Download Bacteria morphology

Monera
Bacteria
Learning Objectives
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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
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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)
Bacterial Shapes
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
Spirillum (spiral)
• E.g.Treponema pallidum
• Causes syphilis
Bacterial size
Bacterial Structure
Bacterial Structure
Cell wall
flagella
cytoplasm
plasmid
capsule
Cell
Strand of DNA membrane
Functions of Parts of Bacterial Cell
Part
Flagellum
Capsule (slime layer)
Cell Wall
Plasmid (DNA)
Cytoplasm
Storage granules
Chromosome
Function
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?
Bacterial reproduction
•
Bacteria reproduce asexually
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The method used by a bacteria to reproduce is
called Binary Fission
Binary Fission
The chromosome attaches to the plasma membrane
and the DNA is replicated
Cell wall
Cytoplasm
Plasma
membrane
Chromosome
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
Bacterial Reproduction
•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.
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 microorganisms 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 (multiresistant). 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
Endospore
• The parent cell then breaks down and the
endospore remains dormant
Endospore formation
• When good conditions return the endospores
absorb water, break their walls and reproduce
by binary fission
Bacterial Nutrition
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:
Autotrophic and Heterotrophic
1. Autotrophic – organisms which make their own
food
2. Heterotrophic – organisms which take in food
made by other organisms
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
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 microorganisms
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 microorganisms 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 microorganisms
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