NEET Biology : Biomolecules Short notes, Class 11 Biology Chapter 9 NCERT solutions

*Hello NEET Aspirants! 👋

NEET Dropper here dropping Ch-9: Biomolecules

Complete Notes + PYQ Tod + No Ratta Only Samajh 🧠

4-5Q Pakka NEET 2027 me! NEET 2027: Chapter 9 BIOMOLECULES - Complete Short Notes* 🧬  

_Class 11 Biology | NCERT Line-by-Line + PYQ King Chapter | 4-5Q Fix Aate Hain_  

### *1. How to Analyse Chemical Composition?* `Board + NEET Basic`

Living Tissue → Grind in Trichloroacetic Acid → Slurry

Filter → Filtrate = Acid-soluble pool = Micromolecules < 1000 Da

Retentate = Acid-insoluble pool = Macromolecules > 1000 Da + Lipids

*NEET Trap*: Lipids molecular weight < 1000 Da but acid-insoluble kyunki _cell membrane ka part_ ban jaate hain = Vesicles.  

*% Composition of Cell* `1Q Fix`

Water = 70-90% > Proteins = 10-15% > Nucleic Acid = 5-7% > 

Carbohydrates = 3% > Lipids = 2% > Ions = 1%

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### *2. CARBOHYDRATES* `1Q Pakka`  

*A. Monosaccharides* = Simple Sugar = (CH2O)n

Triose = 3C = Glyceraldehyde, Dihydroxyacetone

Pentose = 5C = Ribose = RNA, Deoxyribose = DNA

Hexose = 6C = Glucose = Blood Sugar, Fructose = Fruit, Galactose = Milk

NEET Point: Glucose + Fructose = Isomers, Glucose + Galactose = Epimers

*B. Disaccharides* = 2 Monosaccharide + Glycosidic Bond

Maltose = Glucose + Glucose = α 1,4 = Malt Sugar

Lactose = Glucose + Galactose = β 1,4 = Milk Sugar = Reducing

Sucrose = Glucose + Fructose = α 1,2 = Table Sugar = Non-Reducing

*Trick*: *M*altose = *M*alt = Glu + Glu, *L*actose = *L*addu = Milk, *S*ucrose = *S*ugar = Common

*C. Polysaccharides* = Long Chain = Non-sugar

**Name** **Monomer** **Bond** **Function** **NEET Point**

**Starch** Glucose α 1,4 + α 1,6 Plant Storage Helical, Iodine = Blue

**Glycogen** Glucose α 1,4 + α 1,6 Animal Storage Branched, Liver + Muscle

**Cellulose** Glucose β 1,4 Plant Cell Wall Straight, Iodine = No colour

**Chitin** N-acetyl Glucosamine β 1,4 Fungi + Exoskeleton 2nd most abundant

**Inulin** Fructose β 2,1 Dahlia Root GFR test me use

*Reducing vs Non-Reducing* `NEET 2023`

Reducing = Free aldehyde/ketone = Fehling + Benedict = Red ppt

All Monosaccharides + Maltose + Lactose = Reducing

Sucrose + All Polysaccharides = Non-Reducing

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### *3. LIPIDS* `Fat = 1Q`  

*A. Simple Lipid* = Fatty Acid + Glycerol + Ester Bond

Fatty Acid: R-COOH = Hydrocarbon chain

Saturated = No C=C = Solid = Palmitic, Stearic = Animal Fat

Unsaturated = C=C = Liquid = Oleic, Linoleic = Plant Oil

Essential FA = Body nahi bana sakta = Linoleic, Linolenic, Arachidonic = LLA

*NEET Point*: Oils have lower melting point kyunki unsaturated = C=C pe kink.

*B. Compound Lipid*

Phospholipid = Glycerol + 2 FA + Phosphate = Cell Membrane = Lecithin

Glycolipid = Lipid + Carbohydrate = Brain

*C. Derived Lipid*

Cholesterol = Steroid = 4 Rings = Animal membrane + Hormone precursor

Prostaglandin = Hormone-like = Inflammation

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### *4. PROTEINS* `2Q Fix = Most Important`  

*A. Amino Acids* = Building Blocks = 20 types

Structure: NH2 - CH - COOH + R group = Variable

             |

             R

Essential AA = 9 = Body nahi banata = MVTLLP HIT = Met, Val, Thr, Leu, Lys, Phe, His, Ile, Try

Non-Essential = 11 = Body banata

Zwitterion = Amino Acid in solution = NH3+ - CH - COO- = Dipolar

*NEET Trick*: Glycine = R = H = Simplest, Optically inactive.  

Proline = Immino acid = Ring structure.

*B. Protein Structure* `Diagram + 1Q`

1. Primary = Sequence of AA = Peptide Bond = CONH = Insulin = 51 AA

2. Secondary = α-Helix + β-Pleated = H-Bond = Keratin, Silk Fibroin

3. Tertiary = 3D = S-S, H-Bond, Ionic = Myoglobin = Functional

4. Quaternary = >1 Polypeptide = Haemoglobin = 2α + 2β = 4 Chains

*NEET Point*: Primary structure agar change = Protein function change = Sickle Cell Anaemia = Glu → Val.

*C. Types of Protein*

Fibrous = Secondary = Structural = Collagen, Keratin = Insoluble

Globular = Tertiary = Functional = Enzyme, Hormone, Antibody = Soluble

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### *5. NUCLEIC ACIDS* `DNA vs RNA = 1Q`  

*A. Structure*

Nucleotide = Nitrogen Base + Pentose Sugar + Phosphate

Nucleoside = Nitrogen Base + Pentose Sugar = No Phosphate

Base: Purine = A, G = 2 Rings, Pyrimidine = C, T, U = 1 Ring

Sugar: DNA = Deoxyribose, RNA = Ribose

Bond: N-glycosidic = Base + Sugar, Phosphodiester = Between Nucleotides

*B. DNA vs RNA* `Table Pakka`

**Feature** **DNA** **RNA**

**Sugar** Deoxyribose Ribose

**Base** A, T, G, C A, U, G, C

**Strand** Double Helix Single

**Function** Genetic Material Protein Synthesis

**Types** B-DNA = Right handed mRNA, tRNA, rRNA

*Chargaff Rule*: A=T, G≡C. Purine = Pyrimidine.  

*NEET 2022*: If A=20% then T=20%, G+C=60% so G=30%, C=30%.

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### *6. ENZYMES* `2Q Fix = Sabse Scoring`  

*A. Basics* `NEET Fav`

Enzyme = Protein = Ribozyme = RNA enzyme = Only exception

Holoenzyme = Apoenzyme + Cofactor

Cofactor = Prosthetic group = Tight = Haem, Coenzyme = Loose = NAD, NADP

Metal ions = Activator = Zn = Carboxypeptidase

*B. Mechanism*

E + S → ES Complex → EP Complex → E + P

Active Site = Pocket = Substrate binds = Specific

Activation Energy = Enzyme kam kar deta = Rate badh jaata

*C. Theories* `1Q`

1. Lock & Key = Emil Fischer = Rigid = Substrate = Key, Enzyme = Lock

2. Induced Fit = Koshland = Flexible = Hand-in-Glove model = Accepted

*D. Factors Affecting Enzyme Activity* `Graph Wala Q`

1. Temperature = Bell Curve = Optimum 37°C Human = Q10 = 2-3

2. pH = Bell Curve = Pepsin = 2, Trypsin = 8, Most = 6-8

3. Substrate Conc = Hyperbolic = Vmax pe saturate = Km = 1/2 Vmax

   Km = Michaelis Constant = Low Km = High Affinity

*E. Enzyme Inhibition* `NEET 2024, 2021`

1. Competitive = Inhibitor = Substrate jaisa = Vmax same, Km badh jaata

   Ex: Malonate vs Succinate for Succinic dehydrogenase

2. Non-Competitive = Inhibitor = Allosteric site = Vmax kam, Km same

   Ex: Cyanide for Cytochrome oxidase

*F. Classification* `Trick: OTHLIL`

1. Oxidoreductase = O = Oxidation-Reduction = Dehydrogenase

2. Transferase = T = Group transfer = Kinase

3. Hydrolase = H = Hydrolysis = Pepsin, Trypsin

4. Lyase = L = Remove group = Decarboxylase

5. Isomerase = I = Isomer banata = Phosphohexose isomerase

6. Ligase = L = Joining = C-C bond = DNA Ligase

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### *7. LAST 5 YEAR PYQ ONE LINERS* `Ratta Maar Le`  

1. *Km Value* = Substrate conc at 1/2 Vmax = Low Km = High affinity = NEET 2024  

2. *Competitive Inhibition* = Vmax same, Km increase = Malonate = NEET 2024  

3. *Prosthetic Group* = Tightly bound = Haem in Catalase = NEET 2023  

4. *Reducing Sugar* = Maltose + Lactose = Not Sucrose = NEET 2023  

5. *Phosphodiester Bond* = Between nucleotides = DNA backbone = NEET 2022  

6. *Zwitterion* = Amino acid in solution = NEET 2022  

7. *Glycogen* = α 1,4 + α 1,6 = Animal starch = NEET 2021  

8. *Chitin* = N-acetyl glucosamine = Fungi cell wall = NEET 2021  

9. *Ribozyme* = RNA enzyme = Not protein = NEET 2020  

10. *Essential Amino Acid* = 9 = Valine, Leucine = NEET 2020  

11. *Collagen* = Most abundant protein in animal = NEET 2019  

12. *Inulin* = Polymer of Fructose = GFR = NEET 2019  

13. *Peptide Bond* = CONH = Between AA = NEET 2018  

14. *Cellulose* = β 1,4 = Straight chain = NEET 2017  

15. *Lipid in Acid Insoluble* = Form vesicles = NEET 2016  

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### *8. GOOGLE SE HATKE TRICKS* 🔥  

*A. Amino Acid Yaad Karne ka Tareeka*

Essential 9: PVT TIM HLL = Private TIM Hall

Pro, Val, Thr, Try, Ile, Met, His, Lys, Leu

*B. Enzyme Class Trick: OTHLIL*

O = Oxidation, T = Transfer, H = Hydrolysis, L = Lyase = Todna, I = Isomer, L = Ligase = Jodna

*C. Km Value ka Matlab*

Km = 50 Shades of Enzyme = Km kam = Enzyme substrate se chipka rehta = Affinity high

Agar exam me puche: Which has highest affinity = Lowest Km wala

*D. DNA ka Hisab*

Agar A = 30% to T = 30% = Total 60%

Bacha 40% = G + C, to G = 20%, C = 20%

Purine = A+G = 30+20 = 50%, Pyrimidine = T+C = 30+20 = 50%

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*Diagrams for NEET*: Enzyme Action, DNA Double Helix, α-Helix + β-Pleated, tRNA Clover Leaf  

*4-5Q Pakka Distribution*:  

1Q = Carbo/Protein/Lipid basic, 1Q = DNA/RNA, 2Q = Enzyme = Km + Inhibition + Class, 1Q = Match column