2 Learning Objectives Name 3 types of bacterial cell Explain reproduction of bacteriaExplain nutrition of bacteriaState the factors affecting growth of micro-organismsDefine the term pathogenicDefine the term antibioticsState the role of antibioticsOutline the potential abuse of antibioticsName 2 Beneficial & 2 Harmful bacteria
3 BacteriaBacteria are the oldest living organisms on earth They are Prokaryotic – they have no true nucleus, mitochondia or chloroplasts.
4 Habitat Bacteria are found in every possible habitat Soil, Air, Fresh water, Sea water, Skin, Intestines etc.Some bacteria can withstand extreme conditions e.g. temperatures of 80 degrees C in hot springs or extreme cold and high pressure on the sea bed.
15 Functions of Parts of Bacterial Cell FlagellumCapsule (slime layer)Cell WallPlasmid (DNA)CytoplasmStorage granulesChromosome
16 Cell Parts & Function Cell wall - shape & structure Cytoplasm - contains ribosomes and storage granules but no mitochondria or chloroplastsNuclear material -single chromosome of DNACapsule* - protectionFlagella* - movementPlasmid* -circular piece of DNA containing few genes for drug resistance* Sometimes present.*Sometimes present
17 Cell wall: made of protein and polysaccharide, rigid and permeable Cell membrane: selectively permeable.Cytoplasm: contains a large number of ribosomes.Nuclear material = DNA (1 circular chromosome and 1 plasmid - small loops of DNA . Plasmids contain genes that are responsible for bacterial resistance to antibiotics.No organelles (except ribosomes) i.e. no nucleus, mitochondria, chloroplast. Flagella: movement Capsule: slimy protective coat, in parasitic species for protection. Helps cell to attach to different surfaces. chlorophyll mesosomes: infoldings in cell membrane which carry out respiration and help during cell division. pili: hair-like projections which allow the bacterium to attach to other cells.
19 Quiz – Variety of Organisms Write down each question and answer:Name the five kingdoms used to classify organisms?Define the word species?Which kingdom has organisms that are prokaryotic?Amoeba and algae are members of which kingdom?
23 Objectives for today’s class Textbook pg 220 Quiz on Classification of organismsHomework pg. 228Asexual reproduction in bacteriaMutations in BacteriaAntibioticsBacterial EndosporesNutrition in BacteriaConditions necessary for growth
31 Bacterial Reproduction Bacteria reproduce asexually - their offspring are genetically identicalBacteria has a very short lifecycle (some can reproduce every 20 minutes).A single bacterium could reproduce over a million bacteria in 7 hours.
33 Mutations in BacteriaBacteria reproduce asexually so their offspring are genetically identical. Bacteria can evolve very fast due to the speed at which new mutations can spread within the rapidly growing bacteria. The short life cycle of bacteria mean mutations (changes) can be passed on very quickly so bacteria become resistant to antibiotics very fast.
34 AntibioticsAntibiotics are chemicals produced by micro-organisms which stop the growth of or kill other micro-organisms without damaging human tissue. Most famous antibiotic is Penicillin
35 AntibioticsThe first antibiotic Penicillin isolated from a fungus by Sir Alexander FlemingNow antibiotics are mostly produced by genetically engineered bacteria
36 Alexander fleming “the wonder drug” youtube AntibioticsPenicillin FungusThe first antibiotic, penicillin, was discovered in 1929 by Sir Alexander Fleming, who observed inhibition of staphylococci on an agar plate contaminated by a Penicillium mould.Alexander fleming “the wonder drug” youtube
37 AntibioticsAntibiotics can be used to control bacterial and fungal infections but do not effect viruses
38 AntibioticsWhen an antibiotic is used to treat an infection most of the bacteria are killedMutations in bacterial genes can allow bacteria to develop antibiotic resistance.Antibiotics will then kill ‘sensitive’ bacteria and favour resistant bacteria.Bacterial strains have emerged which are resistant to almost all known antibiotics (multi-resistant). As a result present day antibiotics become ineffective. MRSA is one example.
39 Misuse Over use of antibiotics This results in the increased growth of antibiotic resistant bacteriaFailure of some patients to complete a course of antibiotics prescribed to them by a doctor allows the bacteria to survive and re-grow
40 Endospore formationSome bacteria can withstand unfavourable conditions by producing endospores.These are resistant cells which enable the bacteria to survive.
41 Endospores Endospores are very difficult to kill. They can survive a lack of food, water, high temperatures and most poisons.They are normally not even killed by boiling water.Some endospores can survive for hundreds of years.
42 A white blood cell injests a disease causing bacteria
43 These are formed when the bacterial chromosome replicates Endospore formationThese are formed when the bacterial chromosome replicates
44 The parent cell then breaks down and the endospore remains dormant Endospore formationThe parent cell then breaks down and the endospore remains dormant
45 Endospore formationOne of the new strands becomes enclosed in a tough-walled capsule called an endosporeThe parent cell then breaks down and the endospore remains dormantEndospore
46 Endospore formationWhen good conditions return the endospores absorb water, break their walls and reproduce by binary fission
57 Learning check Name the three different types of bacteria? By what method do bacteria reproduce?Describe the steps involved in this method of reproduction?
58 Quiz 1. How do bacteria develop resistance to antibiotics? 2. Name the 2 main categories of bacteria with regard to their nutritional methods?
59 Factors affecting the growth of bacteria The growth of bacteria is affected by 5 factors:TemperatureOxygen concentrationpHExternal solute concentration5. Pressure
60 Factors affecting the growth of bacteria Too much or too little of any of the factors will slow down the growth of bacteria.Factors that slow down a process when they are in short supply are called limiting factors.
61 1. TemperatureThe rate of bacterial growth is affected by temperature. Most bacteria grow well between 20°C and 30°C.Some can tolerate much higher temperatures without their enzymes becoming denatured.Low temperatures slow down the rate of reaction of enzymes resulting in slower growth.
62 2. pH Bacterial enzymes are designed to work at a specific pH. If a bacterium is placed in an unsuitable pH its enzymes will become denatured.Some bacteria can tolerate very low (acidic) (e.g. Helicobacter bacteria in about 50% of Irish population stomachs) pH and some can tolerate very high (alkaline) pH.
63 Oxygen concentrationAerobic bacteria require oxygen for respiration e.g. StreptococcusThis is why oxygen is sometimes bubbled through bioreactors
64 New Vocabulary1. Aerobic Bacteria: require oxygen for respiration 2. Anaerobic Bacteria: do not require oxygen for respiration e.g. Clostridium bacteria 3. Faculative Anaerobes: Can respire with or with out oxygen. E.g. E. Coli in human intestine 4. Obligate Anaerobes: Can only respire in the absence of oxygen e.g. Clostridium tetani
65 External Solute concentration Bacteria can gain or lose water by osmosisIf the external solute concentration ishigher than the bacterial cytoplasm water will move out of the bacteria (Dehydration)Food preservation techniques are based on this
66 External Solute concentration Bacteria can gain or lose water by osmosisIf the external solute concentration islower than the bacterial cytoplasm solute concentration water will enter the bacteriaCell wall will prevent bursting in most cases
67 Pressure The growth of most bacteria is inhibited by high pressures. Some bacteria can withstand high pressures. Pressure tolerant bacteria for use in bioreactors can be formed by genetic engineering techniques.
68 Phases in Bacterial Growth Lag PhaseBacteria adapt to their environment and make chemicals to prepare for growth.B Log PhaseBacteria divide as fast as possible. Growth is exponential due to ideal conditions.C Stationary PhaseThe number of bacteria dying is the same as the number growing.D Decline PhaseMost of the bacteria start to die.E Death or Survival PhaseA few survive as Endospores.
70 Economic importance of bacteria Beneficial bacteriaLactobacillus are used to convert milk to products such as cheese and yoghurtGenetically modified bacteria e.g. E. Coli are used to make products e.g. insulin, enzymes, drugs, food flavourings
71 Economic importance of bacteria Harmful bacteriaE.g. Bacillus anthracis causes anthrax in humansOther bacterial cause diseases include tuberculosis, typhoid, cholera, diphtheria and brucellosis
72 Beneficial and harmful bacteria Lactobacillus converts milk to yoghurt and cheeseAntibiotics can be formed by some microorganismsBacteria in the colon help produce vitaminsG.M.O.’s are used to make insulin and other useful compoundsBacteria are active in the Carbon and Nitrogen CyclesHARMFULPathogenic Bacteria can cause diseases in humans and animals.Pathogenic Bacteria can cause diseases in plants.Bacteria can cause food spoilageBacteria can cause tooth decay.
73 Bio-reactors Bioreactors Bacteria can be grown in Bioreactors. These are vessels to which food and oxygen are added.The bacteria have to be kept at a certaintemperature and pressure.The bacteria also produce wastes thatmust be removed so that they don't get contaminated.The bacteria are grown to makeantibiotics, food colouring, perfumes, etc.
75 Depth of treatmentBacterial cells: basic structure (including plasmid DNA), three main types. Reproduction. Nutrition.Factors affecting growthUnderstanding of the term “pathogenic”Definition and role of “antibiotics”
76 Pathogen A pathogen is a micro-organism that causes disease. Pathogens include bacteria and some fungi.e.g. TB and food poisoning
77 Lab procedures when growing micro-organisms Micro-organism (bacteria, fungi & viruses) can only be seen with an electron microscope.Colonies (groups) of bacteria and fungi may be grown in the lab on agar plates
78 Lab ProceduresAgar is a substance that contains all the nutrients and minerals bacteria and fungi need to grow.Agar plates and Agar are sterilised before use.
79 SterileA place or substance is sterile if all micro-organisms have been removed. Sterilisation can be down by heating a substance to 120 C for 20 minutes using a special oven called an autoclave
80 AsepsisAsepsis uses techniques to remove disease causing (pathogenic) micro-organisms and reduce their spread e.g. washing hands, wearing sterile gloves etc.
81 Safety Rules when working with micro-organisms Many rules including:Handle all micro-organisms carefully and treat them as if they could cause infection.Seal all petri-dishes with parafilm to prevent micro-organisms escaping.Sterilise all containers by heating them to 120 C for 20 minutes.
82 Contemporary issues and technology Economic importance of bacteria: examples of any two beneficial and any two harmful bacteria.Potential abuse of antibiotics in medicine.
83 Food ProcessingBacteria are used in large, stainless steel vats (bioreactors) to produce a large range of foods and other products.Two methods used:Batch food processingContinuous flow food processing
84 The methods differ in that each method favours different phases of the bacterial growth curve. Batch FlowIn batch flow the bacteria are grown until the stationary phase.After this the bacteria are stopped and removed.The Bacteria are stored then till more product is needed.This is the better system and costs less money.Many antibiotics are made this way.
85 Continuous Flow Processing In continuous flow the bacteria are kept growing in the Log Phase.The dead bacteria and wastes are removed constantly to save the live bacteria.The Bacteria are kept growing to produce constant product (e.gin. sulin).This system needs constant monitoring and costs more money.Single Cell Proteins (Quorn/TVP) are made this way.
86 Food ProcessingModern bioprocessing uses bacteria and fungi to make food products.These include cheese, yoghurt, sweetners, amino acids, vitamins. flavourings,flavour enhancers, beer and wines.Humans usually get protein from meat but other sources are now available.These Single Cell Proteins may be better for the environment and for our health
87 Not just humans take antibiotics Antibiotics given to animals can be passed on in meat.This means that the animals help make resistant bacteriathat we may then eat and have inside us.This could lead to a huge pandemic that could kill millions