Water, PH and buffer

Specific properties of water

Hydrogen binding,

Acidity, H+, PH and buffer

مبحث این آموزشی اهداف

: کلی آن اهداف مبحث این ارائه از هدف : دانشجو که است

•. نماید درک را بیوشیمی علم اصول

مفهوم • و آن حیاتی نقش آب، ویژه خواص

PH. بفهمد را

•. نماید درک را آن نقش و بافر ماهیت

: ویژه این اهداف آموزش از پس دانشجو رود می انتظارباشد قادر :مبحث

. نماید بندی تقسیم و تعریف را بیوشیمی علم. نماید فهرست را آن اجزاء اصلی نقش و بندی تقسیم را سلولها. نماید بندی تقسیم و تعریف را بیوملکولها. دهد توضیح را آن علل و آب معمول غیر خواص. نماید مقایسه را قطبی غیر و قطبی ترکیبات. دهد توضیح را هیدروفوبیک و هیدروژنی پیوندهای و هیدروژن یون غلظت محلول، یک اسیدیته .PHارتباط دهد شرح را. نماید مشخص را آن حیاتی اهمیت و نموده تعریف را بافر. نماید مشخص را آنها اهمیت و تعریف را ضعیف باز و اسید تفسیر را بافر تهیه با را آن ارتباط و ضعیف اسید تیتراسیون منحنی

نماید.. ببرد نام را بیولوژیک بافرهای

 

Biochemistry Biochemistry is the Chemistry of life(Gk ,bios “life” Area for study: cell biology, molecular biology and molecular

genetics Aim of Biochemistry: Describe and explain ,in molecular

terms ,all chemical process of living cells( exm. contractibility in muscle cells)

How life began Scope of biochemistry

Classification Medical biochemistry

• General biochemistry

• Clinical biochemistry

Interrelationship of biochemistry and medicine Two – way street(structure and function:

normal and sickle cell Hb,PKU,alkaptonuria,….)

Health All disease has a biochemical basis Treatment of disease Inborn error of disease

Water, PH and buffer

Example of the two-way street connecting bioch. And medicine

MEDICINE

LIPID

ATHERO-SCLEROSIS Diabetes mellitus

Carbohydrates

Biochemistry

proteins

Sickle cell anemia

Nucleic acids

Genetic disease

Normal biochemical processes are the basis of health

WHO and define of health Biochemical research has impact on

nutrition and preventive medicine

Water, PH and buffer

A knowledge of Biochemistry is essential to all life sciences

Genetic, Physiology Immunology Pharmacology& pharmacy Toxicology Pathology, Microbiology, Zoology, Botany RESUT; Biochemistry as common language

Human genome project(HGP)

Sequencing of human genome(1990,2000)

International human genome sequencing consortium and Celera Genomics

This project completed in 2003 (after 50ys discovery of ds DNA)

HGP had many effects on research Human genome project

HGP

PROTEOMICS

BIOTECNOLOGY

BIOETHICS

Synthetic biology

Molecular diagnosis

Stem cell biology

bioengineering

metabolomics

Cell as unit of life

Prokaryote Eukaryote Cell organelle

• Cell membrane

• Cytosol

• Nucleus

• Mitochondria

• Endoplasmic reticulum

• Golgi

Prokaryotic cell

Eukaryotic cell

Cell fractionation

Cell suspension (Blender) Cell homogenization (Poter) Cell extract Centrifugation

• Density gradient

• Sequential sedimentation

• Sequential floatation

Cell fractionation

Purification techniques

Simple centrifugation Salting out Ultracentrifugation Dialysis Electrophoresis Chromatography

• Gel filtration

• Ion exchange chromatography

• Affinity chromatography

Centrifugation

Column chromatography

Column chromatography

Paper chromatography

Paper Electrophoresis

Gel Electrophoresis

Dialysis

Water and pH TWO- THIRD OF TOTAL BODY WEIGHT(55-65%) IN MEN AND 10%

LESS IN WOMEN It is distributed in intracellular and extracellular fluid Regulation of water balance depends on hypothalamic

mechanism ADH(2% increase in extracellular fluid osmolarity) Kidney And others Non osmotic mechanism(10% decrease in extracellular volume Physiologic pH and buffer systems( bicarbonate, phosphate and

proteins)

Special properties of water

Water, the most vital molecule

• High melting point

• High boiling point

• High thermal content

• High dielectric constant

• …………………………..

Polar nature

Water

Hydrogen bonds

H-bonding of water molecules

Polar compounds

Polar (hydrophilic) molecules

Urea

Ionic (hydrophilic) molecules

Non-polar (hydrophobic) molecules

Water ionization

Ionization of water

H2O ↔ H+ + OH-

K= [H+] [OH-] / [H2O] = 1.8 × 10-16

K= [10-7][10-7]/[55.56]=1.8x10-16 mol/L

Kw =(K)[H2O]= [H+] [OH-] = 1 × 10-14

(1.8x10-16 mol/L)(55.56)=1X10-14(mol/l)2

PH = -log [H+]

PH + POH = 14

What is a Buffer?

introduction: Definition of acid or base Strong acid H2SO4 2H+ +SO4-2 Strong base NaOH Na+ +OH- Weak acid and base

What is a Buffer?

A buffer consists of a mixture of a weak acid and conjugated base.

An acid is a proton donor and base is a proton acceptor.

AH ↔ A- + H+

Proton donor ↔ proton acceptor

Weak acid ↔ conjugated base

HA A- + H+ Ka =[A-][H+]/[HA] [H+]=Ka[HA]/[A-] Log[H+]=log(ka [HA]/[A-]) Log[H+]=logka+log[HA]/[A-] -Log[H+]=-logka-log[HA]/[A-] pH=pKa+log[A-]/[HA]

Henderson – Haselbach equation

Henderson – Haselbach equation

Relation between PH and base to acid ratio described by Henderson – Haselbach equation.

Buffer capacity

Buffer systems tends to be most effective when the PH is equal to their weak acid PKa. (a range PKa±1)

More concentrated buffers are more effective.

Titration curve for weak acid

CH3COOH

CH3COOH

CH3COO-

CH3COO-

PK

Titration curve of weak acids

Titration curve of Glycine(amino acid)