Nucleic+Acids+and+Lipids+Lecture+Notes

The Chemistry of Life

Introduction

  • Learning changes everything.

  • Discusses the foundational aspects of chemistry in biological contexts.

Nucleic Acids

Basics

  • Nucleic acids include DNA and RNA.

  • They carry genetic information essential for the synthesis of proteins.

  • The primary structure of each protein in a cell is determined by the nucleic acids.

Components of Nucleotides

  • Nucleic acids are made up of monomers called nucleotides.

  • Each nucleotide consists of:

    • A phosphate group.

    • A five-carbon sugar (ribose in RNA, deoxyribose in DNA).

    • A nitrogenous base.

Nitrogenous Bases

  • There are five different nitrogenous bases that can be attached:

    • Adenine (A)

    • Cytosine (C)

    • Guanine (G)

    • Thymine (T) (only in DNA)

    • Uracil (U) (only in RNA)

  • The combination of these bases results in the formation of five distinct types of nucleotides.

Nucleic Acid Formation and Breakdown

  • Dehydration synthesis is the process that binds nucleotides together to form chains of nucleic acids.

    • This forms a dipeptide in protein context.

  • Conversely, hydrolysis is the method used to separate nucleic acids back into individual nucleotides.

Lipids

Characteristics

  • All lipids are characterized as hydrophobic (water-repelling).

  • They encompass a variety of structures and functions distinct from carbohydrates, proteins, and nucleic acids.

  • Unlike others, lipids are not formed from chains of monomers.

Classes of Lipids

  • Different classes of lipids include:

    • Triglycerides (fats and oils) which are energy-rich and crucial for long-term energy storage.

    • Steroids characterized by a four-ring structure.

Structure of Triglycerides

  • Formed by covalently attaching three fatty acid molecules to a glycerol molecule.

  • Connected through dehydration synthesis, forming a triglyceride.

  • Hydrolysis can separate fatty acids from glycerol when necessary.

Saturated vs. Unsaturated Fatty Acids

  • Saturated Fatty Acids

    • All carbons are bonded to four other atoms, resulting in a straight shape.

  • Unsaturated Fatty Acids

    • Contains at least one double bond, resulting in a bent shape.

Physical Properties of Lipids

  • The saturation level influences the properties of triglycerides:

    • Unsaturated fatty acids prevent tight packing, resulting in liquid forms like oils at room temperature.

Role of Steroids

  • Implies importance in cellular functions:

    • Cholesterol helps regulate fluidity in animal cell membranes.

    • Serves as a precursor for many sex hormones.

Conclusion

Chemical Properties and Life

  • The properties of organic molecules in our cells are dictated by their atomic composition and connections (chemical bonds).

  • These compounds are fundamental for life processes.