Animal Plant Fungi Protist Eubacteria Archea Heterotroph/ Autotroph/ Both Mulitcellular/ Unicellular Cell Wall? If so, what material? Prokaryote/ Eukaryote
I.What is a bacterium? A.Unicellular prokaryote.
I.What is a bacterium? B. Anatomy 1. Cell Wall – often made of peptidoglycan 2. DNA – usually in single, circular strand 3. Plasmids – extra DNA, codes for nonvital traits 4. Ribosomes – assemble amino acids 5. Flagellum – movement 6. Plasma Membrane – under cell wall 7. Pilus – use for attachement
I.What is a bacterium? C. Bacterial Shapes
I.What is a bacterium? D. Bacterial Classification 1. Gram Positive/Negative Gram Positive display peptidoglycan in cell wall.
I.What is a bacterium? D. Bacterial Classification 2. Metabolism: a. Photoautotroph: Use light as energy source. b. Chemoautotroph: Autotrophs that use inorganic compounds as energy source. c. Heterotroph
II. Bacterial Growth and Reproduction A.Asexual: Prokaryotic Fission Circular DNA (lacking histones) replicates, then is divided between two new cells.
Fig. 22.7, p. 358 a Bacterium (cutaway view) before DNA replication. The bacterial chromosome is attached to the plasma membrane. b DNA replication starts. It proceeds in two directions away from the same site in the bacterial chromosome. c The new copy of DNA is attached at a membrane site near the attachment site of the parent DNA molecule. d New membrane grows between the two attachment sites. As it increases, it moves the two DNA molecules apart. e At the cell midsection, deposits of new membrane and new wall material extend down into the cytoplasm. f The ongoing, organized deposition of membrane and wall material at the cell midsection divides the cell in two.
II. Bacterial Growth and Reproduction B.Sexual Recombination: Bacterial Conjugation A plasmid (extrachromosomal DNA) can be transferred from one bacterium to another through the extension of a sex pilus.
Fig. 22.8, p. 359 a A conjugation tube has already formed between a donor and a recipient cell. An enzyme has nicked the donor’s plasmid. b DNA replication starts on the nicked plasmid. The displaced DNA strand moves through the tube and enters the recipient cell. c In the recipient cell, replication starts on the transferred DNA. d The cells separate from each other; the plasmids circularize. nicked plasmidconjugation tube
II. Bacterial Growth and Reproduction C. Transduction: DNA transferred through virus When a virus infects a bacterium, it may transfer bacterial DNA when it infects other bacteria.
III. Bacterial Diversity Prokaryotes are too diverse to fit into one kingdom, ‘Monera’ A.Archea: Extremophiles, Live in extreme environments. 1. Methanogens: Swamps, animals guts; anaerobic. 2. Halophiles: Salt-loving 3. Thermophiles: Heat-loving
III. Viruses A.Noncellular Infectious Agent B.Contain either DNA or RNA (never both) C.Have outer protein coat (capsid) D.May have tail or other attachment adaptation E.Smaller than bacterium
III. Viral Infection A. There are four stages to a viral infection: Attachment – the virus must be of the correct shape to ‘fool’ a host cell into importing the genetic material (remember, large and charged items can’t pass through a cell membrane, so the virus can’t just pass through with no resistance). Penetration – the entire virus, or just the genetic material, is injected into the host cell. Assembly – the viral DNA is read and transcribed by the host cell. In some cases, restriction enzymes cut the host DNA and the viral genes are inserted directly into the host genome (this is how the first restriction enzymes were discovered). Release – once the viral genetic material has been translated, the new viruses are released from the cell and are set to infect other cells.
Fig a, p. 366 e Lysis of host cell is induced; infections particles escape. a Virus particles bind to wall of suitable host cell. Viral genetic material enters cell cytoplasm. c Viral protein molecules are assembled into coats; DNA is packaged inside. d Tail fibers and other parts are added to coats. LYTIC PATHWAY
IV. Viral Infection B. Lytic Virus: Cause host cell to lyse, or burst. C. Lysogenic Virus: Displays latent period, during which virus DNA is inserted into host DNA and ‘quietly’ replicates. D. Retrovirus: Insert RNA, then use ‘reverse transcriptase’ to copy back into DNA.