Ch. 19 (Part I): Bacteria (Monera)
Monera everywhere! How many “angels” can fit on the head of a pin!
Discuss: What are Monera?
Monera Structure
= bacteria (singular: bacterium)
Characteristics of Monera:
-Lack membrane-bound nucleus (prokaryotes)
-Ribosomes are slightly different
-Smaller than almost all other organisms
-Large, single molecule of DNA (w/ extra circular pieces = plasmids)
-Other possible structures:
** capsule:
** flagella: whip like tail for locomotion
** cilia:
** 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:
-Sexual Reproduction:
-Conjugation:
-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 =
-Endospores:
-Can survive but may be inactive for up to 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, acid)
-archae =
Three types:
a. Methogens:
b.
: Hot water (60 to 250 degrees Celsius)
c. Halophiles:
2. (Kingdom) Eubacteria
-Eu = true (bacteria)
-so many that they are hard to classify!
2 Major Phylums (of 12 total)
Phylum
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
Responsible for
Phylum
Tiny unicellular, prokaryotic organisms, which can be found
everywhere Characteristics: one-celled, most absorb food (can be
saprophytes or parasites);
Other ways to identify & classify Moneras
a. Cell Shape
1.
2.
3.
**Also: Strepto (chains) and Staphylo (clusters)
**Example:
b. Cell wall composition
**Gram stain
-Purple =
-Pink =
**Used to determine susceptibilities to antibiotics, toxins they
produce, and how they react to disinfectants
c. Nutrition
1.
: need food from another source
2. Autotrophs:
: use sun/CO2 (ex. cyanobacteria)
-Chemotrophs:
d. Respiration
1.
: use oxygen
2. Anaerobic:
-Obligate Anaerobe:
-Facultative Anaerobe:
Moneras in the Biosphere
Ecological roles
**Most numerous organism on earth!
Decomposers:
-critical in many of the life cycles
Symbiosis:
-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)
**
**Some bacteria are very harmful
: poisons or toxins produced by certain bacteria, made of lipids
or carbohydrates (usually gram negative)
-Exotoxins:
**
**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 =
-example:
**Antibiotics: life savers, must be produced all the time to stay ahead of bacteria
**
**Other uses:
**Your health: Are infections good for your immune system?
Ch. 19 (Part II): Viruses
-From what you know about viruses and biology, are viruses living?
Structure of Viruses
Virus:
-Smaller than the smallest cell (polio = 20 nm diameter [10-9 meters])
-They do posses structural parts:
Capsid:
-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:
-Envelopes found only on viruses that infect animal cells
-Envelope has projections used for recognition and binding to animal cells
Virulent viruses:
Temperate viruses:
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 can not replicate on their own! They require a host.
Host:
-Provide all the materials that viruses need to copy themselves
-A cell infected with a virus has two options:
1. Lytic Cycle:
-Examples:
-Process: Attachment: Virus attaches to cell
Penetration:
Replication/Synthesis: Virus takes control of cell and makes
more virus nucleic acid & protein components
Assembly:
Release: Cell lyses causing release of newly produced virus
New viruses ready to enter other cells
2. Lysogenic Cycle:
-Examples:
-Latent period involved (called Latency)
-When the host cell divides, the viral DNA in replicated along
with its own
-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:
2.
==> Ex. Adenovirus, geometric shaped
3. Helical viruses ==> Ex:
4.
Discuss:
==> Ex: bacteriophage, polyhedral capsule &
helical tail
1. Myths of the common cold (cold weather not a cause)
2. New Rx lessens severity of common cold (zinc works too)
-Host:
1. Plant
2.
3. Bacteria (bacteriophage)
**Note: Most viruses invade only a specific organism (always exceptions!)
Example:
Exception:
**Specificity due to viral proteins on capsid/envelope that attach to host
receptor
-Function:
Ex: Retrovirus (such as HIV) = RNA virus
**
**
One more time: Are viruses living?
Viruses:
contain either DNA or RNA
Cells:
structure: cell wall/membrane,
cytoplasm, organelles...etc...
does not grow (in size)
able to reproduce by
mitosis/meiosis
carries out metabolic activity
Smaller than Viruses!?!
Viroids:
-No protein coat, but folding protects them from environment
-Cause millions of dollars worth of plant destruction yearly
Prions:
-Examples: Bovine spongiform encephalopathy (Mad Cow Disease)
Kuru, Creutzfeldt-Jakob disease (human), Scrapie
(sheep)
Viruses in the Biosphere
Ecological Roles
-Varying degrees of effects
Small:
Drastic:
-Animal viruses: distemper, rabies, and pneumonia
-Plant viruses:
**Major problem in society: Prescribing of antibiotics to fight viruses!Why?
Frontiers of biology
Beneficial uses of viruses:
-Vaccines: viruses used against themselves to produce vaccines
Vaccination:
1. Virus either weakened or dead
2.
3. Used to eliminate smallpox, polio, and measles
-Genetic engineering:
**Viruses can be used to carry genes into cells (still experimental)
**Virologist:
-Agriculture:
**No pollution
**Can be used to produce more beautiful flowers (ex.
-Interferon:
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 can be plant-like, animal-like, decomposers, even parasitic
**
**All eukaryotic organisms!
Origin and Diversity of Protists
**Early eukaryotes (roughly 1.5 billion years old) may be ancestors of first
unicellular protists
**
**Diversity reflects several significant evolutionary developments
-examples: size, shape, and colors
**
Protists are organized into 3 groups, based on nutritional requirements:
1. Animal-like (heterotrophs) (nearly 65,000 species!)
2.
3. Fungus-like (decomposers)
Animal-like Protists - Protozoans
**
Why are they not considered animals if they are heterotrophs?
-Protozoans do not have specialized tissues, organs, or systems
Phylums classified according to how they move:
1. sarcodinians
-”psuedo” means false, “pod” means foot (ex. ameba)
-contractile vacuole:
-some have hard shells, extend cytoplasm through holes
-examples:
-Ameba (some other protists) can form cysts to survive
adverse conditions (ex. amebic dysentery)
2. zooflagellates
-about 2500 species
-flagella used in various ways (circular or back and forth)
-example:
3. ciliophorans (ciliates)
-over 8000 species
-cilia:
-example: Paramecium
4. sporozoans
-over 6000 species
-life cycles include both sexual and asexual phases
-parasitic forms of protists, example:
Plant-like Protists - Algae
Characteristics of Algae
**Plant-like because they can undergo photosynthesis
**
**Unlike plants, algae do not contain specialized tissues or organs
**Organized into two groups:
**Diverse, 7 divisions (see useful chart on p. 527)
1. Unicellular Algae
-Differences in covering and means of movement help categorize
-Include:
a. dinoflagellates
-cellulose plates cover and give unique shapes
b.
-snowflake shaped organisms,thousands of possible shapes
-pores in walls allow transport of materials
-among the most abundant organisms in the ocean
*
c. euglenoids (Euglenophyta)
-resemble both algae and protozoans (kind of a mix of plant and
animal traits)
-
2. Multicellular Algae
-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
-can be unicellular (ex. Chlamydomonas), colonial (ex.
Volvax), or multicellular (ex. Ulva)
2. Red Algae (Rhodophyta)
-about 4000 species
-contain accessory pigments (phycobilins) that gather other
wavelengths of light & produces distinctive color
-
3. Brown Algae (Phadophyta)
-about 1500 species
-group included largest organism, giant kelp
-some have complex life cycles called alternation of
generations (see p. 528)
-spore-producing stage =
-gamete-producing stage =
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
-single cell with many nuclei
-unfavorable conditions and plasmodium creeps elsewhere or...
-Fruiting body
-haploid spores combine to form diploid zygote
2. Cellular slime molds
-feeding stage are single cells that move and digest food
-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)
-
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
**
**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 :
-Alginates, carageenan: dairy stabilizers (ice cream) etc. algal proteins
increase nutritional value
Disease Caused by Protists
**Not all protists are beneficial
**Trypanosoma causes
**Giardia cysts that are ingested in human cause intestinal problems
**Gonyaulax
**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.
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.
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)