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.