BCH 302 Chemistry and Metabolism of Carbohydrates Lecture 1 PDF

BCH 302 Chemistry and Metabolism of Carbohydrates Lecturers, Department of Biochemistry Dr Palmah Nyadar Dr Jamila Omale Mrs Funmi Audu Mr Yunusa Imam 2023/20...

BCH 302 Chemistry and Metabolism of Carbohydrates Lecturers, Department of Biochemistry Dr Palmah Nyadar Dr Jamila Omale Mrs Funmi Audu Mr Yunusa Imam 2023/2024 Session - 2 Units: LH 30 Focus:  Chemistry and function of some polysaccharides.  Isolation and purification of some polysaccharides.  Calvin pathway.  Disorders of Carbohydrate metabolism. Dr Palmah Nyadar Dept. of Biochemistry University of Abuja  Early Observations and Terminology: In ancient times, people recognized the sweetness of fruits and honey, which are rich in simple sugars such as glucose and fructose. However, the scientific classification of these sweet substances as "carbohydrates" had not yet been established. In the late 1600s, scientists began investigating the chemical composition of various organic substances. Robert Boyle, an Irish chemist, observed that burning plant materials produced water and carbon dioxide, but the specific molecular structures of these substances were not yet understood.  Discovery and Identification: The term "saccharine" was used by chemists to describe sweet-tasting The concept of "carbohydrates" as a class of compounds was introduced by French chemist Joseph Louis Proust in the early 1800s. Proust studied sugars and other plant-derived substances, recognizing that they were primarily composed of carbon, hydrogen, and oxygen. His work established that (𝐶𝐻2𝑂)𝑛, many plant-based substances shared a common empirical formula, roughly leading to the term "carbohydrate," meaning "hydrates of carbon.“ Notably in the 1820s: French chemist Jean-Baptiste Dumas and German chemist Justus von Liebig further formalized the concept of carbohydrates. They studied various sugars and starches, identifying the consistent presence of carbon, hydrogen, and oxygen in specific ratios, which reinforced the Carbohydrates are one of the four major classes of biomolecules, alongside proteins, lipids, and nucleic acids. They are essential for life, serving as the primary source of energy for living organisms and playing vital roles in various biological processes. Structurally, carbohydrates are organic molecules composed of carbon (C), hydrogen (H), and oxygen (𝐶𝐻2𝑂)𝑛. (O), typically in a ratio of 1:2:1, with the general formula  Types of Carbohydrates Carbohydrates can be classified into three main categories based on their structure and complexity, namely:  Monosaccharides: These are the simplest form of carbohydrates, consisting of a single sugar molecule. Monosaccharides are the building blocks for more complex carbohydrates.  Glucose: A primary energy source for cells, often referred to as "blood sugar.“  Fructose: Found in fruits and honey, known for its sweet taste.  Galactose: Typically found in dairy products, often linked with glucose to form lactose.  Types of Carbohydrates  Disaccharides: These carbohydrates are formed by the linkage of two monosaccharide molecules through a glycosidic bond.  Sucrose: Common table sugar, composed of glucose and fructose.  Lactose: The sugar found in milk, composed of glucose and galactose.  Maltose: Found in germinating seeds, composed of two glucose molecules.  Types of Carbohydrates  Polysaccharides: These are complex carbohydrates formed by the linkage of multiple monosaccharide units. They can be branched or unbranched and serve various functions in organisms.  Starch: A storage polysaccharide in plants, composed of glucose units. It is found in foods like potatoes, rice, and wheat.  Glycogen: The storage form of glucose in animals, stored primarily in the liver and muscles.  Cellulose: A structural polysaccharide that makes up the cell walls of plants, providing rigidity and strength. It is a major component of dietary fiber in human diets.  Chitin: Found in the exoskeletons of arthropods and the cell walls of fungi.  Structures of some Carbohydrates 1. Starch is a polysaccharide made up of glucose units linked primarily by α(1→4) glycosidic bonds, with occasional α(1→6) bonds at branching points. Starch exists in two forms: a. Amylose: A mostly linear, unbranched polymer of glucose, which forms a helical structure. b. Amylopectin: A branched polymer of glucose, with branches occurring every 24-30 glucose units.  Structures of some Carbohydrates 2. Glycogen is a highly branched polysaccharide composed of glucose units linked by α(1→4) glycosidic bonds, with branches formed by α(1→6) glycosidic bonds occurring every 8-12 glucose units. Glycogen has a more open, branched structure due to the α-configuration and branching points, allowing enzymes to easily access the glucose units for energy release or storage.  Structures of some Carbohydrates 3. Cellulose is a linear polymer of glucose molecules linked by β(1→4) glycosidic bonds. This configuration allows the formation of long, straight chains that pack together to form strong fibers. Cellulose has a rigid, linear structure due to the β-configuration and lack of branching, which allows the chains to pack together tightly and provide structural support in plant cell walls.  Structures of some Carbohydrates 4. Chitin is a polysaccharide composed of N- acetylglucosamine (a derivative of glucose) units linked by β(1→4) glycosidic bonds. Its structure is similar to cellulose, but with an acetylated amino group replacing a hydroxyl group. N-acetylglucosamine is a vital molecule in various biological processes and structures, contributing to the integrity and function of cells and tissues.  Functions of Carbohydrates Carbohydrates perform several critical functions in living organisms such as: i. Energy Source: Carbohydrates are the body's primary energy source. During digestion, they are broken down into glucose, which is then used by cells to produce ATP (adenosine triphosphate) through cellular respiration. ATP is the energy currency of the cell, powering various biological processes. ii. Energy Storage: Carbohydrates are stored as glycogen in animals and starch in plants. These storage forms can be broken down into glucose when the body needs energy between meals or during physical activity. iii. Structural Role: Some carbohydrates, like cellulose in plants and chitin in arthropods, provide structural support.  Functions of Carbohydrates iv. Cell Recognition and Signaling: Carbohydrates attached to proteins and lipids on the cell surface play a role in cell-cell recognition, communication, and signaling. These carbohydrate molecules, known as glycoproteins and glycolipids, are essential in immune responses and the identification of cells. v. Dietary Fiber: Although not digestible by humans, dietary fiber (mainly composed of cellulose and other polysaccharides) is crucial for maintaining a healthy digestive system. It helps regulate bowel movements, prevent constipation, and may reduce the risk of certain diseases such as colon cancer and cardiovascular diseases.  Dietary Carbohydrates Carbohydrates are a fundamental part of the human diet and are found in a wide variety of foods, including grains, fruits, vegetables, legumes, and dairy products. They can be categorized as simple or complex carbohydrates based on their structure: Simple Carbohydrates: These include monosaccharides and disaccharides. They are quickly digested and absorbed by the body, providing a rapid source of energy. However, consuming too many simple carbohydrates, especially refined sugars, can lead to health issues like obesity, insulin resistance, and type 2 diabetes. Complex Carbohydrates: These include polysaccharides like starch and fiber. They take longer to digest, providing a slower and more sustained release of energy. Foods rich in  Health and Carbohydrates While carbohydrates are vital for overall health, the type and quantity consumed play crucial roles in maintaining well- being. Diets high in refined sugars and low in fiber are associated with an increased risk of chronic diseases such as obesity, diabetes, and heart disease. Conversely, diets rich in complex carbohydrates and fiber are linked to better health outcomes, including improved digestive health and a lower risk of chronic conditions. Notably: Carbohydrates are vital biomolecules that play numerous roles in the body, from providing energy to supporting cellular structure and communication. They are a cornerstone of human nutrition and are found in a wide variety of foods. Understanding the types and functions of  Assignments 1. a. Define polysaccharides and explain their general structure. b. Discuss the types of monosaccharides that can form polysaccharides. 2. a. Describe the roles of polysaccharides in living organisms b. Discuss the importance of polysaccharides in various fields such as i. Food industries ii. Pharmaceuticals iii. Biomedical applications. 3. Discuss the difference on energy utilization from glycogen and cellulose. Questions? Thank you for listening…