Cell Biology Lecture: Introduction to Cell Biology PDF

Cell Biology Biochemistry I (02-06-08 101) (code) Lecture: Introduction to Cell Biology Lecturers: Dr. Mohamed Elkewedi Dr. Doaa Fathy  Personal Introduction Dr. Mohamed Mostafa Hassan Lecturer at Bio...

Cell Biology Biochemistry I (02-06-08 101) (code) Lecture: Introduction to Cell Biology Lecturers: Dr. Mohamed Elkewedi Dr. Doaa Fathy  Personal Introduction Dr. Mohamed Mostafa Hassan Lecturer at Biochemistry Department Faculty of Pharmacy, Alexandria University PhD/ Doctor rerum naturalium (Dr. rer. nat.) 2019 MDC/FUB, Berlin,Germany. Master of Biomedical Sciences (MSc) 2013 CMU, Cardiff, UK. Bachelor of Pharmaceutical Sciences 2010 Alexandria University, Faculty of Pharmacy, Alexandria (Egypt).  The Science of Biology ▪ The science of biology is the study of living organisms and their environments. ▪ All living things share seven basic characteristics. (1) Organized. (2) Acquire materials and energy. (3) Reproduce. (4) Grow and develop. (5) Homeostatic. (6) Respond to stimuli. (7) Adapt and evolve.  Only the highlighted red sentences are to be memorized Cell Biology ▪ Cell biology is a branch of biology that studies the different structures and functions of the cell and focuses mainly on the idea of the cell as the basic unit of life. ▪ Cell biology explains the structure, organization of the organelles they contain, their physiological properties, metabolic processes, signaling pathways and life cycle. ▪ This is done both on a microscopic and molecular level as it in prokaryotic and eukaryotic cells.  Cell: The Basic Unit of Life Features of Cell: - Smallest biological, structural & functional unit of life. - Cells are the building blocks of organisms. - Organisms may be unicellular or multicellular. - Cells cluster up → tissues → organs → system → organism. Cell: The Basic Unit of Life Read for reference. Not to be memorised  Only the highlighted red sentences are to be memorized Cell Theory As originally postulated by Schwann in 1839, the cell theory had two basic principles: 1- All organisms consist of one or more cells. 2- The cell is the basic unit of structure for all organisms. Less than 20 years later, a third principle was added. By 1855 Rudolf Virchow, a German physiologist, concluded that cells arose only by the division of other preexisting cells. 3- All cells arise only from pre-existing cells.  Only the highlighted red sentences are to be memorized Modern Cell Theory 4- Cells contain hereditary information in their DNA. This information is passed on to new cells through cell division. 5- All cells have the same basic chemical composition. 6- Energy flow (metabolism and biochemistry) occurs within cells.  The Emergence of Modern Cell Biology Although cytology, biochemistry, and genetics began as separate disciplines, they have increasingly merged since about 1925. Cytology Cell Biology Biochemistry Genetics  Only the highlighted red sentences are to be memorized The Emergence of Modern Cell Biology 1-The Cytological Strand Deals with Cellular Structure Historically, the limited resolving power of the light microscope did not allow us to see details of structures smaller than about 0.2 μm (200 nm), but modern light microscopes (as fluorescence microscope) are surpassing that limit. A major breakthrough in resolving power came with the development of the electron microscope, which was invented in Germany in 1931 by Max Knoll and Ernst Ruska. The electron microscope uses a beam of electrons, rather than visible light, for imaging specimens. It can magnify objects up to 100,000 with a resolving power of less than 1 nm, enabling us to view subcellular structures such as membranes, ribosomes, organelles, and even individual DNA and protein molecules. Resolving Power of Microscopes  Only the highlighted red sentences are to be memorized The Emergence of Modern Cell Biology 2- The Biochemical Strand Covers the Chemistry of Biological Structure and Function Discoveries in biochemistry have revealed how many of the chemical processes in cells are carried out, greatly expanding our knowledge of how cells function. Major discoveries in biochemistry were the identification of enzymes as biological catalysts, the discovery of adenosine triphosphate (ATP) as the main carrier of energy in living organisms, and the description of the major metabolic pathways cells use to harness energy and synthesize cellular components. Several important biochemical techniques that have allowed us to understand cell structure and function are subcellular fractionation, ultracentrifugation, chromatography, electrophoresis.  Only the highlighted red sentences are to be memorized The Emergence of Modern Cell Biology 3- The Genetic Strand Focuses on Information Flow The chromosome theory of heredity states that the characteristics of organisms passed down from generation to generation result from the inheritance of chromosomes carrying discrete physical units known as genes. Each gene is a specific sequence of DNA that contains the information to direct the synthesis of one cellular protein. DNA itself is a double helix of complementary strands held together by precise base pairing. This structure allows the DNA to be accurately duplicated as it is passed down to successive generations.  The Emergence of Modern Cell Biology 3- The Genetic Strand Focuses on Information Flow  Characteristics of living cells 1- Presence of a membrane around the cell, which restricts entry to certain molecules, beside allowing free passage of water and some of gases as oxygen and carbon dioxide. The membrane separates the inside space of cell from the surroundings. 2-The energy, which is produced by cell, is conserved in form of ATP. 3- A cell has its one genetic information, which it has received from its parent cell. 4- The cell has its own machinery by which it can carry out the following: Genes ==> transcription ==> translation ==> structure & regulation DNA ==> mRNA ==> proteins ==> subunits & enzymes  Read for reference. Not to be memorised Cellular Unity All cells share a set of common characteristics 1. Common biochemistry: all cells use the same basic building blocks (e.g. DNA, RNA, amino acids, lipids, and carbohydrates). 2. Common macromolecules and supramolecular structures and physiology (e.g. lipid bilayers, ribosomes, using ATP as energy).  Read for reference. Not to be memorised Cellular Diversity Cell’s shape and structure gives indications about its function. For example, 1- The large surface area of the microvilli on our intestinal cells aids in maximizing nutrient absorption. 2- The spiral thickenings in the cell walls of plant xylem tissue give strength to these water-conducting vessels in wood. 3- The highly branched cells of a human neuron allow it to interact with numerous other neurons.