Biological Molecules 3 Flashcards
What are the two sugars found in DNA and RNA?
DNA: β-D-2-deoxyribofuranose; RNA: β-D-ribofuranose
What is the key structural difference between ribose and deoxyribose?
Deoxyribose lacks an -OH at the C2 position.
What is a nucleoside?
A sugar + base (no phosphate).
What is a nucleotide?
A sugar + base + phosphate.
What are the four bases in RNA?
Adenine (A), Guanine (G), Cytosine (C), Uracil (U).
What bonds link nucleotides together?
Phosphodiester bonds (C3 of one sugar to C5 of the next).
What is the direction of nucleic acid synthesis?
5’ → 3’ direction.
What are Watson-Crick base-pairing rules?
A-T (2 H-bonds), G-C (3 H-bonds) (A-U in RNA).
Why do purines always pair with pyrimidines?
To maintain a constant strand distance.
What is the primary structure of DNA?
A linear sequence of nucleotides.
What is the secondary structure of DNA?
A double helix with antiparallel strands.
What are the three main functions of lipids?
Membrane structure, energy storage, and cell signaling.
What are the two major types of lipids?
Simple lipids (e.g., steroids, waxes) and Complex lipids (e.g., phospholipids).
What are fatty acids?
Long-chain carboxylic acids (12-20 carbons).
How do saturated and unsaturated fatty acids differ?
Saturated = no double bonds, solid at room temp. Unsaturated = 1+ double bonds, liquid at room temp.
What are Omega-3 and Omega-6 fatty acids?
Omega-3 = Double bond at C3 from methyl end. Omega-6 = Double bond at C6 from methyl end.
What are prostaglandins?
Fatty acid derivatives that regulate inflammation, blood clotting, and digestion.
How do PGE and PGF differ?
PGE: Carbonyl at C9. PGF: Hydroxyl at C9.
What are triglycerides?
Esters of glycerol and three fatty acids.
Why are saturated fats solid and unsaturated fats liquid?
Saturated fats pack tightly (solid), unsaturated fats have kinks (liquid).
What is hydrogenation of fats?
Adding H₂ to unsaturated fats to make them saturated (solid).
Why are trans fats unhealthy?
They increase bad cholesterol (LDL) and can clog arteries.
What is the structure of phospholipids?
Glycerol + 2 fatty acids + phosphate group.
How do phospholipids arrange in a membrane?
Hydrophilic heads face outward, hydrophobic tails face inward.
What are common phospholipid derivatives?
PC (choline), PE (ethanolamine), PS (serine), PI (inositol).
