LESSON 2: BACTERIA
Republic of the Philippines
UNIVERSITY OF EASTERN PHILIPPINES
University Town, Northern Samar
Website: http://uep.edu.ph Email: uepnsofficial@gmail.com
COLLEGE OF EDUCATION
BIOLOGY
Prepared by:
JOHN REY P. BALANQUIT
BSEd-Science 3
NAME OF STUDENT:________________________________________
COURSE & YEAR:__________________________________________
PROFESSOR:______________________________________________
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LESSON 2: BACTERIA
TABLE OF CONTENTS
Introduction………………………………..…………………………………3
Recall Check………………………………………………………………….5
TOPIC 2: Bacteria……………………………………………………………6
Activity…………………………………………………………….……7
Discussion……………………………………………………………..8
Definiton of Bacteria…………………………………………..8
General Characteristics……………………………………….8
Pathogenicity……………………………………………….…11
Where do they live?...........................................................12
Sources……………………………………………………..….13
Mode of Transmission……………………………………….13
Summary…………………………………………………………………..…15
Application…………………………………………………………………..16
Feedback…………………………………………………………………….16
References…………………………………………………………………..17
Suggested Readings……………………………………………………....17
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LESSON 2: BACTERIA
TOPIC 2:
BACTERIA
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LESSON 2: BACTERIA
I.
INTRODUCTION
Hello there! Welcome to this new and fun semester of this course. This module will
serve as your reference for learning more of the subject Major 18: Microbiology and
Parasitology. Here’s the proper way to use this.
1.
2.
3.
4.
5.
Read the directions of the module.
Read the basic competence, indicator, and learning objectives.
Read the dialog from left to right in order to understand the materials.
Comprehend the topic in order to understand the materials.
Do the necessary activities included in the material.
Did you understand the guidelines in using this module? Great! Now, you are all set
to utilize this module as much as you can. Now, if you find it confusing and
challenging, you can always restudy what you have learned. Goodluck!
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LESSON 2: BACTERIA
RECALL CHECK!
Since we’re about to study new topic, let’s have a review of what
you have learned about the previous topic. These question will
make you think of the difference between prokaryotic and
eukaryotic cells. Let’s start!
INSTRUCTION: Write TRUE if the statement is correct and FALSE if not. Write your
answers on the space provided.
________1. Prokaryotes are single-celled organisms that lack a nucleus.
________2. Cyanobacteria were probably the first organisms to photosynthesize.
________3. Bacteria and algae are prokaryotic cells.
________4. Eukaryotes contain linear DNA while prokaryotes have a circular DNA.
________5. Eukaryote are usually multicellular organisms and the cells are larger in
size.
After trying to answer the above questions, you may now proceed reading the full
text of the lesson.
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LESSON 2: BACTERIA
Topic 2: Bacteria
OVERVIEW
Microorganisms are a heterogeneous group of several
distinct classes of living beings. Based on the difference in cellular organization and
biochemistry, the kingdom protista has been divided into two groups namely
prokaryotes and eukaryotes. Bacteria and blue-green algae are prokaryotes, while
fungi, other algae, slime moulds and protozoa are eukaryotes. Bacteria are prokaryotic
microorganisms that do not contain chlorophyll. They are unicellular and do not show
true branching, except in higher bacteria like actinomycetales.
LEARNING PLAN
At the completion of this module, you should be able to:
1. Define bacteria;
2. Enumerate the characteristics of bacteria in terms of size, shape and
arrangement;
3. Understand the concept of bacterial pathogenicity;
4. Differentiate aerobic bacteria from anaerobic bacteria;
5. Identify the sources and mode of transmission of bacteria;
6. Construct ways how to be safe from bacterial infection.
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LESSON 2: BACTERIA
ACTIVITY
Balloon Bacteria Demonstration
MATERIALS
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Balloons
A pitcher of water
Paper cups
Pencils
Food coloring (any color)
PROCEDURES
This activity is a fun way to demonstrate how infectious diseases, including
those with bacteria, can easily spread.
1. Prior to the activity, assemble the materials, including balloons, a pitcher of
water, paper cups, pencils and some color tablets or food coloring that doesn't
stain, such as Color Fizzers.
2. Mix the colors or tablets with water in the paper cups.
3. Organize the students into small groups, and give each group a balloon and
a paper cup. Have the students place a few drops of the colored water into their
balloons.
4. Have the students blow up and then tie off the balloons. All but one student
in each group should form a circle; that student should stand in the center and
hold the balloon above everyone's heads.
5. On your count, the students holding the balloons should pop them with a
pencil. Have the students check their bodies for any signs of colored water,
which represents the fact that they've been contaminated with bacteria as a
result of an uncovered sneeze.
OBSERVATIONS:
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LESSON 2: BACTERIA
DISCUSSION
1. What is Bacteria?
Bacteria are microscopic, single-celled organisms that exist in their millions, in every
environment, both inside and outside other organisms.
Some bacteria are harmful, but most serve a useful purpose. They support many
forms of life, both plant and animal, and they are used in industrial and medicinal
processes.
Bacteria are thought to have been the first organisms to appear on earth, about 4
billion years ago. The oldest known fossils are of bacteria-like organisms.
Bacteria can use most organic and some inorganic compounds as food, and some
can survive extreme conditions.
A growing interest in the function of the gut microbiome is shedding new light on the
roles bacteria play in human health.
2. GENERAL CHARACTERISTICS
The major characteristics of Bacteria are based on their size, shape and
arrangements.
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LESSON 2: BACTERIA
2.1
Size of the Bacteria
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Bacteria are very small in size
➢cocci are approx. 0.5 to 1.0 μm in diameter.
➢ rods range from 2 to 5 μm in length by 0.5 to 1.0 μm in width
➢ Spirochetes are longer (up to 20 μm) and narrower (0.1 to 1.0
μm)
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varies with the medium and growth phase
usually smallest in the logarithmic phase of growth
Bacteria are smaller which can be visualized only under
magnification
Bacteria of medical importance generally measure 0.2 – 1.5 µm
in diameter and about 3 – 5 µm in length
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LESSON 2: BACTERIA
2.2 Shape of the bacteria
Depending on their shape, bacteria are classified into several varieties
1. Cocci (from kokkos meaning berry) are spherical or oval cells
2. Bacilli (from baculus meaning rod) are rod shaped cells
3. Vibrios are comma shaped curved rods and derive their name from their
characteristics vibratory motility.
4. Spirilla are rigid spiral forms.
5. Spirochetes (from speira meaning coil and chaite meaning hair) are
flexuous spiral forms
6. Actinomycetes are branching filamentous bacteria, so called because of a
fancied resemblance to the radiating rays of the sun when seen in tissue
lesions (from actis meaning ray and mykes meaning fungus)
7. Mycoplasmas are bacteria that are cell wall deficient and hence do not
possess a stable morphology. They occur as round or oval bodies and as
interlacing filaments.
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LESSON 2: BACTERIA
2.3 Arrangement of the Bacteria
Bacteria sometime show characteristic cellular arrangement or grouping.
According to the plane of cellular division, cocci may be arranged in pairs
(diplococci), chains (streptococci), groups of four (tetrads) or eight (sarcina), or
grape like clusters (staphylococci).
3. PATHOGENICITY
A microbe that is capable of causing disease is referred to as a
pathogen, while the organism being infected is called a host. The ability to
cause disease is referred to as pathogenicity, with pathogens varying in their
ability. An opportunistic pathogen is a microbe that typically infects a host
that is compromised in some way, either by a weakened immune system or
breach to the body’s natural defenses, such as a wound. The measurement of
pathogenicity is called virulence, with highly virulent pathogens being more
likely to cause disease in a host.
It is important to remember that there are many variables to take into
account in a host-pathogen interaction, which is a dynamic relationship that
is constantly changing. The virulence of the pathogen is important, but so is the
number of microbes that gained entry to the host, the location of entry,
the overall health of the host, and the state of the host’s defenses.
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LESSON 2: BACTERIA
Exposure to a pathogen does not ensure that disease will occur, since a host
might be able to fight off the infection before disease signs/symptoms develop.
4. WHERE DO THEY LIVE?
Bacteria can live in various environmental conditions, specifically with or without
presence of oxygen.
What are anaerobic bacteria?
Anaerobic Bacteria
Anaerobic bacteria are microorganisms that survive in the absence of
oxygen. They cannot tolerate oxygen at all and will die if exposed to an
environment that has a high quantity of oxygen. Anaerobic metabolism involves
organic or inorganic redox reactions, fermentation reactions and anaerobic
reaction which produces highly volatile fatty acids and gaseous molecules such
as methane and alcohol.
Anaerobic Bacteria Examples
Bacteroides,
Bifidobacterium,
Fusobacterium,
Porphyromonas,
Prevotella, Actinomyces, Propionibacterium, Clostridia, etc are the examples
of such bacteria. Anaerobic bacteria are medically significant as they cause
many infections in the human body. For example, various species of Clostridia
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LESSON 2: BACTERIA
can cause food poisoning, soft-tissue infection, etc, whereas Actinomyces can
cause head, neck, abdominal and pelvic infections.
What are Aerobic Bacteria?
As the name suggests, aerobic bacteria come under the class of
microorganisms which grow and survive in an oxygenated environment, in
short, aerobic bacteria require oxygen to live. Aerobic bacteria are critical for
biological decomposition. The presence of oxygen hastens the decomposition
of hydrocarbons. This type of decomposition can be seen on the forest floor,
where aerobes are decomposing leaves and other organic debris. Organic
material decomposition is an aerobic process. As the amount of carbon dioxide
in the atmosphere rises, the rate of decomposition slows. Surprisingly, aerobic
composting does not produce a foul odour. It's critical to know what the
anaerobic process is before proceeding. A process that takes place in the
presence of oxygen is known as an aerobic process.
Aerobic Bacteria Examples: Some examples of aerobic bacteria are
Nocardia sp. Pseudomonasaeruginosa, E. Coli, Citrobacter, Klebsiella,
Proteus, Salmonella, Achromobacter Mycobacterium tuberculosis etc.
5. SOURCES OF BACTERIA
Bacteria can come from many different sources such as pet waste, septic
systems, agriculture, wildlife, and combined or sanitary sewage
overflows.
Contaminated food, especially undercooked ground beef, unpasteurized
(raw) milk and juice, soft cheeses made from raw milk, and raw fruits and
vegetables (such as lettuce, other leafy greens, and sprouts).
Contaminated water, including drinking untreated water and swimming in
contaminated water.
6. MODE OF TRANSMISSION
An infection starts with exposure to a pathogen. The natural site or home
for a pathogen is known as a reservoir and can either be animate (human or
animal) or inanimate (water, soil, food). A pathogen can be picked up from
its reservoir and then spread from one infected host to another. Carriers play
an important role in the spread of disease, since they carry the pathogen but
show no obvious symptoms of disease. A disease that primarily occurs within
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LESSON 2: BACTERIA
animal populations but can be spread to humans is called a zoonosis, while a
hospital-acquired infection is known as a nosocomial infection.
The mechanism by which a pathogen is picked up by a host is referred to as
mode of transmission, with the main mechanisms listed below:
Direct contact
Direct contact includes host-to-host contact, such as through kissing or sexual
intercourse, where one person might come in contact with another person’s
skin or body fluids. An expectant mother may transmit a pathogen to her infant
by vertical contact while pregnant, or during the act of giving birth.
Droplet transmission
Droplet transmission is often considered to be a form of direct contact as well.
It involves transmission by respiratory droplets, where an infected host expels
the pathogen in tiny droplets by coughing or sneezing, which are then inhaled
by a host nearby.
Indirect contact
Indirect contact involves the transfer of the infectious agent through some type
of intermediary, such as a contaminated object or person. The pathogen might
be deposited on an inanimate object, called a fomite, which is then used by
another person. This could include a shared toy or commonly-touched surface,
like a doorknob or computer keyboard. Alternatively, a healthcare worked might
transmit a pathogen from one patient to another, if they did not change their
gloves between patients.
Airborne transmission
Aiirborne transmission occurs due to pathogens that are in small particles or
droplets in the environment, which can remain infectious over time and
distance. An example might be fungal spores that are inhaled during a dust
storm.
Fecal-oral transmission
Fecal-oral transmission occurs when an infected host is shedding the pathogen
in their feces which contaminate food or water that is consumed by the next
host.
Vectorborne transmission
Vectorborne transmission occurs when an arthropod vector, such as
mosquitoes, flies, ticks, are involves in the transmission. Sometimes the vector
just picks up the infectious agents on their external body parts and carries it to
another host, but typically the vector picks up the infectious agent when biting
an infected host. The agent is picked up in the blood, and then spread to the
next host when the vector moves on to bite someone else.
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LESSON 2: BACTERIA
SUMMARY
To aid you in reviewing the important concepts in this module, here are
the highlights:
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Bacteria are microscopic, single-celled organisms that exist in their millions, in
every environment, both inside and outside other organisms.
The major characteristics of Bacteria are based on their size, shape and
arrangements.
Bacteria are smaller which can be visualized only under magnification.
Bacteria of medical importance generally measure 0.2 – 1.5 µm in diameter
and about 3 – 5 µm in length.
Bacteria are classified into several varieties, namely: cocci, bacilli, vibrios,
spirilla, spirochetes, actinomycetes, and mycoplasmas. Bacteria
sometime show characteristic cellular arrangement or grouping. It can be
arranged in pairs, chains, groups of four (tetrads) or eight (sarcina), or
grape like clusters.
The ability to cause disease is referred to as pathogenicity.
The virulence of the pathogen is important, but so is the number of microbes
that gained entry to the host, the location of entry, the overall health of
the host, and the state of the host’s defenses.
Bacteria can live in various environmental conditions, specifically with or without
presence of oxygen.
Anaerobic bacteria are microorganisms that survive in the absence of oxygen.
Aerobic bacteria require oxygen to live.
Bacteria can come from many different sources such as pet waste, septic
systems, agriculture, wildlife, and combined or sanitary sewage
overflows.
The mechanism by which a pathogen is picked up by a host is referred to as
mode of transmission. It can be through a direct contact, droplet transmission,
indirect contact, airborne transmission, fecal-oral transmission, and
vectorborne transmission.
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LESSON 2: BACTERIA
LET’S APPLY!
Every Filipino homes, whenever there is occasion, loves of
having so much foods on their table. Thus, there are lots of leftover foods which
are prone to contamination. Now, as a science major student, think and list
some home practices that can help to prevent and avoid any food
contamination.
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FEEDBACK
Do you have any question relative to our topic? Write them below.
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LESSON 2: BACTERIA
REFERENCES
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https://www.medicalnewstoday.com/articles/157973#:~:text=Bacteria%20are%20mic
roscopic%2C%20single%2Dcelled,in%20industrial%20and%20medicinal%20process
es.
https://bio.libretexts.org/Bookshelves/Microbiology/Book%3A_Microbiology_(Bruslind
)/21%3A_Bacterial_Pathogenicity
https://www.hrwc.org/our-watershed/threats/bacterialcontamination/sources/#:~:text=Bacteria%20can%20come%20from%20many,combi
ned%20or%20sanitary%20sewage%20overflows.
https://study.com/academy/lesson/bacteria-activities-games.html
Sharda, R., SHAPE, SIZE AND ARRANGEMENT OF BACTERIA, ndvsu.org,
https://www.ndvsu.org › MicroPDF SHAPE, SIZE AND ARRANGEMENT OF
BACTERIA
https://www.google.com/url?sa=t&source=web&rct=j&url=https://bio.libretexts.org/Bo
okshelves/Microbiology/Book%253A_Microbiology_(Bruslind)/21%253A_Bacterial_P
athogenicity&ved=2ahUKEwih_8ejkvv8AhVa0GEKHWjsBhEQFnoECAsQAQ&usg=A
OvVaw1nSnwQSVPU-yg1cS77Cw7F
https://study.com/learn/lesson/bacteria-overviewcharacteristics.html#:~:text=Five%20characteristics%20of%20bacteria%20include,ar
e%20shared%20by%20all%20bacteria.
https://www.vedantu.com/question-answer/state-whether-the-following-statementsare-true-class-11-biology-cbse-5f621a6263724b11dbedfce4
SUGGESTED READINGS
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https://biologydictionary.net/bacteria/
https://www.medicalnewstoday.com/articles/157973#where-do-they-live
https://www.foodsafety.gov/food-poisoning/bacteria-andviruses#:~:text=Contaminated%20food%2C%20especially%20undercooked%20grou
nd,and%20swimming%20in%20contaminated%20water.
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LESSON 2: BACTERIA
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