infectious diseases rm

disease

any condition that interferes with how an organism, or any part of it, functions

Pathogen

an infectious agent that causes diseases

Viruses

A noncellular pathogenic agent, containing either DNA or RNA, that can only reproduce inside a living host cell

Bacteria

microscopic unicellular organisms that do not have a nuclear membrane or membrane bound organelles – they are prokaryotic

Fungi

A diverse kingdom of spore producing eukaryotic organisms; they have a cell wall made of chitin; they do not possess chloroplasts; they have complex cell cycle, in which spores can develop into hyphae then grow into a mycelium; they can be unicellular, but are mostly multicellular

Protists

An organism in the kingdom Protista that is eukaryotic but may have plant animal or fungus like features; a protist usually unicellular and tiny

Viral disease examples

Influenza

Ross river virus disease

Viral diseases of honeybee

Bacterial disease examples

Tuberculosis

Crown gall of plants

Fungal disease example

Chytridiomycosis

Protist disease examples

Malaria

Jarrah dieback

zoonotic diseases

infectious diseases that can be transmitted from one vertebrate group to another

reservior

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

Vector

Vector is an agent that transmits pathogens from one host to another; in genetics it refers to a vehicle used to transfer DNA sequences from one organism to another

Virulence

the intensity of the effect of the pathogen, measure of the severity of the disease it causes

incubation period

the time between infection and the onset of symptoms

Obligate parasite

An organism that can only survive in another organism; it is obliged to live in another organism

steps in viral replication in a eukaryotic host

Attachment

Entry of virus, nucleic acid into the 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 protein assemble at the hosts cell membrane

Receptors

A site on a cell membrane that receives a signal, or the site on a host cell where a virus may attach prior to endocytosis

Steps of virus reproducing inside a bacterial cell

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

Tall fibres and other components are added to coats

Host cells undergoes lysis and dies. Infectious virus particles are released

Fungi structure

Are eukaryotic cell structure with membrane bound organelles

Have a cell wall made of chitin

Are unicellular or multicellular

Can be microscopic or macroscopic

Can be made up of filaments

Can have a body consisting of a mass of hyphae, known as mycelium

Bacteria structure

Unicellular, prokaryotes

Have no membrane bound organelles

Circular DNA and plasmids

May have flagella for movement

Reproduce via binary fission or budding off spores

Are microscopic, 1-10 micrometres

Spherical, rod shaped, spiral or vibrio

Vary in their ability to be stained (Gram stain)

flagellum

a long, thin, whip like structure attached to a cell. It acts as a tiny motor. It helps microscopic cells and single cell swim through liquid

virus structure

Non cellular, not living

Have no membrane bound organelles

Have nucleic acid (DNA or RNA)

Reproduce using host cells

Have a protective protein coat called a capsid

Are microscopic 30-200 nanometres

Protist structure

Relatively small 2-1000 micrometers

Are eukaryotes, with a membrane bound nucleus

Mostly unicellular

Reproduce asexually and sexually

Can exist in different forms during their life cycle, depending on their classification

Can be plant like, animal like or fungi like in structure or reproduction

sporozites

tiny infectious cell form of a parasite, it is often infective agent that enters the host

life cycle of Pathogen step 1

Infected host or other reservoir. The pathogen lives in an infected host or in another reservoir where it can survive

Life cycle of Pathogen step 2

Site for replication of infectious agent. Enter the host, Multiply in the host tissues, The host will resist or not which will stimulate the host defence mechanisms, Damages the host

Life cycle of pathogen step 3

Portal of exit, e.g. bite, digestion, respiratory system, reproductive system, roots and leaves

Life cycle of pathogen step 4

Other possible reservoirs e.g. soil, water, animals

Life cycle of a pathogen step 5

Mode of transmission, Direct or indirect

direct transmission examples

Touching

Sexual contact

Contact with nasal and oral secretions

Biting

Direct contact with blood and bodily fluid

Direct contact with roots or leaves

indirect transmission examples

Airborne- sneezing

Touching an infected surface

Contaminated food or water

Infected surgical equipment

Vectors

life cycle of a pathogen step 6

Portal of entry

pathogen life cycle step 7

Susceptible host becomes infected if the pathogen enters their body.

airborne droplet transmission

sneezed or coughed into the air and are suspended in air currents for a period of time before being inhaled or landing on a surface such as a table or tissue

Indirect because it does not occur until later or occurs over long distance

Crown Gall in Plant pathogen type

Bacterial

Crown Gall in Plant Pathogen name

Agrobacterium tumefacians

Crown Gall in Plant life cycle Step 1

Bacterial spores released from infected plant galls

Crown Gall in Plant life cycle step 2

Direct and indirect modes of transmission, spores are transmitted by contact or by vehicle into wounded routes in a susceptible plant - portal of entry is through a wound

Crown Gall in Plant life cycle step 3

Bacterium attaches to a wounded plant cell and multiplies

Crown Gall in Plant life cycle step 4

Bacterium transfers a plasmid into plant cells. Plasmid contains genes for uncontrolled cell growth

Crown Gall in Plant LIFE CYCLE step 5

Plant cell genome transforms and starts to divide, rapidly forming galls

Crown Gall in Plant life cycle step 6

Galls grow around the crown of the lant and stunted growth results

Crown Gall in Plant life cycle step 7

Spores can be released to continue the cycle