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Bio > Chapter 12 - Infectious diseases > Flashcards

Chapter 12 - Infectious diseases Flashcards

1
Q

infectious

A

Caused by an invading pathogen and able to be transferred from one organism to another (communicable)

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2
Q

pathogen

A

a disease causing agent

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3
Q

host

A

An organism that is infected by a pathogen

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4
Q

infection

A

the invasion of host by a pathogen, where it establishes itself and replicates

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5
Q

micro organism

A

a microscopic organism (eg bacteria). Not a pathogen unless it causes a disease

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6
Q

how do scientists identify diseases (Koch’s postulates)

A
  1. The potential pathogen must always be present when the disease occurs
  2. The organism can be isolated from the host and grown in pure culture
  3. When organisms from the pure culture are inoculated into healthy, susceptible host and the disease develops
  4. The organism can then be re-isolated, grown in pure culture and compared with the organism first injected for confirmation
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7
Q

how are Koch’s postulates limited

A

as he only investigated bacterial pathogens and some harmless bacteria may acquire extra virulence factors that make them pathogenic.

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8
Q

Virulence

A

measure of the ability of a pathogen to cause severe disease within its host

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9
Q

infectious agent

A

A disease causing agent that can be transmitted from one organism to another

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10
Q

what are the four most common pathogen groups

A
  • Virus: a non cellular pathogenic agent, containing either DNA or RNA, that can only reproduce inside a living host cell
  • Bacteria: Prokaryotic, microscopic unicellular organisms that do not have a nuclear membrane or membrane bound organelles,
  • Fungi: A diverse kingdom of spore producing eukaryotic organisms, have a cell wall made of chitin, do not possess chloroplasts, have complex cell cycle, in which spores can develop into hyphae then grow into a mycelium, can be unicellular but mostly multicellular
  • Protists: An organism that is eukaryotic but may have plant-animal or fungus like features. Usually unicellular
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11
Q

Gall

A

a brown, roughened lump of undifferentiated tissue on the crown of a plant (where roots meet stem or branch meets trunk) looks tumour like

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12
Q

Transmission

A

transport of a pathogen from an infected host or reservoir to a susceptible host

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13
Q

Contagious

A

Able to be transferred by direct contact

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14
Q

Zoonotic diseases

A

a disease that animals pass to humans. An infection that is naturally transmitted between other vertebrate animals and humans

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15
Q

reservoir

A

An organism or habitat in which a pathogen can reside, and sometimes replicate, prior to entering a susceptible host. A reservoir is somewhere in which the pathogen does not go extinct

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16
Q

vector

A

An agent that transmits pathogens from one host to another

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17
Q

Pathogenicity

A

The capacity of a pathogen to cause disease in a host

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18
Q

three virulence factors that determine the pathogenicity of an organism

A
  • The ability to stick to or invade a particular cell type
  • Produce toxins
  • cope with or avoid the host immune system
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19
Q

Susceptibility

A

The likelihood of developing a disease. If the susceptibility of an organism is high, its ability to resist the disease is low

20
Q

incubation period

A

The time between infection and the onset of symptoms. Eg, pathogen may have to divide many times to reach numbers sufficient to cause disease or may take time to reach target tissues.

21
Q

what are the three factors that transmission of infectious diseases depends on

A

The infectious agent, a susceptible host and a mode of transmission

22
Q

what are the reason for an incubation period

A
  • The pathogen may have to divide many times to reach numbers sufficient to cause disease
  • May take time to reach the target tissues that are susceptible to that particular pathogen
  • Toxins produced by bacteria as waste products of metabolic activity may take time to accumulate to level that affects the host
23
Q

What are viruses

A

Viruses are non cellular pathogens consisting of one or more strands of RNA or DNA inside a protein coat. Viruses are not made out of cells and therefore are non living. They posses no metabolic machinery for processes such as cellular respiration. Cannot be classified as prokaryotes or eukaryotes

24
Q

nucleic acid

A

The molecule (DNA or RNA) that forms the genetic code in an organism

25
Q

prokaryotes

A

A single celled organism that lacks membrane bound organelles such as a nucleus

26
Q

Viral replication in a eukaryotic host

A
  • Attachment
  • Entry of virus nucleic acid (DNA/RNA) into host cell
  • Viral DNA/RNA enters the nucleus of the eukaryotic host cell
  • Viral DNA/RNA directs the host cell to replicate it and make copies of viral proteins via translation
  • New viral DNA/RNA and proteins assemble at host cell membrane
27
Q

Viral replication in a prokaryotic host

A
  • Virus particle binds to the wall of host cell and viral DNA enters the cells cytoplasm
  • Viral DNA directs host cell machinery to produce viral proteins and copies of viral DNA
  • Viral proteins are assembled into coats DNA is packaged inside
  • Tail fibres and other components are added to coats
  • Host cell undergoes lysis and dies. Infectious virus particles are released
28
Q

Lysis

A

The process of a cell bursting

29
Q

Lytic phase

A

Part of the life cycle of a virus in which viral components are replicated and packaged to form new viruses that lyse the host cell

30
Q

Obligate parasite

A

An organism that can only survive in another organism

31
Q

Bacteriophage

A

A virus that invades bacteria (T4 phage)

32
Q

capsid

A

the protective protein coat of a virus

33
Q

what are the 6 structural features of viruses

A
  • Non cellular, not living
  • No membrane bound organelles
  • Nucleic acid (DNA or RNA, never both)
  • Reproduce using host cells
  • Have a protective protein coat (capsid)
  • Microscopic (30-300 nanometres)
34
Q

peptidoglycan

A

A protein carbohydrate compound that forms the cell wall of bacteria

35
Q

Adaptations of bacteria

A
  • Flagellum: whip like tail that helps them move about
  • Bacterial capsule: A slimy layer surrounding the cell wall of some bacteria that help them stick to surfaces and increases the virulence of some species as it makes it harder for the immune system or antibiotics to attack the bacterium
  • Endospores: a tough dormant structure that helps resist unfavourable conditions and disperse to new hosts
36
Q

how do bacteria reproduce and why it is an advantage

A

Binary fission or by budding off spores. These asexual forms of reproduction allow bacteria to reproduce very rapidly in favourable conditions

37
Q

binary fission

A

the division of a cell into two cells without mitosis. A prokaryotic cell undergoes binary fission to form two identical daughter cells, a form of asexual reproduction

38
Q

what are the four shapes bacteria can be classified by

A
  • Spherical (coccus)
  • Rod shaped (Bacillus)
  • Spiral (Spirilla)
  • Comma (Vibrio)
39
Q

what are the 8 structural features of bacteria

A
  • Unicellular, prokaryotes
  • No membrane bound organelles
  • Circular DNA and plasmids
  • Flagella for movement
  • Reproduce via binary fission or endospores
  • Microscopic (1-10 micrometres)
  • Spherical, rod shaped, spiral or vibrio
  • Vary in their ability to be stained (gram stain)
40
Q

how do bacteria enter host cells

A

Instead of endocytosis like viruses, bacteria enter host cells via phagocytosis

41
Q

how do bacteria cause disease

A

Some bacteria damage host tissues directly, others produce powerful toxins that disrupt the functioning cells

42
Q

what are the 6 structural feature of fungi

A
  • eukaryotic cell structure with membrane bound organelles
  • cell wall made of chitin
  • unicellular or multicellular
  • microscopic or macroscopic
  • made up of filaments (hyphae)
  • body consisting of a mass of hyphae (mycelium)
43
Q

eukaryote

A

complex cell containing membrane bound organelles, including a nucleus

44
Q

prokaryote

A

single celled organism that lacks membrane bound organelles such as a nucleus

45
Q

Sporangia

A

a spore case in which asexual spores are formed, formed by the mycelium

46
Q

what are the 6 structural features of protists

A
  • Relatively small (2-1000 μm)
  • Eukaryotes with membrane bound nucleus
  • Mostly unicellular
  • can reproduce sexually and/or asexually
  • can exist in different forms in the life cycle, depending on their classification (spores, zoospores, filaments, hyphae, mycelia)
  • Can be plant life, animal like or fungi like in their structural or reproductive features

Bio (17 decks)

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