UNIT THREE

BIOLOGYAREA OF STUDY #2: DETECTING & RESPONDING

EXAM REVISION LECTURE

CHP 7: INFECTION & DISEASE

CHP 7 TOPIC 1: DEFINING DISEASE

The term disease refers to any change that impairs the functioning of an individual in some way. That is, it harms the individual.

Infectious Disease

Chapter 7 - Disease Causing Organisms 3

CHP 7 TOPIC 1: DEFINING DISEASE/ TRANSMISSION

Transmission of Disease

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CHP 7 TOPIC 1: DEFINING DISEASE/ TRANSMISSION

Contact Transmission

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CHP 7 TOPIC 1: DEFINING DISEASE/ TRANSMISSION

Vehicle Transmission

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CHP 7 TOPIC 1: DEFINING DISEASE/ TRANSMISSION

Vector Transmission

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CHP 7 TOPIC 1: DEFINING DISEASE/ TRANSMISSION

Topic CHP 7.1 Questions:

1. Do all pathogens that enter an organism cause disease? Yes / No2. Do all pathogens that enter an organisms of different species cause the same disease? Yes / No3. Is a broken arm by definition, a disease? Yes/ No4. Is cystic fibrosis and infectious disease? Yes/ No5. What kind of microscope would you need to use to identify the presence of:

– Bacteria:_______________– Fungus: ________________– Viriods: ________________– Protozoan: _____________

6. How does a ‘vector’ differ from a ‘host’? _____________________________________ ________________________________________________________________

7. What is the likely method of transmission of infection of the following:– Prions: _________________– Influenza: _______________– E. coli: _________________

/12 Marks

Organism or Agent

Structural Characteristics

Sub Groups Examples of Diseases

Fungi Unicellular or multicellular organisms. Consist of eukaryotic cells. Cell walls composed of chitin. (original source of penicillin)

Yeasts: unicellular fungi. Cells have nuclei. Reproduce by budding.

Candida albicans causes thrush

Moulds: multicellular fungi. Can invade tissue by hyphae.

Many plant diseases: Dutch Elm disease; rust diseases; ringworm (not a worm!), athletes foot.

Protozoa Unicellular (animal like protists- ingest food). Eukaryotes

Amoebas: single celled organisms which move by the use of pseudopodia.

Amoebic dysentery – intestinal infection

Plasmodium causes malariaApicomplexans: spore forming parasitic protozoa

Worms Multicellular, eukaryotic, specialised for the parasitic way of life. Mouthparts may be modified to form hooks; digestive systems a re simple; generally produce numerous offspring

Nematoda worms (round worm, hookworm, pin worm)

Trichinosis causes an often fatal disease in which worms invade muscle tissue. Elephantiasis – worms block lymph vessels

(Flatworms) Flukes and tapeworms

Schistosoma is a parasite of human blood. Intestinal tapeworms pain, discomfort and increased appetite

CHP 7 TOPIC 2: SUMMARY OF DISEASE CAUSING ORGANISMS

Organism or Agent

Structural Characteristics Sub Groups Examples of Diseases

Prion Protein molecule - BSE (mad cows disease), Creutzfeldt-Jacob disease

Viroid A short strand of RNA with no protein coat

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Virus Nucleic acid surrounded by a protein coat. Some are enveloped in a modified membrane

DNA viruses. They may contain single or double stranded DNA molecules

Smallpox, cowpox, herpes, and warts. Common cause of sore throats.

RNA Viruses. They are usually single stranded; some contain two RNA strands

Polio hepatitis, influenza and colds., aids, Ebola, measles, mumps

Bacteria Prokaryotic cells, they lack membrane bound organelles. Contain a single round chromosome (and many plasmids)

Cocci: spherical bacteria Staphylococcus aureus causes skin and wound sores. Streptococcus causes sore throat

Bacilli: rod shaped bacteria Diphtheria, leprosy, tuberculosis

Spirilla: spiral shaped bacteria

Syphilis, lyme disease

Gram Positive/ Gram Negative:

CHP 7 TOPIC 2: SUMMARY OF DISEASE CAUSING ORGANISMS

Topic CHP 7.2 Questions:

1. Circle which of the following would be classified as living:HIV E. coli a Prion plasmodium yeast

2. True/ False: viroids are the smallest known infectious particles

3. List two virus sub groups: _______________ & _________________________

4. Name one protozoan that causes disease in mammals: ____________________

5. True / False: penicilin is affective against bacteria and fungi but not virus’

6. Which of the following are prokaryotic: (circle)

E. coli E. epidermis HIV Plasmodium Yeast

Prion Diseases

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CHP 7 TOPIC 3: CHARACTERISTICS OF DISEASE CAUSING PRIONS

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• prions are unique in that they are both contagious and hereditary• they are also resistant to sterilization

CHP 7 TOPIC 3: CHARACTERISTICS OF DISEASE CAUSING PRIONS

Topic CHP 7.3 Questions:Prions1. Which of the following is a possible source of prion disease:

a) Infected brainsb) Infected intestinesc) Contaminated water

2. Which of the following is a possible cause of prion disease:a) Infection carried by a vectorb) Infection caused by a parasitec) Genetic mutation

3. Prions are infectious proteins. How do they cause disease: _________________________ _________________________________________________________________________

4. True / False: prions can be destroyed or deactivated by heating or cooling

5. True / False: prions have an incubation period up to ten years

6. Name one disease caused by prion infection: _______________________

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Bacteria- Kingdom Monera

CHP 7 TOPIC 4: CHARACTERISTICS OF DISEASE CAUSING BACTERIA

Gram Stains

• 1984, bacteriologist, Joachim Gram developed the gram stain

• Gram stain distinguishes between two main groups of bacteria

• Important stain to help identify which drugs are useful

• Gram Positive bacteria take up the violet colour of the stain– Gram + have a cell wall layer of teichoic acid– Are particularly susceptible to penicillin and sulphonamide drugs

• Gram Negative bacteria fail to take up the stain and by default stain pink– Gram – have no teichoic acid in their walls and smaller amounts of

disaccharides and amino acids– Outer layer of lipid compounds enables these bacteria to resist

penicillin and other drugs– Also makes phagocytosis of the bacteria very difficult– Effective drugs include streptomycin, tetracycline

– S. empidermis: gram negative (susceptible to penicillin)– S. ecoli: gram negative (resistant to penicillin) 16

CHP 7 TOPIC 4: CHARACTERISTICS OF DISEASE CAUSING BACTERIA

Topic CHP 7.4 Questions:Bacteria 1. Which of the following is a possible source of bacterial disease:

a) Infected brainsb) Infected intestinesc) Contaminated waterd) All of the above

2. True / False: all bacteria are pathonogenic

3. True / False: all bacteria contain DNA

4. The cell wall of bacteria is made out of:a) Chitinb) Cellulosec) Protein d) Nofninideae) Carbohydrates, lipids and amino acids

5. Three basic shapes of bacteria include: __________________, ________________ & _____________________6. Most bacteria have a casing around the outside of the cell wall called a : c_________

7. Two organelles (not including cell membrane) present in some bacteria include: ________________, _______________

8. How many chromosomes does each bacterial cell have? 1, 3, more than 3

Viruses• Viruses are the smallest known reproducing things.• A virus comprises of DNA or RNA surrounded by one or more coats of

protein.• The significant feature about viruses is that they cannot reproduce outside a

cell – they need to enter a host cell to reproduce.• Most viruses are only able to invade one host although some have a host

range• Are intracellular parasites to animal, plants, fungi, protists and bacteria

18BACTERIAPHAGE attacks bacteria

CHP 7 TOPIC 5: CHARACTERISTICS OF VIRUS’

How Do Viruses Affect a Host Cell?• Viruses must enter a host cell to reproduce.

• They use components of the host cell as a source of energy and material to make new viruses and ultimately destroy the host cell.

• When a virus infects a cell, its protein coat becomes attached to the cell wall and its DNA is injected into the cell.

• The viral DNA ‘takes over’ the cell and uses energy from the mitochondria and material within the cell to make new viral protein coats and viral DNA.

• The new parts are then assembled into new viruses and in a matter of hours, hundreds of new viruses are produced.

Chapter 7 - Disease Causing Organisms 19

CHP 7 TOPIC 5: CHARACTERISTICS OF VIRUS’

Viral Pathogens

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CHP 7 TOPIC 5: CHARACTERISTICS OF VIRUS’

The Structure of HIV

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True / FalseTrue / False

CHP 7 TOPIC 5: CHARACTERISTICS OF VIRUS’

Topic CHP 7.5 Questions:Virus 1. Which of the following is a possible source of viral disease:

a) Infected brainsb) Infected intestinesc) Contaminated waterd) All of the above

2. True / False: all virus’ are pathonogenic

3. True / False: all virus’ contain either DNA or RNA

4. True / False: viruses are obligate intracellular parasites

5. The cell wall/ coat of virus is made out of:a) Chitinb) Cellulosec) Protein d) Nofninideae) Carbohydrates, lipids and amino acids

6. Why are viruses hard to attack and destroy? _____________________________________

7. True/. False: Bacteriophages are attacked by viruses

8. What name is given to the protein coat of a virus? a _______________

CHP 7 TOPIC 6: CHARACTERISTICS OF DISEASE CAUSING PROTOZOANS

Protozoans

Malaria

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CHP 7 TOPIC 6: CHARACTERISTICS OF DISEASE CAUSING PROTOZOANS

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Malaria

CHP 7 TOPIC 6: CHARACTERISTICS OF DISEASE CAUSING PROTOZOANS

Topic CHP 7.5 Questions:

Protozoans 1. Which of the following is the most likely source of disease caused protozoans:

a) Cooked meat/ fishb) Contaminated waterc) Airborn infection

2. True / False: all protozoan’s are pathonogenic

3. True / False: all protozoans contain both DNA & RNA

4. True / False: disease causing protozoans are obligate intracellular parasites

5. True/. False: mosquiotos cause the disease known as malaria

6. True/ False: humans are the primary host for plasmodium

7. What name is given to the protective capsule used by some protozoans to avoid being destroyed by a host: ______________________________

Fungal& Disease

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CHP 7 TOPIC 7: CHARACTERISTICS OF DISEASE CAUSING: OTHER

Multicellular Parasites

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CHP 7 TOPIC 7: CHARACTERISTICS OF DISEASE CAUSING: OTHER

Insect Parasites

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CHP 7 TOPIC 7: CHARACTERISTICS OF DISEASE CAUSING: OTHER

Parasitic Ticks & Mites

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CHP 7 TOPIC 7: CHARACTERISTICS OF DISEASE CAUSING: OTHER

Parasitic Roundworm

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CHP 7 TOPIC 7: CHARACTERISTICS OF DISEASE CAUSING: OTHER

Parasitic Flatworms

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CHP 7 TOPIC 7: CHARACTERISTICS OF DISEASE CAUSING: OTHER

How do Pathogens infect and affect?

1. Must cause damage to the host (generally one or a combination of the following)

• Invasion of tissue (the pathogen reproduces in and spreads through body tissue , causing breakdown of tissue/ cell death): i.e. enzymes of bacteria

• Production of toxins: exotoxins in bacteria; endotoxins

• Inhibits normal cell function such as metabolism, growth and repair

• Consumes nutrients (i.e. parasites)

• Produces damaging proteins (prions and viruses)

• Body’s own reactions – fever, inflammation and swelling – necessary but harmful!

CHP 7 TOPIC 3: CHARACTERISTICS OF DISEASE CAUSING ORGANISMS

Key Terms:Parasite: organism that lives on or in another organism and feeds from it , usually without killing it.

Endoparasite: parasatistic organism that lives inside the host

Ectoparasite: parasatistic organism that lives/ feeds on the outside of the host

Host: organism or cell that a parasite lives in or on.

Primary Host: in which mature parasite lives its adult stage (final host) before passing on eggs

Intermediate Host: a host necessary for completion of life cycle (not adult form of parasite- site of asexual reproduction)

Vector: an insect or animal that carries a pathogenic organism from one host to another

Exotoxins: toxins secreted (including bacteria) into the surrounding medium

Endotoxins: toxins produced by an organism and released only when the organism disintegrates

Fungicides: chemicals that kill fungi

Alfa toxin: a toxin produced by fungus that may be responsible for some cancers

Pathogen: organism able to cause disease in a host

CHP 7: CHARACTERISTICS OF DISEASE CAUSING ORGANISMS

Antiseptics and Disinfectants:• antiseptics are used to kill pathogens on the skin•Disinfectants are used to kill pathogens on an object•Both work by interfering with cell structures and functions

Antibiotics and Antimicrobials• Antibiotics were originally produced naturally by microorganisms, but some can now be made synthetically. They are active against other microorganisms• antimicrobial agents are chemicals used to inhibit growth of bacteria. They interfere with bacterial cell walls, cell membranes and protein and nucleic acid synthesis

•Fungicides and AntifungicidesHard to develop because of strong similarities in cellular functions between the host and the pathogen

Antivirals• Hard to treat viruses without harming host cells• inhibiting the synthesis of RNA and DNA in retroviruses has been particularly successful•Interferons are antiviral (natural!)

Antiprotozoan and Anthelminthic DrugsVery little research in this area

CHP 7 TOPIC 7: CHARACTERISTICS OF DISEASE CAUSING: OTHER

Topic CHP 7.7 Questions:Prions1. Which of the following is a possible source of parasitic infection:

a) Cooked foodb) Contaminated waterc) Uncooked fish

2. List two examples of Fungi: __________________ & ________________________

3. The cell wall of fungi is made of:a) Chitinb) Cellulosec) Protein d) Nofninideae) Carbohydrates, lipids and amino acids

4. True / False: fungi are autotrophic

5. True / False: fungal infection is called mycosis

6. A parasite that feeds off the outside of its host is called an _______________ parasite

7. Name three adaptations that may be employed by parasites: 1. _____________________________________2. _____________________________________3. _____________________________________