthesis): A reaction where two molecules are joined together by removing a molecule of water. This process forms covalent bonds between monomers to build polymers.

• Hydrolysis: A reaction where a water molecule is used to break a covalent bond in a polymer, resulting in the formation of two smaller molecules (monomers).

• Connection: Condensation builds polymers from monomers, while hydrolysis breaks polymers back into monomers. These reactions are reversible and essential for metabolism.

• Example: The formation of a peptide bond between amino acids (condensation) and its breakdown during digestion (hydrolysis).

Carbohydrates

Structure, Function, and Key Terms

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen, typically with the formula (CH2O)n. They serve as energy sources and structural components in cells.

• Monomers: Monosaccharides (simple sugars, e.g., glucose, fructose, galactose)

• Polymer Bond Name: Glycosidic linkage

• Polymers: Polysaccharides (e.g., starch, glycogen, cellulose)

• Functions:

  • Energy storage (e.g., starch in plants, glycogen in animals)

  • Structural support (e.g., cellulose in plant cell walls, chitin in arthropod exoskeletons)

  • Cell recognition and signaling (e.g., glycoproteins)

• Examples: Glucose, sucrose, lactose, starch, cellulose, glycogen

Classification Table: Types of Carbohydrates

Type	Monomer Unit	Bond	Example
Monosaccharide	Single sugar	—	Glucose
Disaccharide	Two sugars	Glycosidic linkage	Sucrose
Polysaccharide	Many sugars	Glycosidic linkage	Starch, Cellulose

Lipids

Structure, Function, and Key Terms

Lipids are a diverse group of hydrophobic molecules, including fats, oils, phospholipids, and steroids. They are not true polymers but are grouped by their insolubility in water.

• Major Classes: Triglycerides (fats and oils), phospholipids, sterols (e.g., cholesterol), terpenes

• Bond Name: Ester linkage (between fatty acids and glycerol in triglycerides)

• Functions:

  • Energy storage (triglycerides)

  • Membrane structure (phospholipids)

  • Signaling molecules (steroids, some terpenes)

  • Insulation and protection

  • head of a phosphate is hydrophilic and polar

  • tail of phospholipids is hydrophobic and nonpolar

  • phospholipids are 75% membrane lipids

  • Terpenes- built from long chained lipids built from 5 carbon isoprene

    • Essential oils taken from terpenes and terpenoids can have Anit-microbial, anticancer, anti-inflammatory, effects

    Cholesterol

    • a type of steroid

    • precursor from which other steroids are synthesized

    • cholesterol can impact membrane fluidity

    • cholesterol has both polar and non-polar regions

• Examples: Triglycerides, phospholipids, cholesterol, carotenoids

Table: Major Lipid Types

Type	Structure	Function	Example
Triglyceride	Glycerol + 3 fatty acids	Energy storage	Fat, oil
Phospholipid	Glycerol + 2 fatty acids + phosphate	Membrane structure	Phosphatidylcholine
Steroid	Four fused rings	Hormone, membrane	Cholesterol

Polypeptides (Proteins)

Structure, Function, and Key Terms

Proteins are polymers made of amino acid monomers linked by peptide bonds. They perform a vast array of functions in living organisms.

• Monomers: Amino acids

• Polymer Bond Name: Peptide bond

• Functions:

  • Enzymatic catalysis- chemical reactions in the cell

  • Structural support- anchors that attach to other proteins

  • Transport- move ions and molecules

  • Movement

  • Signaling (Receptors)

  • Defense (immune response)

• Examples: Hemoglobin, collagen, actin, myosin, enzymes (e.g., amylase)

• Integral and peripheral proteins

Amino Acid Properties: Hydrophobic vs. Hydrophilic

Classification of Amino Acids

Amino acids can be classified based on the properties of their side chains (R groups):

• Hydrophobic (Nonpolar): Side chains are mostly hydrocarbons; do not interact well with water.

• Hydrophilic (Polar): Side chains contain polar groups (e.g., -OH, -NH2); interact with water.

• Hydrophilic (Charged): Side chains are ionized at physiological pH; can be positively (basic) or negatively (acidic) charged.

• How to Tell: Examine the R group: nonpolar = hydrophobic; polar or charged = hydrophilic.

• consists of a central or alpha carbon group attached to a carbon, amino, carboxyl, or side R variable

Levels of Protein Structure

Four Levels of Organization

Proteins have four levels of structure, each contributing to their final shape and function:

• Primary Structure: The linear sequence of amino acids in a polypeptide chain.

• Secondary Structure: Local folding patterns stabilized by hydrogen bonds (e.g., alpha helix, beta-pleated sheet).

• Tertiary Structure: The overall 3D shape of a single polypeptide, determined by interactions among R groups.

• Quaternary Structure: The association of two or more polypeptide chains into a functional protein complex (e.g., hemoglobin).

• bonded together by peptide bonds

• have optical isomers

• peptide bond joins carboxyl to amino group through condensation

Nucleic Acids

Structure, Function, and Key Terms

Nucleic acids are polymers that store and transmit genetic information. The two main types are DNA and RNA.

• Monomers: Nucleotides (composed of a sugar, phosphate group, and nitrogenous base)

• Polymer Bond Name: Phosphodiester bond

• Functions:

  • DNA: Stores genetic information

  • RNA: Involved in protein synthesis and gene regulation

• Examples: DNA, RNA, ATP, cAMP, NAD+

Table: Nucleic Acid Components

Component	DNA	RNA
Sugar	Deoxyribose	Ribose
Bases	A, T, C, G	A, U, C, G
Strands	Double	Single

5' and 3' Ends; Antiparallel Structure in DNA

Directionality and Double Helix

• 5' End: The end of a nucleic acid strand with a free phosphate group attached to the 5' carbon of the sugar.

• 3' End: The end with a free hydroxyl group on the 3' carbon of the sugar.

• Antiparallel: In DNA, the two strands run in opposite directions (one 5' to 3', the other 3' to 5'), allowing complementary base pairing and double helix formation.

ATP, cAMP, and NAD+: Roles in the Cell

Key Nucleotide Derivatives

• ATP (Adenosine Triphosphate): The primary energy carrier in cells; hydrolysis of ATP releases energy for cellular processes. $\text{ATP} \rightarrow \text{ADP} + \text{P}_i + \text{energy}$

• cAMP (Cyclic Adenosine Monophosphate): A second messenger involved in signal transduction pathways.

• NAD+ (Nicotinamide Adenine Dinucleotide): An electron carrier involved in redox reactions during cellular respiration.