Homework 3  to be submitted to valenciabiologyhw@gmail.com


    1. Describe 2 lines of evidence for the antiquity of life
    2. Describe the contributions of A. I. Oparin, J. B. S. Haldane, S. Miller, and H. Urey made toward developing a model for abiotic synthesis of organic molecules
    3. Provide plausibe evidence to support the hypothesis that chemical evolution resulting in life's origin occured in 4 stages
      1. Abiotic synthesis of organic monomers
      2. Abiotic synthesis of polymers
      3. Formation of probobionts
      4. Origin of genetic information
    4. Describe the basis for the 3-domain and the 6-Kingdom systems
    5. Traditionally, zoologists have placed birds in their own class, Aves. More recently, molecular evidence has shown that birds are more closely related to reptiles than their anatomy reveals. Genetically, birds are more closely related to crocodiles than crocodiles are to turtles. Thus, bird anatomy has become highly modified as they have adapted to flight, without their genes having undergone nearly as much change.

      6. Taxonomically, what should be done with the birds?

      7.  Traditional zoologists have long agreed that birds evolved from dinosaurs. What keeps such zoologists from agreeing that birds, like dinosaurs, should be considered reptiles?

      8. For a proponent of PhyloCode classification, what is true of the reptile clade if birds are not included in it?

      A) It becomes paraphyletic and, thus, an invalid reflection of evolutionary history.

      B) It becomes a subclass, instead of a class.

      C) It becomes a superclass, whereas the birds remain a class.

      D) PhyloCode does not concern itself with what is, or is not, a clade.

The Origins of Life

• Earth is probably ~4.5 billion years old
• Oldest life forms began ~3.5 bya
• How did life begin???
The Origin of Life: Early Ideas
• Spontaneous Generation
– idea popular in the 1600-1700’s
– living things come from the nonliving
– evidence: beetles and other insect larvae arise from cow dung; frogs emerge from mud
• In 1688, the Italian Francisco Redi In 1668, Francesco Redi, an Italian physician, did an experiment with flies and wide-mouth jars. He demonstrated that meat that was covered did not produce maggots
• This may have been the first true scientific experiment…
Francesco Redi experiment with flies and wide-mouth jars
• Observation: There are flies around meat carcasses at the butcher shop.
• Question: Where do the flies come from? Does rotting meat turn into or produce the flies?
• Hypothesis: Rotten meat does not turn into flies. Only flies can make more flies.
• Prediction: If meat cannot turn into flies, rotting meat in a sealed (fly-proof) container should not produce flies or maggots.
• Testing: Wide-mouth jars each containing a piece of meat were subjected to several variations of “openness” while all other variables were kept the same.
• Conclusion: Only flies can make more flies. In the uncovered jars, flies entered and laid eggs on the meat. Maggots hatched from these eggs and grew into more adult flies. In the sealed jars, no flies, maggots, nor eggs could enter, thus none were seen in those jars. Maggots arose only where flies were able to lay eggs. This experiment disproved the idea of spontaneous generation for larger organisms.
Other Ideas: Life from a Biblical Creation?
Christian Creationism states that the world, including all life, was created about 6,000 years ago in six literal days by a God.
…But how does one accurately and fairly test for this?...
What’s the observation, hypothesis, test…?
This idea does not really fit into the confines of a Science course.
Origin of Life:
Another idea
Biogenic-looking features in ALH84001 Martian meteorite
In 1969, a meteorite (left-over bits from the origin of the solar system) landed near Allende, Mexico. The Allende Meteorite (and others of its sort) have been analyzed and found to contain amino acids, the building blocks of proteins.
This idea of panspermia hypothesized that life originated out in space and came to earth inside a meteorite.
The amino acids recovered from meteorites are in a group known as exotics: they do not occur in the chemical systems of living things. The ET theory is now discounted by most scientists, although the August 1996 discovery of the Martian meteorite and its possible fossils have revived thought of life elsewhere in the Solar System.
Anyway….This only moves the problem to elsewhere!
The Latest on Extra-terrestrial Origins…The Raelians
• Raelians believe that humanity was created from the DNA of superior alien scientists
• Follow the teachings of a former French magazine sportswriter and wannabe race-car driver Claude Vorilhon, 56. He took the name "Rael" after he claimed a close encounter of the third kind….
A Plausible History of Life on Earth (A Theory)
• First living organism: primitive bacterium which absorbed and restructured small organic molecules produced nonbiologically in its environment.
• Explosive growth in numbers from lack of competition led to exhaustion of ATP. Early
demise of countless billions, but also step- by-step, from back-to-front, a fermentation
cycle to produce ATP from glucose.
• When free glucose also ran out, resultant biological stress selected for evolution of a biological mechanism to produce glucose from more abundant natural resources: CO + (H S or H O) + sunlight. Photosynthesis, with H O, a waste product is O .
• Gradual increase in atmospheric oxygen led to selective advantage if organisms could exploit this reactive gas in ATP production from glucose: Respiration.
• Consumers (bacteria) now could survive by scavenging organic matter released upon deaths of producers (blue-green algae).
 Origin of Life: Current Theory
• Chemical Evolution
• .....The idea that long ago complex collections of chemicals formed the first cells.
• Life began in the oceans 4 bya from simple chemicals joining together in a “primordial soup”
• Complex chemicals evolved into living cells
Conditions on the Early Earth
• A hot reducing environment
• High temperatures
• H2O, CO2, N2
• H2S, CH4, NH3, H2
• No O2
• Text pg. 451
Miller Experiment
In 1950, a student, Stanley Miller, designed an experiment in which he discharged an electric spark into a mixture thought to resemble the primordial composition of the atmosphere.
From the water receptacle, designed to model an ancient ocean, Miller recovered some amino acids.
• What gases were believed to be present in the early earth’s atmosphere?
• What energy source may have helped create life on earth?
• What complex structures did the Miller-Urey apparatus produce?
• Has life been recreated in this apparatus?
The Tree of Life
An Introduction to Biological Diversity
• Overview: Changing Life on a Changing Earth
• Life is a continuum
– Extending from the earliest organisms to the great variety of species that exist today
• Geological events that alter environments
– Change the course of biological evolution
• Conversely, life changes the planet that it inhabits
• Geologic history and biological history have been episodic
– Marked by what were in essence revolutions that opened many new ways of life
• Conditions on early Earth made the origin of life possible
• Most biologists now think that it is at least a credible hypothesis
– That chemical and physical processes on early Earth produced very simple cells through a sequence of stages
• According to one hypothetical scenario
– There were four main stages in this process
Synthesis of Organic Compounds on Early Earth
• Earth formed about 4.6 billion years ago
– Along with the rest of the solar system
• Earth’s early atmosphere
– Contained water vapor and many chemicals released by volcanic eruptions
• Laboratory experiments simulating an early Earth atmosphere
– Have produced organic molecules from inorganic precursors, but the existence of such an atmosphere on early Earth is unlikely
• Instead of forming in the atmosphere
– The first organic compounds on Earth may have been synthesized near submerged volcanoes and deep-sea vents
Extraterrestrial Sources of Organic Compounds
• Some of the organic compounds from which the first life on Earth arose
– May have come from space
• Carbon compounds
– Have been found in some of the meteorites that have landed on Earth
Looking Outside Earth for Clues About the Origin of Life
• The possibility that life is not restricted to Earth
– Is becoming more accessible to scientific testing
Abiotic Synthesis of Polymers
• Small organic molecules
– Polymerize when they are concentrated on hot sand, clay, or rock
Advantage for Polymerization Reactions in Protocells
• Protobionts
– Are aggregates of abiotically produced molecules surrounded by a membrane or membrane-like structure
• Laboratory experiments demonstrate that protobionts
– Could have formed spontaneously from abiotically produced organic compounds
• For example, small membrane-bounded droplets called liposomes
– Can form when lipids or other organic molecules are added to water
Coacervates & Vesicles
The “RNA World” and the Dawn of Natural Selection
• The first genetic material
– Was probably RNA, not DNA
• RNA molecules called ribozymes have been found to catalyze many different reactions, including
– Self-splicing
– Making complementary copies of short stretches of their own sequence or other short pieces of RNA
• Early protobionts with self-replicating, catalytic RNA
– Would have been more effective at using resources and would have increased in number through natural selection
• : The fossil record chronicles life on Earth
• Careful study of fossils
– Opens a window into the lives of organisms that existed long ago and provides information about the evolution of life over billions of years
How Rocks and Fossils Are Dated
• Sedimentary strata
– Reveal the relative ages of fossils
• Index fossils
– Are similar fossils found in the same strata in different locations
– Allow strata at one location to be correlated with strata at another location
• The absolute ages of fossils
– Can be determined by radiometric dating
• The magnetism of rocks
– Can also provide dating information
• Magnetic reversals of the north and south magnetic poles
– Have occurred repeatedly in the past
– Leave their record on rocks throughout the world
The Geologic Record
• By studying rocks and fossils at many different sites
– Geologists have established a geologic record of Earth’s history
• The geologic record is divided into
– Three eons: the Archaean, the Proterozoic, and the Phanerozoic
– Many eras and periods
• Many of these time periods
– Mark major changes in the composition of fossil species
• The geologic record
Mass Extinctions
• The fossil record chronicles a number of occasions
– When global environmental changes were so rapid and disruptive that a majority of species were swept away
• Two major mass extinctions, the Permian and the Cretaceous
– Have received the most attention
• The Permian extinction
– Claimed about 96% of marine animal species and 8 out of 27 orders of insects
– Is thought to have been caused by enormous volcanic eruptions
• The Cretaceous extinction
– Doomed many marine and terrestrial organisms, most notably the dinosaurs
– Is thought to have been caused by the impact of a large meteor
• The Cretaceous extinction
– Doomed many marine and terrestrial organisms, most notably the dinosaurs
– Is thought to have been caused by the impact of a large meteor
• Much remains to be learned about the causes of mass extinctions
– But it is clear that they provided life with unparalleled opportunities for adaptive radiations into newly vacated ecological niches
• Species, on average, live for roughly a million years before they go extinct---and we’ve increased the rate of extinction by as much as 1000 times.
• One percent of Americas plant and animal species have gone extinct in the last century, and about 10-20 percent of the rest are known to be in some state of endangerment…
• {.interview with E.O Wilson in summer 2008 issue of National Parks Magazine who described a new ant species Pheidole harrisonfordi.. after his friend}
• The analogy of a clock
– Can be used to place major events in the Earth’s history in the context of the geological record
Stromatolites as Fossil Record of Early Unicelluar Organisms
Shark Bay
Western Australia
Hamlin Pool
Hamlin Pool
Stromatolite Morphology
Hamlin Pool
The First Prokaryotes
• Prokaryotes were Earth’s sole inhabitants
– From 3.5 to about 2 billion years ago
Electron Transport Systems
• Electron transport systems of a variety of types
– Were essential to early life
– Have: some aspects that possibly precede life itself
Photosynthesis and the Oxygen Revolution
• The earliest types of photosynthesis
– Did not produce oxygen
• Oxygenic photosynthesis
– Probably evolved about 3.5 billion years ago in cyanobacteria
• When oxygen began to accumulate in the atmosphere about 2.7 billion years ago
– It posed a challenge for life
– It provided an opportunity to gain abundant energy from light
– It provided organisms an opportunity to exploit new ecosystems
• : Eukaryotic cells arose from symbioses and genetic exchanges between prokaryotes
• Among the most fundamental questions in biology
– Is how complex eukaryotic cells evolved from much simpler prokaryotic cells
The First Eukaryotes
• The oldest fossils of eukaryotic cells
– Date back 2.1 billion years
Endosymbiotic Origin of Mitochondria and Plastids
• The theory of endosymbiosis
– Proposes that mitochondria and plastids were formerly small prokaryotes living within larger host cells
• The prokaryotic ancestors of mitochondria and plastids
– Probably gained entry to the host cell as undigested prey or internal parasites
• In the process of becoming more interdependent
– The host and endosymbionts would have become a single organism
• The evidence supporting an endosymbiotic origin of mitochondria and plastids includes
– Similarities in inner membrane structures and functions
– Both have their own circular DNA
Eukaryotic Cells as Genetic Chimeras
• Additional endosymbiotic events and horizontal gene transfers
– May have contributed to the large genomes and complex cellular structures of eukaryotic cells
• Some investigators have speculated that eukaryotic flagella and cilia
– Evolved from symbiotic bacteria, based on symbiotic relationships between some bacteria and protozoans
• Multicellularity evolved several times in eukaryotes
• After the first eukaryotes evolved
– A great range of unicellular forms evolved
– Multicellular forms evolved also
The Earliest Multicellular Eukaryotes
• Molecular clocks
– Date the common ancestor of multicellular eukaryotes to 1.5 billion years
• The oldest known fossils of eukaryotes
– Are of relatively small algae that lived about 1.2 billion years ago
• Larger organisms do not appear in the fossil record
– Until several hundred million years later
• Chinese paleontologists recently described 570-million-year-old fossils
– That are probably animal embryos
The Colonial Connection
• The first multicellular organisms were colonies
– Collections of autonomously replicating cells
• Some cells in the colonies
– Became specialized for different functions
• The first cellular specializations
– Had already appeared in the prokaryotic world
The “Cambrian Explosion”
• Most of the major phyla of animals
– Appear suddenly in the fossil record that was laid down during the first 20 million years of the Cambrian period
• Phyla of two animal phyla, Cnidaria and Porifera
– Are somewhat older, dating from the late Proterozoic
• Molecular evidence
– Suggests that many animal phyla originated and began to diverge much earlier, between 1 billion and 700 million years ago
Colonization of Land by Plants, Fungi, and Animals
• Plants, fungi, and animals
– Colonized land about 500 million years ago
• Symbiotic relationships between plants and fungi
– Are common today and date from this time
Continental Drift
• Earth’s continents are not fixed
– They drift across our planet’s surface on great plates of crust that float on the hot underlying mantle
• Often, these plates slide along the boundary of other plates
– Pulling apart or pushing against each other
• Many important geological processes
– Occur at plate boundaries or at weak points in the plates themselves
• The formation of the supercontinent Pangaea during the late Paleozoic era
– And its breakup during
the Mesozoic era explain
many biogeographic puzzles
• New information has revised our understanding of the tree of life
• Molecular Data
– Have provided new insights in recent decades regarding the deepest branches of the tree of life
Previous Taxonomic Systems
• Early classification systems had two kingdoms
– Plants and animals
• Robert Whittaker proposed a system with five kingdoms
– Monera, Protista, Plantae, Fungi, and Animalia
Reconstructing the Tree of Life: A Work in Progress
• A three domain system
– Has replaced the five kingdom system
– Includes the domains Archaea, Bacteria, and Eukarya
• Each domain
– Has been split by taxonomists into many kingdoms
Cellular Tree of Life
• One current view of biological diversity
Origin of Life on Earth
Origin of Life on Earth
• Modern scientific perspective of transition,
inanimate matter → animate matter,
as a physical rather than a divine process.
• Important steps in creation of life:
– Nonbiological synthesis of organic compounds in nonoxidizing atmosphere.
– Polymerization by removal of water from chemical joints of monomers.
– Survival advantage of protocells that can make polymers.
– Evolution of metabolic chains from back-to-front.
– Natural selection for objects that have genetic apparatus (nucleic acids) for remembering metabolic recipes that can pass down that apparatus (DNA) to daughter cells.
• Importance of sex, eukaryotic cells, and cell differentiation.
Viruses Lie at the Borderline of Life
Historical Context of Ideas
• Before advent of modern science, people’s perception of living and nonliving things were blurred: “ frogs from slime,” “maggots from decaying meat.”
• Careful observation demonstrated that complex organisms always originated from parents (e.g., maggots from flies alighting on meat).
• Discovery of single-celled organisms (e.g., bacteria) and Louis Pasteur’s (1822-1895) theories of fermentation and disease.
• Pasteur’s saving of French wine industry, vaccination against anthrax, cure for rabies.
Pasteur’s Experiment on Spontaneous Generation
Importance of Long Timescale and No Competition
• Charles Darwin in 1871:
  “It is often said that all the conditions for the first production of a living organism are now present, which could ever be present. But if (and oh! What a big if!) we could conceive in some warm little pond, with all sorts of ammonia and phosphoric salts, light, heat, electricity, etc., present, that a protein compound was chemically formed ready to undergo still more complex changes, at the present day such matter would be instantly devoured or absorbed, which would not have been the case before living creatures formed.”
• A. I. Oparin (1894-1980) in Russia and J. B. S. Haldane (1892-1964) in Great Britain stressed the important role of a non-oxidizing atmosphere.
Molecular Clues to the
Origin of Life
Important Steps in Creation of Life from Inanimate Matter
• Creation of small organic molecules in a nonoxidizing atmosphere via lightening strokes, UV light, etc. (Miller-Urey experiments).
• Dissolving of small organic molecules in primitive oceans to form Haldane’s warm and dilute primordial soup. Contribution of phosphates, etc., from rocks.
• Synthesis of ATP, GTP, CTP, UTP, and their deoxy counterparts dATP, dGTP, dCTP, dTTP, as the precursors to nucleic acids. Mostly ATP.
• Polymerization by nonbiological means of amino acids into proteins and of nucleoside triphosphates into nucleic acids (RNA and DNA). Primary difficulty is to remove water in the joints:
monomer: H-M-OH
polymer: H-M1-M2…-Mn-OH
H-M1-…-Mn1-OH + H-Mn-OH → H-M1-…-Mn-OH + H-O-H
Miller-Urey (1953) Experiments
Organic Molecules Formed
Miller Urey Experiment

(Origin of Life)
Remember the Following as the Origin of Life is Considered:
1. The smallest known protein has 51 L-type amino acids in a particular order.
2. One of the smallest living organisms is a mollicute. It consists of 256,000 L-type amino acids in a particular order.
•Does the idea of simple organic molecules being formed prove that they could assemble themselves by random chance into a biologic protein?

 Does the formation of simple organic molecules confirm the idea of life resulting from these molecules?
In 1953 Stanley Miller and Harold Urey performed the first experiment that produced amino acids in what was assumed to be a pre-life atmosphere. They passed a mixture of water vapor, methane, hydrogen and ammonia gases through an electric arc to simulate what would happen if these gases were subjected to lightning.
Miller Urey Experiment Apparatus
•Miller Urey Experimental Results

10 biologic amino acid types
25 non-biologic amino acid types
In considering your answers to the following questions remember that natural selection and mutations only effect living organisms.
Do You Think the Results of the Miller Urey Experiment Indicate That the Biologic Amino Acids Could Separate Themselves From the Non-biologic Amino Acids and other compounds By Random Chance Happenings to Form a Biological Polypeptide?
Are the Odds That This Could Happen Greater Than Those of Winning the Power Ball Lottery?

Could insulin have been formed?
Chicken or Egg?
Advantage for Polymerization Reactions in Protocells
Extremophiles and Archaea
• A major surprise of the past three decades is the discovery of the existence of life under extreme environments – near cracks on the ocean floor, in boiling hot sulfur springs, and at a few km depths in the interior of the solid Earth. These organisms derive their ultimate source of energy and nutrients from below, the deep earth, rather than from above, sunlight.
• “Extremophiles,” the generic name given such organisms, give rise to the hope that life may exist under extraterrestrial conditions much more harsh than believed possible previously.
• Many of the single-celled organisms that belong to the category of “extremophile” form a branch of life, archaea, distinct from the bacteria/blue-green algae and eukarya. The relationship between these three branches is complex, with recent research indicating considerable mixing of genetic material among the different groups.
• Nevertheless, because many of the classic arguments given earlier for a single origin of life still holds, consensus holds that a “last universal common ancestor” (LUCA) existed which gave rise to all these lifeforms. But it is an open question whether LUCA originated near the surface or the deep bowels of the Earth (or more fancifully, from extraterrestrial material brought here via meteorites).
What are Extremophiles?
Extremophiles are microorganisms— whether viruses, prokaryotes, or eukaryotes— that survive under harsh environmental conditions that can include atypical temperature, pH, salinity, pressure, nutrient, oxic, water, and radiation levels
Types of Extremophiles

Types of Extremophiles

Other types include:
• Barophiles -survive under high pressure levels, especially in deep sea vents
• Osmophiles –survive in high sugar environments
• Xerophiles -survive in hot deserts where water is scarce
• Anaerobes -survive in habitats lacking oxygen
• Microaerophiles -survive under low-oxygen conditions only
• Endoliths –dwell in rocks and caves
• Toxitolerants -organisms able to withstand high levels of damaging agents. For example, living in water saturated with benzene, or in the water-core of a nuclear reactor
Environmental Requirements

Surviving the Extremes
Martian Meteorite:
Amoeba Engulfing a Ciliate
Conjugation: Bacterial Sex
Dividing and Conjugating
The Emergence of Multicellular Organisms Among Eukarya
• When there are predatory cells about, it pays to be as large as possible so that you cannot be engulfed. But there exists limits on how large a single cell can grow and still function efficiently. Solution: band together in colonies (filamentous green algae, sponges, etc.). Not directed!
• Advanced multicelluar organisms show more cell differentiation.  Hallmark of higher organisms is ability of its cells to specialize to form tissues, different tissues to act collectively as organs, and different organs to coordinate activities to give the entire specimen.
Traditional Tree of Life
Intelligence and Civilization
• Most remarkable among the specialized cells is the nerve cell, the neuron; and most remarkable among all organs is the brain, a hierarchical arrangement of neurons.
• The ascent of man is due in large measure to humanity’s ability to pass down, not only inherited traits, but the accumulated knowledge and skills of society as a whole: civilization.
• How long has human culture been in existence? Only since the waning of the last ice age, 13,000 years ago.
Power of Hierarchical Structures
for Producing Complex structures
• Literary world: letters of alphabet, words, sentences, paragraphs, chapters, books.
• Physical world: elementary particles, nuclei, atoms, and molecules; minerals and rocks; continents, oceans, and atmosphere; Earth.
• Biological world: elementary particles, nuclei, atoms, small molecules, macromolecules, cells, tissues, organ systems, organisms, societies, civilization.
• Business world: organizational hierarchy, efficiency of modules for mass production.
Number of Different Offsprings Possible in Human Reproduction
• Even without crossover events in meiotic division and fertilization, the number of different fertilized eggs and sperms potentially available to single pair of parents is
• With six billion people on Earth, the number of different possible pairings of father and mother are

Number of Different Offsprings Possible in Human Reproduction
• Thus, the number of potentially different descendants from the current pool of human beings on Earth without mutations or crossover events is

enough to colonize every solar system in the observable universe with a population of humans comparable to the Earth!
• Whether this is desirable even if feasible is debatable. Nevertheless, reproductive success and diversity are the power behind life and a perhaps frightening hallmark of aggressive civilizations.
People are the product of alien-controlled cloning experiments
• On Dec. 13, 1973, Vorilhon said he was walking in the Clermont-Ferrand volcanic mountain range in France when a UFO touched down. Humanoid creatures with pale greenish skin and almond-shaped eyes took him aboard, saying they wanted him to be their messenger to humankind.
• The aliens explained they cloned the first people 25,000 years ago. The little green people said Vorilhon was himself a clone and that they impregnated his mother in 1946 after the use of the first atomic bombs awakened them to mankind's advanced scientific knowledge.
• "When I told my mother and grandmother the true story, my grandmother was relieved because she said that she had seen UFOs lingering around the house over the years and had never told anyone," Vorilhon told the Village Voice last year (2002).
• Vorilhon, who frequently dons flowing white garments, said his mission is to spread the word that there is no God, and that science and our alien forefathers would set people free -- physically and sexually -- and help them live forever.
• Two years after the aliens' first visit, they reappeared and took Vorilhon to another planet where he said he met Jesus, Mohammed and Buddha. All became immortal through cloning, he said.
• Ever since, he's been preaching the message of protecting the rights of the "unreborn" --
Jan. 2003: Raelians claim to clone first human baby
  The Raelian religious cult claim that a company founded by its adherents has cloned the first human baby.
Consider, for one moment, the objective circumstances: a crackpot cult, whose French founder says he got his marching orders from a space alien, calls a press conference in Miami to announce that a cloned child has been born to an unidentified woman in an unspecified place the day after Christmas. Proof, according to the company's CEO -- a chemist named Brigitte Boisselier -- will be forthcoming in nine days --not 10, not eight, but nine.
Sponge Activity-What did you learn today?
• 1. Clay particles may have played an important role in the origin of life because _____. (Concept 26.2)
• 2.Experiments in which electricity was discharged into a vessel containing hydrogen gas, water vapor, methane, and ammonia were conducted by _______. Their results support Oparin's theory on the origin of life. (Concept 26.2)
• 3. The atmosphere of early Earth probably contained no O2 until the emergence of organisms that _____. (Concept 26.3)
• 4. Eukaryotic cells probably arose through _____. (Concept 26.4)
• 5. Until about 500 million years ago, all living things lived where? _____. (Concept 26.5)
• Prepare a slide of yogurt culture:
• 1. Obtain a slide and cover slip. With a bacterial loop or a toothpick transfer a small amount of yogurt to the center of the slide.
• 2. Smear the yogurt in an area slightly smaller than the cover slip. Allow it to dry.
• 3. Place two drops of crystal violet or carbolfuchsin stain on the air-dried yogurt smear.
• 4. Place a coverslip on the stained smear and examine under the microscope.
• Draw the observed bacterial types in the space below
• Cyanobacteria are blue-green algae
• You may be using prepared slides or using fresh cultures of these organisms. A few cyanobacteria are Anabeana, Gloeocapsa, Oscillatoria and Merismopedia. Your instructor may provide a survey culture of various organisms to key out and to exam.
• Draw and label several representatives of cyanobacteria in the space below.
• Anabeana Gloeocapsa Merismopedia Oscillatoria