Download Bacteria and Viruses - Application of Biology - Lecture Slides and more Slides Biology in PDF only on Docsity! Chapter 19 Docsity.com 1. Which of the following characteristics is NOT true of both Archaebacteria and Eubacteria? A.Unicellular B. All heterotrophic C.Prokaryotic D.Have cell walls Docsity.com Bacteria are the simplest and oldest life forms – fossils show bacteria that are 3.5 billion years old! • The oldest fossil evidence on earth is that of Archaebacteria. • Archaebacteria are believed to be the ancestors of both Eubacteria and the other eukaryotic kingdoms Docsity.com Page 472 DNA Cell wall peptidoglycan Docsity.com Bacterial Shapes • Coccus – spherically shaped • Ex: Streptococcus • Bacillus – rod shaped • Ex: Clostridium botulinum • Spirillum – spiral shaped • Ex: Spirillum Docsity.com 4. What would be the name of this bacterial cell? A.Diplobacillus B. Streptococcus C.Staphylococcus D.Streptobacillus Docsity.com Draw the following bacterial cells: • Diplospirillum • Streptobacillus • Staphylococcus Docsity.com Bacteria and You • Foods made with bacteria: yogurt, cheese, sour cream • Decomposition • Bacteria are prevalent in sewage treatment plants, can be used to clean up oil spills, etc. Docsity.com Viruses • poison in Latin • nonliving • don’t fulfill all criteria for life • must infect host cell to reproduce • lack enzymes for metabolism • don’t grow Docsity.com Virus Shape and Structure • Nucleic acid core • Capsid (protein coat) – gives the virus its shape Docsity.com How does a virus infect cells? 1. The virus recognizes a host cell at a specific receptor site. 2. The virus and host cell interlock like a puzzle; a lock and key 3. The virus then destroys the cell’s DNA and takes over metabolic functions • This specificity explains why each virus can only invade certain types of cells. Docsity.com Bacteriophage enzyme lyses the bacterium’s cell wall, releasing new bacteriophage particles that can attack other cells. Bacteriophage proteins and nucleic acids assemble into complete bacteriophage particles Bacteriophage takes over bacterium’s metabolism, causing synthesis of new bacteriophage proteins and nucleic acids Bacteriophage injects DNA into bacterium Bacteriophage attaches to bacterium’s cell wall Bacteriophage Bacteriophage DNA Bacteriophage protein Bacteriophage protein coat Bacteriophage DNA Bacterial chromosome Docsity.com • Lysogenic Viruses attack the host cell, but do not immediately kill it • Viral DNA/RNA (prophage) is inserted into the host cell’s DNA/RNA • Host cell continues normal functioning, but will replicate the prophage every time it divides • This cycle may continue for years, but can go in to the lytic cycle at any time • Examples • Herpes Simplex I and II • Human Immunodeficiency Virus (HIV) Docsity.com Bacteriophage proteins and nucleic acids assemble into complete bacteriophage particles Bacteriophage enzyme lyses the bacterium’s cell wall, releasing new bacteriophage particles that can attack other cells Bacteriophage DNA inserts itself into bacterial chromosome Bacteriophage DNA (prophage) may replicate with bacterium for many generations Bacteriophage DNA (prophage) can exit the bacterial chromosome Bacteriophage DNA forms a circle Bacteriophage DNA Bacterial chromosome Bacteriophage injects DNA into bacterium Prophage Lytic Cycle Lysogenic Cycle Docsity.com
