4Section 1 BacteriaThey are the smallest and simplest organisms on earth.They are also the must abundant.A gram of earth, which is about the size of your pencil eraser, can contain as many as 2.5 million bacteria.All organisms fit into one of the six Kingdoms we discussed last chapter.
5Section 1 continuedThe two Kingdoms that bacteria fall under are Archaebacteria and Eubacteria.These two Kingdoms contain the oldest forms of life on earth, in fact for 2 billion years they were the only life forms on earth.Bacteria are single cell organisms and their cells contain no nucleus. They are prokaryotic cells which you should already know.Prokaryotes are able to perform cellular respiration, move around, and reproduce. Because of these abilities they can function as independent organisms.
6Section 1 continuedProkaryotes reproduce by a simple cell division calledBinary Fission: The process is the DNA replicates before cell division. The DNA and its copy attach to the inside of the cell membrane. As the cell grows and the membrane grows longer, the loops of DNA become separated. When the cell is about double in size, the membrane pinches inward. A new cell wall forms, separating the two new cells and their DNA.
7Section 1 continued Endospores Bacteria that grow a thick protective membrane to protect them from an unfavorable environment. Once they are released from the harsh environment the endospores will break open and become active once again.
8Section 1 continued The most common shapes of Bacteria Bacilla Cocci Rod shaped bacteria. Have a large surface area, which helps them absorb nutrients, but they can also dry out easilyCocciSpherical bacteria. They are more resistant to drying out than rod shaped bacteria.SpirillaLong spiral shaped bacteria. This is the least common shape for bacterium. Spirilla move easily in a corkscrew motion, using flagella at both ends.
9This is a picture of the worlds larges bacteria from the intestines of a surgeonfish. About the size of a pin head. It’s name is Epulopiscium.
10Cocci Spherical bacteria Cocci Spherical bacteria. They are more resistant to drying out than rod shaped bacteria.
11Spirilla Long spiral shaped bacteria Spirilla Long spiral shaped bacteria. This is the least common shape for bacterium. Spirilla move easily in a corkscrew motion, using flagella at both ends.
12Lactobacillus acidophilus (lack-toe-bah-sill-us acid-off-ill-us): one of the bacteria gang wanted for turning milk into yogurt.
13Saccharomyces cerevisiae (sack-arrow-my-seas sair-uh-vis-ee-ay): a. k Saccharomyces cerevisiae (sack-arrow-my-seas sair-uh-vis-ee-ay): a.k.a. baker's yeast. Wanted for making bread rise.
14Streptomyces (strep-toe-my-seas): soil bacteria wanted for making streptomycin, an antibiotic used to treat infections.
15Pseudomonas putida (sue-doe-moan-us poo-tea-dah): one of many microbes wanted for cleaning wastes from sewage water at water treatment plants.
16Escherichia coli (Esh-er-ish-e-ah coal-eye): one of many kinds of microbes that live in your gut. Wanted for helping you digest your food every day.
17Section 1 continued Kingdom Eubacteria This Kingdom is the largest and contains more different types of organisms than any of the other five Kingdoms.Eubacteria are classified by the way they obtain food.Consumers obtain nutrients from other organismsParasites obtain food by invading other organisms to obtain food.Producers make their own food and some use the process of photosynthesis. They contain chlorophyll.
18Section 1 continued Kingdom Archaebacteria They thrive in places where no other living things are found.3 types of ArchaebacteriaMethane Makers, excrete methane gas. Found in swamps and landfills.Heat lovers live in places like ocean rift vents where the temperatures reach 360 degrees Celsius.Salt lovers live in places where the salt concentration is very high like the Dead Sea.
19Section 1 Review Draw and label the three main shapes of bacteria. Describe the four steps of binary fission.How do eubacteria and archaebacteria differ?Many bacteria cannot reproduce in cooler temperatures and are destroyed at high temperatures. How do humans take advantage of this when preparing and storing food?
20Section 1 Review Answers 1. The drawings should resemble the pictures on page 226.2. The cell grows, the DNA replicates, the DNA molecules separate as the cell grows, and the cell splits in two.3. Eubacteria and archaebacteria are genetically different. Their cell walls are also chemically different.4. Humans store food in refrigerators and freezers to slow bacterial growth. Humans also cook food at high temperatures, which helps kill many bacteria.
21Section 2Bacteria’s Role In the World Vocabulary for Section 2BioremediationAntibioticPathogenic Bacteria
22Section 2 ContinuedSome bacteria cause disease and because of this they got a bad reputation.Bacteria do many things that are important to us humans.Life as we know it could not exist without bacteria. They are vital to our environment and we benefit from them in several ways.
23Section 2 Continued Nitrogen-fixing(1st helpful use) Nitrogen is an essential element for all organisms because it is a component of proteins and DNA.Plants must have nitrogen in order to grow properly.You would think this to be easy as 75% of our air is made of nitrogen.Plants, however, cannot take in nitrogen from the air and must get it in a different form.
24Section 2 ContinuedNitrogen-fixing bacteria consume nitrogen in the air and change it into a form that plants can use.Recycling(2nd helpful use)Breaking down dead organic matter, decomposing bacteria make nutrients available again to living things.Cleaning up(3rd helpful use)Bacteria are being used to combat pollution.Bioremediation is the use of bacteria and other microorganisms to change pollution into harmless chemicals.It is used to clean industrial wastes, as well as spills.
25Section 2 Continued Bacteria is good for people Genetically engineered bacteria is used for many things such as medicines, insecticides, cleansers, adhesives, foods.Fighting bacteria with bacteriaAlthough some bacteria cause disease, other bacteria make chemicals that treat diseases.Antibiotics are medicines used to kill bacteria and other microoganisms. Many bacteria have been genetically engineered to make antibiotics in large quantities.
26Section 2 Continued Insulin Again, genetic engineering to the rescue in making human insulin. Scientist put genes carrying the genetic code for human insulin into E. coli bacteria. The bacteria produce human insulin, which can be separated from the bacteria and given to diabetics.
27Section 2 Continued Feeding Time People breed bacteria for food! Every time you eat cheese, yogurt, buttermilk or sour cream, you also eat a lot of lactic acid bacteria. Lactic acid bacteria digest the milk sugar lactose and convert it into lactic acid. The lactic acid acts as a preservative and adds flavor to the food.
28Section 2 Continued Harmful Bacteria Pathogenic Bacteria These bacteria invade the host and obtain nutrients from the hosts cells.Some diseases caused by bacteria are:Dental cavities, ulcers, strep throat, food poisoning, TB, etc.Pathogenic Bacteria also attack plants, protists, fungi, and even other bacteria.
29Section 3 VirusesVocabulary for Section 3VirusHost
30Section 3 It’s a small world About 5 billion of them could fit into a drop of bloodBecause of size and ever changing nature, scientist don’t know how many types of viruses exist.There could be billions
31Section 3, Continued Alive or Not ? They don’t eat, breath, grow, move, or perform any biologic functions.A virus cannot live on its own.It can however reproduce (in the host) and control its host.A host is an organism that supports a parasite.Using the host’s cell as a miniature factory, viruses instruct the cell to produce viruses rather than healthy new cells.
35So Exactly what is a Virus Plain and simpleIt is some form of genetic material enclosed in a protein coat.
36How Destructive HIV is a virus that causes AIDS. The one thing they share with living things is that they reproduce.Their reproductive cycle is called the lytic cycle.In this cycle stage 1 is to find a host cell.Stage 2, the virus enters the cell or injects genes into the cell.Stage 3, once the genes are injected into the cell, the cell becomes a virus factory.Stage 4, The new viruses break out of the host cell ready to find a new host and repeat the cycle.
37Is that all there is?NoSome viruses don’t go straight into the lytic cycle. These viruses inject their genes into the host cell, but no new viruses are made right away.So What?When the host cell divides, each new cell has a copy of the virus’s genes.This is called the lysogenic cycle.The viral genes can remain inactive for a long time until a change in the environment, or stress to the organism causes the genes to launch into the lytic cycle.Just when you thought you were safe!!
38Section 3 ReviewWhat would happen if one generation of measles viruses never found a host?Describe the four stages of the lytic cycle.Do you think modern transportation has had an effect on the way viruses are spread? Explain.
39Review AnswersMeasles would die out. Viruses cannot reproduce themselves without a host.See page 235 for #2People and livestock are much more mobile now, and thus, able to bring viruses to new places.