This slide tries to show how elements can turn into molecules and then complex structures and further develop into organs for building a living organism. This slide is adapted from "Campbell Biology" and for further studies, you can refer to the second chapter of the book. The slide is prepared for freshman Bachelor's students.

1. The Chemistry of Life
(Part One)
University of Tehran
Ahmad V.Kashani, PhD

2. Outlines
• Chemical composition of life:
• Elements and compounds
• Elements’ properties and the structure of the atoms
• Molecules and their formation and function
• Chemical reactions and chemical bonds
• Formation of bonds with Carbon
• Carbon: The backbone of Life
• Hydrocarbons and Isomers
• The molecules of Life
• Polymers vs monomers

3. Outlines
• The molecules of Life
• Carbohydrates
• Monosaccharides
• Disaccharides
• Oligosaccharides
• Polysaccharides
• Lipids
• Proteins
• Nucleic acid

4. Elements and Compounds

5. Elements and Compounds

6. Elements’ properties and the structure of their atoms
• Atomic Number:
• Number of protons= number of
electrons in a neutral atom
• Atomic Mass:
• Number of protons + neutrons
• Isotopes
• Radioactive tracers

7. Elements’ properties and the structure of their atoms
• Electron shells of the
first 18 elements of
the periodic table.

8. Elements’ properties and the structure of their atoms
• Electron Orbitals:

9. • Chemical Bonds:
• Strong Bonds
• Covalent Bonds
• Ionic Bonds
• Weak Bonds
• Hydrogen Bond
• Van Der Waals interactions
Molecules and their formation and function

10. • Covalent Bond: is the sharing of
a pair of valence electrons by
two atoms.
• Most of the strongest chemical
bonds are covalent bonds,
which link atoms to form a
cell’s molecules.
Molecules and their formation and function

11. • Ionic Bond: involves
the electrostatic
attraction between
oppositely charged ions,
and is the primary
interaction occurring in
ionic compounds.
• Charged ions can be:
• Positive (Cation)
• Negative (Anion)
Molecules and their formation and function

12. • Hydrogen bonds: When a
hydrogen atom is covalently
bonded to an electronegative
atom, the hydrogen atom has a
partial positive charge that allows
it to be attracted to a different
electronegative atom nearby.
• In living cells, the electronegative
partners are usually oxygen or
nitrogen atoms.
Molecules and their formation and function

13. • Van Der Waals interactions:
Occur only when atoms and
molecules are very close
together. Ever-changing regions
of positive and negative charge
enable all atoms and molecules
to stick to one another.
Molecules and their formation and function

14. • Van der Waals interactions,
hydrogen bonds, ionic bonds, and
other weak interactions may
form not only between molecules
but also between parts of a large
molecule, such as a protein.
Molecules and their formation and function

15. Chemical reactions and chemical bonds

16. Carbon
• The backbone of life
• Organic chemistry
• Study of carbon compounds

17. Formation of bonds with Carbon

18. Formation of bonds with Carbon

19. Formation of bonds with Carbon
• Carbon skeleton and
molecular diversity:
• hydrocarbons, organic
molecules consisting of only
carbon and hydrogen
• Hydrocarbons are the major
components of petroleum,
which is called a fossil fuel
because it consists of the
partially decomposed
remains of organisms that
lived millions of years ago.

20. Isomers
• Isomers are compounds
that have the same
numbers of atoms of the
same elements but
different structures and
hence different properties.
• Isomers:
• Structural isomers
• Cis-trans isomers
• Enantiomers

21. The Molecules of Life
• Carbohydrates
• Lipids
• Proteins
• Nucleic acid

22. Polymers vs monomers
• Synthesis or breakdown of
polymers:
• E.g: ATP
• E.g: GTP

23. Carbohydrates – Fuel and Building material
• Carbohydrates include sugars
and polymers of sugars.
• Monomers joined by covalent
bond
• Variety of forms:
• Monosaccharides
• Disaccharides
• Oligosaccharides
• Polysaccharides

24. Carbohydrates – Monosaccharides
• Generally have molecular formulas
that are some multiple of the unit
CH2O e.g: Glucose (C6H12O6)

25. Carbohydrates – Disaccharides
• Consists of two monosaccharides
joined by a glycosidic linkage, a
covalent bond formed between
two monosaccharides by a
dehydration reaction (glyco refers
to carbohydrate).

26. Carbohydrates – Disaccharides

27. Carbohydrates – Oligosaccharides
• An oligosaccharide is a
saccharide polymer
containing a small number
of monosaccharides
(typically 3-10)
• Oligosaccharides can have
many functions including
cell recognition and cell
binding.

28. Carbohydrates – Polysaccharides
• Polymers with a few
hundred to a few thousand
monosaccharides joined
by glycosidic linkages.
• Functions:
• Storage Materials
• In plants: starch
• In animals: Glycogen – stored
mainly in liver and muscle
cells
• Building Materials
• Cellulose

29. Carbohydrates – Polysaccharides

30. Summary
• Chemical composition of life:
• Elements and compounds
• Elements’ properties and the structure of the atoms
• Molecules and their formation and function
• Chemical reactions and chemical bonds
• Formation of bonds with Carbon
• Carbon: The backbone of Life
• Hydrocarbons and Isomers
• The molecules of Life
• Polymers vs monomers

31. Summary
• The molecules of Life
• Carbohydrates
• Monosaccharides
• Disaccharides
• Oligosaccharides
• Polysaccharides

32. Questions…?
THANK YOU!