TAKS OBJECTIVE 3 TEKS OBJECTIVE 4(D) Bacteria: The Good and the Bad The student knows that cells are the basic structures of all living things and have specialized parts that perform specific functions, and that viruses are different from cells and have different properties and functions. The student is expected to (D) identify and describe the role of bacteria in maintaining health such as in digestion and in causing diseases..

Many species of bacteria can be found in the human mouth. Which of these explains the great variety of bacteria in the mouth? F Large volumes of air cause bacteria to change form. G Salivary glands cause mutations in bacterial populations. H The presence of nutrients makes the mouth a favorable habitat. J Calcium in the teeth provides a suitable pH environment.

Virus/Bacteria Comparison VirusesBacteria Non-livingLiving Cannot reproduce on their own without a host Can reproduce sexually or asexually Contains DNA or RNA inside a capsid Contain DNA inside a cell membrane and cell wall Always pathogenicSome are pathogenic and some are helpful

Viruses Lytic cycle: –Lytic viruses attack bacteria causing them to burst open –Step 1: Infection- virus attaches to the host bacterium and injects its DNA into the cell –Step 2: Growth- injected viral DNA uses enzymes from bacterium to synthesize viral DNA proteins and proteins –Step 3: Replication- viral DNA and proteins are assembled into hundreds of new viruses inside the bacterium –Step 4: Lysis- bacterium bursts open, releasing all viruses that were created

Bacterial Growth Binary Fission: the production two identical bacterial cells from one Conjugation: exchanging of genetic material between two bacterial cells

Can be Helpful to Your Health Digestion –E. Coli found in the intestine −Beans cannot be digested by ourselves and bacteria digests while producing gas −Produce vitamins B and K −Produce lactase, which breaks down lactose in milk Production of… −Drugs −Hormones −Antibodies

Can be Helpful to the Environment Decomposition –Breakdown of oil –Involved in nitrogen fixation, an essential nutrient for living organisms Fuel Production –Decompose sewage, garbage, and compost to produce methane –Also produces gasoline, biodiesel, and ethanol

Overgrowth Causes Diseases Pathogenic- harmful bacteria that damages tissue or producing toxins Examples: –Streptococcus- infection that causes strep throat –Staphylococcus- infection of the skin; also produces toxins –Dental cavity- causing bacteria

Destroying Bacteria Treated with Antibiotics Prevented with Vaccines by stimulating the immune system Limiting interaction with others with bacteria Antiseptics can kill bacteria on the skin before it enters the body –Antibacterial soap –Hand sanitizer

NECESSARY VOCABULARY: –Binary Fission: asexual reproduction of prokaryote cells where one cell splits into two identical cells –Conjugation: the transfer of genetic material from one bacteria to another –Nitrogen Fixation: process of bacteria converting nitrogen to be used by living organisms –Prokaryote: organism that lacks a nucleus and membrane-bound organelles –Antibiotics: chemical that kills bacteria

Bacteria Cell Shapes and Arrangements Vibrio- slightly curved or commas shaped

TAKS Practice: Which organism lives in the human intestine and aids in the digestive process? A The bacterium Escherichia coli B The fungus Trichophyton rubrum C The protozoan Entamoeba coli D The algae Fucus vesiculosus

Lactose is a naturally occurring sugar found in milk. Some dairy products, such as yogurt, may contain live bacteria. These products are useful to people who lack the ability to digest lactose. What does this information demonstrate? A Bacteria raise the acidity of processed foods. B Some bacteria interfere with digestion. C Bacteria can prevent insulin production. D Some bacteria are beneficial to human health.

Streptococcus infection in a person’s throat can cause pain and fever. Streptococcus can be controlled by antibiotics. Streptococcus is a — F virus G bacterium H protozoan J fungus

Some bacteria thrive in hostile environments, such as salt flats, boiling- hot springs, and carbonate-rock interiors, primarily because of bacteria’s — F biochemical diversity G small sizes H round shapes J methods of movement