The Building Blocks of Life

[Audio] Grade 11 Microorganisms Part 1 Viruses and Bacteria Module 2: Life at molecular, cellular & tissue level.

[Audio] Terminology Micro-organisms – invisible to the naked eye Macro-organisms – visible organisms Acellular – organisms not consisting/containing cells Cellular – organisms that contain cells, can be uni- or multi-cellular Prokaryotes – a single celled organism with no distinct nucleus Eukaryotes – a multicellular organism in which the genetic material is contained in a distinct nucleus Unicellular – organisms characterised by the formation/presence of only a single cell Multicellular – organisms having/consisting of many cells Pathogenic – disease causing organisms.

[Audio] The Diversity of Life Result of over 4 billion years of evolution Viruses, Bacteria, Protists (algae & protozoa) and Fungi evolved early in the history of the Earth Way before plants & animals ❖ Hugely diverse group found in virtually all our planet's environments (even in most extreme – sulphur springs, arctic ice) ❖ Occur in vast numbers ❖ Vary in size ❖ Micro-organisms (microbes) ❖ Macro-organisms (some algae & fungi) ❖ Either cellular (bacteria, protists & fungi) or acellular (viruses) ❖ Cellular forms: ❖ Prokaryotes (bacteria) ❖ Eukaryotes (protists & fungi) ❖ Uni-cellular ❖ Form colonies of similar cells ❖ Made of primitive tissue.

[Audio] Pathogenic vs non-pathogenic organisms Pathogenic Non-pathogenic Disease Causing Harmless to plants & animals Often known as pathogens Common name: germs Include: Viruses Bacteria Some protists & fungi Microbes don't necessarily cause ± 1 in 1 000 microbe is pathogenic to humans disease – only pathogens do!.

[Audio] Viruses Infect animals, plants & bacteria Humans in constant battle with viruses HIV Ebola virus Coronavirus Very difficult to classify (not in a major kingdom).

[Audio] How were viruses discovered? Microbiologists observed the behaviour of viruses long before they could see them. In 1890, a Dutch professor = M. Beijerinck was experimenting with a disease called Tobacco Mosaic in tobacco plants. He found that if he spread the juice of the diseased leaves on healthy leaves, the healthy leaves also became diseased. This has happened even when he filtered the juice to remove any bacteria. This allowed him to realise that this was caused by something smaller than bacteria – sub microscopic sizes He called this infectious substance 'virus' = 'poison' in Latin. In 1940 the first virus was seen through an electron microscope..

[Audio] CharacteristicsofViruses Extremelysmall(smallestmicro-organisms) Onlyseenwithanelectronmicroscope Existin2distinctstates Virus–whenactivewhenincontactwithhostcell Virion–whendormant&notincontactwithhostcell Notreallylivingorganisms Donotexhibitthecharacteristicsoflivingorganisms Donotrespire,feed,excrete,growormoveontheirown Areobligateintracellularparasites–canonlysurviveinsidecellsofotherlivingorganisms Cellsarethehostsofviruses Canonlyreproduceinsidealivingcell ViralNucleicacidsreplicateusingmaterialsofhost'scellstocreatenewviruses Havenocellorganellesorcytoplasmtoallowforreplicationontheirown.

[Audio] Characteristics of Viruses continued Always associated with disease Because when the new viruses leave the host cell, host cell is either damaged or destroyed Can remain in a dormant state (latency) within an organism Herpes simplex virus (can causes cold sores) Chickenpox virus (later in life can cause shingles) Viruses have different shapes Polyhedral (cubical) Adenovirus Helical (helical) Tobacco virus Complex (tadpole-like) Bacteriophage - head, sheath & tail fibres Bacteriophage are viruses that infect bacteria Spherical Influenza virus.

[Audio] Structure of Viruses Viruses are acellular It is not a cell as it has no nucleus, cytoplasm or organelles Simple structure consisting of only a core nucleic acid DNA or RNA Nucleic acids responsible for specific characteristics of the virus Nucleic acid is surrounded by protein coat or capsid Hereditary material not enclosed by nuclear membrane In some viruses (rabies & influenza) the capsid is covered by an envelope of a lipid bilayer Envelope is used to protect the virus from host's nuclease enzymes.

McGraw-Hi" Companies, Permissbn requited tot rectodjcSon Ot Capsid Nucleic acid (a) Naked Nucleocapsid Virus (b) Enveloped Virus Envelope Spike Capsid Nucleic acid.

[Audio] InterestingfactsaboutViruses Viroid–infectiousRNAparticlethatresemblesavirus,butissmaller Causesdiseaseinplants Virusesmustbespreadbyair,fluidortransportedfromonehosttothenextbyaVECTOR Vector–organismthatcarriesadiseasewithoutbeinginfectedbyitBacteriophage.

[Audio] What effect do viruses have on the body? A. Host cells can be affected in 3 ways: 1) Infected cells can be destroyed They may swell and burst e.g.: Nerve cells infected with rabies virus 2) Host cell's functioning may be interfered with e.g.: Ciliated epithelial cells infected with influenza virus 3) Virus can interact with host cell's chromosome causing a mutation e.g.: Warts & Cancer Cells B. The immune system becomes activated which may lead to fever, tiredness or a disease.

[Audio] Examples of human diseases caused by Viruses ❖ Common cold ❖ Influenza ❖ Smallpox Antibiotic are not effective in treating ❖ Measles viral diseases. ❖ Mumps WHY? ❖ Poliomyelitis ❖ HIV/AIDS ❖ Rabies ❖ COVID-19 Viral diseases are treated with antiviral medication (ARV's) and prevented by using vaccines.

[Audio] Rabies Rabies virus contains RNA Family of viruses called Rhabdoviruses Rabies virus is carried in the saliva of infected (rabid) animals. The virus can be transferred to humans by the bite, lick or scratch of an infected animal. The virus must penetrate the skin and enter the body. In South Africa the animals that can be infected are: Wild dogs Bats Cats Black-backed jackals Yellow mongooses Bat-eared foxes Unvaccinated domestic dogs are the usual path of transmission. Dogs that are infected shows symptoms: Aggressive Drool saliva Sometimes they can be very withdrawn and scared.

Brain inflammation Virus transmitted by infected saliva through bite or wound G glycoprotein SPIKES protein bilayer membrane helical nucleocapsid (RNA plus N protein) olymerase (Z proterns).

[Audio] Effectofrabiesvirusonhumanhealth Thevirusreplicatesinmusclecells Earlysymptoms: Feverandothercellssurroundingthesiteofinfection. Headache Thevirusthenentersnervecellsand Soremuscles Numbnessatsiteofinfectiontravelstowardsthebrainalongthecentralnervoussystem. Theviruscontinuestoreproducein Agitationandconfusionfollowasdiseaseprogresses Convulsions Seizuresthebrainandthenspreadstotheotherpartsofthebodyincludingthesalivaryglands. Excessivesaliva Painfulthroatspasm Feartryingtoswallowliquids Paralysis Deathoccurwithin3–5daysaftersymptomsbegin.

[Audio] Management of Rabies  Once symptoms begin there is no cure for the disease.  If treatment is provided immediately after exposure to the virus, then the disease can be prevented.  Treatment consists of an injection containing rabies immune globulin and the rabies vaccine  The rabies immune globulin contains antibodies that will attack the virus and stop it from progressing to the nerves and brain  The vaccine triggers the immune system to fight the virus  How to prevent rabies:  Vaccinate domestic dogs  Vaccinate at-risk individuals such as veterinarians and game rangers.  Avoid any animals behaving strangely.

Human rabies cases, 1997 - 2018 Period 1997-2007 (n=115) Period 2008 - 2018 (n=105) Limmx• Ljmpopo al azu N0fthan Cape Westem cape North vvest Free state Eastern Cape Northem Cape V&stem Carp 0 125 250 No Gmie Free Stab E-a:åern Cape 500 km ulu-Na FACT #1 VACCINATING 70% OF DOGS IN AT RISK AREAS CAN ELIMINATE CANINE RABIES NOT.

[Audio] COVID-19 Notforexaminationpurposes CoronavirusdiseasecausedbytheSARS-CoV-2virus Spreadsbetweenpeopleinclosecontact Commonsymptoms:fever,chills,sorethroat-amongothers Symptomsusuallystart5-6daysafterexposureandlast1-14days Mostpeoplemakeafullrecoverywithoutneedinghospitaltreatment COVID-19vaccinesprovideprotectionagainstsevereillness&death AlthoughyoucanstillgetCOVID-19aftervaccinations,morelikelytohaveno/mildsymptoms Over13billiondosesofvaccineshavebeenadministeredasofJune2023 Treatment: Doctor'swillsuggesttreatmentsbasedontheseverityofthediseaseandtheriskfactorsincreasingchanceofprogressionofdisease Prevention: Avoidingcrowdedareas Wearingaproperlyfittingfacemasktoreducechancesofspreading Cleanhandsregularly Covermouthandnosewhencoughing/sneezing.

COVID-19 vaccines DEBUNKING THE MYTHS VACCINE MYTH The vaccines were rushed and they aren't safe The vaccines can give you COVID-19 The vaccines contain egg proteins The vaccines cause severe side effects The vaccines can make women infertile VACCINE FACT Vaccines approved by Health Canada are backed by data demonstrating their safety, efficacy and quality The vaccines cannot give you COVID-19; they do not contain a live virus strain The vaccines don't contain egg proteins and can be given to people with egg allergies The vaccines are all safe. Most side effects are mild and will resolve within a few days on their own COVID-19 VACCINE There is no evidence that the vaccines cause infertility Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike glycoprotein (S) envelope small membrane protein (E) membrane protein (M) nucleoprotein (N) genomic RNA O Encyclopædia Britannica, Inc. Canadä.

[Audio] HISTORYOFBACTERIA Ancestorsofbacteria=unicellularmicro-organismsthatdeveloped4billionyearsago Theywerethe1stformsoflifetodeveloponearth Bacteriawereonlydiscoveredinthelate1600sbyhumans AntonvanLeeuwenhoekmadethefirstmicroscopesopeoplecouldseebacteria In1683,henoticedtinycellswithdifferentshapesinmaterialheobtainedfromvariousplaces,suchasscrapingsfromhisteethandrainwaterfromgutters. Hereportedthattherewereenormousnumbersof'animalcules'(whathecalledthem)ofdifferentshapes,movingveryfast. In1870GermanscientistRobertKochdiscoveredthatitwaspossibletogrowbacteriafromdifferentsourcesonagrowthmedium. Agar=growthmedium Agarisajelly-likesubstanceextractedfromseaweeds. Kochalsodemonstratedthatbacteriacouldcausespecificdiseases. Heprovedthatthediseaseanthraxwascauseddirectlybythebacterium Bacillusanthracis..

[Audio] General characteristics of bacteria Kingdom Monera Inhabit almost all environments Smallest living organism Exist singly, in chains or in clumps Bacteria are named according to their shape: Coccus – spherical Bacillus – rod shaped Vibrio – comma shaped Spirillium – spiral shaped.

[Audio] General characteristics of bacteria In favourable conditions: Bacteria reproduce very quickly by binary fission A single cell divides via mitosis to produce two identical cells This division can happen every 10 to 15 minutes In unfavourable conditions: Bacteria become dormant by forming spores When favourable conditions return the spore coat splits open and releases the bacteria.

[Audio] Structure of bacteria: Unicellular Can have a slime capsule/waxy cuticle on the outside – mostly in pathogenic bacteria – WHY? ________________________________________ _____________ Rigid cell wall made of peptidoglycans (polysaccharides and amino acids) Cell membrane below cell wall – it is semi/selectively permeable Some bacteria have flagella - __________________________________ ALL bacteria are prokaryotes = __________________________________ Contain a closed loop of DNA (nucleoid).

[Audio] TUBERCULOSIS: Chronic bacterial infections caused by Mycobacterium tuberculosis Can affect all organs of the body, most commonly the lungs Pulmonary TB – contagious disease: In 2021, about 304 000 people caught TB of which an approximate 56 000 died Spread in moisture droplets from an infected person's cough or sneeze etc. The bacterium has a waxy coat – prevents it from drying out, heat and being destroyed by body's immune system Can remain alive outside the host for a long time (3-4 months) Latent/dormant TB: If the immune system is strong – the infection is contained and can lie dormant for years Active TB: If the immune system is weak – bacteria multiply rapidly and the person will be ill with 4 to 6 weeks.

[Audio] TUBERCULOSIS: EFFECTS/SYMPTOMS OF TB: Fevers and night sweats Persistent cough (sometimes coughing up blood) Tired and weak Weight loss Each person with active TB can infected 10 to 15 others per year if left untreated MANAGEMENT/TREATMENT OF TB: Can be cured using antibiotics for 6 months DOTS (Directly Observed Therapy, Short course) Patients are actively monitored to ensure they take their medication Within days the patient is no longer able to infect others Common problem: People feel better and stop taking their medicine Illness is prolonged Patient becomes infectious again MDR and XDR TB have developed.

[Audio] TUBERCULOSIS: Societal management: TB occurrence is usually higher in poverty stricken communities This is due to overcrowded living conditions and malnutrition We can attempt to slow down the spread of TB by: Screening people at high risk e.g. health workers Treating infected patients as soon as they are diagnosed Provide education and public awareness Prevention: BCG vaccine is given to newborn babies HIV and TB: "Death duo" HIV weakens the immune system – person is more likely to be infected by TB.

[Audio] Maintaining a balance in the environment Functions of micro-organisms in the environments: Plant degraders: Cellulose degrading fungi and bacteria decay dead plants in the environment Micro-regulators of nutrients: Plant or animal dies Scavengers/detrivores – feed on the dead matter but organic matter is still left Decomposer micro-organisms breakdown the organic matter into carbon dioxide and nutrients These nutrients can be absorbed by plants to be used again Regeneration of oxygen: Blue-green bacteria (cyanobacteria) and phytoplankton replace oxygen used in the atmosphere Nitrogen transformers: Nitrifying bacteria change nitrogen gas into nitrates Biological control agents: Act as natural "enemies" of pests, pathogens and weeds.

[Audio] Micro-organisms and symbiosis: Symbiosis: Mutualism, commensalism, parasitism Mutualistic relationships: E.coli and humans: ■ Harmless strains of E.coli are found in our intestines ■ Bacteria benefit by receiving glucose and other nutrients from the digested food ■ Humans benefit by: Gaining Vitamin K that the bacteria produces Protection against pathogenic bacteria.

[Audio] Micro-organisms and symbiosis: Mutualistic relationships: Nitrogen-fixing bacteria and plants: ■ Nitrogen gas needs to be changed into nitrates to be used by plants ■ This is done by lightning and nitrogen-fixing bacteria (either symbiotic or free-living in soil) ■ Symbiotic nitrogen-fixing bacteria are in the root nodules of legumes (e.g. pea plant and bean plants) ■ Bacteria gains glucose, nutrients and protection ■ Plants gain nitrates which are used to produce amino acids, which the plant uses to form its proteins.

[Audio] Micro-organisms and symbiosis: Mutualistic relationships: Mycorrhizal fungi and plant roots: 70 – 80% of plants have mycorrhizae Fungi "infect" roots and send out hyphae which extend far out from plants roots Fungi gains glucose for growth Plant gains: ■ Increased absorptive surface area for water and mineral uptake ■ Protection against pests.

[Audio] Economic uses: Economic uses of bacteria: Degrade herbicides in contaminated groundwater Bioremediation – neutralize toxic waste in soil Decompose sewage wastes to harmless sludge Produce food by fermentation e.g. cheese, yoghurt Make probiotics e.g. Lactobacillus Economic uses of algae: Gelling agents Agar plates (growth medium extracted from red seaweeds) Economic uses of fungi: Food source e.g. mushrooms Production of antibiotics Fermentation process e.g. yeast.