4.12 communicable diseases

label this picture of bacteria

how do you know if something is gram positive?

• looks purple/blue under light microscope

what stain do you use to become Gram positive?

• stain with crystal violet

what is an example of something that is gram positive?

• MRSA

how do you know if something is gram negative?

• looks red under light microscope

what stain do you use to become gram negative?

• stain with safranin

what is an example of something that is gram negative?

• E.Coli

what is the process of gram staining on bacteria?

• crystal violet is added then safranin

what is the shape and function of coccus bacteria?

what is the shape and function of spirillum bacteria?

what is the shape and function of bacillus and vibrio bacteria?

how do bacteria reproduce?

• by binary fission

what are problems with bacteria reproducing so quickly?

• food spoilage

• spread of disease

how do bacteria cause disease?

• producing toxins and causing symptoms by cell damage

• damage cell membranes, enzymes or genetic material

what happens in tuberculosis?

• lungs most often affected

• kills cells and tissues

what are symptoms of tuberculosis?

• coughing up blood

• fever

• chest pain

• chills

• night sweats

• weight loss

what happens in tuberculosis?

• infection of the meninges (membrane that surrounds brain and spinal cord)

• becomes swollen and causes damage to the brain and nerves

which category of people are bacterial meningitis most common?

• more common in infants younger than 1yrs

• people ages 16-21 because students are living in dorms or other close quarters that are at increased risk

what are symptoms of meningitis?

• fever

• headache

• stiff neck

• sensitive to light

• vomiting

• confusion

what happens in ring rot?

• ring of decay on potato tuber or tomato

• also leaf wilting

what are symptoms of ring rot?

• cause plant to wilt

• soft cheese-like rotting of the vascular ring

do the labels

how many times smaller is bacteria to a human cell?

• x100 smaller

what is smaller virus or bacteria?

• virus

how many times smaller is a virus than a bacteria?

• x1000

how do virus reproduce?

what is this?

• retrovirus e.g. HIV

• because it stores genetic information not as DNA but as RNA

what virus is this?

• tobacco mosaic virus (TMV)

what is the characteristic of HIV?

• attacks cellist the immune system and compromises the immune system

what is the characteristic of Influenza?

• attacks the respiratory system

• causing muscle pain and headaches

what is the characteristic of Tobacco Mosaic Virus (TMV)?

• causes mottling and discolouration of leaves

what happens in early stages of HIV?

• initially causes a flu like illness

• treatment would be antiretroviral drugs (without these the virus attacks the body’s immune system)

what happens in late stages of HIV/ AIDS?

• when body'‘s immune system is so badly damages

• it can no longer deal with other infections or cancers

how is HIV spread?

• sexual contact

• exchange of bodily fluids e.g. blood when drug users share needles

what is a symptom of TMV?

• distinctive mosaic patterns on leaves which affects the growth due to a lack of photosynthesis

how do yeast reproduce?

• asexual reproduction

what is characteristic of cattle ringworm?

• growth of fungus in the skin with spore cases erupting through skin to cause a rash

what is characteristic of athlete’s foot?

• growth under skin of feet, particularly the toes

what is characteristics of black Sigatoka?

• causes leaf spots on cabana plants, reducing yield

what type of cell are protoctista?

• unicellular

• eukaryotic as contains a nucleus

what is the symptoms of malaria?

• causes recurrent episodes of fever and can be fatal

how do you control the spread of malaria?

• preventing the vectors, mosquitos, form breeing

• using mosquito nets to prevent being bitten

what is characteristic of blight in potatoes / tomatoes?

• affects both leaves and potato tubers

what is characteristic of malaria?

• parasite in the blood that causes heachae, fever and may progress to coma and death

what are 2 types of protozoan disease?

1. blight in potatoes/ tomatoes

2. malaria

what are 3 types of fungal diseases?

1. cattle ringworm

2. athlete’s foot

3. black Sigatoka

what are the 3 viral diseases?

1. HIV/AIDS

2. Influenza

3. TMV

what are the 3 bacterial infections?

1. tuberculosis

2. bacterial meningitis

3. ring rot

what are the 3 ways of direct transmission between animals?

• direct contact

• inoculation

• ingestion

what is direct contact?

• contact with body fluids (STis)

• skin to skin (ringworm and athletes foot)

• microbes from faeces (diarrhoeal diseases)

what is inoculation?

• break in the skin

• animal bite

• puncture wound / sharing needles

what is ingestion?

• taking in contaminated food or drink

• transferring pathogens from hand to mouth

what are the 3 ways of in-direct transmission between animals?

• fomites

• droplet infection

• vectors

what is fomites?

• inanimate objects e.g. bedding, socks, cosmetics

what is droplet infection?

• droplets of saliva and mucus are expelled from your mouth as you talk, cough and sneeze

• other breathe this in and if contaminated with pass on a pathogen

what is vectors?

• vectors transmit disease from one host to another

what are examples of vectors?

• mosquitoes transmit malaria,

• rat fleas transmit bubonic plague

• water can transmit diarrhoeal diseasesfactors that in

factors that increase the transmission of communicable disease in animals

• overcrowded

• poor nutrition

• compromised immune system (HIV/AIDS or after surgery)

• poor disposal of waste

• climate change

• culture

• infrastructure

• socioeconomic factors

what are infectious disease caused by?

• caused by pathogenic organisms

what are non infectious diseases caused by?

• lifestyle, working conditions, genes

through where do pathogens enter the body?

• ears

• eyes

• mouth

• nose

• skin

• anus

• vagina / penis

what are the primary defense that prevent entry to pathogens? And make a brief explanation

• saliva contains antibacterial enzymes

• tears / sweat contain antibacterial enzymes

• hair and mucus in trachea traps dirt and microbes

• blood clotting prevents infection

• skin acts as a barrier and produces antimicrobial substance

• stomach acid has low pH which kills harmful microbes

• ‘good’ gut bacteria out compete the bad

• ciliated cells in the trachea waft mucus up to the throat where it is swallowed

how does your skin act as a primary defense?

• massive protective barrier covering your entire body

• produces an antimicrobial substance (sebum) that inhibits the growth of pathogens

• covered in commensal bacteria - non harmful bacteria that live in harmony with the body

how does blood clotting act as a primary defense?

• if you get cut your blood clots prevent pathogens from getting in

• Thromboplastin is released which causes the blood to clot

• serotonin contract the small blood vessels in the area to reduce blood loss

how does you mouth specifically saliva act as a primary defense?

• saliva contains antibacterial enzymes (lysozymes)

how does expulsive reflexes act as a primary defense?

• coughing and sneezing expel foreign objects and happen automatically

how does the nose act as a primary defense?

• full of hairs and mucus which trap microbes and then you blow it out or sniff it to the back of your throat and swallow it

• the mucus contains lysozymes which destroy bacterial and fungal cell walls

• also contain phagocytes

how does the eye act as a primary defense?

• yee is protected by tears and rapid eye movement (REM)

• REM pushes microbes to the front of your eye

• tears contain water, salts and lysozymes

• microbes usually die in salty conditions

how does your ear act as a primary defense?

• yellow, sticky ear wax traps pathogens

how do ciliated epithelial cells work together to prevent pathogen from entering?

• mucus traps microbes and ciliated eptihelial cells waft it to the back of your throat

• then swallow it

how are we protected from pathogens when we eat?

• microbes ingested in food enter the stomach which contains hydrochloric acid (pH2)

• kills most microbes

How does urine protect us from pathogens?

• urine is mixture of water and urea

• urea is a toxic substance made from products of broken down protein

• microbes don’t usually live in these conditions

• urine also contains lysozymes

how does the female cycle prevent pathogens?

• female cycle ensure that most microbes are ejected from vagine every 28 days with the uterine wall

how does intestine and anus prevent pathogens?

• good gut bacteria outcompete the bad ones

• as most microbes are ejected from anus with faeces

how do platelets become activated for blood clotting?

• if endothelium or vessel is damaged, platelets are exposed to proteins outside which active platelets, triggering blood clotting

how does blood clotting and repair take place?

• activated platelets form a plug over damaged area and release chemical called thromboplastin

• thromboplastin together with Ca²⁺ in blood, now act on blood protein called prothrombin

• this converts prothrombin to thrombin

• thrombin acts on soluble blood protein called fibrinogen, which catalyses formation of insoluble fibrin which forms a mesh, trapping RBCs

• activated platelets also release serotonin which causes smooth muscles to contract, which narrow blood vessels reducing blood flow to damaged area

• overtime both of these form a scab

how does inflammation take place?

• when tissue is damaged, activates mast cells that release histamine, which causes vasodilation of nearby vessels

• so increase blood supply to affected area so area feels hot and appear red

• increased temp reduces pathogens ability to reproduce

• histamine also causes blood vessels to be more permeable, so more tissue fluid forms so causes nearby tissues to swell and feel painful (called oedema)

• cytokines released also attract phagocytes

how does fever take place?

• cytokines released travel to the brain, specifically the hypothalamus and raises body temperature

• because reducing pathogen reproduce as they reproduce at 37^oc or less and specific immune system works faster at higher temperature

what are the 2 types of WBCs?

• phagocytes

• lymphocytes

what are 2 types of phagocytes?

• neutrophils

• macrophages

what are 2 types of lymphocytes?

• B lymphocytes

• T lymphocytes

what are opsonins?

• in blood, and are special molecules that recognise and stick to pathogens, tagging them as forge in

what do opsonins include?

• antibodies and other molecules called complement

how does neutrophils work?

• neutrophils attracted to molecules produced by pathogens

• receptors on phagocyte membrane attack opsonins

• phagocyte engulfs pathogen putting them in a special vacuole called phagosome

• lysosomes fuse with phagosome forming phagolysosome

• lysosome enzymes now break down pathogen and destroy it

how does phagocytes work?

• phagocytes recognises antigens on invading bacterium as forge in or by chemicals

• the cell membrane of the phagocyte fuses around the bacterium engulfing it into a vesicle (phagosome)

• a lysosome fuses with the vesicle (phagolysome) and empties its digestive enzymes to digest / hydrolyse the micro-organism

• antigens are presented on cell surface membrane. Useful products taken into cytoplasm by diffusion / AT and waste products exocylosed

how do macrophages work?

• same as neutrophils but have additional feature called antigen presentation

• at end, glycoproteins from cytoplasm (called Major Histocompatibility complex) (MHC) move to phagolysosome and bind to antigen molecules

• when MHC binds to antigen forms an MHC-antigen Complex which then moves to cell surface membrane and antigens are presented to exterior of cell to lymphocytes

• so say macrophages act as antigen presenting cell (APC)

what is released when phagocyte engulfs a pathogen? And what does it do?

• releases cytokines

• this signal to phagocytes and other immune cells to move to the site of infection

what is an antigen?

• protein on surface of a pathogen (or other cells including our own)

what is an antibody?

• proteins made by a B lymphocyte in response to an antigen

complete the labels

what is the variable region?

• area of antibody that is different on different antibodies but complementary to their specific antigen

what is a constant region?

• area that is the same on all antibodies, has a site where it can bind to immune system cell

what are the bonds between antibodies?

• disulphide bonds

what is the purpose of the hinge region?

• allows flexibility so distance between 2 antigen binding sites can vary

how does an antibody look like

what is another name for antibodies?

• immunoglobulins

what is an antibody made of?

• glycoproteins consisting of 4 polypeptide chains

what part shows disulphide bridges?

• black lines

where do the antigen bind to?

when antigens bind to the antibody what is it called?

• antigen-antibody complex