Chapter 27: Prokaryotes

1. Where can you find prokaryotes?- EVERYWHERE!!- Domain Bacteria & Archae

2. What do you know about bacterial structure, function & reproduction?- 3 shapes: round (cocci), rod (bacilli) & helical (spirilla & spirochetes)

Figure 27.2 The most common shapes of prokaryotes

1 m 2 m 5 m(a) Spherical (cocci) (b) Rod-shaped

(bacilli)(c) Spiral

Chapter 27: Prokaryotes

1. Where can you find prokaryotes?- EVERYWHERE!!- Domain Bacteria & Archae

2. What do you know about bacterial structure, function & reproduction?- 3 shapes: round (cocci), rod (bacilli) & helical (spirilla & spirochetes)- 1 – 5 µm dia. (eukaryotic cells 10 – 100 µm dia.)- Cell wall outside plasma membrane w/ peptidoglycan (not archae)

- Gram (+) – lots of peptidoglycan- Gram (-) – less peptidoglycan (more resistant to antibiotics)

Figure 27.3 Gram staining

PeptidoglycanlayerCell wall

Plasma membrane

Protein

Gram-positivebacteria

20 m

Outermembrane

Peptidoglycanlayer

Plasma membrane

Cell wall

Lipopolysaccharide

Protein

Gram-negativebacteria

(b)(a) Gram-positive. Gram-positive bacteria have a cell wall with a large amount of peptidoglycan that traps the violet dye in the cytoplasm. The alcohol rinse does not remove the violet dye,which masks the added red dye.

Gram-negative. Gram-negative bacteria have less peptidoglycan, and it is located in a layer between theplasma membrane and an outer membrane. The violet dye is easily rinsed from the cytoplasm, and the cell appears pink or red after the red dye is added.

Chapter 27: Prokaryotes

1. Where can you find prokaryotes?- EVERYWHERE!!- Domain Bacteria & Archae

2. What do you know about bacterial structure, function & reproduction?- 3 shapes: round (cocci), rod (bacilli) & helical (spirilla & spirochetes)- 1 – 5 µm dia. (eukaryotic cells 10 – 100 µm dia.)- Cell wall outside plasma membrane w/ peptidoglycan (not archae)

- Gram (+) – lots of peptidoglycan- Gram (-) – less peptidoglycan (more resistant to antibiotics)

- Many have a capsule outside cell wall for adherence- Pili & fimbriae used for adherence

200 nm

Capsule200 nm

Fimbriae

Figure 27.4 Capsule Figure 27.5 Fimbriae

Chapter 27: Prokaryotes1. Where can you find prokaryotes?2. What do you know about bacterial structure, function & reproduction?

- 3 shapes: round (cocci), rod (bacilli) & helical (spirilla & spirochetes)- 1 – 5 µm dia. (eukaryotic cells 10 – 100 µm dia.)- Cell wall outside plasma membrane w/ peptidoglycan (not archae)

- Gram (+) – lots of peptidoglycan- Gram (-) – less peptidoglycan (more resistant to antibiotics)

- Many have a capsule outside cell wall for adherence- Pili & fimbriae used for adherence- Motility (allows for taxis….+/-, photo & chemo)

- Flagella 25 nm wide- Helical filaments in spirochetes- Some secrete slimy chemicals for gliding

- Small genome, circular chromosome & plasmids- Some have specialized infoldings of plasma membrane

Figure 27.7 Specialized membranes of prokaryotes

(a) Aerobic prokaryote (b) Photosynthetic prokaryote

0.2 m 1 m

Respiratorymembrane

Thylakoidmembranes

Chapter 27: Prokaryotes1. Where can you find prokaryotes?2. What do you know about bacterial structure, function & reproduction?

- Cell wall outside plasma membrane w/ peptidoglycan (not archae)- Gram (+) – lots of peptidoglycan- Gram (-) – less peptidoglycan (more resistant to antibiotics)

- Many have a capsule outside cell wall for adherence- Pili & fimbriae used for adherence- Motility (allows for taxis….+/-, photo & chemo)

- Flagella 25 nm wide- Helical filaments in spirochetes- Some secrete slimy chemicals for gliding

- Small genome, circular chromosome & plasmids- Some have specialized infoldings of plasma membrane- Asexual reproduction – binary fission- Genetic recombination by

- Transformation- Conjugation- Transduction

- Some become endospores (Anthrax)

Figure 27.9 An endospore

Endospore

0.3 m

Chapter 27: Prokaryotes1. Where can you find prokaryotes?2. What do you know about bacterial structure, function & reproduction?3. How can prokaryotes obtain energy & carbon?

Table 27.1 Major Nutritional Modes

Chapter 27: Prokaryotes1. Where can you find prokaryotes?2. What do you know about bacterial structure, function & reproduction?3. How can prokaryotes obtain energy & carbon?4. What are the metabolic relationships to oxygen?

- Obligate aerobes – require O2

- Facultative anaerobes – prefer O2 but can do fermentation- Obligate anaerobes – poisoned by O2 – can do fermentation & some can

use anaerobic respiration5. What is the origin of photosynthesis?

- Cyanobacteria (formerly known as blue-green algae)- H2S metabolizing bacteria mutated to use…….- H2O- Released O2 reacted with dissolved iron- Formed iron oxide precipitate

Figure 26.12 Banded iron formations: evidence of oxygenic photosynthesis

Chapter 27: Prokaryotes1. Where can you find prokaryotes?2. What do you know about bacterial structure, function & reproduction?3. How can prokaryotes obtain energy & carbon?4. What are the metabolic relationships to oxygen?5. What is the origin of photosynthesis?

- Cyanobacteria (formerly knowns as blue-green algae)- H2S metabolizing bacteria mutated to use…….- H2O- Released O2 reacted with dissolved iron- Formed iron oxide precipitate

6. Figure 27.12 shows the phylogeny of prokaryotes

Figure 27.12 A simplified phylogeny of prokaryotes

Domain BacteriaDomainArchaea

DomainEukarya

Alp

ha

Bet

a

Ga m

ma

Eps

i lon

Del

ta

Proteobacteria

Chl

amyd

ias

Spi

roch

e te s

Cya

n oba

cter

ia

Gra

m-p

o sit i

veba

cter

ia

Kor

arch

aeo t

e s

Eur

yarc

h ae o

tes

Cre

narc

hae o

tes

Nan

o arc

h aeo

tes

Euk

a ry o

tes

Universal ancestor

Chapter 27: Prokaryotes1. Where can you find prokaryotes?2. What do you know about bacterial structure, function & reproduction?3. How can prokaryotes obtain energy & carbon?4. What are the metabolic relationships to oxygen?5. What is the origin of photosynthesis?

- Cyanobacteria aka blue-green algae- H2S metabolizing bacteria mutated to use…….- H2O- Released O2 reacted with dissolved iron- Formed iron oxide precipitate

6. Figure 27.12 shows the phylogeny of prokaryotes7. What are the differences between each of the domains?

Table 27.2 A Comparison of the Three Domains of Life

Chapter 27: Prokaryotes1. Where can you find prokaryotes?2. What do you know about bacterial structure, function & reproduction?3. How can prokaryotes obtain energy & carbon?4. What are the metabolic relationships to oxygen?5. What is the origin of photosynthesis?6. Figure 27.12 shows the phylogeny of prokaryotes7. What are the differences between each of the domains?8. What are some ecological impacts of bacteria?

- Chemical cycling- Symbiotic relationships

- Mutualism – both organisms benefit (+/+)- Commensalism – only 1 benefits (+/___)- Parasitic – 1 benefits & the other harmed (+/-)

9. How can you determine if a pathogen causes a disease?- Koch’s postulates

1. Find the same pathogen in all diseased individuals2. Isolate the pathogen & grow it in pure culture3. Induce the disease in naïve animals4. Re-isolate the pathogen

Chapter 27: Prokaryotes1. Where can you find prokaryotes?2. What do you know about bacterial structure, function & reproduction?3. How can prokaryotes obtain energy & carbon?4. What are the metabolic relationships to oxygen?5. What is the origin of photosynthesis?6. Figure 27.12 shows the phylogeny of prokaryotes7. What are the differences between each of the domains?8. What are some ecological impacts of bacteria?9. How can you determine if a pathogen causes a disease?

- Koch’s postulates1. Find the same pathogen in all diseased individuals2. Isolate the pathogen & grow it in pure culture3. Induce the disease in naïve animals4. Re-isolate the pathogen

10. How can bacteria harm us?- Disease – Lyme disease- Exotoxin – secreted chemicals – botulism, cholera- Endotoxin – released upon bacterial death - Salmonella