A CLOSER LOOK AT BACTERIA ALGAE AND PROTOzou Women and children harvest and dry spirulina a blue green algae used as a dietary supplement in Brandji Chad in 2009 AFP Getty Images to thicken ice cream Pfiesteria on the other hand can cause an algae bloom that can kill large amounts of fish The word protozoa comes from the Greek words meaning first animal To get food some of these eukaryotes can absorb
INTRODUCTION nutrients through their pellicle or cell cover ing Others devour their prey by surrounding them and entering them into special holes called vacuoles In order to find food many protozoa have special structures that allow them to move Most commonly they use cilia short hairlike extensions that work together in waves or a flagellum a long whiplike tail to get around Others like the amoeba move by the use of pseudopods false feet They simply let some of their watery fluid pour into one area of their body until it forms a long false leg that it can use to propel itself forward While many protozoa are harm less some are parasites such as the genus Plasmodium which causes malaria a disease that kills two million people each year Leeuwenhoek and the many scientists who have discovered other bacteria algae and protozoa have done much to unlock one of the most mysterious domains of the world Scientists today continue to make discoveries by trying to live up to the great lensmaker's motto By diligent labor one discovers mat ters that could not be discerned
CHAPTER 1 THE DIVERSE WoRLD OF BACTERIA The single celled organisms called bacteria live on in and around most living and nonliving things With few exceptions bacteria can be seen only with the aid of a microscope and millions of them would fit on the head of a pin PARTS OF A GENERALIZED BACTERIAL CELL OF THE BACILLUS TYPE capsule cell membrane nuclear matter cell wall flagellum Parts of a bacterial cell Encyclopedia Britannica Inc Io
THE DIVERSE WoRLD OF BACTERIA Although some bacteria are harmful many bacterial species are beneficial Bacteria that live in the intestines of humans are essential in digesting food Other species play a role in fermentation a process that produces foods such as yogurt and cheese Bacteria themselves are vulnerable to infection by viruses called bacteriophages The study of bacteria is called bacteri ology It often is integrated with studies of other microorganisms or microbes a diverse group that includes algae archaea fungi and protozoa These combined studies are called microbiology PersICAL CHARACTERISTICs OF BACTERIA Bacteria are prokaryotes that is they have no distinct nucleus sometimes called the command center of a cel and they lack most of the internal structures found in the cells of more complex organisms called eukaryotes Most biologists classify bacteria as constituting one of three domains of living organisms Along with the domain Bacteria these include the Archaea which consists of prokaryotic organisms that have distinct molecular characteristics separating them II
