Chemistry and Biology Overview

Chemistry in Biology

• The science of Biology is based on chemistry
• The interaction of chemicals determines everything from birth to death
• Chemistry is used daily in everyday life
  • Cooking
  • Cleaning
  • Bathing
  • Watering plants

Atoms, Molecules, Compounds

• Atoms are the fundamental building blocks of all molecules and chemical compounds
• Atoms interact with other atoms through chemical bonds
• Chemical bonds define how chemical compounds form, break down, and reform

The Chemistry of Life

• Organisms are composed mainly of:
  • Oxygen
  • Carbon
  • Hydrogen
  • Nitrogen
• Humans also contain small amounts of sodium, phosphorus, sulfur, and chlorine
• Molecule: When two or more atoms are chemically bonded together
  • For example, H2 (hydrogen gas)

Chemical Bonds

• Atoms can chemically bond in three ways:
  • Ionic bonds
  • Covalent bonds
  • Hydrogen bonds

Organic Compounds

• Contain carbon atoms
• Carbon atoms have four valence electrons, which can covalently bond to up to four other atoms
• This property allows carbon to create an almost endless array of carbon-based structures
• Range in complexity from simple methane (CH4) to complex ring and chain structures
• The reactivity of organic compounds in water makes them useful in biological systems
• Organic compounds are also called macromolecules
• They are made up of smaller building blocks called monomers
• Monomers are joined together by condensation (dehydration) reactions and broken apart by hydrolysis

Dehydration and Hydrolysis Reactions

• Condensation (dehydration) reactions: Monomers join to form a larger molecule by removing a water molecule.
• Hydrolysis reaction: Larger molecules are broken down by adding a water molecule

Four Important Organic Compounds

• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids

Carbohydrates

• The most prevalent organic molecules in organisms
• Composed of carbon, hydrogen, and oxygen in a ratio of about 1:2:1 (e.g., C6H12O6)
• Serve as an energy source for the body
• Many carbohydrates are saccharides (sugars)
• Glucose is a key monosaccharide (simple sugar)

Classification of Carbohydrates

• Monosaccharides: Single-sugar molecules (e.g., glucose, fructose, ribose, galactose)
• Disaccharides: Formed by joining two monosaccharides via a glycosidic linkage (e.g., sucrose, lactose, maltose)
• Oligosaccharides: Longer chains (polymers) of monosaccharides (oligo= few, and poly= many)
• Polysaccharides: Complex carbohydrates, long chains (polymers) of monosaccharides (e.g., glycogen, starch, cellulose)

Polysaccharides

• Glycogen: A polysaccharide that serves as energy storage in animals and stored in muscle and liver tissues
• Starch and Cellulose are polysaccharides in plants
  • They are long chains of glucose molecules, but arranged differently than glycogen
  • Starch: Major energy storage form of glucose in plants
  • Cellulose: Structural polysaccharide in plants

Glucose: Chain and Ring Structures

• In solution, monosaccharides form ring structures

Explore the vital relationship between chemistry and biology in this quiz. Understand how chemical interactions shape all living organisms and the essential compounds that make up life. Test your knowledge about atoms, molecules, chemical bonds, and organic compounds.