Monera Monera (bacteria)(bacteria)

Syllabus linksSyllabus links• 3.1.3 Monera, e.g. Bacteria

Bacterial cells: basic structure (including plasmid DNA), three main types. Reproduction. Nutrition.

IntroductionIntroduction• Are found

everywhere!• Some species can

tolerate extreme environmental conditions

• Range in size from 0.1 to 10 μm in length

• Could similar such microbes be found beyond the Earth…

Structure of a generalised bacteriumStructure of a generalised bacterium

Bacterial typesBacterial types1. Round1. Round

• Are called coccus Are called coccus (plural cocci)(plural cocci)

• Occur in pairs chain Occur in pairs chain or clustersor clusters

Bacterial typesBacterial types2. Rod2. Rod

• Are called bacillus Are called bacillus (plural bacilli)(plural bacilli)

Bacterial typesBacterial types3. Spiral3. Spiral

• Are called spirrillum Are called spirrillum (plural spirilla)(plural spirilla)

Reproduction – binary fissionReproduction – binary fission• Bacteria can divide every 20 minutes if

conditions are suitable

• This means that 1 bacterium could produce over a million bacteria in just 7 hours

• This explains why bacterial infection produces symptoms so quickly

Mutations in bacteriaMutations in bacteria• Bacteria reproduce

asexually so all offspring are clones

• Sexual reproduction drives evolution so what does this mean?

• Bacteria can evolve fast due to the speed at which mutations appear within rapidly growing bacteria and their short life cycles

• So mutations are passed on quickly and this can explain for example how some bacteria have acquired a resistance to antibiotics

The Formation and Growth of an The Formation and Growth of an EndosporeEndospore

Summary of bacterial NutritionSummary of bacterial Nutrition

Syllabus linksSyllabus links• 3.1.3 Monera, e.g. Bacteria

Factors affecting growth.

Factors affecting bacterial Factors affecting bacterial growthgrowth

1. Temperature2. Oxygen

concentration3. pH4. External solute

concentration5. Pressure

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1. Temperature1. Temperature• Bacterial reactions

affected by temperature• Most grow well at

temperatures between 20 and 30oC

• Some can tolerate much higher temperatures with no enzymes being denatured

• Genes from such bacteria are often added to other bacteria that are used in biotechnology

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2. Oxygen concentration2. Oxygen concentration1. Aerobic bacteria –

streptococcus aureus

2. Anaerobic bacteria – Clostridium tetani

3. Faculative anaerobes – Escherichia coli

4. Obligate anaerobes – Clostridiun tetani

3. pH3. pH• Bacterial enzymes

work at specific pH – most at around pH 7

• Some can tolerate extremes of pH

• Helicobacter pylori can tolerate a pH of 2

http://www.hopkins-gi.org/multimedia/database/intro_79_H_pylori.swf

4. External solute concentration4. External solute concentration

Most bacteria live in less concentrated solution

This principle is behind the methods of food preservation

5. Pressure5. Pressure• The growth of bacteria

is inhibited by high pressures

• Again certain bacteria can resist and even thrive at high pressures like our friends living near thermal vents at the bottom of the ocean

• Biotechnological applications

Syllabus linksSyllabus links• 3.1.3 Monera, e.g. Bacteria

CIT: Economic importance of bacteria: examples of any two beneficial and any two harmful bacteria.

11Economic importance of Economic importance of bacteriabacteria

Bacteria can be used in the formation Bacteria can be used in the formation of certain productsof certain products

22Economic importance of Economic importance of bacteriabacteria

Genetically modified Genetically modified bacteria are used to bacteria are used to make useful make useful products like products like insulin, drugs, insulin, drugs, enzymes, amino enzymes, amino acids, vitamins, acids, vitamins, food flavourings, food flavourings, alcohols and a alcohols and a growing range of growing range of new substancesnew substancesEscherchia coliEscherchia coli

Syllabus linksSyllabus links• 3.1.3 Monera, e.g. BacteriaUnderstanding of the term "pathogenic".

Disadvantages of bacteriaDisadvantages of bacteria• Bacteria cause

human, animal and plant diseases – PATHOGENS

• Bacteria causes food decay

Syllabus linksSyllabus links• 3.1.3 Monera, e.g. Bacteria

Definition and role of "antibiotics".Potential abuse of antibiotics in medicine.

11AntibioticsAntibiotics• Are compounds

produced by micro – organisms that stop the growth of, or kill, other micro – organisms without damaging human tissue

• Originally isolated by Sir Alexander Fleming in 1928

22AntibioticsAntibiotics• Most bacteria are killed

by antibiotics however there is the possibility that they might acquire a resistance against the antibiotic e.g. MRSA in hospitals

• Causes of this are overuse of antibiotics and failure of some patients to complete their treatment

Lag phase

Log phase

Stationary phase

Decline phase

Death or survival phase

Food processingFood processing• Modern bio - processing methods involve

the use of bacteria (and other organisms) to produce a wide range of foods and useful products

• Examples include yoghurts, cheeses, artificial sweeteners, amino acids, vitamins etc.

• There is also a growing trend to using micro – organisms as a source of food (single cell protein SCP)

• There are 2 main methods of fermentation1. Batch culture2. Continuous flow

Batch cultureBatch culture

Continuous flowContinuous flow

Differences between batch and Differences between batch and continuous flow culturecontinuous flow culture

Batch Continuous flow

Fixed amount of nutrient added at the start

Nutrients added all of the time

Micro-organisms go through the lag, log, stationary (and sometimes, decline) phases

Micro-organisms maintained in the log phase all the time

Product formed for a short time (and the process may start again)

Product formed all the time for a long period of time

Advantages of batch culturingAdvantages of batch culturing1. It is an easier process to control than

continuous flow culturing2. The product may be needed only in small

amounts3. The product may only be needed at certain

times4. The large volume of product formed allows

for some losses when it is separated and purified

5. Some organisms do not grow well for the long periods of time required in continuous flow methods