Week 4 Flashcards
What is the easy method for multiplying powers of 10?
Add the powers
What is the easy method for dividing powers of ten?
Subtract the powers
What is the easy method for subtracting powers of 10?
Divide the powers
What is the easy method for adding powers of ten?
Multiply them
How many nm in diameter is a red blood cell?
10000
How many nm in length is E.Coli?
3000
How many nm in length is Ebola?
970nm
How many nm in length is Adenovirus?
90nm
What is a viable count?
A sample is often diluted if it is too concentrated to allow a viable count. Used to investigate number of living cells in a culture.
What do serial dilutions allow for?
Countable investigation
What are spread plates used for?
To calculate how many bacteria are in a sample
What would the ideal dilution of a bacterial sample produce upon investigation?
30-300 colonies
In a sample of 1ml with a 10^-6 dilution, 250 Bacteria are present. What was the original bacterial colony?
Show your working out?
250 x10^6
2.5 x10^8
What is the difference in the bacterial count between a 1ml and a 0.1ml plate?
The 0.1ml plate will have a 10x greater bacterial count.
What are serial dilutions on bacteria?
Adding measured amounts of buffer to a bacterial solution to a level where they can be easily counted.
What is the formula for finding the amount of colony forming units per ml of a solution?
(Number of colonies x inverse dilution) / volume of sample
What is often used to identify the number of colonies in a very high cfu sample?
Log cfu/ml
Approximately how many species of Protozoa exist?
65000
Are most Protozoa pathogenic or not?
Not
Where do most Protozoa live?
Freely in the water or in the soil.
Describe the cellularity of most protozoa species.
Unicellular
What types of locomotive structures can protozoa contain?
Flagella, Cilia, Pseudopods
What is the motile feeding stage of the protozoan life cycle called?
Trophozoite
What is the dormant resting stage of a Protozoan life cycle called?
Cyst
How do Protozoa reproduce?
Asexually or sexually
What happens to the Protozoa when moving from the Trophozoite phase to becoming a cyst?
It is dried and nutrient sources are reduced. The cell also rounds up, loses motility and forms a thick wall.
What happens to a Protozoa when moving from the cyst back into the Trophozoite phase?
The cyst wall breaks open as moisture and nutrient sources are restored. This re-activates the Trophozoite.
What can also be present to work alongside a flagella in Protozoa to aid locomotion?
Amoeboid motion
What disease does Trypoanosome Brucei cause?
Sleeping sickness
What are the 2 type of Amoeboid Protozoa?
Amoeba and Radiolarian
What are the features of Amoeba protozoa?
They form Pseudopods
What are the features of Radiolarian Amoeboid protozoa?
They are shelled ameba which undergo Entamoeba Histolytics.
What type of infections can Radiolarian Amoeba Protozoa cause?
Dysentery, abdominal pain, fever, diarrhea, weight loss.
In approximately what % of the worlds population do Radiolarian Amoeboid protozoa cause symptoms?
10%
What are Pseudopods and what are their purpose?
Temporary protections of the cytoplasm of unicellular or Eukaryotic cell membranes. Used for movement, gathering food and protection.
What is the nickname often given to ‘Pseudopods’?
False fee
Outline how pseudopods cause cellular movement.
The cell membrane pushes in one direction and the cytoplasm flows into the bulge. This allows the Protozoan to move and drags the rest of the cell behind it.
Describe the possible structures that Pseudopods can have.
Lobes, be blunt, be branched or be filamentous.
What is the process by which cellular cytoplasm flows into pseudopods?
Ectoplasm
What are the structures of Radiolarians?
They are Amoeboid protozoa with silica-based skeletons.
Where are Radiolarian Amoeboid protozoa often found?
In the sea as part of the zooplankton
Name the type of protozoa that have cilia.
Trophozoites
How many nuclei do ciliated protozoa have?
2
What are the 2 nuclei of ciliated protozoa?
Macro and micro
What are the purposes of the 2 nuclei in ciliated protozoa?
1 controls everyday functions and the other is used for reproduction.
What are the purpose of protozoa having cilia?
They help organisms move, gather food and sense environment.
How do ciliated protozoa reproduce?
By binary fission or conjugation
Outline the parasitic ability of Apicomplexa protozoa.
All parasitic
How do Trophozoites move?
By gliding
How do Apicomplexa protozoa spread their parasites?
Produce sporozoites which are then transferred into a new host.
What is the name for the asexual method by which protozoa reproduce?
Binary fission
How does sexual reproduction occur between Paramecium protozoa?
Conjugation causes 2 paramecia to join and exchange genetic material.
Outline the sexual reproduction process between 2 paramecium protozoa.
Two paramecium individuals have surface contact.
The micronuclei divide by meiosis to produce 4 haploid micronuclei.
Three micronuclei degrade. The remaining micronucleus divides to form male and female pronuclei.
Male pronuclei are exchanged between conjugates.
Males and female pronuclei fuse and individuals separated.
Old macronuclei are absorbed and replaced by new micronuclei.
How are pathogenic protozoa frequently spread between animals and humans?
By insects
What is Zoonoses?
A disease which can be transferred from animals to humans
Where do Amoeboid Protozoa usually live?
In human water or food. And freely in water
In what animals are ciliated protozoa zoonotic?
Zoonotic in pigs
What is Entamoeba Histolytics?
Amoeba protozoa which alternate between a large trophozoite and a smaller cyst.
By what means are trophozoites motile in Entamoeba Histolytica?
By using pseudopods
What are the primary hosts of Entamoeba Histolytics infective Amoebas?
Humans
How do infective Amoebas entered into the human body?
By ingestion of food or water by the human
Where do cysts caused by infective amoebas often appear in humans?
The small intestine
How does the small intestine affect infective amoeba protozoa and why?
The alkaline pH and digestive juices stimulate cysts to release trophozoites. Trophozoites then multiply, move about and feed.
What effect does the release of Ameoba protozoa releasing enzymes have on the human body?
They secrete enzymes into the small intestine causing tissues to dissolve and penetration of deeper layers of mucosa also occurs.
What is mucosa?
Mucous membrane
What are the life threatening manifestations that infective amoebas can cause?
Hemorrhage, perforation, appendicitis and tumour like growths.
What is Amebomas?
A rare complication of Entamoeba Histolytica where in response to the infection Amoeba, there is formation of annular colonic granulation which results in a large local lesion of the bowel.
What is a lesion?
An ulcer, abscess or tumour
What is the fatality rate caused by Entamoeba Histolytica?
10%
What drugs are effective against Entamoeba Histolytica?
Iodoquinol, metronidazole, chloroquine
Which part of the body do the amoeba ‘Naegleria Fowleri and Acanthamoeba’ affect?
The brain
Where do ‘Naegleria Fowleri and Acanthamoeba’ usually live?
In standing water
What contact must occur between Amoeba which cause brain infections and humans?
Nasal contact with infected water or with the eyes
What is meningoencephalitis?
Inflammation of the membranes of the brain and adjoining cerebral tissues.
Where is ‘Ballantidium Coli intestinal ciliate’ found?
In the intestines of domestic animals such as pigs and cattle.
How is ‘Ballantidium Coli intestinal ciliate’ squired?
By ingesting cyst-containing food or water.
How does ‘Ballantidium Coli intestinal ciliate’ cause symptoms in organisms that become infected?
Trophozoites erode the intestine and therefore cause intestinal symptoms.
How are healthy humans affected by ‘Ballantidium Coli intestinal ciliate’?
They are resistant
What are the treatments for ‘Ballantidium coli intestinal ciliate’?
Tetracycline, iodoquinol, nitrimidazine, metronidazole.
Are Giardia Lamblia Flagelata pathogenic?
Yes
Describe the structure of Giardia Lambila Flagelate.
Symmetrical heart shape with concave ventral surface.
Describe the cysts of Giardia Lamblia.
Small, compact, multinucleate
Where are reservoirs of Giardia Lamblia Flagelate found?
Beavers, cattle, coyotes, cats and humans.
How long can the cysts of Giardia Lamblia Flagelate survive for?
2 months
How are Giardia Lamblia usually entering the body?
By ingesting food or water
How many cysts do Giardia Lambila Flagelate usually cause?
10-100
Outline the pathway of Fiardia Lamblia Flagelate cysts once in the body.
Enter the duodenum of the stomach where they germinate and then travel to the jejunum to feed and multiply.
What are the symptoms caused by Giardia Lamblia?
Giardiasis = diarrhoea and abdominal pain.
What is giardiasis?
Infection of the small intestine caused by Giardia Lamblia Flagelate which results in diarrhoea and abdominal pain.
Why is diagnosis of infections caused by Giardia Lamblia Flagelate often difficult?
Organism is shed in faeces intermittently.
What treatments are used against Giardiasis?
Quinacrine or Metronidazole
What are Haemoflagelates?
They are organisms which require hematite obtained from blood haemoglobin.
How are Trypansome Brucei identified?
By their infective stage (trypomastigote) which is very long.
Describe the cell structure of Trypanosome Brucei.
Spindle-shaped cell with tapered ends.
What are the 2 types of Trypanosomiasis ?
T. Bruei
T. Cruzi
What disease does T. Brucei cause?
African sleeping sickness
What disease does T. Cruzi cause?
Chagas disease
Where is Chagas disease endemic?
Central and South Africa
How is African sleeping sickness spread?
By Tsetse flies
What type of subspecies cause African sleeping sickness and in what areas do they act ?
T.b. gambiense - West Africa
T.b. Rhodesiense - East Africa
How does the disease of sleeping sickness infectionst mammals?
The biting of the fly innoculates skin with trypomastigotes, which multiplies in blood and damages spleen, lymph nodes and brain.
What are the symptoms of African sleeping sickness?
Sleep disturbances
Tremors
Paralysis
Comas
How can African sleeping sickness be treated?
Melarsoprol
Eflornitine
How many species of the malaria causing agent are there?
4
What disease does ‘Apicomplexan Plasmodium Toxoplasma’ cause?
Malaria
What is the primary vector of malaria?
Female Anopheles mosquitos
how many new cases of malaria occur each year?
300-500 million
How many deaths occur due to malaria each year?
2 million
What are the symptoms of malaria?
Intense cold followed by hot dry sweats and then drenching swears.
Headaches
Vomitting
What are the long term diseases and medical issues that malaria can cause?
Anaemia
Cerebral malaria
Liver damage
Acute renal failure
In Protozoa, what feature is used to protect the cell membrane?
Pellicle
What is the Pellicle of Protozoa?
A protective Layer of proteins against the cell membrane.
What is the product of sexual reproduction of Paramecium protozoa?
There are no offspring, paramecium are just genetically changed.
Does sexual reproduction of paramecium protozoa produce offspring ?
No
Why are people who wear contact lenses at greater risk of brain infections by Amoeba?
Contact lenses frequently scratch the cornea of the eyes, leaving scratches and eye damage sites through which Amoeba can easily enter the brain and cause infection.
What are the differences in structure between a Trophozoite and a mature cyst of a protozoa?
Trophozoites have a micronucleus whereas nature cysts do not.
Trophozoites also have autosomes and cilia tufts but mature cysts do not.
Mature cysts have cyst walls but Trophozoites do not.
How many nuclei do mature cysts have?
1 - macronucleus
How many nuclei do Trophozoites have?
2
Macro and micro
What features so Trophozoites have that Mature cysts do not?
Micronucleus, cytosine, cilia tufts.
What features do Mature Cysts have that Trophozoites do not?
Cyst wall
What infection/ disease does Giardia Lamblia Flagellate mainly cause?
Giardiasis
How many strains of Trapanasome Brucei are present ?
2
What type of mosquito can spread the malaria virus?
Anopheles females
Why is malaria spreading north?
Malaria is likely to move north due to climate change and thermal increase. If temperature in the North increases, Anopheles female mosquitos may move into these areas and spread malaria.
What is the main issue with malaria virus have an extremely complex life cycle?
Makes treatment very difficult
Where is Malaria generally endemic?
In very poor countries
What method is widely used to prevent spread of malaria ?
Mosquito nets
What is the volume of a spread plate?
0.1ml
What is the volume of a pour plate?
1ml
What are the phases of bacterial growth?
Lag phase
Exponential growth
Stationary phase
Death
What occurs during the bacterial growth phase?
Cells are metabolically active and increase in size whilst they synthesise the enzymes and other factors required for cellular division.
What is meant by ‘exponential’ growth of bacteria?
Growth of bacteria continues to increase more rapidly relative to the total quantity of bacteria present.
Why do bacteria enter a stationary growth phase?
If nutrient sources are depleted so no further growth can occur.
What are the benefits of recording optical density of a bacterial colony?
Allows concentration of bacteria in a sample to be recorded as a quantitative value.
what are the negatives of recording optical density of a bacterial colony?
Spectrophotometers all have different optical configurations so will all show different optical densities of the same sample. Can confuse results.
What are viable bacterial counts?
Viable units grow to form colonies.
What are the positives of only counting viable bacteria?
This is a highly sensitive and specific technique
What are the issues with counting only viable bacteria in a given sample?
Only live bacteria will form colonies that can be counted.
Small clumps or chains of cells may be identified as a single colony when they are actually more than 1.
What is generation time of a bacteria?
The time it takes for a bacterial population to double in size.
By what process do bacteria reproduce?
Binary fission
What is the time between each division in binary fission called?
Generation time
What is generation time of a bacterium?
The time between each division in binary fission.
What is the equation for calculating generation time of a bacterium?
(t x log 2)/ (log b - log B)
What is the name given for the time it takes for a bacterial population to double in size?
Generation time
What are the 2 ways in which bacteria can be grown?
Sessile
Planktonic
What is sessile bacterial growth?
Bacteria are thinly spread over an inert surface and grown on biofilms.
They make 20-30 division’s per 24 hours
How many divisions does a single bacterial cell make per 24 hours during sessile growth?
20-30
What is planktonic bacterial growth?
Bacteria grown in tubed suspension.
Divide 10^7 to 10^9 times per cell per 24 hours
How many divisions does a single bacteria make per 24 hours during planktonic growth?
10^7 to 10^9
What is turbidity of a solution?
The cloudiness of a solution
What type of bacterial growth takes place in turbid suspension?
Planktonic
What type of bacterial growth takes place on biofilms ?
Sessile
In generation time, what do the values t, B and b mean?
t = time between B and b b = number of CFUs at chosen time 1 B = number of CFUs at chosen time 2
What phase of bacteria growth should be used to calculate generation time?
Exponential phase
