• Fatty Acids: These are the building blocks of most lipids. They consist of a long hydrocarbon chain with a carboxyl group (-COOH) at one end. Fatty acids can be saturated (no double bonds) or unsaturated (contain one or more double bonds).

• Triglycerides: These are the most common form of dietary fat. They consist of three fatty acid molecules esterified to a glycerol molecule. Triglycerides serve as a major energy storage form in adipose tissue.

• Phospholipids: These are structural components of cell membranes. Phospholipids consist of two fatty acid chains attached to a glycerol backbone, with a phosphate group and a polar head group. They form lipid bilayers, which provide a barrier that separates the interior of the cell from its external environment.

• Steroids: These are characterized by a four-ring structure. Examples include cholesterol, which is a component of cell membranes and a precursor for steroid hormones, and hormones like estrogen and testosterone.

• Waxes: These are esters of long-chain fatty acids and long-chain alcohols. Waxes are hydrophobic and often serve as protective coatings in plants and animals.

  • Fatty Acids: Building blocks of lipids with a hydrocarbon chain and a carboxyl group. They can be saturated or unsaturated.

  • Triglycerides: Common dietary fat form with three fatty acid molecules esterified to a glycerol molecule, serving as energy storage in adipose tissue.

  • Phospholipids: Cell membrane structural components with two fatty acid chains, a glycerol backbone, a phosphate group, and a polar head group forming lipid bilayers.

  • Steroids: Characterized by a four-ring structure, including cholesterol in cell membranes and as a hormone precursor like estrogen and testosterone.

  • Waxes: Esters of long-chain fatty acids and alcohols, hydrophobic and used as protective coatings in plants and animals.

• Energy Storage: Triglycerides serve as a concentrated form of energy storage in adipose tissue, providing energy reserves that can be mobilized when needed.

• Cell Membrane Structure: Phospholipids are essential components of cell membranes. They form the lipid bilayer that provides a selectively permeable barrier around cells, controlling the movement of substances into and out of the cell.

• Insulation and Protection: Lipids, particularly adipose tissue, serve as insulation to help regulate body temperature and protect organs from mechanical damage.

• Signaling Molecules: Some lipids, such as steroid hormones and eicosanoids, serve as signaling molecules that regulate various physiological processes including metabolism, inflammation, and reproductive function.

• Structural Role: Lipids contribute to the structure of various tissues and organs. For example, lipids are important components of myelin sheaths, which insulate and protect nerve fibers.

  • Energy Storage: Triglycerides in adipose tissue store energy for future use.

  • Cell Membrane Structure: Phospholipids form the cell membrane, controlling substance movement.

  • Insulation and Protection: Lipids, like adipose tissue, insulate and protect organs.

  • Signaling Molecules: Some lipids act as signaling molecules regulating physiological processes.

  • Structural Role: Lipids contribute to tissue and organ structure, like myelin sheaths protecting nerve fibers.

• Primary Structure: The linear sequence of amino acids linked together by peptide bonds. The sequence is determined by the genetic code.

• Secondary Structure: Local folding patterns stabilized by hydrogen bonds between amino acids. Common secondary structures include alpha helices and beta sheets.

• Tertiary Structure: The overall three-dimensional folding of a single polypeptide chain, resulting from interactions between amino acid side chains (R groups). These interactions include hydrogen bonds, disulfide bonds, hydrophobic interactions, and van der Waals forces.

• Quaternary Structure: The arrangement of multiple polypeptide subunits in a protein complex. Some proteins consist of a single polypeptide chain (monomers), while others are composed of multiple subunits (oligomers).

• The arrangement of multiple polypeptide subunits in a protein complex varies. Some proteins consist of a single polypeptide chain (monomers), while others are composed of multiple subunits (oligomers).

1. Enzymatic Activity:

   • Proteins called enzymes catalyze biochemical reactions by speeding up chemical reactions.

   • Enzymes are involved in various processes such as metabolism, DNA replication, and protein synthesis.

2. Structural Support:

   • Proteins provide structural support to cells and tissues.

   • Examples include collagen in connective tissues, keratin in hair and nails, and actin and myosin in muscle fibers.

3. Transport:

   • Proteins facilitate the transport of molecules across cell membranes (e.g., channels and carriers) and throughout the body (e.g., hemoglobin transports oxygen in blood).

4. Defense:

   • Enzymatic Activity:

     Proteins called enzymes catalyze biochemical reactions by accelerating chemical processes.

     Enzymes play a crucial role in various processes such as metabolism, DNA replication, and protein synthesis.

     Structural Support:

     Proteins offer structural support to cells and tissues.

     Examples include collagen in connective tissues, keratin in hair and nails, and actin and myosin in muscle fibers.

     Transport:

     Proteins aid in the transportation of molecules across cell membranes (e.g., channels and carriers) and throughout the body (e.g., hemoglobin transports oxygen in the blood).

     Defense:

     Proteins of the immune system, such as antibodies and cytokines, protect the body against pathogens and foreign substances.

Nucleic acids, including DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), are fundamental macromolecules found in all living organisms. They are composed of nucleotide monomers and play crucial roles in storing, transmitting, and expressing genetic information. Here's an overview of their structure and functions:

Nucleic acids like DNA and RNA are essential macromolecules in all living organisms, made up of nucleotide monomers. They are vital for storing, transmitting, and expressing genetic information.

Structure of Nucleic Acids:

1. Nucleotides:

   • Nucleotides are the building blocks of nucleic acids.

   • Each nucleotide consists of three components:

     • A nitrogenous base (adenine, guanine, cytosine, thymine in DNA, and uracil in RNA).

     • A five-carbon sugar (deoxyribose in DNA, ribose in RNA).

     • A phosphate group.

2. DNA Structure:

   • DNA is typically double-stranded and forms a double helix structure.

   • The two strands are antiparallel, meaning they run in opposite directions.

   • The nitrogenous bases of each strand pair specifically (A with T, G with C), held together by hydrogen bonds.

3. RNA Structure:

   • RNA can be single-stranded or form secondary structures through intra-strand base pairing.

   • RNA contains uracil instead of thymine and ribose sugar instead of deoxyribose, compared to DNA.

     • Nucleotides are the building blocks of nucleic acids, consisting of a nitrogenous base, a five-carbon sugar, and a phosphate group.

     • DNA is double-stranded, forming a double helix with antiparallel strands that pair A with T and G with C.

     • RNA can be single-stranded or form secondary structures, containing uracil and ribose sugar instead of thymine and deoxyribose found in DNA.

Functions of Nucleic Acids:

1. Genetic Information Storage:

   • DNA serves as the primary repository of genetic information in most organisms.

   • It carries instructions for the synthesis of proteins and the regulation of cellular activities.

2. Transmission of Genetic Information:

   • During cell division, DNA is replicated to ensure that each daughter cell receives an identical copy of the genetic material.

   • In organisms that undergo sexual reproduction, DNA is passed from parent to offspring, ensuring genetic continuity between generations.

3. Gene Expression:

   • DNA is transcribed into RNA in a process called transcription.

   • RNA molecules, particularly messenger RNA (mRNA), serve as templates for protein synthesis in a process called translation.

   • RNA molecules also play regulatory roles in gene expression through mechanisms like RNA interference (RNAi) and microRNAs (miRNAs).

4. Regulation of Cellular Processes:

   • Nucleic acids, especially RNA molecules, participate in the regulation of various cellular processes, including transcription, translation, and post-translational modifications of proteins.

5. Energy Transfer and Metabolism:

   • Nucleotide derivatives such as ATP (adenosine triphosphate) and GTP (guanosine triphosphate) serve as energy carriers in cellular metabolism.

   • Coenzymes derived from nucleotides participate in enzyme-catalyzed reactions, facilitating metabolic processes.

6. Structural Support and Catalysis:

   • RNA molecules, such as ribosomal RNA (rRNA) and ribozymes, contribute to the structure and function of ribosomes, the cellular machinery responsible for protein synthesis.

   • Ribozymes, which are catalytic RNA molecules, can catalyze specific biochemical reactions.

     • Genetic Information Storage: DNA holds genetic information and guides protein synthesis and cellular activities.

     • Transmission of Genetic Information: DNA replicates during cell division and is passed from parents to offspring in sexual reproduction.

     • Gene Expression: DNA is transcribed into RNA, which serves as a template for protein synthesis and regulates gene expression.

     • Regulation of Cellular Processes: Nucleic acids, especially RNA, regulate cellular processes like transcription and translation.

     • Energy Transfer and Metabolism: Nucleotide derivatives like ATP and GTP carry energy in cellular metabolism.

     • Structural Support and Catalysis: RNA molecules like rRNA and ribozymes contribute to ribosome structure and function, aiding in protein synthesis and catalyzing biochemical reactions.