Presentation on theme: "Monera Bacteria. Learning Objectives Name 3 types of bacterial cell Explain reproduction of bacteria Explain nutrition of bacteria State the factors affecting."— Presentation transcript:
Learning Objectives Name 3 types of bacterial cell Explain reproduction of bacteria Explain nutrition of bacteria State the factors affecting growth of micro-organisms Define the term pathogenic Define the term antibiotics State the role of antibiotics Outline the potential abuse of antibiotics Name 2 Beneficial & 2 Harmful bacteria
Bacteria Bacteria are the oldest living organisms on earth They are Prokaryotic – they have no true nucleus, mitochondia or chloroplasts.
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.
Bacteria in pond water
Bacteria on apple
Bacteria Bacteria belong to the kingdom Monera. They are unicellular organisms They are classified according to three shapes 1.Spherical (cocci) 2.Rod (bacillus) 3.Spiral (spirillum)
Spherical (cocci) E.g. Staphoolococcus aureus Causes pneumonia
Rod (bacillus) E.g. Bacillus anthracis Cause of anthrax Escherichia coli (E.coli) Live in human gut
Cell wall plasmid Strand of DNA flagella cytoplasm Cell membrane capsule Bacterial Structure
Functions of Parts of Bacterial Cell PartFunction Flagellum Capsule (slime layer) Cell Wall Plasmid (DNA) Cytoplasm Storage granules Chromosome
Cell Parts & Function Cell wall - shape & structure Cytoplasm - contains ribosomes and storage granules but no mitochondria or chloroplasts Nuclear material -single chromosome of DNA Capsule* - protection Flagella* - movement Plasmid* -circular piece of DNA containing few genes for drug resistance * Sometimes present.
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.
Quiz – Variety of Organisms Write down each question and answer: 1.Name the five kingdoms used to classify organisms? 2.Define the word species? 3.Which kingdom has organisms that are prokaryotic? 4.Amoeba and algae are members of which kingdom?
Revision – Bacterial Cell
Label the bacterial Cell
Useful websites for bacteria
Objectives for today’s class Textbook pg Quiz on Classification of organisms 2.Homework pg Asexual reproduction in bacteria 4.Mutations in Bacteria 5.Antibiotics 6.Bacterial Endospores 7.Nutrition in Bacteria 8.Conditions necessary for growth
Bacteria reproduce asexually The method used by a bacteria to reproduce is called Binary Fission Bacterial reproduction
The chromosome attaches to the plasma membrane and the DNA is replicated Binary Fission Cell wall Chromosome Cytoplasm Plasma membrane
Binary Fission The cell elongates and the two chromosomes separate
Binary Fission The cell wall grows to divide the cell in two
Binary Fission Two identical daughter cells are formed
Bacteria reproduce asexually - their offspring are genetically identical Bacteria has a very short lifecycle (some can reproduce every 20 minutes). A single bacterium could reproduce over a million bacteria in 7 hours. Bacterial Reproduction
Mutations in Bacteria Bacteria 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.
Antibiotics Antibiotics 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
Antibiotics The first antibiotic Penicillin isolated from a fungus by Sir Alexander Fleming Now antibiotics are mostly produced by genetically engineered bacteria
Antibiotics Penicillin Fungus The 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
Antibiotics Antibiotics can be used to control bacterial and fungal infections but do not effect viruses
Antibiotics When an antibiotic is used to treat an infection most of the bacteria are killed Mutations 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.
Misuse Over use of antibiotics This results in the increased growth of antibiotic resistant bacteria Failure of some patients to complete a course of antibiotics prescribed to them by a doctor allows the bacteria to survive and re-grow
Endospore formation Some bacteria can withstand unfavourable conditions by producing endospores. These are resistant cells which enable the bacteria to survive.
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.
A white blood cell injests a disease causing bacteria
Endospore formation These are formed when the bacterial chromosome replicates
Endospore formation The parent cell then breaks down and the endospore remains dormant
Endospore formation One of the new strands becomes enclosed in a tough-walled capsule called an endospore The parent cell then breaks down and the endospore remains dormant Endospore
Endospore formation When good conditions return the endospores absorb water, break their walls and reproduce by binary fission
Nutrition Nutrition is the way in which an organism gets it food. Food supplies the energy and chemicals needed for survival and growth.
Nutrition in Bacteria Bacteria get their food by two main methods:
1. Autotrophic – organisms which make their own food 2. Heterotrophic – organisms which take in food made by other organisms Autotrophic and Heterotrophic
Autotrophic Bacteria 1. Photosynthetic bacteria Use light energy to make food E.g. purple sulphur bacteria
Autotrophic Bacteria 2. Chemosynthetic bacteria Use energy from chemical reactions to make food E.g. Nitrifying bacteria that convert ammonia to nitrates in the nitrogen cycle
Heterotrophic Bacteria 1. Saprophytic Bacteria Live off dead organic matter E.g. bacteria of decay in the soil
Heterotrophic Bacteria 2. Parasitic Bacteria Take food from live host Some cause diseases E.g. Bacillus anthracis causes anthrax
Heterotrophic Bacteria 3. Saprophytic Bacteria (decomposers) These are bacteria that live on dead organic matter e.g. dead leaves. Some saprophytic bacteria can be used to clean up oil spills.
Bacterial Nutrition Heterotrophic (Take in food) Saprophytic e.g. bacteria of decay Parasitic e.g. Streptococci Autotrophic (make food) Photosynthetic e.g. Purple sulphur bacteria Chemosynthetic e.g. Nitrifying bacteria
Learning check Name the three different types of bacteria? By what method do bacteria reproduce? Describe the steps involved in this method of reproduction?
Quiz 1. How do bacteria develop resistance to antibiotics? 2. Name the 2 main categories of bacteria with regard to their nutritional methods?
Factors affecting the growth of bacteria The growth of bacteria is affected by 5 factors: 1.Temperature 2.Oxygen concentration 3.pH 4.External solute concentration 5. Pressure
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.
1. Temperature The 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.
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.
3.Oxygen concentration Aerobic bacteria require oxygen for respiration e.g. Streptococcus This is why oxygen is sometimes bubbled through bioreactors
New Vocabulary 1. 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
4.External Solute concentration Bacteria can gain or lose water by osmosis If the external solute concentration is – higher than the bacterial cytoplasm water will move out of the bacteria (Dehydration) – Food preservation techniques are based on this
4.External Solute concentration Bacteria can gain or lose water by osmosis If the external solute concentration is – lower than the bacterial cytoplasm solute concentration water will enter the bacteria – Cell wall will prevent bursting in most cases
5.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.
Phases in Bacterial Growth Lag Phase Bacteria adapt to their environment and make chemicals to prepare for growth. B Log Phase Bacteria divide as fast as possible. Growth is exponential due to ideal conditions. C Stationary Phase The number of bacteria dying is the same as the number growing. D Decline Phase Most of the bacteria start to die. E Death or Survival Phase A few survive as Endospores.
Growth Curve of Bacteria
Economic importance of bacteria Beneficial bacteria Lactobacillus are used to convert milk to products such as cheese and yoghurt Genetically modified bacteria e.g. E. Coli are used to make products e.g. insulin, enzymes, drugs, food flavourings
Economic importance of bacteria Harmful bacteria E.g. Bacillus anthracis causes anthrax in humans Other bacterial cause diseases include tuberculosis, typhoid, cholera, diphtheria and brucellosis
Beneficial and harmful bacteria BENEFICIAL Lactobacillus converts milk to yoghurt and cheese Antibiotics can be formed by some microorganisms Bacteria in the colon help produce vitamins G.M.O.’s are used to make insulin and other useful compounds Bacteria are active in the Carbon and Nitrogen Cycles HARMFUL Pathogenic Bacteria can cause diseases in humans and animals. Pathogenic Bacteria can cause diseases in plants. Bacteria can cause food spoilage Bacteria can cause tooth decay.
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 certain temperature and pressure. The bacteria also produce wastes that must be removed so that they don't get contaminated. The bacteria are grown to make antibiotics, food colouring, perfumes, etc.
Depth of treatment Bacterial cells: basic structure (including plasmid DNA), three main types. Reproduction. Nutrition. Factors affecting growth Understanding of the term “pathogenic” Definition and role of “antibiotics”
Pathogen A pathogen is a micro-organism that causes disease. Pathogens include bacteria and some fungi. e.g. TB and food poisoning
Lab procedures when growing micro- organisms 1.Micro-organism (bacteria, fungi & viruses) can only be seen with an electron microscope. 2.Colonies (groups) of bacteria and fungi may be grown in the lab on agar plates
Lab Procedures Agar is a substance that contains all the nutrients and minerals bacteria and fungi need to grow. Agar plates and Agar are sterilised before use.
Sterile A 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
Asepsis Asepsis uses techniques to remove disease causing (pathogenic) micro-organisms and reduce their spread e.g. washing hands, wearing sterile gloves etc.
Safety Rules when working with micro- organisms Many rules including: 1.Handle all micro-organisms carefully and treat them as if they could cause infection. 2.Seal all petri-dishes with parafilm to prevent micro-organisms escaping. 3.Sterilise all containers by heating them to 120 C for 20 minutes.
Contemporary issues and technology Economic importance of bacteria: examples of any two beneficial and any two harmful bacteria. Potential abuse of antibiotics in medicine.
Food Processing Bacteria are used in large, stainless steel vats (bioreactors) to produce a large range of foods and other products. Two methods used: 1.Batch food processing 2.Continuous flow food processing
The methods differ in that each method favours different phases of the bacterial growth curve. 1.Batch Flow In 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.
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.
Food Processing Modern 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
Not just humans take antibiotics Antibiotics given to animals can be passed on in meat. This means that the animals help make resistant bacteria that we may then eat and have inside us. This could lead to a huge pandemic that could kill millions