Mol_Biol_Lecture_1.pp2j3evv23te2u3etxi2u3s4
- 1. Addis Ababa University College of Natural and Computational Sciences Department of Microbial Cellular & Molecular Biology Molecular Biology (Biol.4052) Zelalem GebreMariam (PhD) Zelalem.gebremariam@aau.edu.et 1
- 2. Course Outline 1. Introduction to Molecular Biology 2. Nucleic Acids: Chemical & Physical Properties 3. DNAReplication 4. Gene Expression: Trancription & Translation 5. Gene Regulation 6. Application of Molecular Biology (MB) 2
- 3. Group work(work in a group of 5 students; 15%) 1. Write a term paper on the application of MB in Wildlife/Biodiversity conservation. 2. Write a term paper on the application of MB in the Industrial Sectors (e.g., food and beverage, pharmaceutical, etc.) 3. Write a term paper on the application of MB in Medicine and Health sectors. 4. Write a term paper on the application of MB in Environmental Protection. 5. Write a term paper on the application of MB in Plant Breeding. 6. Write a term paper on the application of MB inAnimal Breeding. 3
- 4. Group work (work in a group 5 students, 10 %) 1. Write a term paper on the major biological macromolecules, i.e., carbohydrates, proteins, lipids, & nucleic acids. 2. Your writing must be a brief summary on their nature & properties – chemistry, types, structure, function – role played in the various physiological and biochemical processes. 4
- 5. Instructions/Guidelines 1. Your writing must follow the format of standard scientific review paper. 2. Please consult the materials you have covered in your Research Method and Report Writing in Science course. 3. Your writing must have cover page, table of content, introduction, body, summary, reference, etc. 4. You could collaborate with friends but make sure that you are not copying from one another – doing so has a cost. 5. Make sure that every member of the group has actively participated in assigned work – doing so has a reward. 6. You must submit your assignment before the final examination. 5
- 6. Unit I. Structure and Function of Nucleic Acids CHAPTER1: INTRODUCTION TO MOLECULAR BIOLOGY What is molecular Biology? Molecular biology is the study of biology (life) at a molecular level. • Particularly, it deals with the formation, structure, and function of macromolecules (nucleic acids and proteins); especially their role in cell replication and the transmission of genetic information What is life? • Life on earth is remarkably diverse, ranging from the relatively simple unicellular organisms, such as bacteria, to more complex multicellular organisms • Despite their diversity at the macroscopic level, the core molecular features of all organisms are remarkably similar 6
- 7. 3. Complexity and organization Living organisms are constructed from common molecular building blocks. Eukaryotic cells are subdivided into organelles that perform specialized tasks within the cell. Multicellular organisms consist of tissues, organs, and organ systems. Larger organizational categories are species, populations, and ecosystems. 6. Growth, development, and death Each organism has a finite life cycle. The cell shown is in the telophase stage of mitosis, or cell division. 1. Energy acquisition To maintain both complexity and homeostasis, living systems undergo a constant struggle to obtain energy from sunlight, the environment, or other organisms. 4. Transmission of genetic information between generations: Reproduction to produce new cells or organisms is essential for a species to remain part of the biosphere for more than one generation. 2. Adaptation Cells and organisms are sensitive and respond to their external environment. In this case, the cell is adjusting its internal osmotic pressure to adapt to a medium with a higher salt concentration. 5. Homeostasis Within a living cell, parameters such as pH, temperature, ion concentrations, and biomolecule concentrations are all maintained within narrow limits by transport of required substances across cell membranes and by a regulated internal metabolism. Common properties of life Introduction to Molecular Biology…….
- 8. The Three Domains of Life • In the early part of the twentieth century- all life forms were divided into two kingdoms: animal and plant. • Bacteria were considered plants, which is why we still refer to the bacteria in our guts as intestinal “flora.” • But after the middle of the century, this classify classification system was abandoned in favor of a five kingdom system Plants, animals, bacteria, fungi and protists Introduction to Molecular Biology…….
- 9. • In the late 1970s, Carl Woese ( Figure below) performed sequencing studies on the ribosomal RNA genes of many different organisms and reached a startling conclusion • All living things are grouped into three domains: bacteria, eukaryota, and archaea. Although the archaea resemble the bacteria physically, some aspects of their molecular biology are more similar to those of eukaryota. Introduction to Molecular Biology…….
- 10. Evolutionary relationships and the phylogenetic tree of life The phylogenetic tree depicts the evolutionary history—the phylogeny of all cells revealing the three domains. The root of the universal tree represents a point in time when all extant life on Earth shared a common ancestor, the last universal common ancestor, LUCA Introduction to Molecular Biology…….
- 11. Structural classes of cells • two major structural classes of cells: prokaryotic cells and eukaryotic cells • Eukaryotic cells are found in the phylogenetic domain Eukarya. includes plants and animals as well as diverse microbial eukaryotes such as algae, protozoa, and fungi. contain an assortment of membrane-enclosed cytoplasmic structures called organelles and nucleus Eukaryotic cell.pptx • Prokaryotic cells are found in the domains Bacteria and Archaea. have few internal structures, they lack a nucleus, and they typically lack organelles Prokaryotic cell.pptx Introduction to Molecular Biology…….
- 12. Table 1: Comparisons of the three domains of life Introduction to Molecular Biology…….
- 13. Introduction to Molecular Biology…….
- 14. History of DNA as the Genetic Material DNA was discovered in 1869 by Friedrich Miescher. Its true significance as a genetic material was revealed only after hundreds of years later Features of the genetic material: • the ability to store and transmit genetic information to next generation • physical and chemical stability= to minimize loss of information • the potential for heritable change without major loss of parental information. Accordingly scientists conducted several experiments to identify which molecule in the cell served as the genetic material. Introduction to Molecular Biology…….
- 15. • Provided the first clue that DNA was the carrier of hereditary information • first observed in 1928 by Fred Griffith Experiment on bacterium that causes pneumonia, Streptococcus pneumonia. Streptococcus pneumonia kills mice by causing pneumonia. its virulence is determined the capsular polysaccharide ( protect the bacterium from the host) the cells have different capsular polysaccharides. smooth(S) forms are virulent and can kill the mice. rough(R) forms ( have no capsular polysaccharide) are avirulent i. Bacterial transformation in vivo experiments Introduction to Molecular Biology…….
- 16. • Griffith concluded that R type bacteria had been transformed by acquiring the virulence of the dead S bacteria and the change was permanent. He theorized that some substance in the polysaccharide coat of the dead S bacteria might be responsible. So he called this substance the transforming principle. Introduction to Molecular Biology…….
- 17. ii. In vitro experiments: Identification of the transforming principle • After 10 years of research, in 1944 Oswald Avery, Colin MacLeod, and Maclyn McCarty succeeded in isolating and purifying the transforming substance. Extraction of transforming principle.pptx • used enzymes to treat the extract from the heat killed S strain and tested it for transformation. Conclusion: Because only DNase destroyed the transforming substance, the transforming substance is DNA. Introduction to Molecular Biology…….
- 18. • Griffith concluded that R type bacteria had been transformed by acquiring the virulence of the dead S bacteria and the change was permanent. • He theorized that some substance in the polysaccharide coat of the dead S bacteria might be responsible. So he called this substance the transforming principle.
- 19. 2. Identification of the transforming principle • After 10 years of research, in 1944 Oswald Avery, Colin MacLeod, and Maclyn McCarty succeeded in isolating and purifying the transforming substance. • used enzymes to treat the extract from the heat killed S strain and tested it for transformation.
- 20. • Extracts treated with proteases and RNases resulted in transformation. • But the extract that was treated with DNase destroyed the transformation ability. • This study provided the first experimental evidence that DNA was the genetic material.
- 21. Conclusion: DNA—not protein—is the genetic material in bacteriophages iii. The Hershey-Chase experiment T2 Phage.pptx
- 23. • When 32 P labeled phages were mixed with unlabeled E.coli cells, the ‐ 32 P label phage entered the bacterial cells their next generations that burst from the infected cells carried a significant amount of the 32 P label. • When 35 S labeled phages were mixed with unlabeled E.coli, the ‐ 35 S label stayed outside the bacteria for the most part.
- 24. This experiment demonstrated that the outer protein coat of a phage does not enter the bacterium it infects, whereas the phage’s inner material consisting DNA, does enter the bacterial cell. Since the DNA is responsible for the production of the new phages during the infection process, the DNA, not the protein, must be the genetic material
- 25. In Some Viruses, RNA serve as a Genetic material • DNA carries the genetic information in all cellular forms of life and in many viruses. • Prokaryotes such as Escherichia coli bacteria carry their DNA in a double-stranded, covalently closed circular chromosome. • Eukaryotic cells package their DNA in double-stranded linear chromosomes. • DNA viruses carry it in small molecules that are single-or double-stranded, circular, or linear. • By contrast, retroviruses, which include those that cause polio, AIDS, COVID 19 use ribonucleic acid, or RNA as their genetic material.