Ch. 19: Monera (Bacteria)
Monera everywhere! How many “angels” can fit on the head of a pin!
Discuss: What are Monera?
Monera Structure
Monera = bacteria (singular: bacterium)
Characteristics of Monera:
-Lack membrane-bound nucleus (prokaryotes)
-Have cell membranes, but do not have membrane bound
organelles
-Ribosomes are slightly different
-Smaller than almost all other organisms
-Unicellular
-Large, single molecule of DNA (w/ extra circular pieces =
plasmids)
-No chloroplasts, no mitochondria
-Other possible structures:
** capsule: slimy outer layer secreted for
movement/protection
** flagella: whip like tail for locomotion
** cilia: short hair like fibers
** chlorophyll: optional for autotrophic cells- inside but no
chloroplasts
Life Cycle
**Some bacteria can reproduce every 20 minutes
-At this rate: 1 bacteria => 500 (3 hrs) => 1.6 x 107 (8 hours)
-Rate limiting factor = Food and Waste
Reproduction & Growth
-Rapid reproduction!
-Bacteria can reproduce either sexually or asexually
-Asexual Reproduction: most common, called binary fission
-Binary fission: Literally translated to division in half; cell
divides to form two identical cells
-Sexual Reproduction: Rare but accounts for continuity and
diversity of bacteria and for antibiotic
resistance
-Conjugation: The process of exchanging genetic material
through cell-to-cell contact
-Bacteria connect using hair-like projections called pili
-Bacteria may also incorporate genetic information from dead
cells in a process called transformation
-Live in groups called “colonies”
-Unfavorable living conditions = some bacteria may for
endospores
-Endospores: Thick walls resist heat, drought, radiation
-Can survive but may be inactive for centuries!
Origin and Diversity of Moneras
Classification of Moneras
Two types of Bacteria (very different)
1. (Kingdom) Archaebacteria
-often live in harsh environments (hot springs, underwater vents,
acidic environments)
-archae = ancient; these are thought to resemble some of the
original bacteria that 1st populated the earth!
Three types:
a. Methogens: Oxygen free (produce CH4) (ex. cow guts)
b. Thermophiles: Hot water (60 to 250 degrees Celsius)
c. Halophiles: Salt-lovers, can live in high salt conc.
2. (Kingdom) Eubacteria
-Eu = true (bacteria)
-so many that they are hard to classify!
2 Major Phylums (of 12 total)
Phylum Cyanobacteria (blue green algae)
Characteristics: one-celled , some form colonies
make own food, contain chlorophyll but not
chloroplasts, most are blue green in color
Examples: Nostoc, Anabaena, Oscillatoria, Gleocapsa
Causes lake "blooms", when pollution is high (N, P)
Phylum Schizomycetes
Tiny unicellular, prokaryotic organisms, which can be
found everywhere - air, water, food, soil, in living
organisms
Characteristics: one-celled, most absorb food (can be
saprophytes or parasites); some contain chlorophyll
or other pigments; appearance: may be round,
spiral or rod-shaped.
Other ways to identify & classify Moneras
a. Cell Shape
1. Cocci (spheres)
2. Bacilli (rods)
3. Spirilla (spirals)
**Also: Strepto (chains) and Staphylo (clusters)
**Example: Streptococci are chains of spheres
b. Cell wall composition
**Gram stain
-Purple = positive
-Pink = negative (extra lipid bilayer, hard to treat)
**Used to determine susceptibilities to antibiotics, toxins
they produce, and how they react to disinfectants
c. Nutrition
1. Heterotrophs: need food from another source
2. Autotrophs: make their own food
-Phototrophs: use sun/CO2 (ex. cyanobacteria)
-Chemotrophs: make food using ammonia or sulfur
d. Respiration
1. Aerobic: use oxygen
2. Anaerobic: do not use oxygen
-Obligate Anaerobe: can only live in absence of O2
-Facultative Anaerobe: living w/out O2 is an option
Moneras in the Biosphere
Ecological roles
**Most numerous organism on earth!
Decomposers: Break down dead, organic matter & return to soil
-critical in many of the life cycles
-help return N2 to soil
Symbiosis: Relationship involving direct contact between two
organisms in which at least one partner benefits
-other partner may be helped, harmed, or remain unaffected
-example: bacteria in mouth or stomach, excess may result
in tooth decay/stomach problems
Diseases Caused by Monera (The Negatives)
**Food spoilers, cause odors, cause illness
**Some bacteria are very harmful
-Endotoxins: poisons or toxins produced by certain bacteria,
made of lipids or carbohydrates (usually gram negative)
-Exotoxins: poisons or toxins produced by certain bacteria, made
of proteins (usually gram +)
**Robert Koch correlated disease with bacteria
**Example of bacterial diseases: Lymes disease, Strep, Cholera,
Tetanus, tuberculosis (TB), diphtheria, leprosy, syphilis, typhoid
fever, dysentery, gonorrhea, the plague…
Frontiers in Biology (The Positives)
**Photosynthetic bacteria invaluable to producing earth’s atmosphere!
**Bacteria critical in molecular biology (plasmids)
**Used to restore natural environmental conditions = bioremediation
-example: oil eating bacteria, sewage treatment, etc.
**Antibiotics: life savers, must be produced all the time to stay ahead of
bacteria
**Food production (coffee, cheese, yogurt, and vinegar)
**Other uses: Mining ores, biodegradable products, and
pharmaceuticals
**Your health: Are infections good for your immune system?
Ch. 19B: Viruses
-From what you know about viruses and biology, are viruses living?
Structure of Viruses
Virus: An infectious agent made of a core of nucleic acid & a protein coat
-Smaller than the smallest cell (polio = 20 nm diameter [10-9 meters])
-No nucleus or other organelles
-They do posses structural parts:
Capsid: The protein coat that surrounds the core of nucleic acid
-Nucleic acid may either be DNA or RNA, depending on the virus type!
-Viruses have fewer genes than basic cells (as few as 5 genes!)
Envelope: An additional protective coating made of lipids, proteins,
and carbohydrates
-Envelopes found only on viruses that infect animal cells
-Envelope has projections used for recognition and binding to
animal cells
Virulent viruses: are destructive, cause disease
Temperate viruses: effects may not be seen immediately; "dormant"
Origins & History
-1892, Dmitri Ivanovsky ==> first scientist to look for cause of tobacco
mosaic disease
-1897, Martinus Beijerinck ==> found causing agent of TMD was inside cells
-He called this infectious agent a virus (Latin for poison)
-1935, Wendell Stanely ==> isolated crystals of infectious agent
(bacteria do not form crystals, this proved
that bacteria was not the culprit!)
**Where do you think the first virus originated?
**One theory is that the virus was originally part of a host cell, but
somehow adapted to live on its own. Does this sound like a plausible
hypothesis?
Viral Replication
-Viruses replicate, they do not reproduce!
-Viruses can not replicate on their own! They require a host.
Host: An organism that shelters and nourishes
-Provide all the materials that viruses need to copy themselves
-A cell infected with a virus has two options:
1. Lytic Cycle: Viral replication process proceeds rapidly and kills
host cell
-Examples: Cold virus (rhinovirus, adenovirus), influenza
-Process: Attachment: Virus attaches to cell
Penetration: Either whole virus or nucleic acid enters cell
Replication/Synthesis: Virus takes control of cell and
makes more virus nucleic acid & protein
components
Assembly: Cell becomes virus factory, packaging
nucleic acid into protein coats
Release: Cell lyses causing release of newly produced virus
New viruses ready to enter other cells
2. Lysogenic Cycle: Type of replication in which virus does not
immediately kill host
-Examples: Herpes
-Latent period involved (called Latency)
-After virus enters cell, viral DNA inserts itself into host chromosome
-When host cell divides, viral DNA in replicated along with its own
-A stimulus causes viral DNA to splice out of chromosomal DNA
-The cell then enters the lytic cycle
Diversity
-Classifying viruses difficult due to their diversity!
HIV virus
Corona virus
Bacteriophage
Ebola virus
Herpes virus
TMV
Methods of organization:
-Shapes: 1. Filoviruses ==> Ex: Ebola, non-distinct shape
2. Polyhedral viruses ==> Ex. Adenovirus, geometric shaped
3. Helical viruses ==> Ex: TMV, tight spirals or DNA or
RNA in capsid
4. Binal viruses ==> Ex: bacteriophage, polyhedral
capsule & helical tail
Discuss: 1. Myths of the common cold (cold weather not a cause)
2. New Rx lessens severity of common cold (zinc works too)
-Host: Can be organized according to host type
1. Plant
2. Animal
3. Bacteria (bacteriophage)
**Note: Most viruses invade only a specific organism (always exceptions!)
Example: Polio infects humans only!
Exception: Rabies infects both dogs and humans
**Specificity due to viral proteins on capsid/envelope that attach to host
receptor
-Function: Some viruses are classified according to function in a host
Ex: Retrovirus (such as HIV) = RNA virus
**RNA reverse-transcribes into DNA (hence the name)
DNA then enters the host DNA, latent
**Enzyme used called reverse transcriptase (also in virus)
One more time: Are viruses living?
Viruses:
contain either DNA or RNA
structure: capsid, no cell
membrane or wall
does not grow (in size)
requires a host cell for
reproduction
does NOT carry out metabolic
activity
Cells:
always have both DNA and
RNA
structure: cell wall/membrane,
cytoplasm, organelles...etc...
grows
able to reproduce by
mitosis/meiosis
carries out metabolic activity
Smaller than Viruses!?!
Viroids: Stripped down viruses, these are tightly folded strands or
circles of RNA
-No protein coat, but folding protects them from environment
-Cause millions of dollars worth of plant destruction yearly
Prions: Small, naked strands of proteins that cause animal disease
-Examples: Bovine spongiform encephalopathy (Mad Cow
Disease), Kuru or Creutzfeldt-Jakob disease
(human), Scrapie (sheep)
Viruses in the Biosphere
Ecological Roles
-Varying degrees of effects
Small: common cold, measles, chicken pox, and mumps
Drastic: Smallpox, HIV, polio, and influenza
-Animal viruses: distemper, rabies, and pneumonia
-Plant viruses: can cause discoloration of leaves, stunt growth, or kill plant
**Major problem in society: Prescribing of antibiotics to fight viruses!
Frontiers of biology
Beneficial uses of viruses:
-Vaccines: viruses used against themselves to produce vaccines
Vaccination: The process of injecting a person with a harmless
forms of a virus (Jonas Salk’s work)
1. Virus either weakened or dead
2. Vaccine stimulates immune system to produce antibodies
that help destroy that virus if its normal, harmful form
enters the system
3. Used to eliminate smallpox, polio, and measles
-Genetic engineering: manipulating the genes of an organism
**Viruses can be used to carry genes into cells (still experimental)
**Virologist: person who studies viruses
-Agriculture: viruses can be used to control pests that destroy food crops
**No pollution
**Can be used to produce more beautiful flowers (ex. stripes/bright
color combinations on petals of gladiolus and tulips)
- Interferon: a protein produced in small amounts by certain human
cells to "interfere" with viral activities
Ch. 20: Protists
-How would you react if you found yellow blobs in your yard?
-What is your idea of a protist?
Characteristics of Protists
The structure of Protists
**Protists live wherever there is water!
**Protists can be plant-like, animal-like, decomposers, even parasitic
**Range in size (from microscopic to giant seaweeds) and in shapes
**All eukaryotic organisms!
Origin and Diversity of Protists
**Early eukaryotes (roughly 1.5 billion years old) may be ancestors of
first unicellular protists
**Protists may also be multicellular (may have evolved through colonies)
**Diversity reflects several significant evolutionary developments
-examples: size, shape, and colors
**Difficult to classify due to diversity
Protists are organized into 3 groups, based on nutritional requirements:
1. Animal-like (heterotrophs) (nearly 65,000 species!)
2. Plant-like (autotrophs)
3. Fungus-like (decomposers)
Animal-like Protists - Protozoans
**Animal-like protists (heterotrophs) are called Protozoans
Why are they not considered animals if they are heterotrophs?
-Protozoan heterotrophs are unicellular
-Protozoans do not have specialized tissues, organs, or systems
Phylums classified according to how they move:
1. sarcodinians
-flowing movement,extending lobes of cytoplasm (pseudopods)
-”psuedo” means false, “pod” means foot (ex. ameba)
- contractile vacuole:a type of "bailing device" which
collects and excretes excess water; essential in waterdwelling cells to avoid bursting from osmotic pressure
-some have hard shells, extend cytoplasm through holes
-examples: foraminiferans and radiolarians
-Ameba (some other protists) can form cysts to survive
adverse conditions (ex. amebic dysentery)
2. zooflagellates
-about 2500 species
-utilize flagella (a whip-like structure) for movement
-flagella used in various ways (circular or back and forth)
-example: Trichonympha
3. ciliophorans (ciliates)
-over 8000 species
-most numerous and diverse group
-cilia (short, hairlike projections) are used for movement
-example: Paramecium
4. sporozoans
-over 6000 species
-characterized by absence of structures used for movement
-life cycles include both sexual and asexual phases
-complex life cycles, often involve more than one host
-parasitic forms of protists, example: Plasmodium
Plant-like Protists - Algae
Characteristics of Algae
**Plant-like because they can undergo photosynthesis
**Contain chlorophyll, can produce their own food and oxygen
**Unlike plants, algae do not contain specialized tissues or organs
**Organized into two groups: unicellular and multicellular
**Diverse, 7 divisions (see useful chart on p. 527)
1. Unicellular Algae
-Differences in covering and means of movement help categorize
-Include:
a. dinoflagellates
-two flagella that spin in cork-screw fashion
-cellulose plates cover and give unique shapes
-majority live in saltwater habitat, most non-symbiotic
b. diatoms (Bacillariophyta)
-snowflake shaped organisms, thousands of possible
shapes
-glass-like cell walls that contain silica
-pores in walls allow transport of materials
-among the most abundant organisms in the ocean
*contribute to much of earths O2 levels
c. euglenoids (Euglenophyta)
-resemble both algae and protozoans (kind of a mix of
plant and animal traits)
-lack cell walls, move using flagella, have chloroplasts
2. Multicellular Algae
-Have specialized structures that resemble parts of plants
-Considered protists due to lack of true tissues and reproductive
methods are more like protists than plants
-Classified according to color:
1. Green Algae (Chlorophyta)
-about 7000 species
-contain chlorophyll b and a as main pigment
-can be unicellular (ex. Chlamydomonas), colonial (ex.
Volvax), or multicellular (ex. Ulva)
-most live in fresh water or moist soil (few symbiotic or
ocean-dwelling)
2. Red Algae (Rhodophyta)
-about 4000 species
-mostly found in warm, saltwater
-contain accessory pigments (phycobilins) that gather
other wavelengths of light/produces distinctive color
-may also appear green, orange, or black
3. Brown Algae (Phadophyta)
-about 1500 species
-mostly found in cool saltwater habitats
-group included largest organism, giant kelp
-some have complex life cycles called alternation of
generations (see p. 528)
-spore-producing stage = sprophyte generation
(diploid, 2n)
-gamete-producing stage = gametophyte generation
(haploid, 1n)
Fungus-like Protists - Molds
Characteristics of Molds
**Most are small and live in damp, watery places
**Acts as a decomposer
**Organized into three groups:
1. Plasmodial slime molds
-Plasmodium is the feeding stage of its life cycle
-single cell with many nuclei
-unfavorable conditions and plasmodium creeps elsewhere
or...
-Fruiting body is the other stage of life cycle, produces spores
-haploid spores combine to form diploid zygote
2. Cellular slime molds
-may also alternate between spore-producing stage, fruiting
body, and ameba-like form
-feeding stage are single cells that move and digest food
-sources depleted and a chemical is secreted that attracts
nearby cells
-causes cells to form clump called a psuedoplasmodium
-psuedoplasmodium forms fruiting bodies (produce spores)
3. Water molds
-decomposers in freshwater ecosystems
-some are parasitic (attach fish gills or certain land plants)
-asexual reproduction produces spores with flagella
Protists in the Biosphere
Ecological Roles
**Other organisms rely on these abundant organisms
**Protists are a major component of Plankton (microscopic organisms
that float near the surface of oceans and lakes)
**Form base of many food chains
**Algal component of plankton called phytoplankton
**Phytoplankton also carry out more than 70% of Earth’s
photosynthesis!
**Also helps to maintain levels of bacteria and other organisms
**Human uses
-Agar; foods and food processing : chocolate milk salad dressing,
sausage, soup and canned meats
-Diatoms : toothpaste, filters, shampoos and cosmetics
-Alginates, carageenan: dairy stabilizers (ice cream) etc. algal
proteins increase nutritional value
Disease Caused by Protists
**Not all protists are beneficial
**Trypanosoma causes African sleeping sickness (carried by tse tse fly)
**Giardia cysts that are ingested in human cause intestinal problems
**Gonyaulax is found in shellfish & if consumed can produce a deadly toxin
**Phytophthora causes a potato disease called blight
**Toxoplasma often causes birth defects or even fatal to very
young/prenatal. Can be carried by birds, mice, cats, etc.
Frontiers in Biology
**Malaria spread by Anapheles mosquitoes carrying Plasmodium
protozoa
Life cycle: 1. Infected mosquito bites human, protozoans in the form
of sporozoites enters the body
2. In the liver, sporozoites develop into merozoites which
enter red blood cells and reproduce asexually
-causes red blood cells the lyse, resulting in fever
3. Some merozoites do not enter blood cells but remain in
blood as gametocytes
4. Mosquito bites infected individual and picks up
gametocytes along with blood and process continues...
**Other effects of Malaria
-evolution of sickle cell anemia
-drug resistance, such as chloroquine and quinine (tonic)