26. Prokaryotes

Prokaryote Cell Structures

Structure of Bacteria | Part 2 | Structures external to the cell wall | Flagella | Pili | Capsule

Bacteria (Updated)

Prokaryotic vs. Eukaryotic Cells (Updated)

Which are the Cell Surface appendages of Bacteria? Flagella, Pili and Fimbriae

 a thick layer of peptidoglycan surrounded by an outer membrane containing lipopolysaccharides 

 No. Although they do contain an outer membrane with lipopolysaccharides, gram-negative cells do not contain as much peptidoglycan as gram-positive cells. 

 a thin layer of peptidoglycan surrounded by a capsule 

 No. Gram-negative bacteria have a thin layer of peptidoglycan and an outer membrane containing lipopolysaccharides. Whether a species of bacteria has a capsule or a slime layer outside its cell wall is determined by the type of environment in which it lives and is unrelated to its gram-positive or gram-negative nature. 

 No. Cholesterol is a sterol found in animals. 

 No. Cellulose is a cell wall component found in plants. 

 a thin layer of peptidoglycan surrounded by an outer membrane containing lipopolysaccharides 

Why is it convenient to classify bacteria according to their gram-staining characteristics?

A gram-negative cell wall consists of __________.

Pili/ Fimbriae

 No. "Gram-negative" refers to bacteria that have an extra membrane outside the cell wall. 

 No. The answer has to do with the nutritional mode of a certain type of bacteria. 

 All of the listed responses are correct. 

 No. Only one of the other choices is correct. 

For what process would more surface area be beneficial?

Bacteria that __________ tend to have abundant internal membranes.

Prokaryotic Cell Structures 1

Flagella, Fimbriae, and Pili

Differences between Bacterial Pili and Fimbriae

 have cell walls containing peptidoglycan 

 No. Most bacteria have some peptidoglycan. This doesn't offer protection from extreme heat. 

 protect themselves by secreting antibiotics 

 No. Even if they could secrete antibiotics, antibiotics would not protect them from such elevated temperatures. 

 No. Endotoxins would not protect them from such elevated temperatures. 

 No. They are not autotrophic, and even if they were, that would not provide protection from such elevated temperatures. 

Consider adaptions that allow bacteria to survive stressful environmental conditions.

The bacteria that cause tetanus can be killed only by prolonged heating at temperatures considerably above boiling. This suggests that these bacteria __________.

Prokaryotic Cells: The Simplest Kind of Life

Prokaryotic Cell Structure & Function | Cell Biology

 No. Gram-negative bacteria have less peptidoglycan than gram-positive cells, although their cell walls are more complex than the walls of gram-positive cells. 

 No. Gram-negative bacteria have less peptidoglycan than gram-positive cells, but their cell walls are more structurally complex. 

 No. Gram-negative bacteria do have less peptidoglycan than gram-positive cells, but their cell walls are more structurally complex. 

 None of the listed responses is correct. 

What are some of the differences between gram-negative and gram-positive bacteria?

Gram-negative bacteria have __________ peptidoglycan than gram-positive cells, and their cell walls are __________ complex structurally.

 Genes for eukaryotic flagella were taken up and expressed in bacteria. 

 No. Eukaryotic flagella have a completely different structure from bacteria flagella. In any case, eukaryotic genes would be unlikely to function in a prokaryotic environment. 

 Endosymbiosis added flagella to prokaryotes. 

 No. There is no reason to suppose that endosymbiosis is involved in the evolution of the bacterial flagellum. 

 Early bacterial species needed to be able to move and thus developed complex flagella to facilitate this motility. 

 No. Natural selection is not goal-oriented. In other words, the need for a particular structure does not facilitate its origination and evolution. 

 Flagella evolved as extensions of other bacterial appendages such as pili and fimbriae. 

 No. Fimbriae and pili are structurally distinct from flagella. 

 Exaptation recruited non-flagellar proteins to new functions. 

Think about the evolution of the vertebrate eye.

Bacterial flagella have a very complex structure composed of 42 distinct proteins. What is the most likely explanation for the evolution of these complex structures?

Prokaryotic Cell Structure and Function in 5 minutes ||Biologyexams4u

Kingdom Monera - Pili & Fimbriae

Prokaryotic Cell Structures 3

Bacteria | Structure and Function

Unlike plant cell walls that contain cellulose, bacterial cell walls are composed of           .

Prokaryotic Cell Structures 2

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TARGET DENTISTRY

sci-ology

1. Introduction to Biology

2. Chemistry

3. Water

4. Biomolecules

5. Cell Components

6. The Membrane

7. Energy and Metabolism

8. Respiration

9. Photosynthesis

10. Cell Signaling

11. Cell Division

12. Meiosis

13. Mendelian Genetics

14. DNA Synthesis

15. Gene Expression

16. Regulation of Expression

17. Viruses

18. Biotechnology

19. Genomics

20. Development

21. Evolution by Natural Selection

22. Evolution of Populations

23. Speciation

24. History of Life on Earth