Microorganisms and Viruses

 
8.3 Microorganisms and Viruses
 
  1. Microorganisms are tiny organisms and not be seen with naked eyes
  2. Microorganisms can only be seen with the help of light or electron microscope
  3. Microorganisms consists of bacteria,protozoa,fungi and algae
  4. Microorganisms are much smaller particles that do not carry out reproduction and only can develop in host cell
 
Description
Bacteria

Unicellular organisms

Have cell wall, plasma membrane and DNA which is not enclosed by a nuclear membrane

Are heterotrophs or autotrophs

Reproduced by binary fission and conjugation

Form spores under unfavourable condition

Examples: Escherichia sp coli., Lactobacillus sp.

Protozoa

Unicellular organisms

Live in aquatic

Have plasma membrane, nucleus and other membranous organelles

Heterotrophs organisms

Use cilia, pseudopodium and flagellum to move around

Reproduce sexually or asexually

Examples: Paramecium sp., Ameoba sp. and Plasmodium sp.

Algae

Unicellular organisms, non-fillamentaous and multicellular organisms

Able to carry out photosynthesis as they have chloroplast

The cell wall is made up of glycoprotein 

Do not have stems, leaves and roots

Reproduce sexually or asexually

Examples: Chlamydomonas sp. and Spirogyra sp.

Fungi

Unicellular organisms and multicellular organisms

Has no chlorophyll

Saprophytic or parasitic organisms

Secrete extracellular enzymes to breakdown organic matter before they are absorbed

Reproduce by binding or formation of spores

Examples: Yeast, Mucor sp.

Viruses

Not microorganisms

The smallest size

Can only be seen under an electron microscope

Only consists of DNA or RNA covered by a protein coat

Cannot reproduce outside the host cells

All are parasites

Can be crystallised outside host cells

Examples: Bacteriophage, influenza virus and HIV

 

Nitrogen cycle:

 
Source:[Text Book Biology KSSM Form 5]
 

The roles of microorganisms:

 
 
Producer

Examples: Cyanobacteria,phtoplankton (algae) 

  • Provide nutrients to primary consumers
  • Main energy source in a food chain
 
Decomposer

Examples: Saprophytic bacteria,fungi

  • Decompose organic materials to reduce pollution by preventing accumulation of the organic waste remains
  • Return nutrients to soil
 
Symbionts

Examples: Tryconympha sp. (protozoa) and Lactobacillus sp.

  • Tryconympha sp. in a alimentary canal of termites secretes cellulase to digest carbohydrate into glucose to be absorbed by the termites
  • Human colon has symbiotic bacteria which syntheis vitamin B and vitamin K
 
Parasite

Examples: Some bacteria & fungi

  • As predator to form a balanced food chains
  • Also as prey for other consumers
 
 
 

Definition of pathogen and vector:

 
Pathogens
 
  • Definition: An organism which causes diseases
  • Examples:
    • Bacteria
    • Viruses
    • Protozoa
    • Fungi
 
Vector 
 
  • Definition: Organisms which transmit pathogens and cause certain disease
  • Examples:
    • Mosquito
    • Flies
    • Cockroaches
    • Infected wild animals
 

Effects of pathogens on human health:

 
Pathogen, disease and symptoms
 

Virus - Human papillomavirus (HPV)

 
  • Disease: Sexually transmitted disease,cervix cancer and other cancer
  • Symptoms:
    • Warts on hand,leg,face and genital organ
    • Irregular blood spotting after periods
    • Prolonged and more menstruation than normal
    • Postmenopausal bleeding
    • Increased vaginal discharge
 

Bacteria - Salmonella sp.

 
  • Disease: Food poisoning
  • Symptoms: 
    • Vomitting
    • Diarrhea
    • Abdominal cramps
    • Headcahe
 

Protozoa- Plasmodium sp.

 
  • Disease: Malaria
  • Symtpoms:
    • Shrivel is followed by headache
    • Skin becomes yellowish
    • Anaemia
 

Fungi - Tinea sp.

 
  • Disease: Ringworm
  • Symptoms:
    • An erythematous patch with slightly scaly and small erythematous popules present at its periphery
    • The patch will enlarge and with the presence of its central clearing, it will appear ring-like or annular