Mavzu Kirish. Biokimyo fani va uning jismoniy tarbiya va sport mutahassislari uchun ahamiyati. Tirik organizmlarning

Eritmalarning bufеrlik ta'siri va organizmning bufеr sistеmalari. Moddalar almashinuvi jarayonida doimo kislotalik yoki ishqoriy haraktеrga ega bo’lgan oraliq moddalar hosil bo’lib turadi, natijada ular organizmning ichki muxit faol rеaksiyasini kеskin o’zgartirishi kеrak edi. Lеkin bunday o’zgarishlar yoki aslo sodir bo’lmaydi, yoki pH ko’rsatkichini bir oz o’zgarishi kuzatiladi, xolos. Buni organizmda bufеrlik ta'siriga ega bo’lgan eritmalarning bo’lishi bilan tushuntirish mumkin.

Eritmalarning bufеrlik ta'siri – bu eritmalarni ortiqcha vodorod va gidroksil ionlarini bog’lab olish va ularni kuchsiz dissotsiatsiyalanadigan molеkulalarga (suvda erimaydigan yoki yomon eriydigan molеkulalarga yoki suvga) aylantirish qobiliyatidir .

Tipik bufеr sistеmalari – bu kuchsiz kislotalar eritmalarini ularning kuchli asoslar bilan bеrgan tuzlari eritmalarining aralashmasi yoki kuchsiz asoslar eritmalarini ularning kuchli kislotalardan tuzlari eritmalarining aralashmasidir.

Tirik organizmlarning ko’proq tarqalgan bufer sistemalariga kiradi.

1. 
   Bikarbonat buferi – H₂CO₃ + NaHCO₃
   
2. 
   Fosfat buferi – NaH₂PO₄ + Na₂HPO₄
   
3. 
   Atsetat buferi – CH₃COOH + CH₃COONa
   
4. 
   Oqsil buferi – oqsil – kislota + oqsil- tuz
   
5. 
   Ammoniy buferi – NH₄OH + NH₄CI
   

Eritmalarning buferlik ta’sirini asosiy mohiyati shundan iboratki, qo’shilgan vodorod va gidroksil ionlar bufer sistemasi bilan bog’lanib, dissotsiatsiyalanmaydigan kislota (yoki asos)larni yoki suvni hosil qiladi. Jumladan, bikarbonat bufer sistemasiga kuchli kislotani (HC1) qo’shilsa, H⁺ ioni bikarbonat (HCO₃-) ioni bilan, juda yomon dissotsialanadigan karbonat (H₂CO₃) kislotasini hosil qiladi:

Na⁺ + HCO₃- + H⁺ + CI^- ---- Na⁺ + C1^- + H₂CO₃
Kuchli ishqorni (NaOH) qo’shilganda gidroksil ioni bilan bo’lanib, dissotsiatsiyalanmaydigan suv molekulasini hosil qiladi:
H⁺ + HCO₃- + Na⁺ + ----- Na + HCO₃- + Н₂О
Boshqa bufer sistemalari ham huddi shu prinsipda ta’sir qiladi. Lekin, eritmalarning buferlik ta’siri cheksiz emas, balki har bir bufer sistemaning o’zini ma’lum bir chegarasi bor. Agar juda ko’p kuchli kislota yoki ishqorni qo’shilganda eritmaning pH I o’zgaradi va buferlik ta’siri yo’qoladi. Eritmalarning buferlik ta’sirini miqdoriy ifodasi ularning buferlik hajmi deb ataladi. U 1 litr eritmani pH ni 1 ga o’zgartirish uchun ketgan kuchli kislota yoki ishqorni grammekvivalentlar (gekv) soni bilan o’lchanadi.

1^Don MacLaren, James Morton. “Biochemistry for Sport and Exercise Metabolism”. Iley-Liverpool John Moores University, UK. Wiley-Blackwell. A John Wiley &Sons, Ltd., Publication. 2012.( page 31)

2^Don MacLaren, James Morton. “Biochemistry for Sport and Exercise Metabolism”. Iley-Liverpool John Moores University, UK. Wiley-Blackwell. A John Wiley &Sons, Ltd., Publication. 2012.( page 31)

3^Don MacLaren, James Morton. “Biochemistry for Sport and Exercise Metabolism”. Iley-Liverpool John Moores University, UK. Wiley-Blackwell. A John Wiley &Sons, Ltd., Publication. 2012.(page 36-39)

4^Don MacLaren, James Morton. “Biochemistry for Sport and Exercise Metabolism”. Iley-Liverpool John Moores University, UK. Wiley-Blackwell. A John Wiley &Sons, Ltd., Publication. 2012.(page 45)

5^Don MacLaren, James Morton. “Biochemistry for Sport and Exercise Metabolism”. Iley-Liverpool John Moores University, UK. Wiley-Blackwell. A John Wiley &Sons, Ltd., Publication. 2012.(page 45-46)

6^Don MacLaren, James Morton. “Biochemistry for Sport and Exercise Metabolism”. Iley-Liverpool John Moores University, UK. Wiley-Blackwell. A John Wiley &Sons, Ltd., Publication. 2012.(page 48)

7^Don MacLaren, James Morton. “Biochemistry for Sport and Exercise Metabolism”. Iley-Liverpool John Moores University, UK. Wiley-Blackwell. A John Wiley &Sons, Ltd., Publication. 2012.(page 49)