Chapter 1: Introduction to BIOCHEMISTRY

Lecturer: Eng.Mohamed Ali . Bsc & M. Eng.

College of Agriculture and Veterinary, University of Hargeisa.

Overall goal of Biochemistry

To describe life’s processes using thelanguage of molecules, that is, applying theprinciples and methods of chemistry todetermine molecular structure from which itis often possible to explain biological function

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

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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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.

Primary Organic Compounds

1. Carbohydrates2. Lipids3. Proteins4. Nucleic AcidsYou are expected

to learn the structure and functions of these organic compounds:

How much biochemistry do you need to know for this course?

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.

MonomersMacromoleculeCarbohydrates

Lipids

Proteins

Nucleic acids

MonomerMonosaccharide

Fatty Acid

Amino acids

Nucleotides

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.

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.

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.

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).

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.

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

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) .

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?

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 Cell2. Eukaryote Cell

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Prokaryote Cell

Eukaryote Cell

OrganellesOrganelles

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

Non OrganellesNon Organelles

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

granules

Characteristic Bio-membranes and Organelles

MitochondrionSurrounded by a double membrane with a series of foldscalled cristae. Functions in energy production through metabolism. Contains its own DNA, and is believed to have originated as a captured bacterium.

Plasma MembraneA lipid/protein/carbohydrate complex, providing a barrier and containing transport and signaling systems. NucleusDouble 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

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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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.RibosomesProtein 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 apparatusA 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

VacuolesMembrane surrounded "bags" that contain water and storage materials in plants.

Peroxisomes or MicrobodiesProduce and degrade hydrogen peroxide, a toxic compound that can be produced during metabolism.

Cell wallPlants have a rigid cell wall in addition to their cell membranes

Cytoplasmenclosed by the plasma membrane, liquid portion called cytosol and it houses the membranous organelles.

CytoskeletonArrays 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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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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