Fundamentals of Human Biology - Carbohydrates

Fundamentals of Human Biology - Carbohydrates

• Carbohydrates are composed of carbon, hydrogen, and oxygen in a 1:2:1 ratio.
• Carbohydrates are also called hydrates of carbon, reflecting the 2:1 ratio of hydrogen to oxygen (H₂O).
• Carbohydrates include: sugars, starches, glycogen, cellulose, and chitin.
• Sugars and starches are energy sources for cells.
• Cellulose and chitin are structural components.
• Carbohydrates are made of sugar units – saccharides (monosaccharides, disaccharides, polysaccharides).

Learning Outcomes

• The presentation will introduce the four main elements of biological importance.
• It will describe the main classes of organic compounds (carbohydrates, proteins, lipids, and nucleic acids).
• It will discuss the structure of monosaccharides and the glycosidic bond.
• It will explain polysaccharide structure and examples like cellulose, starch, and chitin.
• It will discuss the role of carbohydrates in glycosylated compounds.

Biological Molecules

• FUNBIO.1 - Carbohydrates
• FUNBIO.2 - Proteins
• FUNBIO.3 - Lipids and Nucleic Acids

Organization of Living Matter

• Organisms consist of organ systems, which are made up of organs, tissues, and cells.
• Atoms combine to form molecules, which organize into organelles.
• Chemical levels include atoms, molecules, and macromolecules.
• The diagram illustrates organizational levels from molecules to ecosystems.

Biomolecules

• Biomolecules consist of organic compounds, which include carbon, hydrogen, oxygen, and nitrogen.
• Inorganic compounds include oxygen (O₂), carbon dioxide (CO₂), water (H₂O), inorganic acids, bases, and salts.
• Carbohydrates, proteins, lipids, and nucleic acids are the major classes of organic compounds in biomolecules.

Why are these compounds so important?

• These compounds help build cells and tissues.
• They take part in and regulate metabolic processes.
• They transmit information and provide energy for life.

Types of Carbohydrates

• Sugars are an energy source for cells.
• Starches and cellulose/chitin are structural components.
• Carbohydrates consist of carbohydrate units.

Carbohydrates - Sugars/Starches

• Monosaccharides are single sugar units (e.g., glucose).
• Disaccharides are two sugar units (e.g., sucrose).
• Polysaccharides are many sugar units (e.g., glycogen, starch).

Glucose

• Glucose is the most abundant monosaccharide.
• It is a hexose sugar (C₆H₁₂O₆).
• It's a primary energy source in most organisms, oxidized during cellular respiration.
• Mechanisms regulate blood glucose levels.
• Diabetes is a disruption in these mechanisms.

Glycosidic Bonds

• Glycosidic bonds link monosaccharides to form disaccharides and polysaccharides.
• These bonds are formed by a dehydration reaction (removal of water).

Common Disaccharides

• Sucrose (Glucose + Fructose)
• Lactose (Galactose + Glucose)
• Maltose (Glucose + Glucose)

Polysaccharides

• Polysaccharides are long chains of monosaccharides linked by glycosidic bonds.
• They're the most abundant carbohydrates in nature.
• Examples include starch, glycogen, cellulose, and chitin.

Storage Polysaccharides: Starch

• Plants store carbohydrates as starch (amylose, amylopectin).
• Amylose is a linear polymer of glucose.
• Amylopectin is a highly branched polymer of glucose.
• Amylopectin and amylose are both chains of glucose.

Hydrolysis of Starch

• α-amylase is found in saliva and pancreatic juices.
• It cleaves α(1-4) bonds randomly in starch, producing a mixture of glucose and maltose.
• β-amylase is found in malt.
• It cleaves α(1-4) bonds from the non-reducing end of starch, producing maltose.

Glycogen

• Animals store glucose as glycogen, highly branched.

Cellulose

• Cellulose is a structural polymer found in plant cell walls.
• It's a linear polymer of glucose linked by β(1-4) bonds.
• Humans lack enzymes to digest cellulose.

Chitin

• Chitin is a structural polymer found in the cell walls of fungi and exoskeletons of insects.

Glycoproteins

• Glycoproteins, like integral membrane proteins, have carbohydrate components.
• They regulate cell-cell recognition and communication involved in signaling and cell adhesion.

Phosphorylated Sugars

• Phosphorylated sugars (e.g., glucose-6-phosphate) are intermediates in energy metabolism (glycolysis), becoming anionic and participating in glycosidic bonding.

Reading Materials

• Solomon (10th/11th edition) chapters 3 and 1 have relevant details on specific topics.

This quiz covers the essential aspects of carbohydrates in human biology. You will learn about their chemical composition, types, and functions in living organisms. Additionally, it highlights the significance of saccharides and the roles of carbohydrates in energy and structure.