1. Lecture 6 Acids and Bases & Organic Chemistry Ozgur Unal
NIS - BIOLOGY
Lecture 6
Acids and Bases
& Organic Chemistry
Ozgur Unal

2. Acids and Bases
Remember the polarity of water that can dissolve sugar and salt.
A substance that contain H might release a hdrogen ion (H+) because it is attracted to the Oxygen in water.
These substances are called acids.
Example: Hydrochloric acid (HCl)
Substances that release hydroxide ion (OH-) when dissolved in water are called bases.
Example: Sodium hydroxide (NaOH)

3. pH and Buffers The concentration of H+ or OH+
determines the strength of an acid
or a base.
The measure of concentration of
these ions in a solution is called pH.
pH values lower than 7 indicates
acids, whereas values higher than 7
indicates bases. Water has a pH of 7.

4. pH and Buffers
The majority of biological processes carried out by cells occure between pH 6.5 and 7.5.
In order to maintain homeostasis, it is important to control this pH level.
Buffers are mixtures that can react wit acids or bases to keep the pH within a particular range.
Your blood contains buffers that keep the pH about 7.4

5. Organic Chemistry
Almost all biological molecules contain the element Carbon > life on Earth is carbon-based.
Organic chemistry is the study of organic compounds – compounds that contain carbon.
Why is carbon so special?
Carbon has 4 electrons in its
outermost shell, therefore it can form
4 covalent bonds.
Carbon atoms can bond to each other.
There is a variety of important organic compounds that can be formed thanks to carbon.

6. Macromolecules Carbon atoms can be joined to form carbon molecules.
Cells store smaller carbon compounds to build larger molecules.
Macromolecules are large molecules that are formed by joining smaller organic molecules together.
Biological macromolecules are organized into four major categories:
Carbohydrates
Lipids
Proteins
Nucleic Acids

7. Lecture 7 Biological Macromolecules Ozgur Unal
NIS - BIOLOGY
Lecture 7
Biological Macromolecules
Ozgur Unal

8. Carbohydrates Carbohydrates are composed of hydrogen,
oxygen and carbon in a fixed ratio.
For every carbon atom , there is one oxygen atom and two hydrogen atoms.
The general formula for carbohydrates is written as (CH2O)n.
If the value of n ranges from 3 to 7, the molecules are called sugar or monosaccharides.
Monosaccharides can be linked to form larger molecules (such as disaccharide and polysaccharide).
Check Figure 6.26!

9. Carbohydrates Glucose is a monosaccharide Sucrose (table sugar) and
Lactose (in milk) are disaccharide
Glycogen is a polysaccharide
Carbohydrates are used as
energy stores in a living body.
Excess glucose is stored as
glycogen in the body. When
the body needs energy between
meals, glycogen is broken down
into glucose.

10. Carbohydrates
A carbohydrate, called cellulose, in plants provides structural support to the plants.
Chitin is a polysaccharide containing nitrogen. It is the main component in the hard outer shell of shrimp, lobster etc.

11. Lipids Lipids are molecules made mostly
of carbon and hydrogen that make up the fats, oils and waxes.
The primary function of lipids is to store energy.
A lipid called triglyceride is a fat if it is solid at room temperature, an oil if it is liquid at room temperature.
Plant leaves are coated with lipids
called waxes to prevent water loss.
A honeycomb in a beehive
is made of bees
wax.

12. Structure of Lipids The basic structure of a lipid
includes fatty acid tails.
Saturated fats have only single
bonds between the carbon atoms,
therefore no hydrogen atom
can bond to the tail.
Unsaturated fats have at least
one double bond between carbon
atoms, therefore the tail can
accomodate at least one more
hydrogen.

13. Lipids
Phospholipids are responsible for the structure and function of the cell membrane.
Phospholipids are hydrophobic (meaning they do not dissolve in water). They act as barriers in biological membranes.
Steroids are a type of lipid
that include substances such
as hormones and cholesterol

14. Proteins
Proteins make up 15% of your total mass and are involved in every function in your body.
10,000 different proteins
Structural support
Transport substances
Speed up chemical reactions etc.

15. Proteins
A protein is a compound made of small carbon compounds called amino acids.
Amino acids are small compounds that are made of carbon, oxygen, hydrogen and sometimes sulfur.
All amino acids share the same
general structure.
Central carbon
Hydrogen
Amino group (H2N)
Carboxyl group (COOH)
Variable (R)
There are 20 different variable group.

16. Proteins Amino acids are joined together to form proteins by covalent
bonds called peptide bonds.
A peptide forms between
the amino group of one
amino acid and the carboxyl
group of another.

17. Protein Structure Proteins can have up to four levels of structure.
1- Primary structure: The number
and order of aminoacids
2- Secondary structure: Sequence
of amino acids linked by a hydrogen
bond
3- Tertiary structure: Globular
structure
4- Quarternary structure:
Combining with other proteins

18. Nucleic Acids
Nucleic acids are complex macromolecules that store and transmit genetic information.
Nucleid acids are made of subunits called nucleotides.
Nucleotides are composed of carbon, nitrogen, oxygen, phosphorus and hydrogen atoms.
Three units:
Phosphate
Nitrogenous base
Ribose sugar

19. Nucleic Acids Two types of nucleic acids found in living organisms.
DNA: Deoxyribonucleic aicd
RNA: Ribonucleic acid
In DNA and RNA, sugar of one nucleotide bonds to the phosphate of another nucleotide. (Check Figure 6.31)
A nucleotide with 3 phosphate groups is adenosine triphosphate, ATP.
ATP is used to store
chemical energy that can
be used by cells.