Biochem
Here’s an in-depth cheat sheet to help you absolutely ace your final exam. It's detailed but structured for quick review. Let’s make this your ultimate guide!
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### CARBOHYDRATES
1. Reducing Sugars:
- Contain a free aldehyde (-CHO) or ketone (-C=O) group.
- Test with Benedict’s reagent: Turns red/orange in the presence of reducing sugars like glucose or fructose.
2. D vs. L Isomers:
- Based on the configuration of the furthest chiral carbon from the functional group.
- D: Hydroxyl (-OH) on the right.
- L: Hydroxyl (-OH) on the left.
3. Alpha vs. Beta Forms (Anomers):
- Alpha: The -OH on the anomeric carbon is down in the cyclic form.
- Beta: The -OH on the anomeric carbon is up in the cyclic form.
4. Disaccharides:
- Maltose: Glucose + Glucose (\( \alpha \)-1,4 bond).
- Lactose: Galactose + Glucose (\( \beta \)-1,4 bond).
- Sucrose: Glucose + Fructose (\( \alpha \)-1,2 bond).
5. Polysaccharides:
- Starch: Energy storage in plants (amylose and amylopectin).
- Glycogen: Energy storage in animals, highly branched.
- Cellulose: Structural in plants, \( \beta \)-1,4 bonds (humans can’t digest).
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### LIPIDS
1. Saturated vs. Unsaturated Fatty Acids:
- Saturated: No double bonds; solid at room temp (e.g., butter).
- Unsaturated: One or more double bonds; liquid at room temp (e.g., olive oil).
2. Phospholipids:
- Amphipathic (hydrophilic head + hydrophobic tails).
- Form bilayers in cell membranes.
3. Prostaglandins:
- Derived from arachidonic acid.
- Function in inflammation, pain, and fever.
- Aspirin inhibits prostaglandin synthesis by blocking cyclooxygenase (COX) enzymes.
4. Steroids:
- Have a common steroid nucleus (four fused rings).
- Examples: Cholesterol (membrane fluidity), testosterone, progesterone.
5. Lipoproteins:
- HDL: Transports cholesterol to the liver ("good cholesterol").
- LDL: Delivers cholesterol to tissues ("bad cholesterol").
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### PROTEINS
1. Structure Levels:
- Primary: Sequence of amino acids (peptide bonds).
- Secondary: Alpha helices and beta sheets (hydrogen bonds).
- Tertiary: 3D folding due to R-group interactions (hydrophobic, ionic, disulfide bonds).
- Quaternary: Multiple polypeptide chains (e.g., hemoglobin).
2. Denaturation:
- Caused by heat, pH extremes, or chemicals.
- Disrupts secondary, tertiary, and quaternary structures (not primary).
3. Protein Functions: Enzymes, transport (hemoglobin), structural (collagen), hormones (insulin).
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### ENZYMES
1. How Enzymes Work:
- Lower the activation energy of reactions.
- Speed up reaction rates.
2. Active Site Models:
- Lock-and-Key: Substrate fits perfectly into the enzyme.
- Induced Fit: Enzyme changes shape to fit the substrate.
3. Factors Affecting Activity:
- pH: Too high/low → denaturation.
- Temperature: Optimal range; too high → denaturation.
4. Inhibitors:
- Competitive: Compete with substrate for the active site.
- Noncompetitive: Bind elsewhere, altering enzyme shape.
5. Examples of Enzymes:
- Lipase (fats), amylase (carbs), protease (proteins).
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### MOLECULAR GENETICS
1. DNA Structure: Double helix, deoxyribose sugar, A-T, G-C base pairing.
2. RNA: Single-stranded, ribose sugar, A-U, G-C base pairing.
3. Processes:
- Replication: DNA → DNA (semi-conservative).
- Transcription: DNA → RNA.
- Translation: RNA → Protein (occurs in ribosomes).
4. Mutation Types:
- Point Mutation: Single nucleotide change.
- Frameshift Mutation: Insertion/deletion alters the reading frame.
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### CARBOHYDRATE METABOLISM
1. Glycolysis:
- Glucose → 2 pyruvate + 2 ATP + 2 NADH.
- Occurs in the cytoplasm.
2. Gluconeogenesis:
- Reverse of glycolysis; occurs in the liver.
3. Regulation:
- Insulin: Promotes glycolysis and glycogenesis (lowers blood sugar).
- Glucagon: Promotes gluconeogenesis and glycogenolysis (raises blood sugar).
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### AEROBIC RESPIRATION
1. Citric Acid Cycle (Krebs):
- Acetyl CoA → 3 NADH, 1 FADH2, 1 GTP/ATP per turn.
- Produces CO2 as a byproduct.
2. Electron Transport Chain:
- NADH and FADH2 donate electrons.
- Final electron acceptor: Oxygen → forms water.
- Produces ~34 ATP.
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### FATTY ACID METABOLISM
1. Beta-Oxidation:
- Fatty acids → acetyl CoA + NADH + FADH2.
2. Ketogenesis:
- Excess acetyl CoA → ketone bodies (e.g., during fasting).
3. Hormonal Regulation:
- Insulin: Promotes fat storage.
- Glucagon: Promotes fat breakdown.
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### HENDERSON–HASSELBALCH EQUATION
\[
\text{pH} = pK_a + \log \left( \frac{[\text{A}^-]}{[\text{HA}]} \right)
\]
- Use for buffer systems.
- Example: \( pK_a = 4.76 \), \( [\text{A}^-] = 0.2 \, M \), \( [\text{HA}] = 0.1 \, M \):
\[
\text{pH} = 4.76 + \log\left(\frac{0.2}{0.1}\right) = 4.76 + 0.3 = 5.06
\]
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### KEY POINTS FOR SUCCESS
1. Practice Calculations:
- ATP yield (NADH = 3 ATP, FADH2 = 2 ATP).
- Henderson–Hasselbalch equation.
2. Draw Diagrams:
- DNA/RNA structures, glycolysis, citric acid cycle, cell membranes.
3. Focus on Hormones: Know how insulin, glucagon, and adrenaline regulate pathways.
4. High-Yield Topics:
- Glycolysis vs. Gluconeogenesis.
- Protein structures.
- Lipid types and metabolism.
Great question! These terms often appear in biochemistry exams because they are key to understanding metabolic processes. Let’s break them down and connect them to your final exam topics:
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### Key Definitions
1. Anabolic:
- Definition: Processes that build larger molecules from smaller ones. Think of it as "construction."
- Energy Usage: Requires energy (ATP).
- Examples in Your Final:
- Gluconeogenesis: Synthesizing glucose from non-carbohydrate sources.
- Glycogenesis: Storing glucose as glycogen.
- Fatty Acid Synthesis: Creating triglycerides or phospholipids.
2. Catabolic:
- Definition: Processes that break down molecules into smaller ones. Think of it as "destruction."
- Energy Release: Produces energy (ATP, NADH, FADH2).
- Examples in Your Final:
- Glycolysis: Breaking glucose into pyruvate.
- Beta-Oxidation: Breaking down fatty acids into acetyl CoA.
- Citric Acid Cycle: Breaking acetyl CoA into CO2 while generating energy.
3. Aerobic:
- Definition: Processes that require oxygen.
- Examples in Your Final:
- Citric Acid Cycle: Occurs in the mitochondria and needs oxygen.
- Electron Transport Chain: Uses oxygen as the final electron acceptor to produce ATP.
4. Anaerobic:
- Definition: Processes that occur without oxygen.
- Examples in Your Final:
- Glycolysis: Happens in the cytoplasm and doesn’t need oxygen.
- Lactic Acid Fermentation: Converts pyruvate into lactate when oxygen is scarce (e.g., during intense exercise).
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### How These Terms Apply to Your Final Exam
1. Carbohydrate Metabolism:
- Anabolic:
- Gluconeogenesis (synthesis of glucose).
- Glycogenesis (storing glucose as glycogen).
- Catabolic:
- Glycolysis (breakdown of glucose into pyruvate).
- Glycogenolysis (breakdown of glycogen to release glucose).
- Aerobic: Citric acid cycle and oxidative phosphorylation (produce large amounts of ATP).
- Anaerobic: Glycolysis and lactic acid fermentation (limited ATP).
2. Lipid Metabolism:
- Anabolic:
- Fatty acid synthesis (storing energy in triglycerides).
- Catabolic:
- Beta-oxidation (breaking down fatty acids for energy).
3. Protein Metabolism:
- Catabolic:
- Deamination (removing amino groups from amino acids).
- Amino acids can enter the citric acid cycle for energy.
- Anabolic:
- Protein synthesis (building polypeptides).
4. Aerobic Respiration:
- Catabolic processes like the citric acid cycle and electron transport chain require oxygen.
5. Anaerobic Processes:
- Glycolysis is catabolic and functions in both aerobic and anaerobic conditions.
- If oxygen is absent, lactic acid fermentation takes over.
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### Quick Way to Remember These Terms
- Anabolic = Add: Builds molecules and requires energy.
- Catabolic = Cut: Breaks molecules and releases energy.
- Aerobic = Air: Needs oxygen to proceed.
- Anaerobic = Anti-Air: Happens without oxygen.
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Let me know if you need example questions or more clarification!