Human Bio Unit 4 Chp 3 Microorganisms

OBJQ

What are 3 causes of disease?

Microorganisms (pathogenic) 

Lifestyle 

Genetic

What is disease?

A condition with a specific cause in which one or all parts of the body function less effectively and abnormally.

What are 4 types of pathogens?

Bacteria, virus, fungi, protozoa

Explain how bacteria, viruses, fungi and protozoa affect the organisms.

• Bacteria→release toxins as they multiply. Affect tissues 

• Virus→enter living cells to disturb metabolic systems of the cell. The genetic material of the virus takes over the cell→produces more viruses

• Fungi→hyphae secrete digestive enzymes→break down tissue→growth of hyphae→physically damage tissue

Some fungi→toxins→allegic reactions

• Protozoa→no set pattern 

Explain about bacteria

- Unicellular 

-Decomposer 

- No nucleus and membrane-bounded organelles

- Plasmid and flagellum (only ⅔)

-Asexual reproduction of binary fission

-Spherical 

-Rods

-Spirals

Explain bacterial cells and their functions

1. Capsule—> Hydration, prevents itself from antibiotics and WBC attack

2. Call wall—>Made out of peptidoglycan—>Extra protection

3. Cell surface membrane—>Control movement of substances in and out

4. Chromosome (nucleoid)—>Division and reproduction

5. Plasmid—>Extrachromosomal DNA—>Genetic engineering

6. Flagellum—>Movement

How to grow bacteria?

In a Petri dish containing agar or liquid called broth.

Binary fission of bacteria formula

2^n x number of bacteria given

Name the viruses and diseases caused by them, including symptoms.

Virus	Disease
Common cold	Cold အအေးမိ
Measles	Measles ဝက်သက်
Influenza	Flu တုပ်ကွေး
SARS-CoV-2	COVID-19
Disease HIV (Human Immunodeficiency Virus)	Syndrome AIDS (Acquired Immune Deficiency Syndrome)
Plant  Tobacco mosaic virus	Impaired chloroplast synthesis→discoloration of leaf→imparied photosynthesis

Dengue virus

Dengue သွေးလွန်တုပ်ကွေး

Poliomyelitis virus

Polio

Mumps virus	Mumps ပါးချိတ်ရောင်ရောဂါ
Rubella virus  (German measles)	Rublella virus (ဂျိုက်သိုးရောဂါ or ဂျာမန်ဝက်သက်)

Ebola virus

Ebola

Name the bacteria and diseases caused by them

Bacteria	Disease / infection
Pneumococcus	Pneumonia (အဆုတ်ရောင်ရောဂါ)
Staphylococcus	Skin infection
Streptococcus	Pneumonia (အဆုတ်ရောင်ရောဂါ)
Spirochete	Syphilis ကာလသားရောဂါ
Salmonella typhi	Typhoid အူရောင်ငန်းဖျား
Vibrio cholerae	Cholera ကာလဝမ်းရောဂါ

Neisseria gonorrhoeae

Gonorrhoea ဆီးပူညောင်းကျ

OBJR
Name the protist and the diseases caused by them

Protist	Disease
Amoeba	Amoeba
Chlorella	Infection
Plasmodium	Malaria ငှက်ဖျားရောဂါ

Trypanosoma

Trypanosomiasis (sleeping sickness)

OBJR 

Name the fungi and diseases caused by them

Fungi	Diseases
Dermatophyte	Athlete’s foot

Candida albicans	Thrush
dermatophytes	Ringworm

OBJQ

Define 'virus'.

-Acellular 

-Only composed of genetic material (RNA or DNA) and a protein coat. 

-Can’t perform life processes except reproduction, but only in a host cell.

What are the limiting factors in the stationary and death phases?

-Run out of nutrients 

-Build up toxic materials

What are the requirements for a culture of bacteria?

Favourable temperature and pH and enough nutrients

OBJQ

How do viruses reproduce?

• They enter the host cell and take over the host's genetic machinery to make more virus particles. 

• After virus particles have been made, host cells die, and particles are released to infect more cells.

Why do doctors sometimes give antibiotics to patients while patients suffer from the virus?

To prevent secondary bacterial infections or opportunistic disease from attacking the host cell.

State the meaning of 'incubation period'.

The period of time between when a person is infected with a pathogen and when they first show signs and symptoms 

Patients won’t feel sick during the incubation period but are infectious to others. The period can range for different diseases.

What is the difference between signs and symptoms?

Sign-visible to other people, heard, measured, seen EXAMPLE: By using a stethoscope and blood-measuring devices.

Symptom–not usually visible to other people. EXAMPLE: Patients experience symptoms like pain, dizziness, and nausea.

What is endemic, epidemic and pandemic?

Endemic—disease always present in a population of a particular geographical area

Epidemic—a widespread outbreak of infectious disease with many people getting infected at the same time. 

Pandemic—disease spread across the world.

OBJQ

Explain the bacterial culture sigmoid curve

Lag phase → adapt to new environment 

Exponential or log phase → grow exponentially 

Stationary phase → number of deaths = number of births

Death phase = organisms start to die

OBJR + OBJQ

What are 7 methods of disease transmission?

• Air droplet 

• Animal vector 

• Eating contaminated food 

• Drinking contaminated food 

• Direct contact 

• Blood-to-blood 

• Through sexual intercourse

OBJQ

Which cell does HIV infect, and what is the function of the infected cell?

• HIV infects a type of white blood cell, a lymphocyte called a T-helper cell. 

• The function of the T-helper cell is to help other lymphocytes to become active and start fighting infections.

OBJQ
Explain how HIV approaches humans.

1. HIV is a retrovirus. The genetic material of HIV is RNA. The virus makes DNA from the RNA, and this DNA becomes incorporated into the DNA of the T-helper cell. 
   
   

Retrovirus = A virus that can change its genetic material to match the host’s.
RNA of HIV uses the reverse transcriptase enzyme to make DNA

2.  At some point in the infection, the HIV DNA is activated. It then instructs the lymphocyte to make HIV proteins and more RNA.
   
   

3.  The HIV proteins and RNA are assembled into new virus particles.

4.  Some of the HIV proteins end up as antigens on the surface of the cell.
   
   

5. These HIV proteins are recognised by the person’s immune system as being ‘foreign’ to the body.
   
   

6.  The lymphocyte is destroyed by the immune system.

7.  The assembled virus particles escape to infect other lymphocytes.

8. The cycle repeats itself for as long as the body can replace the lymphocytes that have been destroyed

9. Eventually the body will not be able to replace the lymphocytes as quickly as they are being destroyed.

10. The number of free viruses in the blood increases rapidly, and HIV may infect other areas of the body, including the brain.

11.  The immune system is severely damaged, and other disease-causing

Microorganisms infect the body.

12. The death of a person is caused by “opportunistic” diseases such as TB and pneumonia or cancer such as Kaposi’s sarcoma.

OBJQ

What are 3 main ways of HIV transmission?

Sexual intercourse, vertical transmission, blood-to-blood contact

What is the medicine prescribed for HIV?

PreP (often recommended to take before intercourse)

OBJQ

What are control measures for HIV?

• Prevent sharing sterile needles

• Be faithful to 1 sexual partner 

• Use of condom/femidom 

• Testing blood used for transfusion

(A transfusion is a safe medical procedure where donated blood or parts of blood—such as red blood cells, platelets, or plasma—are put directly into your vein)

What are the first symptoms of Ebola?

Fever, muscle pain, headache, sore throat, followed by vomiting, diarrhoea and damage to liver and kidney functions.

What is the natural host of Ebola?

African fruit bat

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Explain types of transmission of Ebola

Body fluids (semen, blood, saliva, faeces) 

Bedding 

Broken skin, mucous membranes such as the mouth and intestine

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What are 2 types of treatment for Ebola?

Oral Rehydration Therapy

IV drips (Giving fluids intravenously)

OBJQ

State preventive measures for Ebola

-Checking their contact 

-Dealing with individual patients 

-Having laboratory testing facilities 

-Organising safe burials

OBJQ

Explain Oral Rehydration Therapy

-ORT is a pack containing a solution of salt and glucose mixed with sterile water (Isotonic solution) 

-Helps to rehydrate tissues and prevent furthur damages such as death.

Explain latency period

• Period that a person is infected in the body but there are no signs or symptoms shown 

• Highly infectious to others

• Can last up to 20→50 years or even 70 or more

OBJQ
Explain cholera in terms of cause, method of transmission, time for symptoms to show, how they infect and its preventive measures.

Cause: Vibrio cholerae

Method of transmission: contaminated food and drinks, poor hygiene 

Time for symptoms to show: a few hours or days after infection

Infection: bacteria enter gut→if survive acidic condition in stomach→reach small intestine (reproduce, secrete toxin) → upset the functions of epithelial lining→toxin cause water loss or salt from intestine→severe diarrhoea→dehyrated→heart rate increase→low blood pressure→muscle cramp→death (sometimes) 

Preventive measure: antibiotic and ORT

OBJQ

Explain typhoid in terms of cause, method of transmission, incubation period, symptoms, how they infect and its preventive measures.

Cause: Salmonella Typhi

Method of transmission: Drinking water that is contaminated by stool or flies transferring bacteria from stool to food 

Incubation: 2 weeks

Symptoms: Flu-like symptoms: high fever, headache, cough and feeling unwell, stomach cramp, constipation, diarrhoea, vomiting, delirium (mental confusion)

Infection: Diarrhoea leads to dehydration and can be life-threatening as bacteria attack the intestinal lining and cause bleeding and even holes in the gut wall. Toxins→inflammation of heart and organ failure

Preventive measures: ORT, antibiotics, good sanitation and hygiene

OBJQ
Explain gonorrhoea in terms of cause, method of transmission, general symptoms, untreated threat and preventive measures

STD or STI

Cause: Neisseria gonorrhoeae 

Method of transmission: sexual intercourse

Symptoms (women): discharge from vagina, bleeding during menstruation

Symptoms (men): discharge of pus from the penis and pain during urination. 

Untreated threat: infection spreads to the uterus, oviduct, and ovaries→infertile women

Preventive measure: antibiotics, limit sexual partners

OBJQ

Explain Athlete’s foot in terms of cause and method of transmission, infection sites, effects of bad infections, treatment and hygiene measures.

Cause: Pathogenic fungi

Method of transmission: Direct contact

Infection sites: skin, nail, mucous membranes of mouth and vagina 

Effects of bad infections: sore, raw patches

Treatment: 1. 30-40% is cured by humans immune system

2. Antifungal drug 

Hygiene measures: 1. Avoid changing rooms

2. Wear protective food cover

3. Wear cotton socks and loose-fitting shoes

4. Toenails cut short

5. Avoid sharing or using other people's personal wears

OBJQ

Explain malaria in terms of cause, method of transmission and symptoms, time span of malarial parasite and preventive measures.

Cause: Plasmodium Protozoa

Method of transmission: Anopheles mosquito vector 

Symptoms: Alternating cold sweats and fever, vomitting, joint pain, anaemia.

Time span of malarial parasite: 2 weeks to several months. 

Preventive measures: Control the number of Plasmodium parasites

Control the number of mosquitoes 

-Insecticides

-Draining swamps and pools

-Use drugs to target various stages of the protozoan life cycle. 

- Wear long-sleeved shirts, insect repellents

- Introduce Tilapia→feed on larvae of mosquito 

- Use mosquito nets

Infection step by step

FAQ + Once exam question

Explain sickle cell anaemia in terms of cause, symptoms, and beneficial point of sickle cell anaemia.

Cause: mutation

Symptoms: Tiredness, less oxygen and energy supply, difficulty breathing 

Beneficial point: Patients with sickle cell anaemia won’t suffer from malaria because malarial parasites don’t recognise RBCs as their site of reproduction of sex cell.

Explain innate and adaptive immune responses.

Innate→general immune response (phagocytes) and perform phagocytosis

Adaptive→produce antibodies (specific)

Explain phagocytosis in 3 steps.

1. The phagocyte changes shape by pseudopods (false feet) and surrounds pathogens. 

2. Pseudopods envelop pathogens, and the cell membrane joins, trapping the target inside a food vacuole. The pathogen is used to help feed the phagocyte. 

3. Digestive enzymes are poured into

the food vacuole to kill and break down the pathogen into tiny, harmless parts. The phagocyte is then ready to attack again.

OBJQ

Explain how lymphocytes, upon binding to 2 types of cells, are produced after cell division

1. The receptor and antigen bind to the receptor on the lymphocyte.

2.  Upon binding, the lymphocyte becomes activated and divides by mitosis (somatic)  (proliferates).

3. Produces 2 types of cells that can recognise the antigens. 2 types: Plasma cells (produce antibodies) and memory cells.

4. Kill pathogen cells and become memory cells in lymphnode/lymphoid tissue.

5. Secondary Immune Response of lymphocyte

   1. Antigen binds to the receptor on the lymphocyte. 

   2. Memory cells become activated. 

   3. Proliferated

   4. Produce many antibodies and kill pathogens.

What is another way to address “antigens”?

Marker chemicals

What are 2 general purposes of antibodies?

Neutralising the largest threat, like binding to the target to stop infection from spreading to more cells; causing a pathogen to burst open; and binding to pathogenic toxins in the blood to neutralise

Recruiting other cells and chemicals to combat the threats, like acting as markers to attract phagocytes to pathogens and cause pathogens to clump together (inactive and easily killed by phagocytes)

Explain memory cells.

• Immune to disease in the future

• Remain in blood for many years or, in some cases, a lifetime 

• If the same microorganisms re-infect, memory cells start to reproduce and make antibodies. (Except for viruses or pathogens that can change shape.)

State 3 characteristics of secondary immune response.

Quicker/faster 

More antibodies 

Stay longer in the blood

OBJQ

Explain briefly about 4 types of immunity

	Active (making own antibodies)	Passive (acquired antibodies)
Natural	Recovering from infection	Breastfeeding and placenta
Artificial	Vaccine	Injecting antibodies

What are the advantages of active and passive immunity?

Active→long term

Passive→immediate result

OBJQ

Explain the ways of giving vaccination, its mechanisms and 5 components that might be in the vaccine (attenuated)

• Orally or by injection 

• Lymphocytes recognise the antigens and multiply as microorganisms enter the bloodstream. 

• Form memory cells and make us immune to disease.

• Dead microorganisms→Typhoid and whooping cough

• Weakened part of actual microorganisms→TB and measles

• Harmless bacteria (genetically modified to carry antigens)  remove toxigenicity, keep antigenicity→hepatitis B

• Modified bacterial toxins→Tetanus, diphtheria

• Antigens on their own→influenza

Explain herd immunity.

What are the pros and cons of vaccination?

Pros	Cons
Cheaper than other options	Needle phobia
Helps control the spread of infectious diseases	May develop reactions or side effects
Reduced number of deaths	People might take fewer precautions

OBJQ

What is meant by antibiotics?

Chemicals that kill microorganisms or reduce their growth to treat bacterial or fungal infections. (Do not work on viruses)

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What are natural antibiotics produced from, and its example?

Bacteria and fungi. 

1st antibiotics→by fungus Penicillium→Penicillin→kill bacteria

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What are 3 types of antibiotics and their functions?

Bactericidal→kill bacteria

Bacteriostatic→stop bacteria from reproducing 

Broad-spectrum antibiotics→act against a range of bacteria

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What are 3 effects of antibiotics?

1. Interfere with manufacture of cell wall→weaken cell wall→osmotic lysis (water enters by osmosis and bursts the cell)

2. Interfere with DNA replication→cell division is impossible, so can’t multiply. 

3. Interfere with protein synthesis→stop the production of enzymes.

How do bacteria become antibiotic-resistant?

Random gene mutation

OBJQ

Explain Methicillin-resistant Staphylococcus aureus and how it becomes a problem.

Known as a “superbug” • resistant to many antibiotics. Major problem in hospitals.