Copyright © 2005 Pearson Prentice Hall, Inc. Chapter 19 The Diversity of Viruses, Prokaryotes, and...

Copyright © 2005 Pearson Prentice Hall, Inc.

Chapter 19

• The Diversity of Viruses, Prokaryotes, and Protists


Viruses, Viroids, and Prions

• A Virus Consists of a Molecule of DNA or RNA Surrounded by a Protein Coat– The sizes of microorganisms (F19.1 p. 360) – Viral structure and replication (F19.2 p. 361)

Eukaryotic cells(10–100 µm)

Prokaryotic cells(0.2–10 µm)

cyanobacterium

Viruses (0.05–0.2 µm)

Escherichia coli

Staphylococcus1 µm


chromosome(nucleoid region)

pili

ribosomes

food granule

prokaryoticflagellum

capsule orslime layer

cell wall

plasma membranecytoplasm

plasmid (DNA)

Copyright © 2005 Pearson Prentice Hall, Inc.mitochondrion vesicle

cytoplasm

flagellum

lysosome

centriole

Golgi complex

vesicle

nuclear pore

nuclear envelope

chromatin (DNA)nucleolus

nucleus

ribosome

free ribosome

microtubules

rough endoplasmicreticulum

Smooth endoplasmicreticulum

plasmamembrane

intermediatefilaments


central vacuole

plastid mitochondrion

vesicle plasmodesma

cell wall

plasmamembrane

intermediatefilaments

free ribosomeribosomes

nucleusnucleolus

nuclear porechromatin

nuclear envelope

Golgi complex

chloroplast

Microtubules (part of cytoskeleton)

smoothendoplasmicreticulum

roughendoplasmicreticulum

glycoproteins

proteincoat

envelope(lipid bilayer)

spikes

coreproteins

reversetranscriptase

genetic material(viral RNA) coated with protein



– Viruses Are Host-Specific• Viruses come in a variety of shapes (F19.3 p. 361)

• Some viruses infect bacteria (F19.4 p. 361) • How viruses replicate (FE19.1 p. 362)

rabies virus herpes virus

bacteriophage

tobaccomosaic plant virusmeasles virus


(nucleus)

DNARNA

mRNA

(cytoplasm)

HIV virus, a retrovirus, invades a white blood cell.RNA core

envelope

coat


(nucleus)

DNA RNA

mRNA

(cytoplasm)

RNA coreenvelope

coat


HIV virus, a retrovirus, invades a white blood cell.

mRNA

DNA

(cytoplasm)

(nucleus)

Herpes virus, a double-stranded DNA virus, invades a skin cell.

coat

DNA

envelope

mRNA

DNA

envelope

coat

DNA

(cytoplasm)

(nucleus)

Herpes virus, a double-stranded DNA virus, invades a skin cell.



– Viral Infections Are Difficult to Treat

• Some Infectious Agents Are Even Simpler Than Viruses– Prions: Puzzling proteins (F19.5 p. 364)

• No One Is Certain How These Infectious Particles Originated


Organisms Of the Prokaryotic Domains—Bacteria and Archaea

• Bacteria and Archaea Are Fundamentally Different– Classification of Prokaryotes Within Each Domain Is

Difficult

• Prokaryotes Differ in Shape and Structure– Three common prokaryote shapes (F19.6 p. 366) – The prokaryote flagellum (F19.7 p. 367)

0.10 µm

0.25 µm

outermembrane

peptidoglycanlayer

plasmamembrane

cellwall

"wheel-and-axle” base

(b)


Organisms of the Prokaryotic Domains—Bacteria and Archaea

– Many Bacteria Form Films on Surfaces• The cause of tooth decay (F19.8 p. 367)



– Protective Endospores Allow Some Bacteria to Withstand Adverse Conditions

• Spores protect some bacteria (F19.9 p. 367)

endospore

bacterium



• Prokaryotes Reproduce by Binary Fission– Reproduction in prokaryotes (F19.10 p. 368)



– Prokaryotes May Exchange Genetic Material Without Reproducing

• Conjugation: Prokaryotic “mating” (F19.11 p. 368)



• Prokaryotes Are Specialized for Specific Habitats– Some prokaryotes thrive in extreme

conditions (F19.12 p. 369)



• Prokaryotes Exhibit Diverse Metabolisms– Cyanobacteria (F 19.13 p. 369)



• Prokaryotes Perform Functions Important to Other Organisms– Prokaryotes Capture the Nitrogen Needed by

Plants• Nitrogen-fixing bacteria in root nodules (F19.14 p. 370)

cellwalls

N2-fixingbacteria



– Prokaryotes Are Nature’s Recyclers

• Some Bacteria Pose a Threat to Human Health– Some Anaerobic Bacteria Produce Dangerous

Poisons– Humans Have Battled Bacterial Diseases

Throughout History– Some Common Bacterial Species Can Be Harmful– Most Bacteria Are Harmless


Protists?

• The Major Groups of Protists (T19.1 p. 372)


Protists

• Most Protists Are Single-Celled– Protists Use Diverse Modes of

Reproduction and Nutrition• Protistan reproduction and gene exchange

(F19.15 p. 373)


Protists

– Protist Systematics Are in Transition

• The Chromists Include Photosynthetic and Nonphotosynthetic Organisms– Water Molds Have Had Important Impacts

on Humans• A parasitic water mold (F19.16 p. 374)


Protists?

– Diatoms Encase Themselves Within Glassy Walls

• Some representative diatoms (F19.17 p. 374)


Protists

– Brown Algae Dominate in Cool Coastal Waters

• Brown algae, a multicellular protist (F19.18 p. 375)


Protists

• The Alveolates Include Parasites, Predators, and Phytoplankton– Dinoflagellates Swim by Means of Two

Whiplike Flagella• Dinoflagellates (F19.19 p. 375)

• A red tide (F19.20 p. 376)


Protists

– Apicomplexans Are Parasitic and Have No Means of Locomotion

• The life cycle of the malaria parasite (F19.21 p. 377)

(in mosquito)

(in human)

male gamete

female gamete

saliva with larvae areinjected into human

larvaemigrate tosalivary gland

larvaedevelop

larvae enter liver;develop throughseveral larval stages

parasites emerge from liver and enter red blood cells

liver

some parasitesbecome gametocytes

malegametocyte female

gametocyte

synchronized rupture of red blood cells, releasing the parasites and toxins, causes the recurring fever of malaria

parasites reproduce in red blood cells, which burst, liberating new parasites that infect more red blood cells

female Anopheles mosquito bites human and ingests gametocytes, which become gametes

fertilization produces a zygote that enters the wall of the mosquito’s stomach


What Are Protists

– Ciliates Are the Most Complex of the Alveolates

• The complexity of ciliates (F 19.22 p. 377)

• A microscopic predator (F19.23 p. 378)

macronucleus

oral groove

food vacuoleforming

cilia

contractilevacuole

anal pore

food vacuole

micronucleus



Protists

• Slime Molds Are Decomposers That Inhabit the Forest Floor– Acellular Slime Molds Form a Multinucleate

Mass of Cytoplasm Called a Plasmodium• The acellular slime mold Physarum (F19.24 p. 378)

nucleus

spores

fruiting bodies

Cellular Slime MoldsProtists

Live as Independent Cells

Aggregate into a Pseudoplasmodium

When Food Is Scarce

(F19.25 p. 379)


Protists

• Euglenoids Lack a Rigid Covering and Swim by Means of Flagella– Euglena, a representative euglenoid (F19.26 p. 379)

flagellum eyespot

contractilevacuole

stored food

nucleus

nucleolus

chloroplasts


Protists• Red Algae Live Primarily in Clear Tropical

Oceans– Red algae (F19.27 p. 380)


Protists

• Trypanosoma:

• causes African

sleeping sickness

• transmitted by Tsetse Fly


Protists• Giardia: the Curse of campers (F19-29 p. 380)


Protists?

• Various Protists Move by Means of Pseudopods– The amoeba (F19.30 p. 381) – Heliozoans (F19.31 p.

381) – Foraminiferans and radiolarians (F19.32 p. 381)

pseudopod


Protists?

• Green Algae Live Mostly in Ponds and Lakes– A form of green algae (F19.33 p. 382)

Copyright © 2005 Pearson Prentice Hall, Inc. Chapter 19 The Diversity of Viruses, Prokaryotes, and...

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