Distinguish passive and active transport — Hinglish notes

2.4.6 · Biology › Cell Membrane & Transport

HUM KYA distinguish kar rahe hain?

Sabse gehri dividing line yeh nahi hai ki "kya isme protein use hota hai?" (kuch passive transport bhi proteins use karta hai). Asli line yeh hai:

$Direction relative to the gradient \Rightarrow Energy needed or not$

KYUN direction energy cost decide karti hai? (Scratch se derive karo)

Sab kuch free energy se shuru hota hai — ek mole solute ko side $1$ se side $2$ move karne ki:

$Δ G = R T ln \frac{C _{2}}{C _{1}} + z F Δ V$

Chalo ise term by term banate hain — yeh aisa kyun dikhta hai?

Concentration term $R T ln (C_{2} / C_{1})$ .
- Log kyun? Entropy of mixing $ln (concentration)$ ke saath scale karti hai. Particles ko phailana disorder badhata hai, aur disorder change number density mein logarithmic hota hai.
- Agar $C_{2} < C_{1}$ (dilute side ki taraf move karna), toh $ln (C_{2} / C_{1}) < 0$ , isliye yeh term negative hai.
Electrical term $z F Δ V$ (ions ke liye, charge $z$ , Faraday constant $F$ , voltage difference $Δ V$ ).
- Kyun? Charge ko voltage ke across move karne ka kaam = charge × voltage.
- Concentration term ke saath milke yeh electrochemical gradient banata hai.

YAHI answer hai question ka: passive transport ka hamesha $Δ G < 0$ hota hai, toh nature kaam karta hai. Active transport mein $Δ G > 0$ hota hai, isliye cell ko $A T P$ use karke "pay" karna padta hai.

KAISE: sub-types jo tumhe pehchanne chahiye

Feature	Simple diffusion	Facilitated diffusion	Primary active	Secondary active
Class	Passive	Passive	Active	Active
Direction	gradient ke saath	gradient ke saath	gradient ke against	gradient ke against (driven solute)
Protein?	Nahi	Haan (channel/carrier)	Haan (pump)	Haan (co-transporter)
Energy source	gradient	gradient	direct $A T P$	primary pump dwara banaya gradient
Example	$O_{2}$ , $C O_{2}$	glucose via GLUT, ions via channels	$N a^{+} / K^{+}$ ATPase	$N a^{+}$ -glucose symport (SGLT)

Figure — Distinguish passive and active transport

Worked Examples

Common Mistakes (Steel-manned)

Recall Feynman: ek 12-saal ke bachche ko explain karo

Ek pahaad imagine karo marbles ke saath. Passive transport matlab marbles ko neeche roll hone do — woh khud karte hain, tumhe push nahi karna. Active transport tab hota hai jab tum chahte ho marble upar jaye — tumhe use push karna padta hai, aur push karna tumhe thaka deta hai (yahi cell ka $A T P$ "energy snacks" jalana hai). Kuch marbles ek slide se neeche roll karte hain (yeh ek protein channel hai) — phir bhi neeche roll kar rahe hain, phir bhi free hai. Toh sawaal kabhi "kya slide hai?" nahi hota — sawaal yeh hai "kya marble neeche ja raha hai (free) ya upar (energy lagti hai)?"

Active-Recall Flashcards

Kaun sa ek factor decide karta hai ki transport active hai ya passive?

Electrochemical gradient ke relative movement ki direction (neeche = passive, upar = active).

Kya facilitated diffusion ko ATP chahiye?

Nahi — yeh passive hai; protein sirf downhill movement ke liye raasta deta hai.

Membrane ke across solute move karne ki free-energy equation likho.

Δ G = R T ln (C_{2} / C_{1}) + z F Δ V

Passive vs active transport mein

Δ G

ka sign?

Passive

Δ G < 0

(spontaneous); active

Δ G > 0

(energy input chahiye).

Primary active transport kya hai?

Transport jo directly ATP hydrolysis se power hota hai (e.g. Na⁺/K⁺ ATPase).

Secondary active transport kya hai?

Uphill transport jo ek second ion ke downhill flow se power hota hai jiska gradient ek primary (ATP-using) pump ne banaya hota hai.

Na⁺/K⁺ pump active kyun hai?

Yeh Na⁺ bahar aur K⁺ andar dono ko unki pehle se higher sides ki taraf move karta hai (uphill), isliye ΔG>0, ATP chahiye.

Kya osmosis active hai ya passive?

Passive — paani aquaporins ke through apne gradient ke neeche diffuse karta hai, koi ATP nahi.

Active transport drive karne ke liye ATP hydrolysis ka approx ΔG?

Lagbhag −30.5 kJ/mol.

Concentration term mein logarithm kyun hota hai?

Kyunki particles ko mix/spread karne ki entropy ln(concentration) ke saath scale karti hai.

Connections

Cell Membrane Structure — fluid mosaic channels aur pumps provide karta hai.
Facilitated Diffusion — passive lekin protein-mediated.
Sodium-Potassium Pump — classic primary active example.
Osmosis and Water Potential — passive water movement.
ATP and Cellular Energy — active transport ke liye energy ka source.
Electrochemical Gradient — concentration + charge ko combine karta hai.
Nernst Equation — electrical part $z F Δ V$ ko quantify karta hai.