Cell Biology Lecture 1 PDF

Cell Biology Amira Afify Assistant Professor at faculty of science, Cairo university [email protected] [email protected] Code of conduct Lecture 1 ‫التوقعات‬ Objectives By the end of this lecture, each student will learn:- 1- Cell...

Cell Biology Amira Afify Assistant Professor at faculty of science, Cairo university [email protected] [email protected] Code of conduct Lecture 1 ‫التوقعات‬ Objectives By the end of this lecture, each student will learn:- 1- Cell biology, cell theory. 2-Instrumental analysis of biological structures. 3-Cell structure 3.1. Prokaryotic cell 3.2. Eukaryotic cell 3.3. Animal cell 4. Plasma membrane 4.1 Membrane models 4.2. Plasma membrane structure and function 4.2.1. fluidity of the plasma membrane 4.2.2. Mosaic Quality of the membrane 4.2.3. Cell-Cell Recognition 5. Modification of cell surface 5.1.Junctions between cells 1- Cell biology = Cytology  Definition:Biological science that deals with morphology, Taxonomy, biochemistry, cytochemistry , physiology, genetics and developmental Biology.  Human and other multi cellular organisms contain billions or trillions of cells organized into complex structures.  Many organisms consist of a single cell.  The cell is the basic unit of life. The Cell theory states that:  All organisms are composed of one or more cells.  Cells are the basic living unit of structure and function in organisms.  All cells come only from other cells. The cell:-  The smallest unit of a living structure of independent existence.  A fundamental unit of structure, function and organization in all living organisms.  Like ourselves, the individual cells that form our bodies can: Grow, Reproduce, Process information, Respond to stimuli, Carry out an amazing array of chemical reactions.  These abilities define the life. The levels of organizations:-  Cells: The basic building block.  Tissues: Cells that work together To perform a function.  Organs: Tissues that work together to perform a function.  Organ System: Organs that work Together to perform a function. 2- Instrumental analysis of biological structures. Light microscope Transmission electron microscope Scanning electron microscope 3-Cell structure:- Cell= membrane + protoplasm Protoplasm= nucleus + cytoplasm  Cytoplasm : the area of space outside the nucleus; contains the organelles and cytosol.  Organelles (small organ): are tiny structures in the cytoplasm which perform various jobs for the cell.  Cytosol: is the fluid part of the cytoplasm. Approximate Molecular Composition of the Cell  Water ~ 70%  Macromolecules (proteins, nucleic acids, lipids, carbohydrates) ~ 24%  Small molecules (amino acids, sugar, nucleotides) ~ 5%  Inorganic ions (Na+, K+, Cl- …..) ~ 1% Cellular organisms are subdivided into Two Major Classes Prokaryotes Eukaryotes (before nucleus) (true nucleus) 3.1. Prokaryotic Cells  Primitive Cells”  Example : Bacteria & Blue-Green Algae.  1-10 µm in linear size.  Mainly unicellular.  Mainly have anaerobic metabolic activities  Lack a nuclear membrane and any other membrane covered organelles in their cytoplasm.  Have circular DNA in cytoplasm.  RNA and protein are synthesized In same compartment.  Have no cytoskeleton, endocytosis or exocytosis.  For cell division: chromosomes pulled apart by attachments to plasma membrane (Binary fission). 3.2.Eukaryotic Cells  Mainly multicellular = have aerobic metabolic activities  Example : Protists (protozoa, algae), Fungi, Plants and Animals.  5-100 µm in linear size.  Have very long linear DNA molecules bounded by nuclear envelope.  RNA synthesized in nucleus; proteins synthesized in cytoplasm.  Contain many membrane bound organelles in their cytoplasm.  Have cytoskeleton, endocytosis & exocytosis (biological processes).  For cell division: chromosomes pulled apart by cytoskeletal spindle apparatus. Cells have different sizes, shapes and functions 3.3.Animal cell  Activity (Think-pair-share)  Think: 1 min  Pair: 2 min  Share: 2 min Ask questions about the Eukaryotic cells part? 4. Plasma membrane A plasma membrane encloses every cell, and protects a cell by acting as a barrier between its living contents and the surrounding environment It regulates what goes into and out of the cell and marks the cell as being unique to the organism. 4.1. membrane models 4.2.Plasma membrane structure and function Phospholipids Polar/Nonpolar Hydrophylic (charged) head Hydrophobic (uncharged) tail Interacts with water Hydrophobic interactions is the main force involved in the formation of lipid bilayer.  Activity (Participation)  Working time:  10 min One of each group will summarize the last session. 2.1. fluidity of the plasma membrane  The fluidity of the membrane, which is dependent on its lipid components, is critical to the proper functioning of the membrane’s proteins.  Activity (Participation)  Working time:  10 min One of each group will summarize the last session. 2.2. Mosaic Quality of the membrane  The mosaic pattern of a membrane is dependent on the proteins, which vary in structure and function.  Channel proteins:- Allows a particular molecule or ion to cross the plasma membrane freely.  Carrier protein:- Selectively interacts with a specific molecule or ion that it can cross the plasma membrane  Receptor protein:- has a shape that allows a specific molecule to bind to it.  Enzymatic protein:- That carry out metabolic reactions directly.  Activity (Participation)  Working time:  10 min One of each group will summarize the last session. 2.3. Cell-Cell Recognition  The carbohydrate chains of glycolipids and glycoproteins serve as the fingerprints of the cell.  The possible diversity of the chain is enormous; it can vary by the number of sugars, by whether the chain is branched, and by the sequence of the particular sugars. 3- Modification of cell surface 3.1.Junctions between cells  Three types of junctions are seen between the cells: adhesion junctions(desmosomes), tight junctions, and gap junctions. 1- Adhesion junctions(desmosomes) Intercellular filaments run between two cells. 2-Tight junctions Form an impermeable barrier because their adjacent plasma membranes are joined. 3- Gap junctions Allow communication between two cells because adjacent plasma membrane channels are joined.  Activity (Brain storming) Working time:-10 min. Suggest questions Wrapping up