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Biochemistry
Definition
Is the science concerned with various biomolecules that occur in the living cell and organism and their chemical reactions
Aims of biochemistry
1- is to describe and explain in molecular terms all chemical processes of living cell
2- To understand how life is began
3- knowledge of biochemistry is essential to all life sciences
Bio-medicine relationship
All diseases have biomedical bases
Most of biomedical reaction has been discovered after following a course of a disease
Biomedical techniques used for diagnosis of diseases
Biochemistry used for formulation of drugs
In order to study biochemistry a little information should be known about the cell
The cell smallest unit of live capable of doing all living processes
Cell divided into :
1- eukaryotic cell2- prokaryotic cell
Biomolecules
Complex molecules that is formed living organisms they include:
1- carbohydrates
2- protein
3- lipids4- nucleic acids
5- minerals6- vitamins
7- water
All are composed of atoms
All except minerals contain elements of water
All except minerals and water are organic molecules
All except minerals ,water and vitamins yield energy
Homeostasis
Is the maintenance of composition of the internal environment for good health and this include:
1- water distribution
2- pH
3- electrolytes concentration
WATER , pH and BUFFERS
Water
Is the principle end product of oxidative catabolism of food Is the most important molecule for life
No life without water
All elements and processes in some how needs water
Water distribution
This depends on
Control of thirst by hypothalamus
Anti-diuretic hormone
Retention or excretion of water by
-Kidney (micturition)- skin (perispiration)-Lung (respiration)
Water disbalance occurs when there is state of water depletion or excess
Water depletion (dehydration)Result from
1- decrease intake (comma)
2- increase loss (severe sweating, renal loss, diarrhea cholera …
Physical properties of water
1- high heat of vaporization
2- high melting
3- low freezing point
4- neutral pH
solvent Melting point
Boiling
point
Heat of vaporizatio
n
1 water 0 100 22602 methanol -98 65 11003 ethanol -117 78 8544 acetone -95 56 5235 benzene 6 80 3946 chloroform -63 61 2477 Hexane -98 69 423
1- tetrahedral
Chemical properties of water
2- bipolar
3- formation of hydrogen bonds
4- Partial dissociation
5- React as acid or base
6- high ionic product
pH
Is –log [H+]
Normal pH 7.35 – 7.45
pH scale 1—147 neutral
Potential hydrogenHydrogen ion concentration
Molecules that resist change in pH when acid or alkaline are added to a solution
Buffers
They are week acids and their conjugated base
Normal occurring buffers inside human body include:
1- carbonic acid and bicarbonate
2- organic phosphoric acid and phosphate
3- proteins
Covalent bonds
Strong bonds
Needs high energy to be broken
Examples are
Peptide bondsGlycosidic bondsEster bondsDisulfide bridge
Peptide bonds
Covalent bond
Form between amino group of one molecule and carboxyl group on another molecule
Glycosidic bond
Covalent bond
Form between two different alcohol groups Can be
1- N-glycosidic
2- O-glycosidic
3- S-glycosidic
The non-covalent bonds
This include
1- hydrogen bond2- hydrophobic interaction
3- Electrostatic bond
4- Van Der Waal forces
Hydrogen bond
Non-covalent bond
Occur between positive hydrogen ion in a molecule ad negative ion in another one
Is very week bond
The hydrophobic interaction
Is tendency of a molecule for folding around it self to hide the non-polar part from water when put in solution
In this case the polar part come to the out side to contact water
Electrostatic interaction (ionic bridge,salt bridge)
Non-covalent bond
Occur between a positive ion in one molecule and most negative ion in another molecule
Van Der Waal forces
Is the attractive and repulsive forces that occur between two adjacent atoms in a molecule