Introduction to Medical Biology and Genetics PDF

Introduction to Medical Biology and Genetics Dr. Hilal Eren Gözel Contact Info [email protected] 1st Floor, Room #129  Universal features of cells There are more than 10 million species on Earth. Although each species is different, they all rep...

Introduction to Medical Biology and Genetics Dr. Hilal Eren Gözel Contact Info [email protected] 1st Floor, Room #129  Universal features of cells There are more than 10 million species on Earth. Although each species is different, they all reproduce yielding a progeny that represent the copies of themselves (Heredity). This hereditary information drives a complex system of chemical processes that are crucial for the cell organization and its survival. Although, the organisms can be unicellular or multicellular(like us), the whole organism has been generated by cell divisions from a single cell. The single cell, therefore, is the vehicle for all of the hereditary information that defines each species.  Universal features of cells All cells store their hereditary information in the same chemical code system: DNA (or RNA for viruses) DNA or RNA codes (A, C, G, T or U) and their structures are universal in all organisms. The mechanisms that take part in reading the hereditary information (Protein synthesis) or replication of it, occur very similarly in different species. All cells use proteins as catalysts (to increase rate of chemical reactions). All cells use ATP as their free energy source. All cells are enclosed in a plasma membrane across which nutrients and waste materials must pass. All cells have ribosomes.  Differences of Cells: Size Shape Chemical requirements 1 mm Similar And Different! The scientific study of how living things are classified is called taxonomy. Similar And Different! The binomial nomenclature system combines two names into one to give all species unique scientific names.  Divisions of life Cells are the basic structural and functional units of every organism. They have two distinct types: Prokaryotic and Eukaryotic. Prokaryotic cells: Bacteria and Archaea Eukaryotik cells: Protists, fungi, animals, and plants Prion, Viroid and Virus!!!  Divisions of life Prokaryotic cells Eukaryotic cells No nuclear membrane (Nucleoid) True nucleus, consisting of nuclear membrane No Membrane-enclosed organelles Lysosomes, Golgi complex, endoplasmic reticulum, mitochondria & chloroplasts Cell Wall: Usually present; chemically complex (typical Cell Wall: When present, chemically simple bacterial cell wall includes peptidoglycan) Plasma membrane: No carbohydrates and generally lacks Plasma membrane: Sterols and carbohydrates that serve as sterols receptors present Cytoplasm: Simpler cytoskeleton Cytoplasm: Cytoskeleton; cytoplasmic streaming Ribosomes smaller in size (70S) Larger size (80S) Single circular DNA, lacks histones Linear DNA with histones Cell division: Binary Division Cell division: Mitosis Sexual reproduction: No meiosis; transfer of DNA fragments Meiosis only (conjugation) Divisions of life present in (ribosome-studded) and smooth regions Nucleolus: nonmembranous mal cells, structure involved in production cluster of of ribosomes; a nucleus has NUCLEUS ANIMATION Rough ER Smooth ER Nuclear envelope Rough www.mast within an one or more nucleoli endoplasmic NUCLEUS Nucleolus Smooth BioFlix® 3-D he plasma reticulum endoplasmic Animal Cell membrane Chromatin: material consisting Chromatin reticulum of DNA and proteins; visible in a dividing cell as individual me: region condensed chromosomes the cell’s bules are ontains a centrioles Plasma membrane: Ribosomes (small b membrane enclosing the cell Central vacuole: promin in older plant cells; func breakdown of waste pr N: Golgi apparatus macromolecules; enlarg shape; major mechanism of pla movement; e made of Microfilament es: Intermediate aments filaments Microtubules aments Ribosomes (small brown tubules dots): complexes that make proteins; free in cytosol or bound to rough ER or nuclear Mitochondrion envelope Peroxisome li: Chloroplast: photosynthe at Plasma membrane organelle; converts energ l’s sunlight to chemical ener ea stored in sugar molecules Cell wall: outer Golgi apparatus: organelle layer that maintains active cell’s shape and protects cell from in synthesis, modification, sorting, mechanical damage; made of cellulose, and secretion of cell products other polysaccharides, and protein Plasmodesmata: cytoplasmic In plant cell channels through cell walls that Chloroplast connect the cytoplasms of Central vacu Wall of adjacent cell Cell wall ganelle adjacent cells Plasmodesm ecialized In animal cells but not plant cells: ions; Lysosome: digestive Lysosomes Mitochondrion: organelle where organelle where Differences Between Plant and Animal Cells Differences Between Plant and Animal Cells  Divisions of life Prion (Proteinaceous infectious particle): Prions are not considered living organisms because they are misfolded protein molecules which may propagate by transmitting a misfolded protein state. If a prion enters a healthy organism, it induces existing, properly folded proteins to convert into the misfolded prion form. In this way, the prion acts as a template to guide the misfolding of more proteins into prion form.  Divisions of life Bovine spongiform encephalopathy (BSE): It is commonly known as mad cow disease, is a neurodegenerative disease of cattle. Symptoms include abnormal behavior, trouble walking, and weight loss. Time from onset of symptoms to death is generally weeks to months.  Clinical Correlation Creutzfeldt–Jakob disease (CJD): It is a form of brain damage that leads to a rapid decrease of movement and mental function.  Divisions of life - Virus Virus: A virus is a small infectious agent that replicates only inside the living cells of other organisms. They reproduce by creating multiple copies of themselves through self-assembly by using host’s metabolism. This infectious particle consisting of nucleic acid enclosed in a protein coat(capsid) and, for some viruses, surrounded by a membranous envelope. No organelles, only some genes. Their genomes may consist of double-stranded DNA, single-stranded DNA, double- stranded RNA, or single-stranded RNA, depending on the type of virus.  Divisions of life RNA Capsomere DNA Membranous envelope RNA Capsid Head DNA Virus: Capsomere Tail of capsid sheath Tail fiber Glycoprotein Glycoproteins 18 × 250 nm 70–90 nm (diameter) 80–200 nm (diameter) 80 × 225 nm 20 nm 50 nm 50 nm 50 nm (a) Tobacco mosaic virus has (b) Adenoviruses have an (c) Influenza viruses have an (d) Bacteriophage T4, like a helical capsid with the icosahedral capsid with a outer envelope studded with other “T-even” phages, has a overall shape of a rigid rod. glycoprotein spike at each glycoprotein spikes. The complex capsid consisting of vertex. genome consists of eight an icosahedral head and a different RNA molecules, each tail apparatus. wrapped in a helical capsid.  Clinical Correlation: Influenza viruses Seasonal influenza (the flu) is an acute respiratory infection caused by influenza viruses. It is common in all parts of the world. Most people recover without treatment! Influenza spreads easily between people when they cough or sneeze. Vaccination is the best way to prevent the disease.  World Health Organization – Facts There are around a billion cases of seasonal influenza annually, including 3–5 million cases of severe illness. It causes 290 000 to 650 000 respiratory deaths annually. Ninety-nine percent of deaths in children under 5 years of age with influenza-related lower respiratory tract infections are in developing countries. There are four types of influenza viruses: A, B, C, and D. Influenza A and B viruses cause seasonal epidemics of disease in people (known as flu season) almost every winter. Influenza A viruses are the only influenza viruses known to cause flu pandemics (i.e., global epidemics of flu disease). A pandemic can occur when a new and different influenza A virus emerges that infects people, has the ability to spread efficiently among people, and against which people have little or no immunity. Influenza C virus infections generally cause mild illness and are not thought to cause human epidemics. Influenza D viruses primarily affect cattle but are not known to infect people to cause illness. Influenza A viruses Influenza A viruses are classified by subtypes based on the properties and combinations of their surface proteins: [hemagglutinin (HA), neuraminidase (NA)]. RNP: Ribonucleoprotein HA binds to a virus receptor on the host cell and mediates virus attachment to the cell surface. The hydrolytic enzyme NA cleaves sialic acid from viral receptors and Influenza viruses Swine flu Influenza viruses Mahal, A., Duan, M., Zinad, D. S., Mohapatra, R. K., Obaidullah, A. J., Wei, X.,... & Zhu, Q. (2021). Recent progress in chemical approaches for the development of novel neuraminidase inhibitors. RSC advances, 11(3), 1804-1840. Levels of Organization  Cell Cells are the smallest units that still retain the characteristics of life, including complex organization, metabolic activity and reproductive behavior. 1665, Robert Hooke observed tiny, empty compartments of a thinly sliced piece of cork under microscope. He gave them the Latin name «cellulae» (small rooms)  Theories in Science A scientific theory is an explanation of an aspect of the natural world that can be repeatedly tested and verified in accordance with the scientific method, using accepted protocols of observation, measurement, and evaluation of results. A theory is general enough to spin off many new, specific hypotheses that can be tested.  Cell theory «Schleiden» 1838 - Plant tissues are made of cells. «Schwann» 1839 - Animal tissues are made of cells. All living organisms are composed of one or more cells. The cell is the basic living unit of organization for all organisms. All cells arise from preexisting cells. References & Thank You WHO – who.org cdc.gov Mahal, A., Duan, M., Zinad, D. S., Mohapatra, R. K., Obaidullah, A. J., Wei, X.,... & Zhu, Q. (2021). Recent progress in chemical approaches for the development of novel neuraminidase inhibitors. RSC advances, 11(3), 1804-1840.