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Viruses, Monera, and Protista
Diff. Biology
April 13, 2005
Viruses
• Viruses are nonliving
particles that reproduce
only inside specific host
cells.
• 3 Classes of viruses
– Nucleic acid; either single
or double stranded
– Viral size and shape
– Presence or absence of
outer envelope
• Has at least 2 parts
– Protein capsid
– DNA core
Source: http://en.wikipedia.org/wiki/Virus_(biology)
Viruses
• Bacteriophages – attack bacteria
• Animal viruses – can be RNA or DNA
• Retroviruses – RNA animal viruses that have a
DNA stage.
– Enzyme reverse transcriptase allows retrovirus to
produce a cDNA copy of their genes which becomes
integrated into the host genome.
– HIV is a retrovirus
– Retroviruses have also been connected to cancer.
Kingdom Monera
• Eubacteria and Archaebacteria
• Prokaryotic cells, contain only ribosomes.
• No nuclues, but do have a nucleoid that
contains a chromosome
• They are surrounded by a capsule (helps
with protection).
• Move by means of flagella or cillia
• Attach/Anchor by means of fimbriae.
Kingdom Monera
• Metabolism of bacteria
– Obligate anaerobes; cannot live in the
presence of oxygen
– Facultative anaerobes; can live with or without
oxygen.
– Aerobic; must have oxygen to live.
Kingdom Monera
• Heterotrophic by absorption, helping with
decomposition of organic matter.
• Nutrition
– Photosynthetic
– Chemosynthetic
Classification of Bacteria
•
•
•
•
Rods (Bacilli)
Round (Cocci)
Spiral (Spirilli)
Streptococcus - cocci
in chains
• Staphylococcus –
cocci in clusters
Gram negative or positive
• Gram-positive bacteria retain a dye-iodine
complex and appear purple or blue. Have
a thick layer of peptidoglycan that retains
the color.
• Gram-negative do not retain the complex
and appear pink or red. Thin layer of
peptidoglycan and an outer membrane.
More detrimental to good health.
Gram-Negative Bacilli
Gram-Positive Bacilli
Bacteria Reproduction
• Reproduce asexually by binary fission
• Sexual exchange can occur in three ways:
– Conjugation: cell-to-cell contact via the sex
pilus.
– Transformation: takes up the DNA released in
the medium
– Transduction: bacteriophages carry DNA from
one bacterium to another.
Kingdom Protista
• Eukaryotic, Unicellular organisms
• Algae, Protozoans and Molds make up this
kingdom.
– Algae are autotrophic and non-motile.
– Protozoa are mostly heterotrophic and motile.
– Molds are heterotrophic and non-motile
Common Life Cycles
• Diplontic Cycle
– Adult is always 2n
– Meiosis produces gametes
• Alternation of Generations
– Sporophyte is 2n generation
– Meiosis produces spores
– Gametophyte is haploid generation
• Haplontic Cycle
– Zygote is 2n stage
– Meiosis produces a spore
– Adult is always haploid
Algae
•
•
•
•
•
Green Algae
Brown Algae
Red Algae
Diatoms
Dinoflagellates – bound by
cellulose plates and have two
flagella.
• Euglena – have both plant and
animal like characteristics. 1/3
have Chloroplasts, but lack a cell
wall and swim by flagella, two of
them.
Protozoans
• Are similar to animals,
but are not considered so
in our study because they
are not multicellular or
undergo embryonic
development.
• Four types
–
–
–
–
Amoeboids; pseudopods
Ciliates; cilia
Zooflagellates; flagella
Sporozoa; no locomotion
Source: www.btinternet.com/ stephen.durr/volvoxc.jpg
Malaria
Source: post.queensu.ca/~forsdyke/ images/pfalcip04.gif
Slime and Water Molds
Slime molds usually exist as a plasmodium, a
diploid multinucleated cytoplasmic mass
enveloped by a slime sheath that creeps along,
phagocytizing decaying material. In unfavorable
conditions they can create spores to disperse
themselves in the wind to find a better place and
reproduce, starting the cycle again. Water molds
can live in water and on land. They are
saprotrophic and have a filamentous body.