This document provides an introduction to biochemistry. It defines biochemistry as the study of chemical reactions in living organisms and the structure and function of biomolecules like proteins, carbohydrates, lipids and nucleic acids. The overall goal of biochemistry is to describe life's processes using the language of molecules. The key biomolecules are made of monomers that polymerize to form larger structures. Carbohydrate monomers are monosaccharides, lipid monomers are fatty acids, protein monomers are amino acids, and nucleic acid monomers are nucleotides. The document discusses the basic components of cells, including organelles and biomolecules, and compares characteristics of prokaryotic and eukaryotic cells.

1. College of Agriculture and Veterinary, University of Hargeisa.
Chapter 1: Introduction to
BIOCHEMISTRY
Lecturer: Eng.Mohamed Ali . Bsc & M. Eng.

2. Overall goal of Biochemistry
 To describe life’s processes using the
language of molecules, that is, applying the
principles and methods of chemistry to
determine molecular structure from which it
is often possible to explain biological function

3. What is Biochemistry ?
 Biochemistry – a branch of chemistry
concerned with the chemical reactions
occurring in living organism
Definition 2 : Biochemistry is the study of
chemistry of life , and the structure and
function of cellular components such as
proteins, carbohydrates, lipids,
nucleic acids and other biomolecules

4. Bio-molecules : Chemical Elements of Life
 Just like cells are building blocks of tissues likewise molecules
are building blocks of cells.
 Animal and plant cells contain approximately 10, 000 kinds of
molecules (bio-molecules)
 Chemical substances present in living organisms six
elements (C, H, O, N, P, S) make up approximately
95% of the mass of cell weight
 Human body also consists of ~60% water of cells content
by weight.
 Ions like Na+, K+ and Ca+ may account for another 1%
 Most bio-molecules considered to be derived from
hydrocarbons.
 The chemical properties of organic bio-molecules are determined
by their functional groups.
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5. There are a vast number of different
biomolecules many are complex and
large molecules that are composed
of similar repeating subunits. Each
class of polymeric biomolecule has a
different set of subunit types.

6. Primary Organic Compounds
1. Carbohydrates
2. Lipids
3. Proteins
How much
biochemistry do
you need to know
for this course?
You are expected 4. Nucleic Acids
to learn the
structure and
functions of these
organic
compounds:

7. Polymers and Monomers
 Each of these types of biomolecules are
polymers that are assembled from single
units called monomers.
 Each type of macromolecule is an
assemblage of a different type of
monomer.

8. Monomers
Macromolecule
Carbohydrates
Lipids
Proteins
Nucleic acids
Monomer
Monosaccharide
Fatty Acid
Amino acids
Nucleotides

9. Monomers and Polymers
 Monomers and polymers are a structural basis in
which the four main macromolecules , (
Carbohydrates, lipids, proteins, and nucleic acids)
of biochemistry are based on.
 Monomers: are smaller micromolecules that are
put together to make macromolecules.
 Polymers: are those macromolecules that are
created when monomers are synthesized
together.

10. How do monomers form polymers?
 In condensation reactions (also called
dehydration synthesis), a molecule of
water is removed from two monomers as
they are connected together.

12. Hydrolysis
 In a reaction
opposite to
condensation, a
water molecule
can be added
(along with the
use of an
enzyme) to split
a polymer in
two.

13. CARBOHYDRATES
 A molecule of sucrose (glucose +
fructose), a disaccharide.
 Carbohydrates have monomers called
monosaccharides. Some of these
monosaccharides include glucose
(C6H12O6), fructose (C6H12O6), and
deoxyribose (C5H10O4).

14. LIPIDS
 A triglyceride with a glycerol molecule on the left
and three fatty acids coming off it.
 Lipids are usually made up of a molecule of
glycerol and other molecules. In triglycerides, or
the main lipid, there is one molecule of glycerol,
and three fatty acids. Fatty acids are considered
the monomer in that case, and could be saturated
or unsaturated.

15. PROTEINS
 A protein is a complex, high-molecular-
mass organic compound
that consists of amino acids
arranged in a linear chain linked by
peptide bonds.
 Proteins are large molecules, and
have monomers of amino acids.
There are 20 standard amino acids,
and they contain a carboxyl group,
an amino group, and "R" group. The
"R" group is what makes each amino
acid different.
Amino Acid

16. NUCLEIC ACIDS
 Nucleic Acid is any of various
macromolecules composed of nucleotide
chains that are vital constituents of all living
cells
 Their monomers are called nucleotides.
 Nucleic acids are very important in
biochemistry, as they are what make up
DNA, something all cellular organism use to
store their genetic information. The most
common nucleic acids are deoxyribonucleic
acid (DNA) and ribonucleic acid (RNA) .

17. Review Questions
 What is Biochemistry?
 What is the goal of Biochemistry
 What are the six elements that important in life?
 What is Monomer and Polymer?
 How do Monomers form Polymers?
 What is Hydrolysis reaction?
 What are monomers of Nucleic acid, Protein,
Carbohydrate and lipids?
 Define what is protein, carbohydrate, lipids and
nucleic acid?

18. The Cells
 Basic building blocks of life
 Smallest living unit of an organism
 Grow, reproduce, use energy, adapt, respond to their
environment
 Many cannot be seen with the naked eye
 A cell may be an entire organism or it may be one of billions of
cells that make up the organism
 Basis Types of Cells :
1. Prokaryotic Cell
2. Eukaryote Cell
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19. Prokaryote Cell

20. Eukaryote Cell

21. OOrrggaanneelllleess
 Biologically differentiated structures and living materials of
Cytoplasm.
 Essential for different bio-synthetic activities of the cell .
 Include:
 (1) Cell membrane
 (2) Endoplasmic reticulum-Rough and smooth
 (3) Mitochondria
 (4) Golgi apparatus
 (5) Centrosome with centrioles
 (6) Ribosomes (free and attached)
 (7) Lysosomes
 (8) Peroxisomes
 (9) Filaments
 (10) Microtubules
 (11) Vesicles

22. NNoonn OOrrggaanneelllleess
 (1) Protein
 (2) Fat
 (3) Carbohydrate (Glycogen)
 (4) Water
 (5) Inorganic materials
 (6) Pigments like Melanin , lipofuscin
 (7) Cellular Products: Yolk & Secretory
granules

23. Characteristic Bio-membranes and Organelles
Plasma Membrane
A lipid/protein/carbohydrate complex, providing a barrier and
containing transport and signaling systems.
Nucleus
Double membrane surrounding the chromosomes and the nucleolus.
Pores allow specific communication with the cytoplasm. The
nucleolus is a site for synthesis of RNA making up the ribosome
Mitochondrion
Surrounded by a double membrane with a series of folds
called cristae. Functions in energy production through metabolism.
Contains its own DNA, and is believed to have originated as a
captured bacterium.
Chloroplasts (plastids)
Surrounded by a double membrane, containing stacked thylakoid
membranes. Responsible for photosynthesis, the trapping of light
energy for the synthesis of sugars. Contains DNA, and like
mitochondria is believed to have originated as a captured
bacterium.
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24. .
Rough endoplasmic reticulum (RER)
A network of interconnected membranes forming channels within the
cell. Covered with ribosomes (causing the "rough" appearance) which
are in the process of synthesizing proteins for secretion or
localization in membranes.
Ribosomes
Protein and RNA complex responsible for protein synthesis
Smooth endoplasmic reticulum (SER)
A network of interconnected membranes forming channels within the
cell. A site for synthesis and metabolism of lipids. Also contains
enzymes for detoxifying chemicals including drugs and pesticides.
Golgi apparatus
A series of stacked membranes. Vesicles (small membrane
surrounded bags) carry materials from the RER to the Golgi
apparatus. Vesicles move between the stacks while the proteins are
"processed" to a mature form. Vesicles then carry newly formed
membrane and secreted proteins to their final destinations including
secretion or membrane localization.
Lysosymes
A membrane bound organelle that is responsible for degrading
proteins and membranes in the cell, and also helps degrade materials
ingested by the cell. 24

25. Vacuoles
Membrane surrounded "bags" that contain water and storage
materials in plants.
Peroxisomes or Microbodies
Produce and degrade hydrogen peroxide, a toxic
compound that can be produced during metabolism.
Cell wall
Plants have a rigid cell wall in addition to their cell membranes
Cytoplasm
enclosed by the plasma membrane, liquid portion called cytosol
and it houses the membranous organelles.
Cytoskeleton
Arrays of protein filaments in the cytosol. Gives the cell its
shape and provides basis for movement.
E.g. microtubules and microfilaments.
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26. Comparison between prokaryotic and eukaryotic cells
Characteristics prokaryotic eukaryotic
Size small (1-10um) large(10-100um
Cell membrane rigid cell wall flexible plasma membrane
Sub-cellular organelles Absent Distinct organelles found
Nucleus not well defined,
DNA is found
Nucleus is well defined,
DNA is associated with
histones
Energy Metabolism Mitochondria
absent
Mitochondria present
Cell division usually fission &
no mitosis
Mitosis
Cytoplasm organelles &
cytoskeleton
absent
contain organelles &
cytoskeleton
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