Water, PH and buffer
Specific properties of water
Hydrogen binding,
Acidity, H+, PH and buffer
‫اهداف آموزشی این مبحث‬
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‫اهداف کلی‪ :‬هدف از ارائه این مبحث آن است که دانشجو‪:‬‬
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‫• خواص ویژه آب‪ ،‬نقش حیاتی آن و مفهوم ‪ PH‬را بفهمد‪.‬‬
‫• ماهیت بافر و نقش آن را درک نماید‪.‬‬
‫اصول علم بیوشیمی را درک نماید‪.‬‬
‫اهداف ویژه‪ :‬انتظار می رود دانشجو پس از آموزش این مبحث قادر باشد‪:‬‬
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‫علم بیوشیمی را تعریف و تقسیم بندی نماید‪.‬‬
‫سلولها را تقسیم بندی و نقش اصلی اجزاء آن را فهرست نماید‪.‬‬
‫بیوملکولها را تعریف و تقسیم بندی نماید‪.‬‬
‫خواص غیر معمول آب و علل آن را توضیح دهد‪.‬‬
‫ترکیبات قطبی و غیر قطبی را مقایسه نماید‪.‬‬
‫پیوندهای هیدروژنی و هیدروفوبیک را توضیح دهد‪.‬‬
‫ارتباط اسیدیته یک محلول‪ ،‬غلظت یون هیدروژن و ‪ PH‬را شرح دهد‪.‬‬
‫بافر را تعریف نموده و اهمیت حیاتی آن را مشخص نماید‪.‬‬
‫اسید و باز ضعیف را تعریف و اهمیت آنها را مشخص نماید‪.‬‬
‫منحنی تیتراسیون اسید ضعیف و ارتباط آن را با تهیه بافر را تفسیر نماید‪.‬‬
‫بافرهای بیولوژیک را نام ببرد‪.‬‬
Biochemistry
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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
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General biochemistry
Clinical biochemistry
Water, PH and buffer
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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
Example of the two-way street
connecting bioch. And medicine
Biochemistry
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Nucleic acids
Genetic disease
proteins
Sickle cell anemia
MEDICINE
LIPID
ATHEROSCLEROSIS
Carbohydrates
Diabetes mellitus
Water, PH and buffer
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Normal biochemical processes are the
basis of health
WHO and define of health
Biochemical research has impact on
nutrition and preventive medicine
A knowledge of Biochemistry is
essential to all life sciences
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Genetic, Physiology
Immunology
Pharmacology& pharmacy
Toxicology
Pathology, Microbiology, Zoology, Botany
RESUT; Biochemistry as common language
Human genome project(HGP)
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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
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Human genome project
PROTEOMICS
metabolomics
bioengineering
Stem cell biology
BIOTECNOLOGY
HGP
BIOETHICS
Synthetic biology
Molecular diagnosis
Cell as unit of life
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Prokaryote
Eukaryote
Cell organelle
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Cell membrane
Cytosol
Nucleus
Mitochondria
Endoplasmic reticulum
Golgi
Prokaryotic cell
Eukaryotic cell
Cell fractionation
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Cell suspension (Blender)
Cell homogenization (Poter)
Cell extract
Centrifugation
• Density gradient
• Sequential sedimentation
• Sequential floatation
Cell fractionation
Purification techniques
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Simple centrifugation
Salting out
Ultracentrifugation
Dialysis
Electrophoresis
Chromatography
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Gel filtration
Ion exchange chromatography
Affinity chromatography
Centrifugation
Column chromatography
Column chromatography
Paper chromatography
Paper Electrophoresis
Gel Electrophoresis
Dialysis
Water and pH
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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
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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+ + OHK= [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?
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introduction:
Definition of acid or base
Strong acid H2SO4
2H+ +SO4-2
Strong base NaOH
Na+ +OHWeak acid and base
What is a Buffer?
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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
Henderson – Haselbach equation
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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
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Relation between PH and base to acid
ratio described by Henderson –
Haselbach equation.
Buffer capacity
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Buffer systems tends to be most
effective when the PH is equal to their
weak acid PKa. (a range PKa±1)
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More concentrated buffers are more
effective.
Titration curve for weak acid
CH3COO-
CH3COOH
CH3COO-
PK
CH3COOH
Titration curve of weak acids
Titration curve of Glycine(amino acid)