14. Microbes and Disease Part 1.pptx

MICROBES AND DISEASE Human pathogens  PART 1 INTRODUCTION  WHAT ARE MICRO-ORGANISMS? Micro-organisms, or microbes for short, are very small living creatures. Most of them cannot be seen without using a microscope. Bacteria (orange)...

MICROBES AND DISEASE Human pathogens  PART 1 INTRODUCTION  WHAT ARE MICRO-ORGANISMS? Micro-organisms, or microbes for short, are very small living creatures. Most of them cannot be seen without using a microscope. Bacteria (orange) on the tip of a pin. Magnification x1600 when the image is printed 10 cm high. The tip of the pin is approximately 20 µm across and the bacteria are around 5 µm long. WHAT ARE MICRO-ORGANISMS? They are classified into 5 different groups Viruses Bacteria Fungi Algae Illustration of microbes Protozoa WHAT ARE MICRO-ORGANISMS? What does the word ‘microbe’ mean to you? To most people microbe only means……. INFECTION But….  Only a small number cause disease, many more are helpful.  Microbes play a key role in maintaining life on earth, fixing gases and breaking down dead plant and animal matter into simpler substances that are used at the beginning of the food chain.  Their activity is exploited for the production of medicines, food and enzymes.  They are used to breakdown sewage and other INFECTION AND DISEASE What is a pathogen? A pathogen is a micro-organism that has the potential to cause disease. What is an infection? An infection is the invasion and multiplication of pathogenic microbes in an individual or population. What is disease? Disease is when the infection causes damage to the individual’s vital functions or systems. Disease prevents an organism from functioning effectively in its surroundings An infection does not always result in disease!  Types of Diseases  Diseases can either be infectious/communicable (you can “catch” it) or non-infectious/ non-communicable (you can’t “catch” it)  Infectious diseases are caused by a DISEASE pathogen S INFECTIOUS DISEASES NON-INFECTIOUS DISEASES caused by pathogen (e.g. can be genetic, nutritional, bacterium, fungus, protozoan, environmental or caused by worm, insect or virus) physiological malfunction can be transmitted cannot be transmitted Examples: covid-19, Examples: diabetes, tuberculosis, HIV cancer, motor neuron INFECTIOUS DISEASES disease  PATHOGENS Pathogens may be microorganisms such as bacteria, protozoa and fungi, macro-parasites such as ticks and worms, or non-cellular (non-living) agents such as viruses and prions. Pathogens Pathogens  Features of Bacteria: Checklist They are prokaryotes - single celled organisms where no membranes bound organelles They do not have a true nucleus, but a circular strand of DNA. They do not contain mitochondria. They may have a tail, known as a flagellum, to help it move. They produce toxins that damage cells and tissues. They are living cells. The largest bacteria are 10 micrometres long. Examples: lactobacillus, Bacteria shapes  Features of Viruses: Checklist They are not cells/acellular or non-living. They are much smaller than bacteria. They reproduce rapidly inside host cells. They consist of genetic material and a protein coat. Once inside a cell, viruses can make thousands of copies of itself. This continues until the cell bursts open. It is this cell damage that makes humans feel unwell. Measles, mumps, chicken pox and colds are all caused by VIRUSES CYCLE EXAMPLES OF VIRUSES  Features of Protists: Protists, or protozoa,Checklist are eukaryotes. They are single celled organisms. They can be parasitic, this means they live on or inside another organism causing harm. They can be animal-like, plant-like, or fungi-like. Malaria is a well-known illness caused by protists and transmitted by mosquitos. CLASSIFICATION OF PROTISTS PROTISTS  Life Cycle of Malarial Protists A healthy person is bitten by an infected mosquito. The parasite is injected into the blood stream. The parasite invades the liver and red blood cells causing the illness to develop. If a mosquito feeds on the blood of an infected person, the parasite enters the mosquito. When the mosquito feeds on a healthy person, the parasite is passed on. Features of Fungi: Checklist Toadstools, mushrooms and moulds are examples of multi-cellular fungi. The cell wall of fungi is made from chitin. Fungi use saprotrophic nutrition - they secrete enzymes to digest food and then absorb it. Fungi have thread like structures called hyphae. Hyphae can produce spores enabling the fungus to be easily spread. FUNGAL PATHOGENS: SHAPE-SHIFTING INVADERS Fungal pathogens grow in different shapes that influence their ability to disseminate an infection. For example, small spores (conidia) penetrate deep into the lung, budding cells that are about the size of a red blood cell disseminate in the bloodstream, and long hyphal filaments grow invasively into solid tissues. Some fungi undergo shape shifting in the host to form larger cells, or clusters of cells, that are too big to be eaten (phagocytosed) by leukocytes. Other fungi form small yeasts that have developed strategies for surviving inside the phagosome where they are safe from attack by other immune cells. This also allows them to disseminate throughout the host in a Trojan horse mechanism. Fungal shape shifting can also enhance growth in the host by SHAPE SHIFTING FUNGAL PATHOGENS Representation of escape mechanisms in pathogenic fungi Macroparasit es at all, but  These are not microorganisms are still pathogens and can cause diseases.  They can be seen with the naked eye  Some examples are head- lice, fleas, ticks and worms Life Cycle of Schistosomiasis PRIONS  A prion is a very simple infectious particle made up of an abnormal form of a normally harmless protein.  Prions mainly cause neuro-degenerative diseases that are fatal. Example - Mad-cow disease  When infected, prions cause misfolding of normal proteins in the brain.  These abnormal shapes of proteins destroy neurons causing the brain to riddle with holes.  PRIONS For example: mad cow disease and Creutzfeldt- Jakob disease