BC121
Two days. No panic. I'm going to give you sticky, unforgettable ways to remember the answers to every single one of these questions. We're using dark humor, stupid stories, and mnemonics that your brain can't un-see.
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VITAMIN QUESTIONS (The "Deficiency = Disaster" Section)
Question: Active form of Vitamin D
Answer: 1,25-Dihydroxycholecalciferol
Story: Vitamin D is a lazy bum. It goes to the liver and gets one OH added (25-hydroxy). Then it goes to the kidney and gets ANOTHER OH added (1,25-dihydroxy). It needs TWO hydroxylations to get off the couch and work. "1,25" = "One, two-FIVE me my active form."
Think: Liver puts on one shoe. Kidney puts on the second shoe. NOW it can walk. 1,25 = two shoes on.
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Question: Vitamin A deficiency causes
Answer: Xerophthalmia
Mnemonic: "A" for "Aye, I can't see!"
Xerophthalmia = dry eyes → blindness. Vitamin A is the "eye vitamin." No A = no sight.
Dark joke: "What do you call someone with no Vitamin A? A person who didn't see that coming."
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Question: Vitamin required for hydroxyproline in collagen
Answer: Vitamin C
Story: Collagen is a rope. Proline is a weak fiber. Hydroxyproline is a strong fiber. Vitamin C is the factory worker that adds the -OH to make it strong. No Vitamin C = weak rope = scurvy = your teeth fall out.
Mnemonic: "C for Collagen." Vitamin C is the glue that holds you together. Without it, you literally fall apart. Pirates got scurvy because no oranges at sea.
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Question: Amino acid required for niacin formation
Answer: Tryptophan
Story: Tryptophan is the turkey amino acid (makes you sleepy). But your body can also turn it into Niacin (Vitamin B3) if needed. 60 mg of Tryptophan = 1 mg of Niacin.
Mnemonic: "Try to make Niacin" = Tryptophan makes Niacin.
Pellagra (niacin deficiency) = the 4 D's: Dermatitis, Diarrhea, Dementia, Death. If you don't eat niacin, eat tryptophan. Same fix.
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Question: Pellagra is caused by deficiency of
Answer: Niacin
Story: Pellagra was an epidemic in the American South where poor people ate only corn. Corn has niacin, but it's BOUND and can't be absorbed. So they got the 4 D's.
Memory hook: "Pellagra = Poor People's Plague." Caused by no Niacin (Vitamin B3). Treated with niacin or tryptophan.
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CARBOHYDRATE QUESTIONS (The "Sugar Daddy" Section)
Question: Bond in lactose
Answer: Beta 1,4 glycosidic bond
Story: Lactose is Galactose + Glucose. The bond is β(1→4).
Mnemonic: "Lactose is a BAD sugar." B = Beta. A = (filler). D = (filler). Beta 1,4.
Also: Lactose = Left-handed bond. Beta bonds point UP. Alpha bonds point DOWN. Beta is the odd one, like being left-handed.
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Question: Which is an aldose sugar?
Answer: Glucose
Logic: Aldose = has an ALDEHYDE group (–CHO). Glucose has an aldehyde at C1. Fructose and Ribulose are KETOSES (ketone at C2). Dihydroxyacetone is a ketotriose.
Mnemonic: "Glucose = Good Aldehyde." Fructose = Fake (ketone).
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Question: GAG without uronic acid
Answer: Keratan sulfate
Mnemonic: "Keratan is the K-exception." All GAGs have uronic acid EXCEPT Keratan sulfate, which has GALACTOSE instead.
Think: Keratan is the "vegan" GAG. It refuses to use uronic acid. It uses galactose instead.
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Question: Amylopectin branch interval
Answer: 24-30 glucose units
Comparison:
· Glycogen: Branches every 10 (tense, tight, animal).
· Amylopectin (starch): Branches every 24-30 (loose, relaxed, plant).
Mnemonic: Plants are chill. Animals are stressed. Stressed = tight branches (10). Chill = loose branches (24-30).
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Question: Maltose formed by hydrolysis of
Answer: Starch
Logic: Starch is a long chain of glucose linked by α(1→4) bonds. Cut the chain = Maltose pieces fall out.
Mnemonic: "Starch is MALTOSE on a string." Snip the string, you get maltose beads.
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PROTEIN QUESTIONS (The "Bend It Like a Protein" Section)
Question: About amino acids (TRUE statement)
Answer: All amino acids are optically active except glycine
Why: Glycine's R group is just H. No asymmetric carbon = no optical activity. It's the only symmetric amino acid.
Mnemonic: "Glycine is the BLAND one." Nothing special. Just an H. No chirality, no drama.
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Question: About collagen (TRUE statement)
Answer: It contains hydroxyproline and hydroxylysine
Why: These are collagen's signature modifications. Hydroxyproline holds the triple helix together. Hydroxylysine attaches sugars. Vitamin C makes BOTH.
Mnemonic: "Collagen = Pro-lys." PROline and LYSine are the stars. They get hydroxylated. They're the power couple of connective tissue.
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Question: Denaturation results in
Answer: Unfolding of the structure
Logic: Denaturation breaks weak bonds (H-bonds, hydrophobic, ionic). The protein UNFOLDS. But the peptide bonds (primary structure) STAY INTACT.
Dark joke: "Denaturation is like a bad breakup. You fall apart, but your core (primary structure) is still there."
Key: 1° structure = NEVER broken by denaturation. Only peptide bonds break with enzymes/acid hydrolysis.
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Question: Methionine and cysteine are
Answer: Sulfur containing amino acids
Mnemonic: "Meth and Cyst are SULFUR SISTERS."
· Methionine has S-CH₃ (methyl-thiol).
· Cysteine has S-H (thiol).
· Both have SULFUR.
Think: They smell like rotten eggs when broken down. That's the sulfur.
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Question: β-alanine and D-glutamate are
Answer: Non-proteinogenic amino acids
Logic: These are NOT found in proteins. They have no genetic code. β-alanine is in Coenzyme A. D-glutamate is in bacterial cell walls.
Mnemonic: "If it's got Beta or D, it's not in a protein for me."
· β-alanine (beta position, not alpha).
· D-glutamate (D form, not L form).
Proteins use ONLY L-α-amino acids. Anything else = non-proteinogenic.
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Question: Sulfur containing amino acid (Single choice)
Answer: Methionine
From the options: Methionine, Leucine, Valine, Asparagine. Only Methionine has sulfur.
Mnemonic: "Methionine = Methane with sulfur." Smells like gas.
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Question: Branched chain amino acids
Answer: Valine, Leucine, Isoleucine
Mnemonic: "VIL branches" (VIL = Valine, Isoleucine, Leucine). They're the "villains" of maple syrup urine disease (when they accumulate).
Think: These three have FORKED side chains (like branches of a tree). They're the ONLY branched AAs.
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Question: Alpha helix hydrogen bond
Answer: C=O of each amino acid to the CH₂ of the 4th amino acid in sequence
Story: An alpha helix is like a spiral staircase. You hold hands with the person 4 steps ahead of you, NOT the person right next to you.
Mnemonic: "3.6 residues per turn, bond to the 4th." 3.6 ≈ 4. So you bond to the 4th amino acid ahead.
Think: "I'll see you in 4 turns, buddy."
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LIPID QUESTIONS (The "Fat Chance" Section)
Question: Hydrolysis of sphingomyelin produces all EXCEPT
Answer: Serine
Sphingomyelin structure: Sphingosine + Fatty Acid + Phosphoric Acid + Choline.
What you get on hydrolysis: Sphingosine, one fatty acid, phosphocholine. NO serine. Serine is in phosphatidylserine, not sphingomyelin.
Mnemonic: "Sphingo has Choline, not Serine." Don't confuse sphingomyelin with phosphatidylserine. Different head groups.
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Question: Cardiolipin found almost exclusively in
Answer: Mitochondrial membrane
Story: Cardiolipin is the "heart lipid" (found first in heart). But it's actually concentrated in the inner mitochondrial membrane. It's the ONLY phospholipid that's antigenic (your body can make antibodies against it in syphilis).
Mnemonic: "Cardiolipin keeps your MITOCHONDRIA pumping." Heart needs energy → mitochondria → cardiolipin.
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Question: Which is FALSE regarding oleic acid 18:1 Δ⁹?
Answer: (The false one is about double bond position when counting from methyl group)
Oleic acid = 18 carbons, 1 double bond at position 9 from the carboxyl end.
Notation: 18:1 Δ⁹ means the double bond is between C9 and C10 FROM THE CARBOXYL END.
The ω (omega) notation counts from the METHYL end. For oleic acid, it's ω-9. If the statement confuses Δ (delta, from COOH) with ω (omega, from CH₃), that's false.
Mnemonic: "Δ counts from the COOH end. ω counts from the tail (methyl end)."
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Question: Eicosanoids are
Answer: Cyclic compounds derived from arachidonic acid after its cyclization
Logic: Eicosanoids (Prostaglandins, Thromboxanes, Leukotrienes) come from Arachidonic Acid (20C, "eicosa" = 20). The key is that cyclization happens FIRST, THEN they become active.
Mnemonic: "Arachidonic Acid CYCLES into Eicosanoids." Like a snake curling up before striking.
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Question: Primary structure of proteins is determined by
Answer: Peptide bonds
Simple: Primary structure = sequence of amino acids. Amino acids are linked by PEPTIDE BONDS.
Mnemonic: "1° = Pep-tide." "Pep" = primary. Nothing else holds the primary structure.
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Question: All enter protein structure EXCEPT
Answer: Homoserine
Logic: Homoserine is a non-protein amino acid. It's an intermediate in metabolism (methionine, threonine pathway). It has NO genetic code.
Glycine, Phenylalanine, Alanine = all proteinogenic.
Mnemonic: "Homo is a wannabe." Homoserine, Homocysteine = metabolic intermediates, never in proteins. They're the actors who never got cast.
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Question: Keratin is
Answer: Simple protein
Logic: Simple proteins = only amino acids, no prosthetic group. Keratin (hair, nails) is pure protein = simple. It's also FIBROUS, not globular.
Mnemonic: "Keratin is SIMPLE." Just amino acids. No extras. No bling. Just protein.
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TRUE/FALSE QUESTIONS – QUICK ANSWERS
Statement T/F Why?
Cholesterol synthesized 1 mg/day F It's 1 GRAM/day (1000 mg), not 1 mg.
Asparagine is essential F Non-essential. Body can make it from Aspartic acid.
O₂ & CO₂ transport is passive T Simple diffusion, no carrier needed.
Glucose & Mannose are epimers T Differ at C2 only.
Lactose relative sweetness 0.16 T Lowest natural sugar sweetness.
Plasma lipids 360-820 mg/dL T Normal range.
Glycine is neutral amino acid T Monoamino-monocarboxylic. Neutral at body pH.
Domain is functional unit of polypeptide T Domains are independently folding functional units.
Glycoproteins act as receptors T Many cell surface receptors are glycoproteins.
Active transport needs carrier & energy T Definition of active transport (ATP or gradient).
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MATCHING – QUICK ANSWERS
Item Match
L-Fucose 6-Deoxy-L-Galactose
Non-essential AA Glutamic acid, Alanine, etc.
Unsaturated FA Oleic acid, Linoleic acid
D-Ribose Form co-enzymes & HMP shunt intermediate
Amino acids Can act as dipolar ions
Non-Essential FA Saturated & Mono-Unsaturated FA
Mainly synthesized in liver Amino acids
Domain Three-dimensional structural unit of polypeptide
Aquaporins Way for water movement through cell membrane
Symporter (SGLT1) Sodium-glucose linked transporter
D-Lyxose Part of Lyxoflavin in human heart muscle
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SHORT ACCOUNT ANSWERS (BARE ESSENTIALS)
1. Hyaluronic Acid
· Type: GAG (Glycosaminoglycan).
· UNIQUE: Only GAG with NO sulfate and NOT protein-bound.
· Structure: Repeating disaccharide (Glucuronic acid + N-acetylglucosamine), β(1→3) linkage.
· Location: Synovial fluid, vitreous humor of eye, cartilage, embryonic tissue.
· Function: Lubricant & shock absorber in joints. Permits cell migration during wound repair. Compressibility of cartilage.
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2. Main Types and Functions of Proteins in Cell Membrane
Type Function
Receptors Bind hormones, neurotransmitters, drugs. Trigger intracellular signals.
Transport Proteins (Channels/Carriers) Passive (aquaporins, ion channels) or Active (Na⁺/K⁺ ATPase, SGLT).
Enzymes Catalyze reactions at membrane surface (e.g., brush border enzymes).
Structural Proteins Anchor cytoskeleton to membrane. Maintain cell shape.
Cell Adhesion Molecules Cell-cell recognition, tissue formation.
Antigens (Glycoproteins) Blood group antigens, MHC molecules (immune recognition).
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3. Essential Fatty Acids (EFA)
· Definition: MUST be obtained from diet. Body cannot synthesize them (cannot introduce double bonds beyond C9).
· The Two Main Ones:
1. Linoleic Acid (18:2 Δ⁹,¹²; ω-6) → precursor of Arachidonic acid.
2. Linolenic Acid (18:3 Δ⁹,¹²,¹⁵; ω-3) → found in linseed oil.
· Sources: Vegetable oils (corn, soybean, sunflower, cottonseed). Fish oils (ω-3).
· Functions:
· Normal growth.
· Structure of phospholipids & cholesterol esters.
· Precursor of Eicosanoids (Prostaglandins, Leukotrienes).
· Maintain reproductive system & healthy skin.
· LOWER serum cholesterol (atheroprotective).
· Deficiency: Fatty liver, Retinitis pigmentosa, poor wound healing.
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4. Di-Palmityl-Lecithin (Lung Surfactant)
· What it is: A specific lecithin (phosphatidylcholine) with TWO palmitic acid (16C saturated) chains.
· Where: Secreted continuously by Type II alveolar cells in the lungs.
· Function: Lung surfactant. Reduces surface tension in alveoli → Prevents lung collapse during expiration → Makes breathing (especially first breath) easier.
· Clinical Importance: Respiratory Distress Syndrome (Hyaline Membrane Disease) in premature babies. Lungs haven't started making enough surfactant → Alveoli collapse → Respiratory failure. Treatment: Give mother glucocorticoids before birth to accelerate surfactant production.
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5. Fibrous Proteins
· Definition: Proteins with axial ratio (length/width) > 10. Elongated shape. Insoluble in water. Provide mechanical support.
· Examples & Functions:
· Collagen: Most abundant protein in body. Tendons, bone, skin, teeth. Triple helix structure (Gly-X-Y repeats, rich in hydroxyproline).
· Keratin (α-Keratin): Hair, nails, skin outer layer. α-helical, forms coiled-coil structures. Rich in cysteine (disulfide bonds → permanent waves).
· Elastin: Elastic fibers in lungs, arteries, ligaments. Allows stretch and recoil. Rich in desmosine cross-links.
· Myosin: Muscle thick filaments. Coiled-coil tail, globular head.
· Fibrin: Blood clot formation. From fibrinogen by thrombin action.
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BATTLE PLAN FOR TWO DAYS
Day 1:
1. Memorize the Vitamin questions (5 facts, easy points).
2. Master the Carbohydrate questions (lactose bond, aldose, GAGs, amylopectin, maltose, epimers, L-fucose, sugar acids, sorbitol, optical activity).
3. Drill the True/False and Matching (these are pattern recognition, not deep thinking).
Day 2:
1. Master Protein questions (collagen, denaturation, sulfur AAs, branched AAs, alpha helix, non-protein AAs, keratin).
2. Master Lipid questions (sphingomyelin, cardiolipin, oleic acid, eicosanoids).
3. Write out the Short Accounts from memory once each. Use bullet points only.
Night before: Read through this whole guide once. Close your eyes and recite the mnemonics. Sleep. Let your brain cement it.
You've got this. Two days. Focused. No distractions. Just smart memorization.