Concept Questions

Take some time to write answers to these questions. If you can answer them, you have a good grasp of the material!

1. Name several general characteristics that could be used to define the procaryotes. Do any other microbial groups besides bacteria have procaryotic cells? What does it mean to say that bacteria are ubiquitous? In what habitats are they found? Give some general means by which bacteria derive nutrients.

2. Describe the structure of a flagellum and how it operates. What are the four main types of flagellar arrangement? How does the flagellum dictate the behavior of a motile bacterium? Differentiate between flagella and periplasmic flagella. List some direct and indirect ways that one can determine bacterial motility.

3. List the components of the cell envelope. Explain the position of the glycocalyx. What are the functions of slime layers and capsules? How is the presence of a slime layer evident even at the level of a colony?

4. Differentiate between pili and fimbriae. How do their structures differ? How do their functions differ?

5. Compare the cell envelopes of gram-positive and gram-negative bacteria. What function does peptidoglycan serve? To which part of the cell envelope does it belong? Give a simple description of its structure. What happens to a cell that has its peptidoglycan disrupted or removed? What functions does the LPS layer serve?

6. What is the Gram stain? What is there in the structure of bacteria that causes some to stain purple and others to stain red? How does the precise structure of the cell walls differ in gram-positive and gram-negative bacteria? What other properties besides staining are different in gram-positive and gram-negative bacteria? What is the periplasmic space, and how does it function? What characteristics does the outer membrane confer on gram-negative bacteria?

7. List five functions that the cell membrane performs in bacteria. What are mesosomes and some of their possible functions?

8. Compare the composition of the chromatin body and plasmids. What are the functions of each?

9. What is unique about the structure of bacterial ribosomes? How do they function? Where are they located?

10. Compare and contrast the structure and function of inclusions and granules. What are metachromatic granules, and what do they contain?

11. Describe the vegetative stage of a bacterial cell. Describe the structure of an endospore, and explain its function. Describe the endospore-forming cycle. Explain why an endospore is not considered a reproductive body. Why are endospores so difficult to destroy?

12. Draw the three bacterial shapes. How are spirochetes and spirilla different? What is a vibrio? A coccobacillus? What is pleomorphism? What is the difference between the use of the term bacillus and the name Bacillus? Staphylococcus and staphylococcus?

13. Rank the size ranges in bacteria according to shape. Rank the bacteria in relationship to viruses and eucaryotic cell size.

14. What characteristics are used to classify bacteria? What are the most useful characteristics for categorizing bacteria into families? In what ways is ribosomal RNA an important method for differentiating bacteria and groups of organisms?

15. How is the species level in bacteria defined? Name at least three ways bacteria are grouped below the species level. In what ways are they important?

16. Describe at least 2 circumstances that give rise to L forms. How do L forms survive? In what ways are they important? Name several ways in which bacteria are medically and ecologically important.

17. Explain the characteristics of Archaea that indicate it is a unique domain of living things that is neither a bacterium nor a eucaryote. What leads microbiologists to believe the Archaea are more closely related to Eukarya than to Bacteria? What is meant by the term extremophile? Describe some archaeal adaptations to extreme habitats.

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