Diversity of Organisms
Contents
The five kingdom classification
system
Monera – cell diagram– types
Spore formation
Reproduction
Two types of nutrition
Factors affecting growth rate
Beneficial & Harmful Bacteria
Antibiotics
Antibiotic resistant strains of
bacteria
Growth curve of bacteria
Continuous flow production
Batch flow production
Fungi
Types of fungi
Rhizopus – Structure
Reproduction – asexual – sexual
Beneficial & harmful fungi
Yeast structure – reproduction –
economic importance
Asepsis
Protista – Amoeba
Plant & animal kingdoms
Prokaryotic nature of bacteria
Eukaryotic nature of fungi 2
The five
kingdom
classification
system
3
What is in each kingdom?
(1/2)
Prokaryote (Monera )kingdom: simple singlecelled organisms that feed by a number of
different methods.
Protista (Protoctist) kingdom: complex singlecelled organisms and all of the algae (including
multicellular algae) that feed by a number of
different methods.
4
What is in each kingdom?
(2/2)
Fungus kingdom: multicellular organisms with
little cellular differentiation that feed
heterotrophically by absorption.
Plant kingdom: multicellular organisms that feed
by photosynthesis.
Animal kingdom: multicellular organisms that feed
heterotrophically by ingestion.
5
Monera
Bacteria
Bacterial cell - Diagram
Cell wall
Cell or plasma
membrane
Cytoplasm
Nuclear or genetic
material
Plasmid
Capsule
Flagellum
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Types of bacterial cell
 Cocci – single, chains, pairs, clusters
 Rods – single, chains, with or without flagella
 Spirals – often have flagella
8
Bacterial shapes
9
Mixed bacteria showing shapes
10
Spore formation
Occurs during unfavourable conditions
 Contents of cell shrinks
 Tough outer coat formed within the cell
 This is the endospore
11
Endospore
 Resists desiccation
 Resists high temperatures – hard to kill
When favourable conditions return
 Endospore absorbs water
 Expands
 Breaks tough outer wall
 Divides by binary fission
12
Bacterial endospore
13
Reproduction
Usual method of asexual reproduction is known as
binary fission
 DNA replicates
 Cell grows to full size
 Cell divided across the centre
 Forms two cells same size each with their own
DNA
14
Mutations and bacteria
 Favourable mutations are rare
 Bacteria have a short life cycle – can reproduce
about every 20 minutes in favourable conditions
 Numerous generations can be produced in a
very short time – approx 72 in 24 hours
 Favourable mutations will become the norm very
quickly
 Can give rise to resistant strains of bacteria
15
Two types of Nutrition
Autotrophic bacteria – make their own food by
 Photosynthesis or
 Chemosynthesis e.g. nitrifying bacteria in soil
Heterotrophic bacteria – eat food already made –
can be aerobes or anaerobes
 Saprophytes – free-living
 Symbiotes – three types : –
Mutualism, Commensalism, Parasitism
16
Bacterial nutrition summary
17
Factors affecting growth rate
1.
2.
Temperature – each has their own optimum
Presence or absence of oxygen
Facultative anaerobes
Obligate anaerobes e.g. Clostridium botulinum
Obligate aerobes
3.
4.
5.
pH – each has their own optimum
External solute concentration – osmosis, jams,
Dead Sea bacteria
Pressure – some found exclusively at sea
depths
18
Beneficial & Harmful Bacteria
Beneficial Bacteria
Produce
Streptomyces sp. (species)
Lactobacillus sp.
Escherichia coli
Antibiotics
Yoghurt or cheese
Vitimin K in the colon
Harmful Bacteria
Causes
Salmonella typhi
Typhoid
Vibrio cholerae
Cholera
Mycobacterium tuberculosis Pulmonary TB
19
Pathogen
A pathogen is an organism that causes a disease.
They are parasitic bacteria that are capable of
causing a disease in their host e.g. diphtheria,
whooping cough and tetanus (3 in 1) are
diseases caused by bacteria.
20
Antibiotics
(1/3)
 Are chemicals produced by micro-organisms
(m/os) that are toxic to bacteria.
 antibiotic: substance produced by living microorganisms (e.g. Penicillium notatum) which
destroy or inhibit the growth of other microorganisms especially bacteria or fungi e.g.
penicillin, streptomycin, tetracycline, etc. – has
no effect on viruses.
21
Antibiotics
(2/3)
 They are naturally occurring chemicals produced
by one m/o to prevent the growth of another m/o
and thus reduce competition for food, minerals,
etc.
 Consequently there are m/os that can grow in
the presence of these antibiotics i.e. they are
resistant to the antibiotic.
22
Antibiotics
(3/3)
 The gene for this resistance is carried on the
plasmids in the bacteria
 These plasmids can be passed from one
bacterium to the next
 And from one species to another
 This leads to the development of antibiotic
resistant strains of bacteria
23
How antibiotic resistant strains
of bacteria may develop
(1/2)
 Person given an antibiotic
 All bacteria (good and bad) killed
 If there is an antibiotic resistant strain of bacteria
present
 Have no competition
 Can increase in numbers rapidly
 Colonise the person
24
How antibiotic resistant strains
of bacteria may develop
(2/2)
 If a pathogen arrives it can get the antibiotic
resistance from the resident bacteria
 Antibiotics will now not affect it
 Effectiveness of antibiotics is being reduced
because of this e.g. multiple drug-resistant
tuberculosis.
25
Antibiotic Resistance in Bacteria
 Intensive farming often involves the addition of
small amounts of antibiotics to the food
 Healthier animals that grow quicker produced
 Facilitates the development of resistant strains of
bacteria
 Residues of antibiotics in meat consumed by
humans
 Assists the development of more antibiotic
26
resistant bacteria
Growth Curve of bacteria
4
3
1
2
Go to next slide
27
Explanation of graph
(1/2)
Lag phase: bacteria are settling in, adjusting to
their new environment, and beginning to produce
the correct enzymes to digest the new food.
Back to Graph
Exponential (Log or Logarithmic) phase: a
period of rapid growth – numbers double every
time it replicates, due to abundance of
resources. Back to Graph
28
Explanation of graph
(2/2)
Stationary phase: birth rate = death rate due to
competition for food, space and the build-up of
toxic wastes. Back to Graph
Death (Decline) phase: numbers decline due to
increased competition for food, space and the
build-up of toxic wastes. Back to Graph
29
Continuous flow production
 Some microbes are eaten as a protein substitute
(animal feed) – single cell protein (SCP)
 Made in a fermenter
 Production kept at the exponential phase to
produce the maximum quantity
 Fresh nutrients added to the top and SCP drawn
off from the bottom
 Fermenter cleaned after six months – build up of
toxic by-products, etc.
30
Simple
diagram of
continuous
flow method
of microbe
production
31
Batch flow production
 Usually used when microbes are producing a
product that is required e.g. penicillin
 Fermenter filled with nutrients and culture
 Stirred and temperature controlled
 Liquid removed and culture removed by filtration
 Penicillin crystallised from remaining fluid
32
Diagram
showing
batch
production
of
penicillin
33
Fungi
Types of Fungi
 Parasites – on people and crops e.g. athlete’s
foot, Dutch Elm disease, etc.
 Saprophytes – important in decomposition e.g.
Dry rot in timber, mildew on clothes, etc.
 Fruiting bodies of many saprophytic fungi are
edible e.g. mushrooms, but some are highly
poisonous or fatal e.g. Death cap.
35
Mushroom (Agaricus) close up
36
Mushroom – showing gills
37
Gill of mushroom showing spores
38
Rhizopus – bread mould
 Saprophytic
 Multicellular
 Aseptate = no crosswalls dividing the cytoplasm
into separate cells - no cells, has nucleii.
39
Rhizopus – types of hyphae
 3 types of hyphae.
Stolons: Grow horizontally on surface of substrate
Rhizoids: Grow downwards into substrate anchorage and absorption of food.
Sporangiophores: Grow upwards away from
substrate - function in reproduction.
The three types of hyphae that make up the fungus
are collectively called the Mycelium
40
Structure of Rhizopus
To Asexual Reproduction
41
Rhizopus - nutrition
Saprophyte - hyphae secrete enzymes onto the
substrate on which they are growing –
digestion is external (e.g. starch to sugar, lipids to
?, proteins to ?) –
hyphae then absorb soluble products of digestion
by diffusion.
42
Reproduction
Two types
 Asexual (sporulation) - does not involve the
manufacture or union of sex cells or gametes involves only one parent and all the offspring are
genetically identical
 Sexual - involves the union of sex cells or
gametes,
two parents and results in genetically different
offspring
43
Asexual reproduction
(1/2)
 usual method in suitable conditions i.e. supply of
food, water and a suitable temperature
 Tip of sporangiophore develops a swelling
(sporangium)
Diagram
 Separated from rest of sporangiophore by
crosswall (columella) Diagram
44
Asexual reproduction
(2/2)
 Spores produced within sporangium by mitosis
 Sporangium bursts when ripe - spores released
in dry conditions and carried by the wind
 Germinate into new hypha and mycelium
45
Sexual reproduction
(1/2)
 plus and minus strains of hyphae growing close
together (structurally similar, chemically different
- no male or female)
 short side branches (progametangia) grow
towards each other
 tips swell (gametangia) and produce a haploid
(n) gamete
 tips meet each other – gametes fuse to form a
diploid zygote (2n) – develops into the
zygospore (2n)
46
Sexual reproduction
(2/2)
 resistant to adverse conditions
 after a time of dormancy
 meiosis - germination
 produces one sporangium – forms spores
 bursts when ripe – spores released
 germinate into new hypha
47
Sexual
reproduction
in Rhizopus
48
Beneficial & Harmful Fungi
49
Yeast – structure
Saccharomyces
Unicellular fungus – (e.g. on fruit skins - apple and
grape)
ovoid or spherical cells found singly or in groups
 thin cell wall,
 granular cytoplasm,
 nucleus and
 large storage vacuoles
50
Yeast – reproduction
(1/2)
 Asexually by budding – usual method
 modified mitotic division
 bulge (bud) forms on side of cell
 Enlarges and fills with cytoplasm
51
Yeast – reproduction
(2/2)
 nucleus divides in two by mitosis and one goes
into the bud
 the bud may remain attached to the parent and
undergo further budding to form a colony
 or separate from the parent and form a new
colony itself
52
Economic importance
Brewing industry - yeast respire anaerobically
producing ethanol + carbon dioxide
C6H12O6  Energy + 2C2H5OH + 2CO2
Baking industry - the CO2 produced by yeast
causes the dough to rise - the heat evaporates
the ethanol
C6H12O6  Energy + 2C2H5OH + 2CO2
53
Precautions when working with
micro-organisms
Assume that all are
hazardous until
otherwise proven.
54
Asepsis
or aseptic techniques – methods used to prevent
microbes entering an area. These include: Sterilisation of working area, all equipment,
instruments and materials – before and after use
Flaming of containers, needles and loops during
use
Containment methods and safe disposal of
unwanted materials after use
55
Containment methods
 Work in laboratories with negative pressure
outside – microbes drawn back into lab
 Use laminar airflow cabinets – microbes kept
behind a flow of filtered air
 Use of protective clothing and masks
All materials are sterilised before disposal or re-use
56
Sterile
This refers to a substance that is free from all types
of microbes – the substance may have been
treated to kill all the microbes.
Sterilising is the killing of all microbes e.g. by moist
heat (120°C for 20 minutes) using an autoclave.
57
Protista
Amoeba
Protista e.g. Amoeba
Cell membrane
Ectoplasm
Cytoplasm
Endoplasm
Mitochondrion
Ribosome
59
Plant and Animal Kingdoms
Plant Kingdom Vs Animal Kingdom
Multicellular
 Photosynthetic
 Cells with cell walls
 Include a large number
of phyla e.g.
 Bryophyta,
 Pteridophyta,
 Spermatophyta

Multicellular
 Heterotrophic
 Cells without cell walls
 Include a large number
of phyla e.g.
 Porifera, Cnidaria,
 Platyhelminthes,
 Annelida, Mollusca,
 Arthropoda

61
Prokaryotic nature of bacteria
(1/2)
 No membrane-bound nucleus or organelles
 Circular piece of DNA (the chromosome)
attached to cell membrane known as the
nucleoid
 This chromosome does not contain proteins
 Ribosomes, food storage granules and enzymes
found in cytoplasm
62
Prokaryotic nature of bacteria
(2/2)
 Cytoplasm surrounded by plasma or cell
membrane
 Cell membrane surrounded by cell wall made of
peptoglycan
 Cell wall may be surrounded by a capsule
 Some may have flagella
63
A diagram
of a
bacterium
64
Eukaryotic nature of fungi
 More advanced cellular structure
 Contain many membrane-bound cellular
organelles, including a nucleus
 May have developed as a result of a number of
prokaryotic cells coming together
 Chloroplasts and mitochondria contain their own
DNA
65
END
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