Biology 2201
Unit 2- Biodiversity
Classifying Living Things
Ch. 5 – Mostly Micro-organisms
Ms. K. Morris – 2010-2011
Section 5.1
• Kingdom Bacteria
• Kingdom Archaea
–p. 132 - 139
Kingdom Bacteria
General Characteristics:
• Cell Type: all are prokaryotic.
• Body Form: most are unicellular, some are
colonial.
– Three main shapes are:
• cocci which are round
• bacilli which are rod shaped
• spirilli which are spiral shaped
– Also grow in patterns:
• diplo are in pairs
• staphylo are in clusters
• strepto are in chains
• Cell Wall: most bacteria have one, often
contains peptidoglycan.
• The cell wall structure and thickness is
determined by using a Gram Stain which was
developed by Hans Gram.
– Gram-positive bacteria have thick walls and
peptidoglycan, which is carbohydrates and
proteins. These stain purple.
– Gram-negative bacteria have two cell walls. These
stain pink. This type is more common.
• Locomotion: Many are motile, some are nonmotile. The ones that are motile move by
means of cilia or flagella.
• Nutrition: They can be autotrophs
(photosynthetic or chemosynthetic) and they
can be heterotrophs.
• There are four groupings based on nutrition:
– photoautotrophs
– photoheterotrophs
– chemoautotrophs
– chemoheterotrophs
• Refer to page 133
• Reproduction:
• Asexual Reproduction by Binary Fission:
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One parent
Genetic material replicates.
Cell elongates.
Septum forms to make two distinct cells.
Daughter cells are formed; they are exact copies of parent cell.
This can occur every 20 minutes.
• Sexual Reproduction by Conjugation:
– Two parents (or more in the case of bacteria)
– cells become linked and exchange chromosomes.
– Other possible types of bacteria reproduction:
• Gene transfer through plasmids. This is used in genetic
engineering.
• Spore formation. Involves the production of endospores which
are composed of DNA and a small amount of cytoplasm. They
can resist extreme heat or cold, dryness and chemicals.
• Bacteria play vital roles in ecosystems. They are
needed for the survival of ecosystems because
are important in the nutrient cycles; such as the
carbon and nitrogen cycles.
• They are classified by their shape, the structure
of their cell walls, and their sources of food and
energy.
• Bacteria are found in the air, in the soil, in the
water, and on and inside you. They make up the
greatest number of organisms.
• They can cause infection inside humans if they
build up to a large number. Antibiotics are used
to stop the growth of bacteria. Sometimes,
bacteria can create a resistance to the antibiotics
and then their usefulness declines.
• Examples:
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Bacteria
Cyanobacteria
Blue-green algae
E. Coli
Kingdom Archaea
General Characteristics:
• Cell Type: all are prokaryotic.
• Body Form: most are unicellular, some are
colonial.
– There is considerable variation in size; from the
microscopic unicellular arrangements to the very
long (over 200m long filaments).
– They can be cocci (round), bacilli (rod-shaped), and
spirilli (spiral) shapes (some are triangular and
square shape).
• Cell Wall: Archaea have a different cell wall
structure than bacteria - No peptidoglycan.
• Archaea have unusual lipids (fats) that remain
stable at very high temperatures or very low
temperatures.
• Locomotion: Some archaea, like bacteria, do not
have movement. Others that can move, do so
through 1 or more flagella (same as bacteria). So,
many are motile, some are non-motile.
Nutrition: Archaea are chemosynthetic
(chemotrophic) bacteria species which can make
their own food by converting inorganic substances
such as methane and sulphur into organic food.
They can be autotrophs:
• Photosynthetic
• Chemosynthetic
They can be heterotrophs
• Reproduction:
Asexual (binary fission)—most common
Sexual (conjugation)
– See bacteria notes on this
Many members of this kingdom are
extremeophiles that is they live in extreme
environments, including water whose
temperature exceeds that of boiling water (such
as hot spring geysers and sub sea (sea floor)
vents). They are also found in acidic or alkaline
environments, saline (salty) environments,
inside volcanoes, as well as deep below the
earth surface.
They are very diverse, both in form and
function. These organisms are used in
biotechnology
– Archaea differ from the Bacteria in many
important respects, as well as from the
eukaryotes.
– These differences include:
• The wall structure and chemistry
• The lipids that make up their membrane
• Their metabolism
• They look like members of kingdom Bacteria
but their genetic material is very different.
• There is also something special about members of this
kingdom because some are able to do cellular
respiration without the presence of a certain chemical:
Oxygen.
• So, Archaea can be Aerobic or Anaerobic.
– Aerobic: use oxygen to carry out life’s processes.
– Anaerobic: do not need oxygen to carry out life’s processes.
• Instead they use:
– Methane ( CH4)
– Carbon Dioxide (CO2)
– Nitrogen Gas (N2)
– Hydrogen Sulfide (H2S)
• Examples:
• Some are methanogens - organisms which can
use methane for food. These live in the guts of
animals, such as cows.
• Others are thermophiles - organisms which
live under extreme temperatures in hot
springs. They often can convert the sulphur in
hot water springs into food.
• Halophiles live in salt lakes.
Life Cycle of E. Coli
A bacteria representing the Kingdoms Bacteria & Archaea.
• Reproduce asexually using method called binary fission. Can
also reproduce sexually using a method called conjugation .
Binary Fission (Asexual) (see diagram in text p. 134, fig. 5.4)
• Each bacteria has a single chromosome. Before fission, the
bacteria makes a copy of this chromosome, so it has 2
chromosomes.
• Binary fission has 4 stages:
– A. Elongation - when ready to divide , the bacteria gets longer.
– B. A septum begins to form - an extension of the cell wall.
Chromosomes separate to opposite sides of the cell.
– C. The septum fully forms, separating the bacteria into 2 cells.
– D. the bacterium splits into 2 genetically identical bacteria.
• Binary fission takes about 20 min in good conditions. This leads to
exponential growth of their populations.
• Binary fission rate is limited by:
– (1) predation
– (2) unfavorable conditions
– ( 3) food
• Has a huge reproductive capacity ( 1 bacterium dividing can result
in 1,000,000 offspring being produced in 10 - 12 hours)
• Waste products from some types of disease - causing bacteria
produce toxins that lead to food poisoning or infections in
humans. Many bacteria are beneficial to us.
• We use bacteria to treat sewage, decompose compost, make
cheese and yogurt. Their ability to rapidly multiply is useful for
such processes.
Conjugation (Sexual) (see diagram on p. 135, fig. 5.5)
• Happens during less favorable conditions
• Produces genetic variation in offspring - mixes up the
genes for better chances of survival.
• Conjugation has 4 stages:
– A. A pilus forms (Pilus - bridging structures made up of
hair-like tubes that allow microscopic organisms to
exchange genetic material during a form of sexual
reproduction, such as conjugation)
– B. Two bacteria become connected via the pilus
– C. one bacteria transfers all or part of its chromosome to
the other bacteria
– D. the recipient bacteria uses the received chromosome
material and later starts to divide by using asexual binary
fission. In this way , all of the offspring are now genetically
different than either parent.
Section 5.2
• Kingdom Protista
–p. 140 - 151
Kingdom Protista
General Characteristics:
• Cell Type: all are eukaryotic.
• Body Form: most are unicellular, some are
colonial, some are simple multi-cellular.
– There are a few forms that are multi-cellular,
for example the brown and red algae.
– Most though are single-celled organisms, and
are typically only 0.01-0.5 mm in size, too
small to be seen without a microscope.
• Cell Wall: some have cell walls, some do not.
Composition will vary.
• Locomotion: many are motile (flagella or
cilia), some are non-motile.
• Nutrition: some are autotropths, some are
heterotrophs (ingestion and absorption) and
some both.
• Reproduction: asexual reproduction and/or
sexual reproduction.
• The Kingdom Protista is one of the commonly
recognized biological kingdoms. They include all the
eukaryotes except for the plants, fungi, animals, and
sometimes other groups which are treated in separate
kingdoms.
• They are most easily defined by what they are not;
they are not bacteria, plants, animals or fungi. This is
the garbage bucket kingdom where some organisms
are placed that cannot fit into the other kingdoms.
• Protists are widespread throughout wet environments
and the soil. They are able to survive dry periods by
forming cysts; a few others are significant parasites.
– There are 3 groups of Protista, based upon how
they get their nutrition:
1. Protozoa (animal-like protists)
2. Algae (plant-like protists that contain
chloroplasts)
3. Slime & Water Molds (fungus-like protists)
Protozoa (animal-like)
• Feeding on and engulfing other organisms or
dead matter. They can be scavengers, predators,
or parasites (that can live inside humans).
• They lack cell walls
• Four groups based on their method of
movement:
– Flagellates - one flagella
– Sarcodines - form limb-like extensions of cytoplasm
called pseudopodia (false feet) (amoeba)
– Ciliates - hundreds of cilia (paramecium)
– Sporozoans - parasites which form spores
(plasmodium vivax)
Algae (plant-like)
• Simple and aquatic (live in water)
• Contain chlorophyll and carry out photosynthesis
(make their own food)
• Once classified as plants
• Six types based on types of pigments:
– Green algae - chlorophyll and cellulose cell walls
– Brown algae - seaweeds with cell walls of cellulose and
pectin
– Red Algae - seaweeds with cell walls containing agar
– Diatoms - most abundant unicellular algae with rigid cell
walls (plankton)
– Dinoflagellates - unicellular and cellulose protective coats
– Euglenoids- can be autotrophic or heterotrophic
Slime Molds & Water Molds (fungus-like)
• Produce spores at some point in their life cycle (which is
what makes them be similar to fungi).
• Ingest food like protozoa
• They are heterotrophs that obtain their food by:
• Feeding off others
• They can be saprotrophs (that feed off dead matter)
• Parasites (that feed of living things)
• Cellulose cell walls like plants
• Three types:
– Water Moulds - live on dead organic matter (saprotroph)
but some are parasites
– Slime Moulds - plasmodium crawl on plants and ingest
small particles of food
– Cellular Slime Moulds - individual cells with one nucleus
which ingest tiny bacteria or yeast cells
• Examples:
– Protozoa
• Amoeba
• Paramecium
– Algae
– Slime & Water Molds
• Plasmodium
Life Cycle of Plasmodium (Slime Mold) (p. 150 - 151)
A representative of Kingdom Protista
• Slime mold is very unusual and is difficult to classify because it has
characteristics similar to protists, fungi and plants.
• Visible to naked eye as tiny slug - like blob , called a plasmodium.
Plasmodia creep over the soil surface, living off decaying material. They
take in food particles by using endocytosis.
• Plasmodium - part of the life cycle of a slime mold. It resembles a slimy
mass and contains many nuclei.
• Reproduce via sexual reproduction:
• Sporangia - spore-bearing structures developing from a plasmodium
(slime mold) during its sexual reproduction process.
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1. plasmodium develops sporangia (sporangium - singular).
2. Sporangia produce spores.
3. Spores are released
4. Spores produce two types of cells:
• amoeboid cells (move like an amoeba)
• flagellated cells (move using flagella)
– 5. Each Amoeboid cell fuses with a flagellated cell
– 6. A zygote forms
– 7. zygote grows into a new plasmodium.
Section 5.3
• Kingdom Fungi
–p. 152 - 158
Kingdom Fungi
General Characteristics:
• Cell Type: all are eukaryotic.
• Body Form: some are unicellular (yeasts), many are
multi-cellular. Many are plant-like in their
appearance.
• Most fungi have vegetative bodies (called a thallus
or soma) that is made up of single cell-thick
filaments called hyphae.
• Generally they do not merge into a visible object,
but instead form a microscopic network within the
substrate, called the mycelium, through which food
is absorbed.
• Cell Wall: Exists. Usually composed of chitin.
• Nutrition: all are heterotrophic (unlike plants).
They get their food from other organisms. They
digest food outside of their body by secreting
enzymes and then absorb it. (parasites and
saprophytes). The fungi are absorptive
heterotrophs.
• Locomotion: they are non-motile (do not move).
• Reproduction: Asexual and Sexual. The more
conspicuous parts of fungi like mushrooms are
fruiting bodies, reproductive structures that
produce spores.
• Fungi live in symbiotic relationships with plants or
animals.
• There are four groups of fungi:
– Zygospore Fungi - bread moulds which reproduce both
asexually and sexually by conjugation
– Club Fungi - mushrooms
– Sac Fungi - truffles and single-celled yeasts
– Imperfect Fungi - penicillin which reproduce only
asexually
• The Fungi (singular: fungus) are a large group
of organisms. They include important
decomposers and many parasites. Parasitic
fungi infect animals, including us, other
mammals, birds, and insects, with results
varying from mild itching to death.
• Other parasitic fungi infect plants, causing
disease such as Potato Blight. Many vascular
plants are associated with mutualistic fungi,
called mycorrhizae, which help with the
absorption of nutrients and water. Some fungi
are used as food, such as mushrooms and
truffles; others are very poisonous and can
cause death if eaten.
• Examples:
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Mushrooms
Yeasts
Mold
Bread Mold (Rhizopus)
• Life cycle of a sample organism from the Kingdom Fungi:
“Rhizopus” (common bread mold - see p. 154)
• Hyphae - a network of fine filaments found in a fungus.
• Mycelium - loose, branching network of hyphae under the
substrate that makes up the main bulk of a fungus.
• Rhizoid - downward growing hyphae present in the mycelium of
a bread mold, which penetrates the bread and anchors the
mycelium.
• Stolon - horizontal hyphae present in the mycelium of a bread
mold.
• Sporangiophore - form of hyphae that projects upwards above
the mycelium of a bread mold. Used during asexual
reproduction.
• Zygospore - diploid structures that develop after two haploid
bread mold hyphae of opposite types (called + and -) combine
and fuse their nuclei together.
• Sexual Reproduction in Rhizopus: (involves the stolons)
• The stolons are either plus (+) or minus (-) strains. Each one
is haploid. If environmental conditions are unfavorable, (+)
and (-) strains of stolons fuse at their tips to produce a
diploid structure called a zygospore (see diagram p. 154).
• The zygospore can survive long periods of time and bad
environmental conditions and stays dormant until conditions
become good again (e.g. warm and damp).
• When conditions improve, it becomes active by growing
producing a sporangia. The sporangia produces haploid
spores. Each spore blows away on air currents. Each spore
can produce a new fungus mycelium.
• Sporangia- hyphae structure that grows out of a zygospore;
produces haploid spores.