SUBJECT: SCIENCE FORM: 5

TOPIC: MICROORGANISMS AND THEIR EFFECTS ON LIVING THINGS

CLASSIFICATIONS OF MICROORGANISMS

o Type of microorganisms

- Definition:

Tiny living things that cannot be seen by naked eyes, but can be seen by electron microscopes. They are also known as microbes.

Some of microbes are harmful, but some of them are useful too

- Classification:

There are 5 main groups for microbes:

a) Bacteria Beruk

b) Protozoa Pergi

c) Fungi Filipina

d) Algae Angkat

e) Viruses Van

o Characteristics of various type of microorganisms

1. Bacteria

Definition:

2nd smallest living things can be seen by electron microscope, have the simplest structure, and have the largest number among the five groups of microbes.

Size:

Consists only one cell (about 0.5 to 10 micrometer)

Shape:

There are four general shapes:

a) Cocci Cium

b) Bacili Baboon

c) Spirilia Sampai

d) Vibrio Vietnam

Structure:

Nutrition:

Some bacteria have chlorophyll, so they can make their own food by photosynthesis process. Some of bacteria don’t have chlorophyll, so they have to be:

a) Saprophytes - get food from decaying matters

b) Parasites - get food from other living organisms

Respiration:

Some of bacteria carry out aerobic respiration, and some of them carry out anaerobic respiration.

Reproduction:

a) By binary fission

b) By spores

Habitat:

Bacteria live in any damp places.

2. Protozoa

Definition:

Animals which are made up of only one cell. They are unicellular. Example: amoeba, paramecium and etc.

Size:

Consists only one cell (about 5 to 250 micrometer)

Shape:

Have various shapes, but mostly they have irregular shape (no fixed shape)

Structure:

Nutrition:

Some of protozoa live as parasites. E.g: plasmodium. Some of them obtain food from their surroundings. E.g: amoeba and paramecium. Some of protozoa make their own food.

Respiration:

All of protozoa carry out aerobic respiration

Reproduction:

a) By binary fission

b) By asexual reproduction (spore formation)

c) By sexual reproduction (conjugation)

Habitat:

Protozoa live independently in any ponds, river, damp soils or in other organisms, and they lives in colonies

Exercise:

1. Name the five main groups of microorganisms2. Bacteria can live in unfavorable conditions. Under such conditions, they…………….3. Label the part of bacteria below

4. Size of protozoa is about……………………5. What is the shape of paramecium? ............................

3. Fungi

Definition:

Plants which do not have chlorophyll. They include mushrooms, moulds and yeast. They do not have root, stems or leaves

Size:

Some of them are large (i.e mushroom), and some of them are tiny (i.e moulds and yeast)

Shape:

Have various shapes: i- round ballii- long filamentsiii- oval-shaped

Structure:

Nutrition:

Most of fungi live as parasites (i.e moulds) or saprophytes (i.e mucor) .

Respiration:

Most of fungi carry out aerobic respiration

Reproduction:

a) By spores

Fungi such a mushrooms form spores within their caps. Mucor form sporangium (containing spores). When it ripe, it bursts open and disperses the spore.

b) By budding

Habitat:

Fungi live in damp dark habitats.

Example: Mucor grows on damp stale bread placed in the dark

4. Algae

Definition:

Very simple plants which have chlorophyll. Algae do not have root, stems or leaves

Size:

Some of them are large (i.e seaweed), and some of them are tiny (i.e diatoms, euglena and etc)

Shape:

Have various shapes: i- round ballii- long filamentsiii- oval-shapediv- network-like structure

Structure:

Nutrition:

Algae possess chlorophyll, so that they can make their own food by photosynthesis.

Respiration:

Most of fungi carry out aerobic respiration

Reproduction:

a) By asexual reproduction (binary fission)

b) By asexual reproduction (fragmentation)

Algae reproduced by breaking a long filament into two.

c) By sexual reproduction (conjugation)

Habitat:

Algae live in fresh water, salt water, damp soil or on damp bark of trees.

5. Virus

Definition:

Smallest microorganisms and it do not respire, do not excrete waste products, and do not possess nucleus, cell membrane and cytoplasm

Size:

About 0.02 – 0.4 micrometer, and can be seen only by electron microscope

Shape:

Have various shapes, maybe in spherical, rectangular or rod-shaped

Structure:

Nutrition:

Viruses live as parasites in living cell.

Reproduction:

Habitat:

Viruses live only in living cell.

Exercise:

1. How do fungi continue its generation under adverse condition?2. Why algae look greenish?3. What a different between algae and tree?4. Which of microorganisms cannot survive outside living cells?

A. Bacteria C. VirusesB. Algae D. Protozoa

6. State 3 properties of viruses which are not characteristics of living things

FACTOR WHICH AFFECTS TO THE GROWTH OF MICROORGANISM

There are 5 main factors that affect the growth of microorganism:

1. Nutrients

Microorganisms need nutrient to live, and they get it by being:

a) autotrophicb) saprophyticc) parasitic

2. Humidity

Microorganisms need living place with high level of humidity. That means, they need moisture or water to live, and they will die if they do not get water for a period of time.

However, some bacteria can live in a place without water’s presence by forming spores. For amoeba, they form cyst (spore with outer ring).

3. Light

Most of virus, fungi and protozoa and some of bacteria prefer dim or dark habitat, while algae and few of bacteria tend to live in bright place since they have chlorophyll to carry out photosynthesis process.

4. Temperature

Most suitable temperature for the microorganism’s growth and live is about 37ºC (human’s body temperature).

High temperature will kill microorganisms, while low temperature makes them inactive.

5. pH value

Most of microorganisms prefer to live in neutral medium (pH = 7)

In very acidic (pH = 1 to 3) and very alkaline (pH = 12 to 14) conditions, most of microorganisms will be killed.

USEFUL MICROORGANISMS

1. In the Digestion of Food

Some bacteria and protozoa help herbivores (e.g: rabbit, goat, cows and etc) and termites digest their food

They produce an enzyme called cellulose to help herbivores and termites digest cellulose into glucose

cellulose glucose

2. In Decay

2.1 Formation of humus

Some of saprophytic bacteria and fungi decompose organic matter into humus

2.2 Production of biogas and fertilizers

Some of saprophytic bacteria decompose organic waste (e.g: waste from oil palm, paddy and coconut) and turn it into methane gas

2.3 Disposal of oil spills

Some of bacteria break up oil spills and decompose it into less harmful substance.

3. In Medicine

3.1 Antibiotics

There are 2 common antibiotics in world, which are:a) Penicillin (prepared from penicillium notatum bacteria) b) Streptomycin (prepared from streptomyces griseus bacteria)

Antibiotics can only kill bacteria

3.2 Vaccines

Vaccines are prepared from dead or very weak bacteria and viruses. It used to stimulate the body to produce antibodies.

Vaccination refers to an injection containing certain vaccines that can prevent a person being infected to a certain disease. Example: BCG injection for dry cough disease.

enzyme

cellulase

4. In Agriculture

4.1 Maturing of tobacco leaves

Bacteria used to make tobacco leaves mature, so that they can emit desirable smell and taste.

4.2 Nitrogen cycle

Figure 4.2- A (Simple nitrogen cycle)

4.3 Productions of chemicals from algae

Some algae used to produce beneficial chemicals for human beings. For the example:

a) beta-carotene – which has anti cancer propertiesb) fatty acids – which make cholesterol level in human’s blood become low

5. In Industry

5.1 Making breads and cakes

Yeast is used in the making breads and cakes. It is mixed with flour, sugar and water; and made into dough

Yeast will reacts with sugar to produce alcohol (ethanol), carbon dioxide and energy. By the way, this process is known as fermentation.

yeast + sugar carbon dioxide + ethanol + energy

Carbon dioxide released makes the dough rise, so that breads and cakes become very soft.

enzyme

zymase

Nitrogen gas

Plant and animal proteinsNitrates

Ammonium compounds

Denitrifying bacteria

Nitrifying bacteria

Bacteria of decay

Nitrogen-fixing bacteria

5.2 Making ethanol

Yeast is also used to produce alcohol (ethanol) instead of carbon dioxide.

5.3 Production of vinegar, and yoghurt

Vinegar (ethanoic acid) is prepared by using bacteria to change ethanol into ethanoic acid.

ethanol (alcohol) + oxygen ethanoic acid (vinegar) + water

Yoghurt (contains lactic acid) is prepared by the action of bacteria on milk. Bacteria will reacts with lactose in milk and turns it into lactic acid.

lactose lactic acid

5.4 Production of soy sauce

Soy sauce is produced from the fermentation of a mixture containing mould, yeast, flour and soy beans. Salt is added to make it become salty.

Exercise:

1. List all factors affect to the growth of microorganism

2. Which microorganisms that can live in bright place?

3. Tell the range of air humidity which most of microorganisms are very active.

4. What is true about microorganisms?

A. High temperature will kills microorganisms but low temperature will make them inactive

B. All microorganism grow faster in dry conditionsC. All microorganism cannot produce their own nutrientsD. All microorganism can be seen under light microscope

5. In which bacteria cultures in petri dishes A, B, C or D is the highest density of the bacteria colony?

Petri dish pH Light MoistureA 3 Bright MoistB 7 Bright DryC 7 Dark MoistD 10 Dark Dry

bacteria

bacteria

HARMFUL EFFECT BY MICROORGANISMS

- Microorganisms which can cause disease called pathogens. They can be either bacteria or viruses or fungi or protozoa.

- Before that, disease can be defined as any conditions which actively harm the normal functioning of the body.

1. Diseases Caused by Bacteria

DISEASEMETHOD OF INFECTION

SYMPTOM TREATMENT/PREVENTION

1.Tuberculosis(Batuk kering)

1. Through food2. Through infected air breathed into the lung

1. Patient loss weight and appetite for food2. Patient coughs often, and in advanced he coughs out of blood.

1. Can be treated by using antibiotics (i.e streptomycin and isoniazid)2. Can be prevented through immunization by BCG vaccine

2. Cholera(Taun)

1. Through contaminated water and food.

1. Patient has severe diarrhoea and vomits2. Patient feels giddy and pain in abdomen 3. His body becomes dehydrated.

1. Patient given saline drip and antibiotic2. How to prevent from being infected?i - Get vaccineii - Boil all drinking wateriii - Cover all foodiv - Increase the chlorine content in water supply

3. Gonorrhoea 1. Through sexual intercourse

1. For male, his testis becomes inflamed and enlarged. He feels pain during urination.2. For female, she has painful vagina and uterus.

1. Can be treated by using antibiotics (i.e penicillin)2. Can be prevented by avoid having sex with prostitutes.

4. Syphillis 1. Through sexual intercourse

1. Patient has fever and non-itchy rash on the body.2. Patient has sores on the penis or vagina3. Patient has sore throat and pain in the bones and joint.

1. Can be treated by using antibiotics (i.e penicillin)2. Can be prevented by avoid having sex with prostitutes.

5. Tooth decay 1. Through food’s waste on the teeth’s surface.

1. Patient feels pain for infected teeth since teeth’s pulp is badly inflamed

1. Can be prevented by:I - Having a diet low in sugarsii - Wash your mouth and brush your teeth after eating.

Table 9.4 – A (Diseases Caused by Bacteria)

2. Diseases Caused by Viruses

DISEASEMETHOD OF INFECTION

SYMPTOM TREATMENT/PREVENTION

1.Common cold(Selsema)

1. Through contaminated air (when people around sneezes)

1. Patient gets cough, fever, running nose and red or watery eyes2. Patient has a sore throat3. Patient becomes weak

1. NO PROPER TREATMENT2. Can be prevented by:i - having proper dietii - have fresh and clean airiii- keep away from the crowd

2. Dengue fever(Demam denggi)

1. Through Aedes mosquito (inject the virus into patient’s blood)

1. Patient has high fever.2. Bleeding in nose and gums3. Pain in the bones, joints, muscles and eyes4. Blue marks appear on the body

1. NO PROPER TREATMENT2. How to prevent from being infected?i - Keep our living place cleanii - Destroy Aedes mosquito’s habitatiii - Fogging

3. AIDS(Acquired Immune Deficiency Sydrome)

1. Through 3 ways:i -Sexual intercourseii - Sharing of syringes during drug addictsiii- Infected pregnant woman to her baby.

1. Patient has fever and diarrhoea, and coughs very often.2. Patient has loss appetite for food and weight.

1. NO PROPER TREATMENT2. Can be prevented by having healthy clean life.

Table 9.4 – B (Diseases Caused by Viruses)

Life Cycle of Aedes Mosquito

3. Diseases Caused by Fungi

DISEASEMETHOD OF INFECTION

SYMPTOM TREATMENT/PREVENTION

1.Tinea(Panau)

1. Through spore of the fungus

1. Whitish patches appears on the infected skin (usually face or back of the body)

1. Can be treated by suitable anti-fungal drugs2. Can be prevented by:i - keep the body clean and dryii - avoid direct contact with infected person .iii - do not share towel or comb

2. Ringworm(Kurap)

1. Through spore of the fungus

1. A reddish area appears on the infected skin2. Infected skin becomes itchy

1. Can be treated by suitable anti-fungal drugs2. Can be prevented by:i - keep the body clean and dryii - avoid direct contact with infected person .iii - do not share towel or comb

Table 9.4 – C (Diseases Caused by Fungi)

4. Diseases Caused by Protozoa

DISEASEMETHOD OF INFECTION

SYMPTOM TREATMENT/PREVENTION

1.Malaria(Demam kepialu)

1. Through Anopheles mosquito (inject parasitic protozoon plasmodium into blood)

1. Patient has high temperature at intervals2. After fever, patient feels very cold and shivers.3. Got rapid pulse rate4. Got very liitle urine, which is very yellow.

1. Can be treated by suitable drugs such as plasmoquine, quinine, or chloroquine2. Can be prevented by:i - foggingii - Keep our living place clean

Adult mosquito – has black stripes on the abdomen and legs

Egg are laid singly in stagnant water

Egg are hatched and becomes larva

Larva grows and becomes pupa

Table 9.4 – D (Diseases Caused by Protozoa)5. The Transmission of Diseases

- Diseases transmitted from one person to another by FIVE ways:

i- By Air

It occurs when infected person sneezes, coughs or talks. So, a spray or tiny droplets of moistures containing pathogens released into air

Diseases transmitted by air: common cold and tuberculosis

ii- By Water

It occurs when water from ponds, river and sea always contaminated with faeces which usually contains pathogens. So, these pathogens can spread into water supplies due to unsanitary conditions / seeped through the soil

Diseases transmitted by water: cholera and hepatitis A

iii- By Food

It occurs when food contaminated by pathogens due to unhygienic handling or houseflies presence.

Diseases transmitted by food: cholera, food poisoning and hepatitis A

iv- By Contacts

It occurs when there has direct contact between infected people to others or wity objects handled by infected people

Diseases transmitted by contacts: tinea, ringworm, AIDS, gonorrhoea and syphilis

v- By Vector

Vectors: Animals carry pathogens in their bodies. For example: Aedes mosquito, houseflies, rats, dogs and etc

Diseases transmitted through their bite into human’s blood or carrying pathogen onto the food.

Diseases transmitted by vectors: dengue fever, malaria and cholera

PREVENTION OF DISEASES CAUSED BY MICROORGANISMS

1. Prevention through the Control of Vectors

Common vectors, their pathogens and diseases transmitted by them can be shown as following table:

Vector Pathogen DiseaseAedes mosquito Virus Dengue fever

Anopheles mosquito Protozoa (plasmodium) MalariaHousefly Bacteria Cholera

Rats Fleas PlagueTable 9.6 – A (Vectors and its diseases)

1.1 Control of Houseflies

To control houseflies, we must:

a) keep our surrounding cleansb) cover our foodsc) throw organic waste into plastic bags and tied it up for disposald) spray insecticides to keep away the adult fly awaye) keep manure and compost heaps far away from houses.

1.2 Control of Mosquitoes

To control mosquitoes, we must:

a) drain marshes and unused pondsb) clean the house from opened empty tins and coconut shellsc) put anti-larva chemicals or into ponds, drains and stagnant waterd) carry out fogging around living placese) fix wire gauze at doors and windows f) sleep under a mosquito net

2. Prevention through Sterilization

Definition of Sterilization:

Destruction of pathogens and their spores in a substance or object

Type of sterilization:

a) heatb) chemicals

c) radiation2.1 Sterilization using Heat

a) Boiling

- Boiling a substance or an object in water for 20 minutes will kill all bacteria cells and many spores.- Surgical instruments in clinics or hospital are usually sterilized in this way.

b) Autoclave

- An autoclave is a steam sterilizer. The things to be sterilized are kept in closed container and steam under high pressure and temperature of 120ºC for 15-20 minutes- All the bacteria and spores will be destroyed in this way.

c) Dry air oven

- It can be used to sterilize glassware and metal objects. - The things to be sterilized are kept in dry air oven at 170ºC for 15-20 minutes- Effectiveness of sterilization using this way is less compare to using autoclave.

2.2 Sterilization using Chemicals

a) Antiseptics

- It can be used to prevent the growth of some bacteria and destroy some others.- It usually used for cleaning wounds - Example: iodine solution, hydrogen peroxide solution and potassium manganate (VII) solution

b) Disinfectants

- Powerful chemicals to destroy pathogens- It used for sterilizing instruments, containers, cloths, floors, walls and etc.- Example: lysol, formaldehyde, phenol and sodium hypochlorite

2.3 Sterilization using Radiation

a) UV light

- Applied to lamp in surgical operating theatre and lab for air sterilizing.

b) Gamma rays

- It used for sterilizing surgical instruments and certain foods

- Foods that have been sterilized in this way can be kept for a long period of time and it is safe to eat.3. Prevention through Immunization

Definition of Immunization:

Process of increasing a person’s resistance to a particular infection by using antibodies

Definition of Antibodies:

- Chemical substance produced from white blood cells to destroy pathogen or neutralize the toxins produced by pathogen. Each of antibody acts on a particular pathogen.

Type of immunity:

a) Natural

- Refer to situation when a person recovered from an infection, antibodies produced by the person’s body to fight that infection remains in the person’s blood for months or even for his/her whole life.- When same infection comes back again, the person has antibody to fight back

b) Artificial

- Refer to a situation when a person given a vaccination, “injecting a dead or weak pathogens into the person’s body to stimulate his/her body to produce antibody”- Artificial immunity also can be gained when a person is given an injection contains antibody.

c) Passive

- Part of artificial immunity- Can be done by injecting antibody (usually contains antiserum) directly into a person’s body- Effect of this immunity is fast but temporary.

d) Active

- Can be either natural or artificial immunity- Can be done by having antibody after recover from infection or vaccination - Effect of this immunity is slow but permanent.

TREATMENT OF DISEASES CAUSED BY MICROORGANISMS

1. Antibiotics

2. Antiserum

3. Chemotherapy

4. Radiotherapy

5. Surgery