Biological Molecules: Proteins & Nucleic Acids

Proteins

• Proteins are biologically functional molecules that consist of one or more polypeptide chains
• Polypeptides are linear polymers constructed from a set of 20 amino acids linked by covalent peptide bonds
• A protein's structure determines its function
• Proteins can be categorized based on their size: Dipeptides (2 amino acids), Oligopeptides (up to ~20 amino acids), and Polypeptides (20 – thousands of amino acids).

Nucleic Acids

• Nucleic acids are involved in the storage, transmission, and use of genetic information
• They are also called polynucleotides
• A polynucleotide is a chain of nucleotides linked together by covalent phosphodiester bonds
• There are two types of nucleic acids: DNA and RNA

DNA (Deoxyribonucleic Acid)

• Composed of four bases: adenine (A), cytosine (C), guanine (G), and thymine (T)
• Contains deoxyribose sugar
• Double stranded

RNA (Ribonucleic Acid)

• Composed of four bases: adenine (A), cytosine (C), guanine (G), and uracil (U)
• Contains ribose sugar
• Single stranded

Lipids

• Lipids are a class of large molecules that contain mostly hydrocarbons (C, H) and are non-polar
• They are insoluble in water (hydrophobic)
• They are used for insulation, energy storage, cell structure, and cell signaling
• Three types of lipids are:
  • Triglycerides (Fats)
  • Phospholipids
  • Steroids

Triglycerides (Fats)

• Constructed from two types of smaller molecules: glycerol and fatty acids
• Glycerol is a three-carbon alcohol with a hydroxyl group on each carbon
• Fatty acids consist of a carboxyl group attached to a long carbon tail
• Fatty acids are linked to glycerol via a dehydration reaction to form a covalent ester bond

Saturated Fats

• Have the maximum number of hydrogen atoms possible and no double bonds

Unsaturated Fats

• Have one or more double bonds

The Plasma Membrane

• The plasma membrane is a phospholipid bilayer that serves as a permeability barrier
• It regulates the entry and exit of molecules into and out of the cell
• The bilayer is composed of phospholipids and cholesterol, as well as proteins and carbohydrates (glycoproteins and glycolipids)

Membrane Proteins

• Play important roles in cellular processes
• Their functions include: sensing the environment, transporting molecules across the membrane, and mediating cellular communication

The ABO Blood Groups

• are characterized by different carbohydrate structures on the glycoproteins of red blood cell (RBC) membranes
• Carbohydrate tails of glycoproteins on the RBC membrane are responsible for different blood types

Antibodies

• Can be used to probe for specific cell-surface antigens (markers that trigger an immune response)

Sars-CoV-2

• The Sars-CoV-2 virus attaches to the host cell via its spike protein, which binds to a specific receptor protein (hACE2) on the host cell's surface
• The spike protein also contains parts that facilitate the fusion of the viral membrane with the host cell membrane to deliver the viral genome inside the cell

Crude DNA Extraction Lab Activity

• A basic procedure in laboratories
• Important for the study of genetics
• Used in:
  • genetic profiling (DNA fingerprinting) to diagnose genetic diseases
  • establishing paternity
  • forensic analysis
• The extracted DNA can be manipulated for biomedical purposes

Explore the essential structures and functions of proteins and nucleic acids in this informative quiz. Learn about polypeptides, amino acids, and the differences between DNA and RNA in terms of their composition and roles. Gain a deeper understanding of how these biological molecules contribute to life.