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:

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: 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.