Chapter 1. Chapter 18: Prokaryotic Diversity

1.1 Introduction

Welcome to the Interactive Study Guide for Chapter 18: Prokaryotic Diversity! This Study Guide will help you master your understanding of the chapter's Driving Questions, using interactive Infographics and activities, as well as targeted assessment questions. Click "Next" to get started, or select a Driving Question from the drop-down menu to the right.

DRIVING QUESTIONS

• What are the prokaryotic domains of life?
• What are the features of bacteria and of archaea?
• What are the challenges faced by organisms living at Lost City, and how do they face them?

1.2 Driving Question 1:

Why should you care?

Prokaryotic cells measure less than 1/10 the width of the finest human hair, so small that many of them could fit inside one of your cells. So, why care about something so small that it is difficult to find, even under a light microscope? Prokaryotic cells are the most numerous organisms on Earth by a wide margin; the many prokaryotic cells that live on you and inside you keep you healthy and provide many services to your body. Understanding how prokaryotic cells work is essential to knowing how your body works.

We humans have an innate need to categorize our world; it helps us make sense of it. Scientists who study prokaryotes have used several different techniques and lines of evidence to differentiate prokaryotes from eukaryotes. They have since divided the prokaryotes into Bacteria and Archaea. (The three groups: Eukaryotes, Bacteria, and Archaea, are called the three domains of life.) Understanding that there are two forms of prokaryotic life gives you greater insight into the organisms that drive life on Earth.

What should you know?

To fully answer this Driving Question, you should be able to:

1. Compare and contrast the structure of prokaryotic and eukaryotic cells.
2. Describe what conditions prokaryotes are adapted to based on the locations in which they grow and how those conditions influence the energy sources they use.
3. Explain how the three domains of life—Bacteria, Archaea, and Eukarya—are related to one another.

Infographic Focus:

The infographics most pertinent to the Driving Question are 18.3, 18.4, and 18.5.

Compare and contrast the structure of prokaryotic and eukaryotic cells.

Question 1.1

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Question 1.2

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Explain how the three domains of life—Bacteria, Archaea, and Eukarya—are related to each other.

Question 1.5

Using Infographic 18.5, are bacteria or archaea more closely related to the eukaryotes?

Explain how Carl Woese determined that there were two prokaryotic domains.

Many of the names of archeans and bacteria indicate where they live, what they produce, or what they use for food. For each archean or bacterial name below, related English words or combining forms (suffixes or prefixes) are listed. Look up the definition of those words or combining forms in a dictionary for extra insight about the organism.

Organism Name	Related Words or Combining Forms	Meanings
Methanococcus	Methane	gzSKVBDrvH01RmKU
Methanococcus	Coccus	gzSKVBDrvH01RmKU
Cytophagus	Cyto-	gzSKVBDrvH01RmKU
Cytophagus	-phagous	gzSKVBDrvH01RmKU
Theroproteus	Thermic	gzSKVBDrvH01RmKU
Theroproteus	Protean	gzSKVBDrvH01RmKU

Table

Organism Name	Related Words or Combining Forms	Meanings
Methanococcus	Methane	Methane using
Methanococcus	Coccus	Berry or round sphere-like shape
Cytophagus	Cyto-	Cell
Cytophagus	-phagous	Eater of
Theroproteus	Thermic	Heat
Theroproteus	Protean	Sea god who could change his form

Table

1.3 Driving Question 2:

Why should you care?

Bacteria are incredibly diverse and are adapted to an enormous variety of lifestyles. Many people only know of the bacteria that are pathogens and cause disease, but there are many other types of bacteria. Many different kinds of bacteria, including some of the photosynthetic cyanobacteria, are able to convert nitrogen gas from the atmosphere to ammonia or nitrate in a process called nitrogen fixation. Since plants need nitrogen, but cannot use it directly from the atmosphere, nitrogen fixation is essential for plants, the basis of all ecosystems on land, to be able to grow. Knowing that bacteria are diverse will help you understand that most of them are beneficial.

Archaea represent a new frontier in biology and science in general. In the past few decades, they have gone from being largely ignored, overlooked, and misunderstood to becoming a highly studied group. Their importance to life on Earth is becoming increasingly apparent.

What should you know?

To fully answer this Driving Question, you should be able to:

1. Describe the many adaptations that different bacteria have evolved to succeed in a variety of habitats.
2. Explain how archaea have evolved to live in a variety of habitats that often have extreme conditions.

Infographic Focus:

The infographics most pertinent to the Driving Question are 18.4, 18.6, and 18.7.

1.4 Driving Question 3:

Why should you care?

Most evidence available suggests that life began in water; oxygen was scarce, but other compounds and elements, like methane or hydrogen, may have been more plentiful than today. Knowing about how prokaryotes live at Lost City may provide knowledge of how life began.

What should you know?

To fully answer this Driving Question, you should be able to:

1. Describe the extreme conditions created by the hydrothermal vents of Lost City.
2. Describe the abiotic processes and conditions at Lost City that allow life to exist.
3. Explain how autotrophs at Lost City obtain energy without sunlight.
4. Explain how heterotrophic archaea at Lost City can extract energy from food without oxygen.
5. Connect abiotic processes and conditions at Lost City to the lives of the organisms there.

Infographic Focus:

The infographics most pertinent to the Driving Question are 18.1, 18.2, and 18.8.