Biomolecules Lecture 1 PDF

# BIO101 - General Biology ## Biomolecules and the Central Dogma of Life **S. Taiwo Fakorede, Ph.D.** Department of Cell Biology and Genetics [email protected] UNIVERSITY OF FIRST CHOICE AND THE NATION'S PRIDE ## Learning Objectives At the end of this study session, you should be able to:...

# BIO101 - General Biology ## Biomolecules and the Central Dogma of Life **S. Taiwo Fakorede, Ph.D.** Department of Cell Biology and Genetics [email protected] UNIVERSITY OF FIRST CHOICE AND THE NATION'S PRIDE ## Learning Objectives At the end of this study session, you should be able to: - list the four major classes of biomolecules/macromolecules - identify the chemical elements that constitute carbohydrates, fats, and proteins - understand that large biological molecules are synthesized from smaller units - describe how glycosidic, phosphodiester, ester and peptide bonds form - compare and contrast DNA and RNA - understand the genetic code - discuss the flow of genetic information (from DNA to RNA to protein) ## Biomolecules - Biomolecules are molecules that occur naturally in living organisms. - They also include small molecules like primary and secondary metabolites and natural products, that take part in maintenance and metabolic processes. - These are usually obtained from food. ## Organic Compounds - Macromolecules - Carbohydrates - Monosaccharides - Disaccharides - Polysaccharides - Monomer - Lipids - Triglycerides - Fatty acids - Monomer - Proteins - Polypeptides - Amino acids - Monomer - Nucleic Acids - DNA - RNA - Monomer ## Biomolecules - All Biomolecules contain CARBON (C). - Carbon is the most versatile and prominent element of life. - Other elements include: - HYDROGEN (H) - OXYGEN (O) - NITROGEN (N) - SULPHUR (S) - SODIUM (Na) - CALCIUM (Ca) - MAGNESIUM (Mg) ## Levels of Organization Atoms → Molecules → Macromolecules... - City - Cell - Building - Organelle - Brick - Macromolecules Macromolecules are large molecules composed of thousands of covalently connected atoms. ## Functions of Biomolecules - Carbohydrates are the body's main source of energy. - Lipids provide stored energy reserves. This allows us to survive when carbohydrates are not being supplied to the body. - Protein helps us stay strong, by forming new bones and muscles, and helping us fight diseases. - Nucleic acids are responsible for making each person functional and unique; they are the blueprint for our genetic structure. ## Making/Breaking of Macromolecules - Macromolecules are polymers, built from monomers. - A polymer is a long molecule consisting of many similar building blocks known as monomers. - Three of the four classes of life's organic molecules are polymers. These include: - Carbohydrates - Proteins, and - Nucleic acids - A dehydration reaction occurs when two monomers bond together through the loss of a water molecule (also called Condensation). - Conversely, polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the reverse of the dehydration reaction. ## Making of Macromolecules/Polymers **Dehydration:** - Two glucose molecules (monomers)... - ...can bond together to make maltose (dimer). ## Breaking of Macromolecules **Hydrolysis:** - A dimer such as maltose, or any other polymer... - ...can be broken apart into its constituent monomers. ## Polymers - Macromolecules are made of polymers which are made of smaller, repeating parts called monomers. - **Carbohydrates (polymer)** - Monosaccharides are the monomers for carbohydrates, joined by glycosidic bond. - **Proteins (polymer)** - Amino acids are the monomers for proteins (polypeptides), joined by peptide bond. - **Nucleic Acids (polymer)** - Nucleotides are the monomers for nucleic acids, joined by phosphodiester bond. - **Lipids are not considered polymers.** - They have no monomers. ## Carbohydrates - Carbohydrates (polysaccharides) are long chains of sugars. - General formula = (CH₂O)n - Monosaccharides are simple sugars that are composed of 3-7 carbon atoms. They have a free aldehyde (aldoses) or ketone (ketoses) group, which acts as reducing agents and are thus referred to as reducing sugars. ## Carbohydrates - **Building Blocks** - Composed of carbon (C), hydrogen (H), and oxygen (O) in a 1:2:1 ratio - **Components:** - Monosaccharides are the monomer - Examples - Glucose - Galactose - Fructose - **Functions:** - Main source of energy for living things (Monosaccharides) - Energy Storage (polysaccharides) - glycogen in animals - starch in plants - Structural - to build cell walls - cellulose (plants) - chitin (fungi) - **Formula:** - C6H12O6 - **Examples:** - Starch - Cellulose - Glycogen ## Carbohydrates - Oligosaccharide are formed by condensation of 2-9 monosaccharide units. These units are joined with the help of specialized glycosidic linkages. - **Examples of Oligosaccharides** - Disaccharides e.g. lactose, maltose, sucrose - Trisaccharides e.g. raffinose - Tetrasaccharides e.g. stachyose, sesame ## Lipids - Lipids are hydrophobic (water fearing) and do not dissolve in water. - **Lipids can be:** - **Saturated:** The bonds between all the carbons are single bonds. - Solid at room temperature - Mainly animal fats - Clogs arteries (bad) - E.g. stearic acid, palmitic acid, lauric acid, butyric acid - **Unsaturated:** There is at least one double or triple bond between carbons present. - Liquid at room temperature - Mainly plant-based fats - Lowers blood pressure (good) - E.g. linolenic acid, linoleic acid, oleic acid, arachidonic acid ## Lipids - **Building Blocks:** - Mostly made from carbon and hydrogen atoms, some oxygen. - **Components:** - A fat molecule consists of 3 fatty acids joined to a molecule of glycerol. - Phospholipids in cell membranes are made of a phosphate and 2 fatty acid chains. - **Functions and Examples:** - **Long-term Energy storage molecules (fats)** - **Cell Membranes of organisms (phospholipids)** - **Steroid Hormone as chemical signals (testosterone/estrogen)** ## Lipids - **Phospholipids - major lipid-related molecule** - Major component of cell membrane - One fatty acid is replaced by a polar phosphate group which creates: - a hydrophilic "head" region - a hydrophobic "tail" region ## Proteins - Proteins are very large molecules made of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. - Protein molecules are made of smaller molecules called amino acids. ## Proteins - Peptide bonds form between amino acids (polypeptide = many peptide bonds = protein) - All proteins have a central Carbon atom with: 1. carboxylic acid group 2. amino group 3. hydrogen 4. R Group ## Amino Acid Structure - **Structure:** - H - H-N-C-C-OH - Amino Group - R - Side Chain - Carboxylic Acid Group - AAs differ in their properties due to differing side chains, called R groups.