Cell and Tissue Biology Lecture 2, Part A

Study Notes

Cell and Tissue Biology (Lecture 2, Part A)

Lecture covers biological membranes and extracellular matrix (ECM)
Contents: Explores fats (lipids), molecules in the natural world (proteins, amino acids, DNA), biological membranes, ECM, and cell adhesion.
Phospholipids: Essential components of cell membranes.
- Similar to triglycerides
- Formed by condensation reactions
- Contain only two fatty acid chains.
- A "head" group substitutes the third fatty acid, containing phosphorus and nitrogen
- Polar head (hydrophilic): Attracted to water
- Non-polar tail (hydrophobic): Repelled by water
Phospholipid structure: The phospholipid molecule has a polar head and non-polar tail
- This structural feature results in an amphipathic nature of the molecule meaning it has both hydrophilic and hydrophobic properties
Amphipathic nature: The combined hydrophobic and hydrophilic properties enable phospholipids (and other lipids) to organize into membranes. These properties ensure the phospholipids arrange so that the polar heads face the water (water-soluble) and the non-polar tails face away from water (water-insoluble).
Phospholipid bilayer: A fundamental structure of cell membranes.
- Forms a bilayer with hydrophilic heads facing the aqueous environments (inside and outside of the cell) and hydrophobic tails facing each other in the middle.
Phospholipid structures: Under certain conditions, phospholipids can form various structures.
- Micelles: Single phospholipid layer, typically formed in solution
- Liposomes: Double phospholipid layer forming a closed sphere. Often used for drug delivery.
Steroids: Large lipid molecules containing four interconnected carbon rings.
- Cholesterol: The best-known steroid, found in all cell membranes
- Cholesterol plays a role in regulating membrane fluidity and is a precursor to some steroid hormones (sex hormones).
- Sources of cholesterol include diet and the liver can synthesize large amounts
Fatty Acids: Essential components of lipids.
- Provide energy and structural support in the body
- Essential for cellular function
Amino Acids and Proteins: Proteins are a vital part of the human body.
- Consists of a central carbon atom (C) bonded to an amino group, a carboxyl group, a hydrogen atom, and an R-group or side chain.
- Make up about 20% of the human body's weight.
- Composed of amino acids
- Functions: Support, movement, transport. buffering. metabolic regulation, coordination and control, defense.
Protein Structure:
- Proteins are long chains of amino acids (AA)
- AA are joined together by peptide bonds to form polypeptide chains
- 20 different types of AA
- Individual AA differing in R-group/side chain
- Chains form various configurations, determining function.
- Globular proteins (such as hemoglobin and myoglobin have specific roles)
- Fibrous proteins (such as keratin have structural roles)