Medical Biology Lecture Notes PDF - University of Mosul

University of Mosul College of Medicine Lecture: (1) Subject/year: Medical Biology / 1st year Lecturer: Inaam A. Abdulhameed Department: Anatomy Date: 13/11/2024 The AIM of this lecture is - To recognize and describe the characteristics of living organisms. - To identify differe...

University of Mosul College of Medicine Lecture: (1) Subject/year: Medical Biology / 1st year Lecturer: Inaam A. Abdulhameed Department: Anatomy Date: 13/11/2024 The AIM of this lecture is - To recognize and describe the characteristics of living organisms. - To identify different levels of biological organization - To describe what a cell is and the two general types of cell. - To describe the tools of cell biology.   Intended learning outcomes: By the end of this lecture the student will be able to: 1. Define the term “Biology”. 2. Explain the basic characteristics that are common to all living things. 3. Describe the levels of biological organization. 4. Define the term “ Cell Biology”. 5. Compare between prokaryotic and eukaryotic cells. 6. Know the tools of cell biology.  Introduction  Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, evolution, distribution, and taxonomy.  Medical biology is a field of biology that has practical applications in medicine, health care and laboratory diagnostics.  The Characteristics of Life  All living organisms share several basic Characteristics: 1- Organization 5- Metabolism 2- Homeostasis 6- Reproduction 3- Adaptation 7- Growth and Development 4- Response to stimuli Madder, S., S., and Windelelspecht, M., Human biology, 17th ed..Mc Graw – hill, USA, 2023. 1-Organization : Living things are highly organized. All living organisms are made up of one or more cells. 2.Homeostasis: Regulation of the internal environment to maintain a constant state. Stable internal conditions of pH, temperature, water balance, etc. e.g. sweating to reduce temperature. 3.Adaptation: The ability to change over time in response to the environment. 4.Response to stimuli: Organisms respond to stimuli (Temperature, Water, Food Supplies, etc.) in order to survive & reproduce. 5.Metabolism: is the term used to describe all chemical reactions that are involved in maintaining the living state of the cells and the organism. 6. Reproduction: The ability to produce new individual organisms, either asexually from a single parent organism, or sexually from two parent organisms.  7. Growth and Development: Growth recognized by an increase in size and often the number of cells. Development refers to all changes that occur during life. Levels of biological organization  Atom: The smallest part of an element made of protons, neutrons, and electrons. Molecule: Two or more atoms bonded together. Organelle: A small part inside a cell that has a specific job to do. Cell : is the basic structural and functional unit of all known living organisms. Tissue: Many cells of the same type working together to perform a function.  Organ: Different tissues working together to form a structure with a specific function Organ System: Different organs working together to perform a major process in an organism. Organism: A single living thing that has all of the characteristics of life.  Population: Many organisms of the same type in the same place at the same time. Community: All of the different living things in the same place at the same time. Ecosystem: All of the living things (biotic) and the non-living factors (abiotic) in the same place at the same time. Biosphere : The part of the earth's surface where living things can be found.  Cell biology  Cell biology (also cellular biology or cytology) is a branch of biology studying the structure and function of the cell.  Cells are the structural and functional unit of all living organisms, from the unicellular organisms, like bacteria, which are made up of one cell to the multicellular organisms, such as human beings.  Cell biology  All cells have three basic parts: 1- Cell membrane. 2- DNA-containing region. 3- Cytoplasm.  Cell Theory: Consists of three principles : 1. All living things are composed of one or more cells. 2. Cells are the basic units of structure and function in an organism. 3. Cells come only from the replication of existing cells  Type of Cells Biologists classify cells into two basic types; 1. Prokaryotic cell is a simple, single-celled (unicellular) organism that lacks a nucleus, or any other membrane- bound organelle. 2. Eukaryotic cell is a cell that has a membrane-bound nucleus and organelles.  Comparison between prokaryotic and eukaryotic cells.  Similarities: 1- They both have DNA as their genetic material. 2- They are both membrane bound. 3- They both have ribosomes. 4- They have similar basic metabolism.  Differences: Parameter Prokaryotes Eukaryotes Genetic DNA is circular, usually free- DNA is linear, found in nucleus information floating in cytoplasm Organelles No nucleus or membrane- bound Always have nucleus and organelles membrane- bound organelles Size Small cell Larger cells Organisms Bacteria and archaea Animals, plants, fungi , and protists Cell structure Unicellular Unicellular or multicellular Cell division Binary fission Meiosis and mitosis  Tools of Cell Biology The study of cells is performed using several techniques such as :  Microscopes  Cell culture.  Cell fractionation 1- Microscopes:. A microscope: is an instrument used to see objects that are too small for the naked eye.. Two parameters are especially important in microscopy:  Magnification -the power of the microscope to enlarge the image of an object.  Resolution- the power of the microscope to show detail clearly.  Light microscopes: In a light microscope, visible light passes through the specimen and is bent through the lens system, allowing the user to see a magnified image. A light microscope has high magnification. However, it has a low resolution.  Electron microscopes: Electron microscopes differ from light microscopes in that they produce an image of a specimen by using a beam of electrons rather than a beam of light. These microscopes have the highest magnification power and highest resolution available. There are two types of electron microscope:  Transmission electron microscope  Scanning electron microscope 1-Transmission electron microscopy (TEM): In this case, the electron beam is passed through the sample. The result is a two dimensional image. 2-Scanning electron microscopy (SEM): Here the electron beam is projected on the sample. The electrons do not go through the sample but bounce off. This way it is possible to visualize the surface structure of the specimen. The image appears 3 dimensional. Madder, S., S., and Windelelspecht, M., Human biology, 17th ed..Mc Graw – hill, USA, 2023. 2- Cell Culture  When living cells are taken from living tissue and grown in artificial media, this process is referred to as cell culture. 3- Cell fractionation It is the process in which cells are broken up and the different organelles they contain separate out. This is used to help us study cell structures and functions. To summarize: - Biology is a natural science concerned with the study of life and living organisms. - Living organisms have certain characteristics that distinguish them from nonliving objects. - Living organisms have levels of organization - Cell biology is a branch of biology studying the cell. - There are two basic types of Cell. - The study of cells is performed using several techniques  Lets check our knowlege Choose the best answer for each question. Q1 : In this case, the electron beam is passed through the sample. The result is a two dimensional image. A. Transmission electron microscopy (TEM) B. Scanning electron microscopy (SEM) C. Light microscope B. Tissue culture Q2: The ability to produce new individual organisms, either asexually or sexually is called: A. Organization B. Reproduction C. Growth D. Metabolism Q3: Which of the following organisms are prokaryotes? A. Protists B. Archaea and bacteria C. Fungi D. Plants References and recommended further readings: 1. Madder, S., S., and Windelelspecht, M., Human biology, 17th ed. Mc Graw – hill, USA, 2023. 2. Sylvia S. Madder, Biology, 6th ed. Mc Graw-Hill Education, USA,1999.