Chapter 2: Cell Chemistry and Bioenergetics

# Cell Chemistry and Bioenergetics

* Until the 19th century, people knew “Vital Force” to be responsible for all the distinctive properties.
* **Organic Chemistry:** It is the study of hydrocarbons and their derivatives.

## Why chemistry of life is indeed special?

* Firstly, it is based on carbon compounds.
* Secondly, cells are 70% water, and life depends largely on chemical reactions.
* Thirdly, cell chemistry is enormously complex.

### Chemical components of cell:

* It is made up of mainly four elements including carbon(C), hydrogen(H), nitrogen(N), and oxygen(O).
* A cell is formed from carbon compounds.
* Carbon has a property of catenation which helps in the self-linking of atoms of an element to form chains and rings.
* Carbon has a covalency of four.
* It confers stability to form large molecules.
* A cell also contains small organic molecules:
* Sugars
* Fatty Acids
* Nucleotides
* Amino Acids
* Types of bonds:
* **Covalent Bond:** A chemical bond that involves the sharing of electrons to form electron pairs between atoms.
* **Non-Covalent Bond**: The bond in which no sharing of electron pairs takes place is called a non-covalent bond.
* **Hydrogen Bond**: A hydrogen bond is the interaction of a hydrogen atom with an electronegative atom, such as nitrogen, oxygen, or fluorine from another molecule.
* Non-Covalent attractions:
* Electrostatic attractions (ionic bonds)
* Hydrogen Bonds
* Vander Waal attractions
* Hydrophobic force
* **Acids**: Substances that release protons when they dissolve in water thus forming H3O+ are termed acids.
* **Strong** **Acids**: Those who lose their protons quickly. Eg: Hydrochloric acid (HCL).
* **Weak** **Acids**: Those who hold on to their proton more tightly when dissolved in water. Eg: Acetic Acid (C2H5COOH)
* **Bases**: The opposite of acid is a base. Substances that accept a proton from a water molecule are called bases.
* **Strong Base:** Those who readily dissociate in water to form respective ions. Eg: Sodium Hydroxide (NaOH)
* **Weak Base**: Those who have a weak tendency to reversibly accept a proton from water. Eg: Ammonia (NH3)
* **pH Scale**: The concentration of H3O+ is expressed using a logarithmic scale called as pH scale.
* Pure water has a pH of 7.0.
* An acidic solution has a pH of