AP Biology - Chapter 5 Review
Carbohydrates
Elements: Carbon, Hydrogen, Oxygen
Building Block: Monosaccharides
- Ex: Glucose, Fructose, Galactose
- Raw material for amino acids and fatty acids.
- Two functional groups: Multiple hydroxyl (-OH) and one carbonyl (C=O)
- Aldehyde sugar (aka Aldose): Carbonyl is at the end of the molecule
- Ketone sugar (aka Ketose): Carbonyl is in the middle of the molecule.
Disaccharides (polymer): two bonded monosaccharides.
- Bonded through glycosidic linkage by dehydration synthesis.
- Important disaccharides: Maltose (malt sugar), Sucrose (table sugar), Lactose (milk)
◌ Sucrose: glucose + fructose
◌ Maltose: glucose + glucose
◌ Lactose: glucose + galactose
Polysaccharides: energy-storing compounds and structural compounds
- Two categories:
◌ Storage: Starches (plants) and Glycogen (animals)
- Starch: α form of glucose, stored in plastid, digestable
- Glycogen: highly branched polymer of glucose in muscles & liver, quick energy, stores extra sugar (glycogen + insulin)
◌ Structural: Cellulose (plants) and Chitin (animals)
- Cellulose: β form of glucose, most abundant organic compound, not digestible (need microorganisms),
- Chitin: made from glucose + nitrogen group, an exoskeleton for animals, cell wall for fungi, surgical thread from crustaceans.
Diagrams:
Lipids
Hold a lot of energy and are hydrophobic/insoluble in water
- Includes: fats, phospholipids, steroids, and waxes.
Elements: Carbon, Hydrogen, Oxygen
Building Blocks: Glycerol, Fatty Acids, & Phosphate group
- Glycerol: 3-C alcohol
- Fatty Acids: Long carbon chain w/ carboxyl group, store energy in C-H bond
Triacyglcerol (triglycerides):
- Made up of glycerol and fatty acids (Glycerol w/ 3+ fatty acids) → Ester Linkage
- Saturated: Single bonds only
◌ Solid at room temp.
◌ Lard, butter
- Unsaturated: Has double bond(s)
◌ Liquid at room temp.
◌ Can have one double bond (mono) or multiple (poly)
◌ Olive oil, cod liver oil
- Trans Fats: shifts double bond: C-C=C\C → C-C\\C-C
◌ Unsaturated w/ trans double bond, contributes to atherosclerosis.
◌ Skippy/Jif Peanut Butter - no oil layer b/c of hydrogenated oils
- Functions: Store energy, cushions organs, insulates the body, gives long-term food reserves
Phospholipids:
- Glycerol w/ 2 fatty acids attached and one phosphate group
- “Heads”: hydrophilic and “Tails”: hydrophobic
- Micelle: phospholipid droplet in water)
- Phospholipid Bilayer: cell membranes
Steroids:
- Lipid w/ 4 fused carbon rings
- Ex: Cholesterol (cell membrane) - keeps membrane from rigidity or too much movement, and only in animal cells.
- Can be a cell membrane component
- Other examples: Estrogen and cortisol
Proteins
Importance: Instrumental in nearly everything organisms do.
- 50% dry weight of cells; most structurally sophisticated molecule known
3-Dimensional Shape (conformation)
Monomer: Amino acids (20 types)
- Has carboxyl (-COOH), amino group (NH2), H atom, variable group (R)
- Only the “R” group changes
- “R” group can be: polar (hydrophilic), nonpolar (hydrophobic), acid/base (charged)
Polypeptides:
- Dehydration reaction to bond into covalent peptide bonds (Carboxyl → Amino)
Types of Proteins:
- Enzymatic: Accelerate chemical reactions, ex: digestive enzymes
◌ Active site, substrate, and product
- Defensive: Protect against disease, ex: antibodies
- Storage: Store amino acids, ex: Casein (protein of milk - amino acid for baby animals)
- Transport: Move substances, ex: Hemoglobin - transports oxygen around the body.
- Hormonal: Coordination of an organism’s activities, ex: Insulin - regulates blood sugar.
- Receptor: Response of cell to chemical stimuli, ex: Nerve cell receptors receive signals from other nerve cells.
- Contractile/Motor: Movement, ex: Actin/Myosin - responsible for muscle movement.
- Structural: Support, ex: Keratin (protein for hair, horns, feathers, etc.)
Levels of Protein Structure:
Primary Structure: order of amino acids
- Conformation: linear structure determined by DNA
- Refolding can occur by chaperonins
- Incorrect substitutions of amino acids can lead to conditions like sickle-cell anemia
Secondary Structure: due to interactions of the peptide backbone
- Conformation: coils and folds due to hydrogen bonds
- Alpha helix: coiling
- Beta pleated sheet: folds
Tertiary Structure: Interactions of side chains / overall structure
- Conformation: irregular contortions from R group bonding
- Hydrophobic
- Disulfide bridge: Stabilizes the 3-D structure
- Hydrogen bonds
- Ionic bonds
Quarternary Structure: only if there are multiple polypeptide chains
- Conformation: 2+ polypeptide chains aggregated into macromolecule.
- Collagen, hemoglobin
- Same R group bonding as Tertiary to hold chains together
Conditions like:
- High fevers, Cystic Fibrosis, Alzheimers, Parkinsons, and Mad Cow Disease are due to misfolded proteins
Nucleic Acids
Deoxyribonucleic acid (DNA) - carries hereditary information / self-replicates
Ribonucleic acid (RNA) - carries protein-coding instructions from DNA
DNA → RNA → protein (central dogma)
Polymers of nucleotides
- Nucleotide: nitrogenous base, pentose sugar, and phosphate group
Nitrogenous bases: make up the inside (ladder rungs)
- Pyrimidines: cytosine, thymine, uracil - single ring
- Purines: adenine and guanine - double ring (looks fused)
- A → T and C → G (Uracil replaces thymine in RNA)
- DNA: antiparallel - 5’ to 3’ and 3’ to 5’
Phosphate and pentose sugar make up the sides of the helix
Pentoses:
- Ribose (RNA)
- Deoxyribose (DNA)
- Base + sugar is a nucleoside
Polynucleotide:
- Phosphodiester linkages (covalent) - between base and sugar
Inheritance based on DNA replication
Double helix (Watson & Crick - 1953)
- Hydrogen bonds between paired bases
- Van der Waals - between stacked bases