2.5.1
Har living cell ek chhoti si factory + battery system hai. Factory mein hazaaron chemical reactions chalte hain (yahi metabolism hai), lekin koi bhi reaction free mein nahi hota — har ek ko energy chahiye (yani change karne ki ability). Cell ki rechargeable battery jo woh energy chhote, usable packets mein deliver karti hai woh hai ATP . Yeh teen words samajh lo aur tumhe pata chal jaayega kyun cells ko food, oxygen, aur enzymes ki zaroorat hoti hai.
Metabolism ek living organism ke andar hone waale sum total of all chemical reactions hai jo use zinda, growing, aur responsive rakhti hain.
KYA HAI — Yeh do opposite directions mein split hota hai:
Branch
Direction
Energy
Example
Catabolism bada → chhota todta hai
energy release karta hai (exergonic)
glucose → CO₂ + H₂O
Anabolism chhota → bada banata hai
energy chahiye (endergonic)
amino acids → protein
Kyun is tarah split karte hain? Kyunki life ko ek saath do kaam karne hote hain: energy ke liye fuel demolish karna, aur structures construct karna (DNA, membranes, muscle) jo energy se pay hote hain. Catabolism hai income , anabolism hai spending .
HOW yeh linked hain? Ek shared energy currency ke through — aur woh currency hai ATP . Catabolism battery charge karta hai; anabolism use drain karta hai.
CA tabolism = CA sh-in (breakdown, energy out). AN abolism = AN other thing built (energy in). Ya phir: "Cat s cheezein todte hain, An ts cheezein banate hain."
Energy capacity to do work hai — koi change laana jaise movement, molecules banana, gradient ke against transport, ya heat generate karna.
Kyun energy types ki parwah karein? Kyunki cells energy ko ek form se doosri form mein convert karti hain:
Chemical energy — bonds mein stored (jaise glucose, ATP).Mechanical — muscle contraction.Electrical — nerve impulses, ion gradients.Thermal/heat — body warmth (aksar ek "waste" output hota hai).
Key idea — free energy (G
Kisi molecule ki saari energy usable nahi hoti. Jis part ko cell actually kaam karne ke liye harvest kar sakti hai use Gibbs free energy (G kehte hain. Kisi reaction ke liye jo cheez matter karti hai woh hai change , Δ G
ATP (Adenosine TriPhosphate) cell ki universal energy currency hai: ek nucleotide jo energy ko apne phosphate bonds mein store karta hai aur hydrolysis par release karta hai.
KYA bana hai isse? Teen parts:
Adenine (ek nitrogenous base)Ribose (ek 5-carbon sugar)Teen phosphate groups ek chain mein linked: P–P–P
Kyun bonds mein itni zyada energy stored hoti hai? Last do P–P bonds phosphoanhydride bonds repel karte hain. Unhe todne se woh repulsion relieve hoti hai aur products zyada stable hote hain (resonance + better hydration), isliye bahut saari free energy release hoti hai.
ATP/ADP ko ek rechargeable battery socho. ATP = charged (3 phosphates). ADP = partly drained (2 phosphates). Respiration ise wapas plug in karta hai. Ek cell apna poora ATP pool ek minute mein kai baar cycle karta hai — woh zyada store nahi karta, woh tezi se recycle karta hai.
Coupling: kaise ek useless reaction possible banti hai.
Maano glutamate se glutamine banana ho toh Δ G = + 14 kJ/mol − 30.5 kJ/mol Δ G total = + 14 + ( − 30.5 ) = − 16.5 kJ/mol < 0 Yeh step kyun? Do Δ G Yahi ATP ka poora trick hai.
ATP "income" count karna. Ek glucose fully respired hone par ~30–32 ATP yield karta hai.
Yeh step kyun? Glucose mein ~2870 kJ/mol usable energy hoti hai; use 30 ATP mein capture karna (30 × 30.5 ≈ 915 kJ) matlab cells ~32% efficiency trap karti hain — baaki heat ke roop mein jaati hai (tumhe garam rakhti hai). 100% kyun nahi? T Δ S zaroor disorder ke roop mein disperse hogi.
"ATP bonds 'high-energy' hain kyunki bond khud strong hota hai."
Kyun sahi lagta hai: "high-energy bond" strong bond jaisa lagta hai.
Fix: Yeh bilkul ulta hai — woh unstable/tootne mein aasaan hote hain, aur products kaafi zyada stable hote hain. Energy lower-energy, more stable state mein drop hone se release hoti hai, bond ki strength se nahi.
"Metabolism = sirf food todna (digestion)."
Kyun sahi lagta hai: Hum "metabolism" ko loosely calories burn karne ke liye use karte hain.
Fix: Metabolism dono catabolism aur anabolism hai. Proteins aur DNA banana utni hi metabolism hai jitna glucose todna.
"Anabolism impossible hai kyunki use energy chahiye."
Kyun sahi lagta hai: Δ G > 0 Fix: Yeh akele non-spontaneous hai, lekin ATP ke saath energy coupling combined Δ G
Recall Feynman: explain to a 12-year-oldTumhara body ek busy LEGO city jaisi hai. Metabolism us city mein jo kuch bhi ho raha hai woh sab hai — purani buildings todna aur nayi banana. Koi bhi building ya movement karne ke liye tumhe energy chahiye, jo simply hai "kuch happen karne ki power." Lekin tum poora power plant saath nahi le ja sakte, isliye city chhoti rechargeable ATP batteries use karti hai. Jab tum khaana khaate ho, batteries charge hoti hain. Jab tum move karte ho, sochte ho, ya grow karte ho, ek battery "full" (ATP) se "low" (ADP) ho jaati hai aur woh energy ka pop use hota hai. Phir khaana use wapas charge karta hai — baar baar, poora din.
Metabolism is defined as ek living organism mein hone waale saare chemical reactions ka sum total.
Catabolism vs anabolism (direction & energy) Catabolism bada→chhota todta hai, energy release karta hai (exergonic); Anabolism chhota→bada banata hai, energy chahiye (endergonic).
Energy is defined as capacity to do work (change laana).
The equation linking free energy, enthalpy, entropy Δ G = Δ H − T Δ S
Sign of ΔG for a spontaneous (exergonic) reaction Δ G < 0
Full form of ATP Adenosine Triphosphate.
Three components of ATP Adenine (base) + ribose (sugar) + teen phosphate groups.
The reaction releasing energy from ATP ATP + H₂O → ADP + Pᵢ + energy (hydrolysis).
Approximate ΔG°′ of ATP hydrolysis lagbhag −30.5 kJ/mol (−7.3 kcal/mol).
Why ATP phosphate bonds release much energy phosphate groups ke negative charges repel karte hain; products (ADP + Pᵢ) zyada stable hote hain, isliye phosphoanhydride bond todne par free energy release hoti hai.
What is energy coupling ek endergonic reaction ko ATP hydrolysis ke saath link karna taaki combined ΔG negative ho aur reaction proceed kare.
Which branch of metabolism charges ATP catabolism (breakdown/respiration).
Metabolism: all chemical reactions
Catabolism: breaks big to small
Anabolism: builds small to big
Energy: capacity to do work
Delta G = Delta H - T Delta S
