Chapter 12// Communicable Diseases Flashcards
communicable disease
diseases that are caused by pathogens and can be passed from one organism to another, of the same or different species
pathogen
either bacteria, fungi, virus or protoctista microorganisms that cause disease
vector
a living or non-living factor that transmits a pathogen from one organism to another e.g. malaria mosquito
non- communicable diseases
diseases that can not be passed from one organism to another e.g. diabetes/ cancer
Do bacteria have membrane bound organelles?
No
How can bacteria be classified?
By their cell walls— different cell walls react differently with gram staining
GRAM POSITIVE BACTERIA= look purple/ blue under microscope
GRAM NEGATIVE BACTERIA= look red
This is useful as we know by the type of cell wall how bacteria react to different antibiotics
bacteriophage
viruses that attack bacteria use bacterial cells as hosts destroying bacteria after they replicate
what vector transfers malaria and what kingdom does it belong to
plasmodium
Kingdom: protoctista
are protoctista single-celled eukaryotes
yes
are fungi single-celled?
yes
saprotrophic feeding
release enzymes to decompose dead organic matter
Parasitic
feed on living plants/ animals
pathogen modes of action: fungi
fungi digests living cells and destroys them
Some fungi produce toxins
pathogen modes of action: bacteria
bacteria produce toxins causing diseases e.g. some bacterial toxins break down cell membranes or inactivate enzymes
pathogen modes of action: protoctista
Protoctista take over cells by digesting them and using the cell contents to reproduce e.g. malaria
pathogen modes of action: virus
viruses take over cell metabolism// viral genetic material is inserted into host cell, the host cell uses viral DNA to make more viruses, cell bursts and dies releasing more virus = spreads 🦠
What is ring rot caused by, what plants does it affect
Caused by GRAM POSITIVE BACTERIA
affects potatoes, tomatoes + aubergines
What is tobacco mosaic virus caused by, what plants does it affect
caused by TMV VIRUS
Affects tobacco plants, tomatoes, peppers, cucumber + petunias 🥔🍅🥒🚬🌷
What is potato blight caused by, what plants does it affect
Caused by FUNGUS LIKE PROTOCTISTA
Affects tomatoes + potatoes 🥔 🍅
What is black sigatoka caused by, what plants does it affect
Caused by FUNGUS which attacks + destroys leaves, hyphae penetrate + digest cells turning leaves black
Affects bananas 🍌
Tuberculosis
- bacterial disease (Mycobacterium tuberculosis and M.bovis)
- effects humans, cows, pigs, badgers + deer
- TB damages lung tissue and suppresses immune system making body less able to fight disease
- TB is both curable by ANTIBIOTICS and preventable thru vaccination and better living conditions
Bacterial Meningitis
- bacterial infection (streptococcus pneumoniae)
- effects children between 15-19
- infection of meninges of the brain which spreads to rest of the body causing septicaemia (blood poisoning and rapid death)
- antibiotics will cure the disease if delivered early + vaccines protect against some forms
HIV (human immunodeficiency virus) causes AIDS (acquired immunodeficiency syndrome)
- virus (HIV) targets T Helper cells in the immune system, gradually destroying the immune system so ppl affected are open to other infections such as TB/ pneumonia
- effects humans and non-human primates
- HIV is a retrovirus with RNA in its genetic material contains enzyme REVERSE TRANSCRIPTASE which transcribes the RNA to a single strand of DNA which interacts with genetic material of host cell
- there’s no cure but ANTIRETROVIRAL drugs slow the progress of the disease— u must take a combination of antibiotics cuz otherwise get resistant
Retrovirus
Any group of RNA virus which insert a DNA copy of their genome to replicate in host
Give 4 ways HIV can be spread
unprotected sex, through bodily fluids
Shared needles
Contaminated blood
Mother to baby through birth/ breastfeeding
Influenza (flu)
- viral infection : orthomyxoviridae of the ciliated epithelial cells in the gas exchange system, killin them leaving airways open for infection
- flu viruses mutate regularly, sometimes major antigen changes cause a flu epidemic
Malaria
- caused by parasitic plasmodium protoctist spread through ANOPHELES mosquito
The plasmodium parasites reproduce inside female mosquitoes, the fem.mosquito needs protein from blood to lay eggs so feeds on people which is how ppl are infected (invades red blood cells, liver + brain)
There is no vaccine but preventative measures are effective — destroying by insecticide + remove standing water, window screens and clothing to prevent bites
Ring worm
- fungal disease
- affecting humans, cattle,dogs and cats
- antifungal creams are an effective cure
Athlete’s foot
- fungal disease (form of ringworm) caused by TINIA PEDIA
- grows on + digests warm moist skin between toes causing scaling
- antifungal creams effective cure
Direct transmission definition
pathogen transferred directly from one person to another
Indirect transmission definition
Pathogen travels from one individual to another indirectly
Describe 4 ways pathogens are DIRECTLY transmitted in animals
• DIRECT CONTACT
=kissing/sex, direct skin to skin contact, microorganisms from faeces on hands
• INOCULATION
= break in skin (HIV during sex), from animal bites, sharing needles
• INGESTION
= taking in contaminated food/drink
• TRANSMISSION FROM INFECTED ANIMAL
= cat scratch disease/ rabies
Describe 3 ways pathogens are INDIRECTLY transmitted in animals
^FOMITES
= objects like bedding, socks or cosmetics transfer pathogens when shared
^ DROPLET INFECTION (inhalation)
= drops of saliva/mucus expelled from ur mouth contain pathogens breathed in by others
^ VECTORS
=transmit communicable pathogens from one host to another (mosquitoes transfer malaria, water can also act as a vector of disease like diarrhoea)
factors affecting transmission of communicable diseases in animals
- poor nutrition
- compromised immune system e.g. patient w HIV
- poor disposal of waste— become breeding sites for vectors
- climate change
factors affecting transmission of communicable diseases in plants
🦠 overcrowding increases likelihood of contact
🦠 poor mineral nutrition reduces resistance of plants
🦠planting crops susceptible to disease
🦠damp warm conditions, increase spread of pathogens or spores
Ways in which pathogens are DIRECTLY transmitted between plants
direct contract of a healthy plant w any part of a diseased plant
Ways in which pathogens are INDIRECTLY transmitted between plants
- soil contamination = infected plants leave pathogens or reproductive spores from fungi in the soil (e.g. black sigotoka spores left in soil contaminate the next crop)
- vectors such as:
WIND (bacteria or viruses or spores carried by wind to other crops),
WATER (spores in water + raindrops carry pathogens),
ANIMALS (carry pathogens from one plant to another,
HUMANS (pathogens/ spores transmitted by hands)
plant defended against pathogens
PHYSICAL DEFENCES
= when plant attacked by pathogens it sets up mechanical defenders: produces CALLOSE polysaccharide between cell walls to strengthen them (blocks siege plates in phloem sealing off spread of pathogens) and LIGNIN is added to make barrier to invasion
CHEMICAL DEFENCES
= produce insect repellent e.g. citronella, produce insecticides e.g. pyrethins+ caffeine, produce antibiotics e.g. phenols, gossypol, produce anti-oomycetes e.g enzymes that break down GLUCANS found in oomycete cell walls, produce general toxins e.g. cyanide when attacked
