Introduction to Biochemistry Unit ONE !!

The presentation “Introduction to Biochemistry I – Unit 1” gives an overview of the basic concepts of biochemistry. It explains the definition, importance, and scope of biochemistry in understanding life processes. The slides introduce the major biomolecules—carbohydrates, proteins, lipids, and nucleic acids—and describe their roles in cells. It also covers the relationship between chemistry and biology, the structure of cells, and the chemical basis of metabolism. Overall, the presentation serves as a foundation for studying the chemical processes that occur in living organisms.

1. Introduction to Biochemistry UNIT ONE BIOCHEMISTRY ONE BATCH: AGRICULTURE

2. Introduction to Biochemistry Biochemistry is the study of the chemical substances and reactions that occur in living organisms. It helps us understand how cells and tissues function, how energy is produced, and how diseases develop. It connects biology (life) with chemistry (matter and reactions) to explain how life operates at a molecular level.

3. Branches of Biochemistry Biochemistry is divided into three main areas: Structural Biology: Examines the 3D shapes and arrangements of biological molecules such as proteins and DNA. Enzymology: Studies enzymes, their structures, and how they speed up chemical reactions. Metabolism: Looks at the chemical reactions that provide energy and build cellular materials. These three branches are closely related and together explain life’s chemistry.

4. Focus of Biochemistry Biochemistry focuses on understanding how molecules within a cell interact to perform life functions. This includes: How proteins, lipids, carbohydrates, and nucleic acids work together. How chemical reactions in cells support the functioning of organs and systems. It builds the foundation for understanding human physiology and disease.

5. Relationship to Molecular Biology Molecular biology focuses on the molecular mechanisms behind biological processes — for example, how DNA makes RNA, and RNA makes proteins. Biochemistry supports this by explaining the chemical basis of these processes. Together, they help us understand gene expression, cell communication, and cellular regulation.

6. Major Biological Molecules Cells contain four key classes of macromolecules: 1. Proteins: Perform structural and functional roles (enzymes, hormones, antibodies). 2. Nucleic Acids: DNA stores genetic information; RNA helps in protein synthesis. 3. Carbohydrates: Provide energy and structural support. 4. Lipids: Form membranes and store energy. All these molecules interact to keep cells alive and functioning. They provide the structure of cells and perform many of the functions associated with life.

7. Small Molecules and Ions Besides macromolecules, cells also rely on small molecules such as: - Inorganic: Water, minerals, and metal ions (e.g., Na⁺, K⁺, Ca²⁺). - Organic: Amino acids, fatty acids, glucose, and vitamins. These molecules take part in cellular reactions and help maintain the cell’s internal environment.

8. Metabolism Metabolism refers to all the chemical reactions that occur inside a living organism. Also The mechanisms used by  cells to harness energy  from their environment via  chemical reactions  are known as  metabolism . It includes: Catabolism: Breaking down molecules to release energy. Anabolism: Building complex molecules from simpler ones. Metabolism allows cells to grow, repair, and maintain their structures.

9. Applications of Biochemistry The findings of biochemistry are applied primarily in  medicine ,  nutrition  and  agriculture . In medicine,  biochemists  investigate the causes and  cures  of  diseases .  Nutrition studies how to maintain health and wellness and also the effects of  nutritional deficiencies . In agriculture, biochemists investigate  soil  and  fertilizers . Improving crop cultivation, crop storage, and  pest control  are also goals. Biochemistry is essential for healthcare, food production, and biotechnology.

10. Introduction to Cells Cells are the structural and functional units of all living organisms. In other words, All living things are made of cells , the smallest units of life. Each cell performs all vital functions such as energy production, growth, and reproduction. Main parts of a cell: 1. Nucleus – control center 2. Cytoplasm – fluid and organelles 3. Cell membrane – protective boundary

11. Types of Cells The electron microscope allowed classification of cells into two major groups, prokaryotes and eukaryotes, based on the presence and absence of the true nucleus. Eukaryotic cells: Have a well-defined nucleus (e.g., plants, animals, fungi). 2. Prokaryotic cells: No true nucleus (e.g., bacteria, blue-green algae).

12. Eukaryotic Cells Have a nuclear membrane enclosing the nucleus. Contain membrane-bound organelles like mitochondria and Golgi apparatus. Generally larger and more complex than prokaryotes. Found in animals, plants, and fungi.

13. Eukaryotic Organelles Major organelles found in eukaryotic cells include: Mitochondria: Powerhouse of the cell; produce energy (ATP). Lysosomes: Break down waste materials and worn-out parts. Endoplasmic Reticulum (ER): Synthesizes proteins and lipids. Golgi Complex: Packages and distributes proteins and other substances.

14. Prokaryotes Prokaryotic cells are the simplest and most ancient forms of life. The term "prokaryote" comes from the Greek pro (before) and karyon (nucleus), literally meaning "before the nucleus.“ Bacteria and blue green algae belong to the prokaryotes. Lack a true nucleus ; DNA is free within the cytoplasm. Do not have membrane-bound organelle. Have a simple internal structure. Despite their simplicity, they carry out all essential life processes.

15. Main Components of a Cell Cell Membrane (Plasma Membrane) – Controls entry and exit of materials. Cytoplasm – Fluid matrix that holds organelles. Nucleus – Directs all cellular activities. All three parts work together to maintain cell survival and function.

16. Cell Membrane Overview (Plasma Membrane) The cell is enveloped by a thin membrane called cell membrane or plasma membrane. Cell membranes mainly consist of lipids, proteins and smaller proportion of carbohydrates that are linked to lipids and proteins. The cell membrane is an organized structure consisting of a lipid bilayer primarily of phospho-lipids and penetrated protein molecules forming a mosaic-like pattern. Acts as a selective barrier , allowing certain substances to pass while keeping others out. This control maintains a stable internal environment ( homeostasis ).

17. Membrane Lipids The major classes of membrane lipids are: Phospholipids – major structural components. Glycolipids – important for cell recognition. Cholesterol – maintains membrane fluidity. All are amphipathic molecules , meaning they have a hydrophilic (water-loving) head and a hydrophobic (water-repelling) tail. Lipid Bilayer Formation In water, lipids arrange themselves into a bilayer . Hydrophobic tails face inward; hydrophilic heads face outward. This creates a stable, flexible membrane that acts as a boundary between the cell and its environment.

18. Membrane Proteins Two types of proteins are embedded in the lipid bilayer: Integral (Intrinsic) Proteins: Extend across or are deeply embedded in the membrane; include channels and carriers. Peripheral (Extrinsic) Proteins: Loosely attached to the membrane surface; act as enzymes or structural supports.

19. Functions of Membrane Proteins Transport: Move ions and molecules like glucose across the membrane. Enzymatic activity: Speed up reactions on the membrane surface. Receptors: Receive and transmit signals from the environment. Cell recognition: Help cells identify each other during immune responses.

20. The cell membrane is selectively permeable , meaning: Some substances (like oxygen, water) pass easily. Others (like large or charged molecules) need specific transport mechanisms. This property is vital for maintaining cell balance and function.

21. Fluid Mosaic Model In 1972, Singer and Nicolson proposed a theory of membrane structure called the fluid mosaic model , which is now widely accepted. Membrane = fluid lipid bilayer with proteins “floating” within it. Proteins move sideways, giving the membrane flexibility and allowing communication. This dynamic structure helps the cell adapt to its environment.

22. Cytoplasm The cytoplasm fills the space between the nucleus and the cell membrane. It contains the cytosol (a clear, jelly-like fluid) and various organelles. Acts as the site for many chemical reactions essential for life. Provides support and allows movement of materials within the cell.

23. Organelles in the Cytoplasm Six major organelles: Endoplasmic Reticulum (ER) – Produces proteins and lipids. Golgi Apparatus – Modifies and packages proteins. Lysosomes – Digest worn-out cell parts. Peroxisomes – Detoxify harmful substances. Mitochondria – Generate cellular energy (ATP). Nucleus – Stores genetic information and controls cell activity.

24. The Nucleus Usually spherical and located near the center of the cell. Surrounded by a nuclear envelope that separates it from the cytoplasm. Inside is nucleoplasm , containing: Nucleolus: Synthesizes ribosomal RNA (rRNA). Chromatin: DNA and proteins; condense into chromosomes during cell division.

25. Functions of the Nucleus Replication: Produces new copies of DNA before cell division. Transcription: Synthesizes three main types of RNA: rRNA (ribosomal): Builds ribosomes (protein is made) mRNA (messenger ) : Carries genetic information to ribosomes. tRNA (transfer): Brings amino acids for protein synthesis. The nucleus serves as the command center of the cell, directing growth and reproduction.

26. To be Continued…. THANK YOU