The Chemistry Of Life

Dr. Mona Hamed El-Fatatry

Introduction to the chemistry of life

Biochemistry is a wonderfully interesting topic that REFLECT the chemical structure of the molecules that make us up.

Scientists use biochemistry today to explain how our body works

Importance of Biochemistry With biochemistry we can 1- Make medicines that affect the body, 2-Crack the DNA code, 3-Eat the right foods, 4-Explain diseases, 5-Observe chemical reactions,

An In trodu cti on t o the ch emis tr y of l ife Atom

The atom is the smallest unit of element that can exist stably .

Atoms, molecules and compounds Atom : is the smallest unit of element . Element : is the chemical substance whose atoms are all of the same type e.g. iron Compound : is the chemical substance that contain more than one type of atom

Atom

The human body is made up mainly of

( Carbon , Hydrogen

,Oxygen and Nitrogen ) arranged in different variations to form different compounds so most of the body is formed of organic compounds and the human body also contain inorganic compounds Atom

Carbon The main element present in organic molecules is carbon. Carbon is the building block of living things Comprises 18% of body by weight Forms four covalent bonds Can form single or double bonds Can build micro- or macromolecules

Atom Why we study atoms? Through atoms we can understand: How compounds are formed The chemistry of bonds Understand chemical reactions as chemical reactions are Atoms binding and breaking A +B AB

Atom is formed of a central Atomic struct ur e nucleus containing protons and neutrons surrounded by a cloud of electrons in orbital (shells).

Atomic struct ur e

To have different elements they differ in proton number. Number of protons = number of electrons Atomic number : is the number of protons in the nucleus.

Atomic weight : is the sum of protons and neutrons

Atomic st ruct ur e

No. of neutrons = mass No. – atomic No.

Atomic structure

Atomic structure How are electrons arranged in atoms? Arranged in orbitals (shells) around the nucleus. The nearest shell to the nucleus fill first when it is full electrons shift to he second shell . each shell has fixed number of electrons

Examples of electron distribution

1

-

-

2 2

6 8

1

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Isotopes

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Isotopes Isotopes are atoms of the same element with the same number of protons (atomic No.) but different number of neutrons (atomic weight ). Example Isotopes of

Isotopes

Not in book

Radioactive Isotopes Some isotopes as tritium and C-14 have unstable nuclei and emit certain types of radiation ( alpha α , beta β & gamma γ). Medical uses: Cancer treatment e.g. cobalt-60 by γ rays Thyroid gland and radioactive iodine

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Chemical bonds

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Covalent bond It is the sharing of electrons between atoms. It is strong and stable. Most compounds are covalent bonds Example water, O2

Chemical bonds

Ionic bond It is the transfer of electrons from one atom to another, so that we’ll have 2 ions (cation +ve and anion – ve ) attracted to each other. It is weak. Example NaClbonds , CaCl Chemical

Chemical bonds

Chemical bonds Other types: Hydrogen bonds Hydrophobic interactions Van der waal forces Ionic interactions (will be studied with protein structure)

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Electrolytes

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Electrolytes Salts with ionic compounds when dissolved in water an electrolyte is produced ( it can conduct electricity) Importance of electrolytes to human body: Essential for muscle and nerve function. Maintains osmotic pressure in blood and cells. Maintains pH (acid- base) of blood

Electrolytes

Positive electrolytes in the body

Na+ Ca2+ K+ Cations

Electrolytes

ClHCO3PO43Anions

Molecular weight and molar concentaration Molecular weight : It is the sum of atomic weight of the elements forming the molecule e.g. H2O H=1 O=16 Molecular weight of water = 2 H + O = 2*1+16 = 18 What about sodium bicarbonate NaHCO3 Molar concentration: It is for expressing the concentration of substances in the body fluids. Mole (mol) : it is the molecular weight in grams of substance ( one mole O = 16 gm) (H) ? (Na)?

Molecular weight and molar concentaration One mole contain 6.023* 1023 molecules i.e. 16 gm O contain 6.023* 1023 oxygen molecules 1 gm H contain 6.023* 1023hydrogen molecules Molar solution: It is a solution in which one mole of substance is dissolved in one liter 1 molar solution of Na Cl= 23 + 35.5 = 58.5 g per liter 1 molar solution of C = 12 g per liter

Molecular weight and molar concentaration As chemical substances are present in the body in very small amounts Molar = mol/l Millimole = mmol/l Micromoles = μ mol/l I U = international unit ( used for substances of unknown molecular weight e.g. Insulin)

Chemical formula and chemical equation

Not in book

Chemical formula: Valency of element is the number which shows how element combine with each other it is For covalent molecules = number of bonds which the atom can form e.g. C 4 For molecules forming ionic bond = number of electrons transferred( lost or gained) e.g. NaCl Na 1 & Cl 1

Chemical formula and chemical equation

Not in book

Chemical formula: Groups also have valency e.g NO3 has 1 – SO4 has 2.

Not in book

Chemical reaction It consists of substances that react together named reactants producing new substances named products and it is written as follow: Reactants Products A+B C+D Types of writing chemical equation: Work equation Hydrogen + Oxygen water Symbol equation H2 + O2 H2O Balanced equation ( atom equal in both sides ) 2H2 + O2 2H2O

Chemical equations

Chemical reactions

Not in book

A chemical reaction is formation or breaking of chemical bonds. Two general types of reactions: synthesis reactions decomposition reactions. In a synthesis reaction, bonds are formed to join two or more atoms or molecules to make a new compound. In a decomposition reaction, bonds are broken, and a large molecule is changed to two or more smaller ones. One example is the digestion of large molecules of starch into many smaller glucose

Organic compounds to enter chemical reactions are characterized by functional groups:

Functional groups

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Water

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Water

Not in book

Our body can last up to two months without food, but only a few days without water. Our bodies are made up of 55 to 75 per cent water, and we need to drink it to survive.          Hydration is the process of providing an adequate amount of liquid to bodily tissues. If our body does not get enough water, it becomes dehydrated.. Some signs of dehydration are: being thirsty feeling lightheaded, dizzy, or tired rapid heartbeat

Water

Not in Human body is 70% water b o o k

2/3 of our water is inside our cells, 1/3 is outside our cells Why is water important? Water is the solvent for biological systems, so no chemical reactions can occur without it. Types of compounds in relation to water: Hydrophilic compounds = interact (dissolve) with water like –Polar compounds (alcohol , keton,..) –Ionic compounds (NaCl) Hydrophobic compounds = do not interact with water

Water

Water is polar compound

Water

Not in book

Hydrophobic Interactions -A non-polar substance does not readily dissolve in water. -The H-bond network of water reorganizes to accommodate the non-polar solute. -As a result, the

Water

Not in book

Trace elements

Not in book

Trace elements are those that are needed by the body in very small amounts. When they are present in food we often call them minerals, and examples are iron, cobalt, and zinc.

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Acid , alkalis and pH

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Measure of acidity depends on hydrogen [H+] ion concentration. An acid : it is a substance than releases hydrogen [H+] ions when in solution. An alkali ( basic ) : it is a substance that accept hydrogen [H+] ions with release of hydroxyl [OH-] ions when in solution. A salt : it is a substance that releases cations and anions when in solution, like NaCl as it releases [Na+] & [Cl-]

Acid , alkalis and pH

pH values is the measurement of the hydrogen ion concentration in solution. The pH scale ranges from 0 to 14 with 7 the mid point as neutral. pH reading below 7 indicates acid solution. pH reading above 7 indicates alkali solution. pH reading 7 neutral

pH scale

pH sc ale pH scale and body fluids.

pH values in the cell and in the extracellular fluid are kept constant within narrow limits. In the blood, the pH value normally ranges only between 7.35 and 7.45 (see p. 288). This corresponds to a maximum change in the H+ concentration.

pH scale

Buffers A buffer system is a system that maintain the blood pH constant ( homeostasis) i.e. to maintain the blood pH normally . Formed of a chemical or pair of chemicals that minimizes changes in pH by reacting with strong acids or strong bases to transform them into weak acid or weak base. Main organs controls pH are lung and

Buffers Acidosis

Alkalosis

Acidosis is a condition where the blood pH decreases below 7.35

Alkalosis is a condition where the blood pH increase above 7.45

Both a re d amag ing t o th e bo dy Buffers

Than k you Thank you The End