Chemistry of Life

• Topics covered include water and its role in the cell, chemical bonds in biological systems, bonding in biomolecules, and chemical engineering applications in biological systems.

Learning Objectives

• Understand the importance of water in maintaining cellular structure and supporting biochemical reactions.
• Identify key ions and small molecules involved in cellular processes and explain their functions.
• Explain how different types of chemical bonds contribute to macromolecule structure and function.
• Understand the role of pH and buffers in regulating cellular environments and enzyme activity.
• Apply knowledge of chemistry to real-world applications, like biomaterials and bioprocess engineering.

Review of the Cell

• The cell is the basic structural and functional unit of cellular organisms, but not viruses.
• Cell Theory states:
• All organisms are composed of one or more cells.
• Cells are the basic unit of structure and function in organisms.
• All cells come only from other cells.

Water

• It is considered a polar molecule.
• It has a positive and negative end.
• All living organisms depend on water.
• Its structure is the basis for its properties.
• The most important property of water is its ability to form hydrogen bonds.

Importance of Water in the Cell

• Water is a vital chemical of living cells.
• Water makes up 60-90% of the fresh mass of an organism.
• Fresh mass is the sum of solid components and water.
• Dry mass is the solid components.

Water: The Universal Solvent

• Dissolves more substances than any other liquid.
• The bent molecule shape makes it polar, giving the oxygen atom a partial negative charge and the hydrogen atoms partial positive charges.
• Partial charges attract parts of polar molecules to dissolve them.
• Does not dissolve nonpolar molecules.

Water as a Medium for Biochemical Reactions

• Involved in breaking down lipids and carbohydrates
• Involved in photosynthesis

Water for Transport

• It serves as transport medium in blood, lymphatic, excretory, digestive systems, and vascular tissue of plants.

Water to Aid in Lubrication

• Mucus and synovial fluid contains water.
• Mucus assists in the movement of food substances.
• Synovial fluid eases joint movement.

Water For Support

• Provides support in hydrostatic skeletons of organisms like earthworms.

Water In Plant Cells

• Needed for cell enlargement
• Needed for cell turgidity
• Needed for plant support

Cooling Effect of Water

• Provides cooling effect
• Transpiration in plants
• Sweating and panting in animals.

Water for Seed Germination

• Needed for seed germination
• Testa swells and splits after being imbibed.

Water for Osmotic Balance

• Dissolved inorganic salts in water maintain osmotic balance in animal blood and interstitial fluid.

Chemical Bonds

• Several exist in biological systems:
• Covalent bonds
• Ionic bonds
• Hydrogen bonds
• Van der Waals forces

Covalent Bonds

• They form when two non-metal atoms share electrons.
• This achieves a stable electron configuration (full outer shell).
• Atoms share electrons to become more stable by electron sharing.
• Covalent bonds form molecules (e.g., H2, O2, H2O) through molecule formation
• Covalent bonds are strong because of shared electrons.

Ionic Bonds

• An ionic bond forms when one atom transfers electrons to another.
• This creates oppositely charged ions that attract each other.
• One atom loses electrons, becoming positively charged.
• The other gains electrons, becoming negatively charged.
• Oppositely charged ions are held together by electrostatic attraction.
• Ionic bonds are strong but can dissolve in water.

Hydrogen Bonds

• It's a weak interaction.
• It exists between a hydrogen atom covalently bonded to an electronegative atom (like oxygen in water) and another electronegative atom.
• In water (H₂O), the oxygen atom is highly electronegative, creating a partial negative charge (δ-) on oxygen and partial positive charges (δ+) on the hydrogens.

Van der Waals Forces

• Non-covalent interactions are caused by temporary shifts in electron distribution.
• Electrons in atoms or molecules move randomly.
• Temporary positive and negative regions (dipoles) are formed.
• Temporary dipoles cause weak attraction between neighboring molecules or atoms.
• These weak forces are crucial for the properties of gases, liquids, and solids.

Bonding in Biomolecules

• Proteins: Hydrogen and disulfide bonds stabilize protein folding and function.
• DNA: Hydrogen bonds between complementary bases hold the double helix structure.
• Adenine (A) pairs with Thymine (T).
• Cytosine (C) pairs with Guanine (G).
• Lipids: Van der Waals forces contribute to the fluidity of the lipid bilayer in cell membranes.

Explore water's role in cells, chemical bonds in biological systems, and biomolecule bonding. Understand pH, buffers, and the applications of chemical engineering in biology. Learn how chemistry is applied to biomaterials and bioprocess engineering.