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.

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Focus Question: Discuss and record your answer in your packet.

• How can your life be shortened with bacteria?

• How can your life be shortened without bacteria?

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

Viruses Bacteria

Non-living Living

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 pathogenic Some are pathogenic and some are helpful

What is unique to a bacterial cell?

1. Bacteria Cells have _______

2. Bacteria Cells don’t have _______

Bacterial Growth

• Binary Fission: the production two identical bacterial cells from one

• Conjugation: exchanging of genetic material between two bacterial cells

• Contain chemicals (and toxins) to aid in its survival in different environments

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 toxinsExamples:– 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

EXPLANATION• NECESSARY VOCABULARY:

– Binary Fission – – Conjugation – – Nitrogen Fixation – – Prokaryote– Antibiotics –

– 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

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

Which of these conditions is caused by bacteria?

F AIDS

G Seasonal allergies

H Dental cavities

J Colds

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

What I need to remember…• Write down the 3 most important things

about this topic.