Bio lecture 4-7
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What is a functional group?
A specific group of atoms within a molecule that gives the molecule its characteristic chemical properties and reactions.
What is the structure and property of the Hydroxyl group?
Structure: –OH Found in: Alcohols (e.g., ethanol) Properties: Polar, forms hydrogen bonds, increases solubility in water.
What is the structure and property of the Carbonyl group?
Structure: C=O Found in: Aldehydes: if C=O is at the end of a carbon chain Ketones: if C=O is within the carbon chain Properties: Polar, reactive, found in sugars.
What is the structure and property of the Carboxyl group?
Structure: –COOH Found in: Organic acids (e.g., amino acids, fatty acids) Properties: Acidic (can donate H⁺), polar, forms hydrogen bonds.
What is the structure and property of the Amino group?
Structure: –NH₂ Found in: Amino acids, proteins Properties: Acts as a base (can pick up H⁺ to form –NH₃⁺), polar.
What is the structure and property of the Sulfhydryl group?
Structure: –SH Found in: Some amino acids (like cysteine) Properties: Can form disulfide bonds (–S–S–) that stabilize protein structure.
What is the structure and property of the Phosphate group?
Structure: –PO₄²⁻ (phosphorus bonded to four oxygens) Found in: ATP, DNA, RNA, phospholipids Properties: Negatively charged, adds energy potential, polar.
What is the structure and property of the Methyl group?
Structure: –CH₃ Found in: DNA, fatty acids, hormones Properties: Nonpolar, affects gene expression and molecular shape.
Which functional groups are polar?
Hydroxyl, Carbonyl, Carboxyl, Amino, Phosphate (most are hydrophilic).
Which functional group is nonpolar?
Methyl (–CH₃) — it reduces solubility in water.
Q: What is the monomer of carbohydrates?
A: Monosaccharide
Q: What type of bond links monosaccharides to form polysaccharides?
A: Glycosidic linkage (formed by dehydration synthesis)
Q: Why are carbohydrates hydrophilic?
They have –OH groups that form hydrogen bonds with water
What is the generic formula of carbohydrates?
CH₂O (rough ratio of C:H:O in monosaccharides)
How do you number carbons in a sugar ring?
Start after the ring oxygen, go clockwise; carbon #1 = anomeric carbon
Q: Starch vs. cellulose — difference in glycosidic linkage?
A: Starch = α-linkages → helical; cellulose = β-linkages → straight chains
Q: Why are lipids hydrophobic?
They have long nonpolar hydrocarbon chains that repel water.
Q: Why aren’t lipids considered true polymers?
They aren’t made of repeating monomer units; smaller molecules attach to a backbone.
Q: What reaction links fatty acids to glycerol in fats?
A: Dehydration synthesis forming ester bonds.
Q: What is a fat molecule made of?
A: Glycerol + 3 fatty acids.
Q: Difference between saturated and unsaturated fats?
A: Saturated = all single bonds (solid); Unsaturated = ≥1 double bond (liquid).
Q: What parts make up a phospholipid?
A: Hydrophilic head + 2 hydrophobic tails.
Q: What is the basic structure of a steroid?
A: Four fused carbon rings.
Q: How does cholesterol help cell membranes?
A: Stabilizes membrane fluidity by fitting between phospholipid tails.