Homework4 to be emailed to email@example.com
The following table depicts characteristics of five prokaryotic species (AE). Use the information in the table to answer the following questions.
Gram Staining Results
Specialized Metabolic Pathways
(obtains carbon and energy from methane)
Anaerobic butanolic fermentation
Anaerobic lactic acid fermentation
Anaerobic nitrogen fixation and aerobic photosystems
I and II
7 Which two species should have much more phospholipid, in the form of bilayers, in their cytoplasms than most other bacteria?
8 Which species should be able to respond most readily to taxes (plural of taxis)?
9 How many of these species probably have a cell wall that partly consists of an outer membrane of lipopolysaccharide?
10 Gram-variable prokaryotes are, sometimes, those without any peptidoglycan. Which two species are most likely to be archaeans?
11 Species D is pathogenic if it gains access to the human intestine. Which other species, if it coinhabited a human intestine along with species D, is most likely to result in a recombinant species that is both pathogenic and resistant to some antibiotics?
12 Which species might be able to include Hfr cells?
13 Which species is most self-sustaining in terms of obtaining nutrition in environments containing little fixed nitrogen or carbon?
Overview: Theyre (Almost) Everywhere!
Most prokaryotes are microscopic
But what they lack in size they more than make up for in numbers
The number of prokaryotes in a single handful of fertile soil
Is greater than the number of people who have ever lived
Prokaryotes thrive almost everywhere
Including places too acidic, too salty, too cold, or too hot for most other organisms
Biologists are discovering
That these organisms have an astonishing genetic diversity
: Structural, functional, and genetic adaptations contribute to prokaryotic success
Most prokaryotes are unicellular
Although some species form colonies
Prokaryotic cells have a variety of shapes
The three most common of which are spheres (cocci), rods (bacilli), and spirals
Shapes of Bacteria
Chain = Streptoccus
Cluster = Staphylococcus
Chain = Streptobacillus
Vibrio = curved
Kingdom Archaebactreria & Eubacteria formally (Prokaryota & Monera)
Prokaryotes = no membrane bound organelles (no nucleus or mitochondria)
Kingdom Monera: The Prokaryotes
V. The 4 main functions of bacteria
Recycling of nutrients
Food & medicines
Bacteria cause diseases
Nitrogen wastes are excreted & cycled by bacteria
Making cheese & yogurt with bacteria
Strep bacteria of Rheumatic Fever
The Monerans are the most numerous and widespread organisms on earth. They comprise the only kingdom of prokaryotic organisms, those which lack a nucleus or other membrane-bounded organelles.
External to the plasma membrane, most bacteria have a cell wall partially composed of peptidoglycan, a complex structural molecule not found in eukaryotic cells. Let's have a look at the basic flavors of bacteria .
There are three types of archaebacteria, the most ancient of all living things. The thermoacidophiles live in the extremely hot, acidic water and moist areas within and surrounding sulfur hot springs. So closely adapted are they to their bubbly environment that they die of cold at temperatures of 55oC (131oF)!
. Methanogens are obligate anaerobes (free oxygen kills them) which oxidize CO2 during cellular respiration to produce methane (CH4) as a waste product. Although RNA sequencing suggests that all ten known species are evolutionarily related, they exist in environments as diverse as scalding volcanic deep-sea vents and the intestines of mammals.
The reason you can light a puff of flatulence (should you choose to go into show business) is because of the symbiotic methanogens inside your guts. .
. Strict halophiles live in extremely salty solutions such as the Dead Sea, the Great Salt Lake and that can of pickled herring you left open in the cupboard. Their pink carotenoid pigments make them conspicuous when the bacteria are present in large concentrations, as they are on the shores of some salty, land-locked lakes. .
One of the most important features of nearly all prokaryotic cells
Is their cell wall, which maintains cell shape, provides physical protection, and prevents the cell from bursting in a hypotonic environment
Using a technique called the Gram stain
Scientists can classify many bacterial species into two groups based on cell wall composition, Gram-positive and Gram-negative
The cell wall of many prokaryotes
Is covered by a capsule, a sticky layer of polysaccharide or protein
Some prokaryotes have fimbriae and pili
Which allow them to stick to their substrate or other individuals in a colony
Most motile bacteria propel themselves by flagella
Which are structurally and functionally different from eukaryotic flagella
In a heterogeneous environment, many bacteria exhibit taxis
The ability to move toward or away from certain stimuli
Internal and Genomic Organization
Usually lack complex compartmentalization
Do have specialized membranes that perform metabolic functions
The typical prokaryotic genome
Is a ring of DNA that is not surrounded by a membrane and that is located in a nucleoid region
Some species of bacteria
Also have smaller rings of DNA called plasmids
Reproduction and Adaptation
Prokaryotes reproduce quickly by binary fission
And can divide every 13 hours
Many prokaryotes form endospores
Which can remain viable in harsh conditions for centuries
IV 6. Endospores
Metabolic activity is shut down
Protects bacteria against hostile environments
Come back to life when favorable
Heat, irradiation, cold
Boiling >1 hr still viable
Takes time and energy to make spores
Location important in classification
Central, Subterminal, Terminal
Bacillus stearothermophilus -spores
Used for quality control of heat sterilization equipment
Bacillus anthracis - spores
Used in biological warfare
Many organisms form spores:
Rapid reproduction and horizontal gene transfer
Facilitate the evolution of prokaryotes to changing environments
: A great diversity of nutritional and metabolic adaptations have evolved in prokaryotes
Examples of all four models of nutrition are found among prokaryotes
Major nutritional modes in prokaryotes
Metabolic Relationships to Oxygen
Also varies with respect to oxygen
Can survive with or without oxygen
Are poisoned by oxygen
Prokaryotes can metabolize nitrogen
In a variety of ways
In a process called nitrogen fixation
Some prokaryotes convert atmospheric nitrogen to ammonia
Cooperation between prokaryotes
Allows them to use environmental resources they could not use as individual cells
In the cyanobacterium Anabaena
Photosynthetic cells and nitrogen-fixing cells exchange metabolic products
In some prokaryotic species
Metabolic cooperation occurs in surface-coating colonies called biofilms
: Molecular systematics is illuminating prokaryotic phylogeny
Until the late 20th century
Systematists based prokaryotic taxonomy on phenotypic criteria
Applying molecular systematics to the investigation of prokaryotic phylogeny
Has produced dramatic results
Lessons from Molecular Systematics
Is leading to a phylogenetic classification of prokaryotes
Is allowing systematists to identify major new clades
A tentative phylogeny of some of the major taxa of prokaryotes based on molecular systematics
Diverse nutritional types
Are scattered among the major groups of bacteria
The two largest groups are
The proteobacteria and the Gram-positive bacteria
Chlamydias, spirochetes, Gram-positive bacteria, and cyanobacteria
Archaea share certain traits with bacteria
And other traits
Cellular Tree of Life
Live in extreme environments
Thrive in very hot environments
Live in high saline environments
Live in swamps and marshes
Produce methane as a waste product
: Prokaryotes play crucial roles in the biosphere
Prokaryotes are so important to the biosphere that if they were to disappear
The prospects for any other life surviving would be dim
Prokaryotes play a major role
In the continual recycling of chemical elements between the living and nonliving components of the environment in ecosystems
Chemoheterotrophic prokaryotes function as decomposers
Breaking down corpses, dead vegetation, and waste products
Add usable nitrogen to the environment
Live with other organisms in symbiotic relationships such as mutualism and commensalism
Other types of prokaryotes
Live inside hosts as parasites
: Prokaryotes have both harmful and beneficial impacts on humans
Some prokaryotes are human pathogens
But many others have positive interactions with humans
Prokaryotes cause about half of all human diseases
Lyme disease is an example
Pathogenic prokaryotes typically cause disease
By releasing exotoxins or endotoxins
Many pathogenic bacteria
Are potential weapons of bioterrorism
Prokaryotes in Research and Technology
Experiments using prokaryotes
Have led to important advances in DNA technology
Prokaryotes are the principal agents in bioremediation
The use of organisms to remove pollutants from the environment
Prokaryotes are also major tools in
The synthesis of vitamins
Production of antibiotics, hormones, and other products
6 Major Kingdoms:
1 cell, prokaryotes
1 cell, eukaryotes & algae
Multicelled, absorptive feeders
C. Three major differences between the 2 bacteria Kingdoms:
(All are prokaryotes & One celled, Ubiquitous = found everywhere)
Many biochemical differences
Difference cell walls and lipid membranes
Structure & functions of the of the archaebacteria are more similar to the Eukaryotes
Bacteria Kingdom Characteristics:
No free oxygen
Hot sulfur springs
Penicillin mold kills bacteria
Alexander Fleming in 1928
Inhibits the growth of bacteria
Macrophage (WBC) engulfs a bacterium in the immune system:
Classified by shape, size, staining, environment, & color Cynobacteria & Salmonella
For many years, the evolutionary relationships of bacteria were so poorly understood that they were classified only on the basis of their shape and staining characteristics.
These characters can still be useful in the early stages of identification, but more recent advances in DNA and RNA sequencing give us a more accurate idea of origins and relationships among these tiny, vital organisms. ..
. Each of these slides has three separate smears, each with a different shape of bacteria. Rod-shaped bacilli (sing., bacillus) are the most common. Escherichia coli (our mammalian gut symbiont), Lactobacillus spp. (which may be agents of tooth decay or ingredients in yogurt) and Bacillus anthracis (a pathogen causing anthrax in sheep and humans) are examples.
. Spherical cocci (sing., coccus) are also common. Streptococcus spp. are chain-forming cocci responsible for ailments such as strep throat in humans. Staphylococcus spp. form clusters reminiscent of tiny bunches of grapes (staphylo is Greek for "cluster"), and are responsible for those nasty "staph" infections (and often, gangrene) found in untreated puncture wounds.
Spiral-shaped spirilla (sing., spirillum) are the largest of these three types, and the simplest to identify. Maybe you should start with those. . .
Asexual Reproduction in Prokaryotes
You are probably most familiar with mitosis as the mode by which cells reproduce themselves. Because prokaryotes have a single, circular chromosome rather than the sets of chromosomes found in the more familiar eukaryotes, mitosis does not occur in prokaryotes. Instead, most replicate via a process of binary fission.
The "true bacteria" are classified on the basis of several characteristics, of which perhaps the most familiar is the Gram Stain method.
Gram negative Eubacteria
About 75% of known eubacteria are gram negative. They include the gliding bacteria, the spirochetes, the curved (vibrios) and spiral (spirillae) bacteria, gram-negative rods, gram-negative cocci, rickettsias, chlamydias and the photosynthetic cyanobacteria.
Gram negative bacteria form an extremely diverse group. The fact that they are all gram-negative does not necessarily imply that they comprise a monophyletic taxon. .
Gram positive Eubacteria
Not as diverse as the gram-negative bacteria, the gram-positives still make up an impressively varied group. This division includes the gram-positive rods, gram-positive cocci, and the actinomycetes, which exhibit superficial similarity and function (but no evolutionary relationship) to the (eukaryotic) fungi .
Spiral or spirilli)
Bacilli Tuberculosis Bacteria:
Tuberculosis: Bacterial infection
IV 3-4Bacteria reproduction:
Exchange of DNA
IV 5. Aerobic Bacteria require oxygen & can make cavities!
Anaerobic Bacteria live without oxygen, in our intestines & may be in polluted waters
E. Coli from human feces
Helpful in the intestines
Harmful in other parts of the body
?Life on Mars?
Inoculate = to place
Agar = culture medium (nutrients)
One colony (circle)= billions of bacteria
A colony begins from one bacterium
Incubate at 37oC= body temperature
DO NOT OPEN THE PLATES AFTER INCUBATION!
Bactericide test strip:
Kills germs! Versus
6. View under higher magnification with stains for specific types of bacteria
7. Classified by shape:
a. round = cocci
b. rods = bacilli
c. spiral = spirilli
Genetic Engineering of Insulin
Restriction Enzymes:Made by some Bacteria
Warts are a skin virus!
Plant peach virus
Herpes mouth virus:
Hepatitis B virus (Liver)
DNA or RNA for replication
HIV virus structure:
Cow pox vaccination 1749
Artificial injection of a small amount of virus
Bodys immune response makes antibodies
Chicken Pox Virus
Bacteria eating virus
Virus uses the bacteria as a host
For Viral replication
Lytic Cycle (Replication) of a Virus - AVIRAL
HIV virus infects T-cells
HIV virus Weakens the immune system
AIDS patients die of common diseases when T cell (WBC) count falls
AIDS = break down of the immune system & death due to common diseases versus death by AIDS virus
These are the smallest living cells ever discovered, and are believed to have the minimum amount of DNA needed to code for a functioning cell. They lack the cell wall characteristic of the other three types of bacteria.
. Most mycoplasmas exist as intracellular plant or animal parasites, a life history which protects them from environmental osmotic stresses as long as the host cell is functioning properly. Penicillin, an antibiotic lethal to most other bacteria because it interferes will cell wall formation, is not effective against the naked little mycoplasmas. .
.The Many Shapes of Bacteria
As you already know, bacteria come in a vast array of shapes and sizes, and there are several taxonomically distinct groups. Take a slide to your station and observe under the compound microscope. Remember: bacteria are extremely small. Focus with extreme care, on low power first, and don't break the slide!
Bacteria exhibit various modes of locomotion, including "squirming", gliding and propulsion via flagella. The flagellum of a bacterium is quite different from the flagellum of a eukaryote.
It is composed of a protein called flagellin, not found in eukaryotes, whereas the eukaryotic flagellum is composed of a symmetrically arranged series of microtubules. Unlike the eukaryotic flagellum, which beats with a wavelike motion, the bacterial flagellum rotates to propel the little beastie through its substrate. .
Close up of the
Spirilla volutans .
The Economic Importance of Bacteria
. Other organisms may serve as vectors to spread bacteria. Flies, cockroaches, biting insects, rodents and other animals get a lot of the blame for transmitting diseases to humans. But if the truth be told, you're in a lot more danger of contracting something dangerous from personal contact with your fellow Homo sapiens than you are from being licked by a fly (or your dog!). .
Nitrogen-fixing bacteria (such as these Rhizobiumsp.) inhabit the root cells of plants in the legume family (Fabaceae). These moneran symbionts convert gaseous nitrogen from the atmosphere (N2) into usable "fixed" nitrogen (ammonia, nitrite and nitrate) which can be absorbed by the roots and used by the plant to manufacture protein and nucleic acids.
Other bacteria, such as these Streptomyces spp., are sources of life-saving medicines. This genus yields the powerful antibiotic known as streptomycin. Actinomycetes are the source of actinomycin. .
The Enterotube II is a self-contained sterile plastic tube with 12 compartments containing distinct media that permit different biochemical tests to be performed. The Enterotube II has its own enclosed inoculating wire that allows simultaneous inoculation and completion of 15 standard biochemical tests for the identification of enteric unknowns. After incubation, the specific chambers show color changes for positive tests. The identification of the unknown is determined from the BBL Enterotube II Interpretation Guide. Each organism is identified with a 5-digit number based on the positive and negative test reactions in the Enterotube II.
Sponge Activity-What did you learn today?
1. Which choice below can be found in gram-negative bacteria, but not in gram-positive bacteria? (Concept 27.1)
2. The prokaryotic organisms most likely to be found living in salt ponds are the _____. (Concept 27.3)
3. Which clade of archaea contains the extreme halophiles and methanogens? (Concept 27.3)
4. An ecological relationship between organisms of different species that are in direct contact can best be described as _____. (Concept 27.4)
5. Genes for the resistance of antibiotics are usually located _____. (Concept 27.1)