lectures 19-21

Question 1

proteins in microtubules

Answer 1

alpha and beta tubulin

Question 2

3 divisions of eukaryotic organisms

Answer 2

animal parabasilids
plant-protists
diplomonads

Question 3

what are microtubulins involved with

Answer 3

Cell shape
Chromosome movement in cell division
Cell motility (cilia and flagella)

Question 4

energy source of flagella in bacteria

Answer 4

proton pump in membrane

Question 5

energy source of flagella in protists

Answer 5

ATPase dyenin

Question 6

microfilaments

Answer 6

~7nm in diameter
Polymers of actin
Involved in maintaining and changing cell shape

Question 7

hydrogenosome

Answer 7

Lack cristae and the TCA cycle
Present in anaerobic protists
Metabolism is fermentative
Oxidation of pyruvate

membrane enclosed organelle

Question 8

pinocytosis

Answer 8

the uptake of nutrients present in solution

characteristic of protists without a differentiated oral cavity

Question 9

phagocytosis

Answer 9

requires special organelles (e.g. cytostome, oral funnel, pharyngeal basket, etc.)
three steps: food capture, phagosome formation, and digestion

Question 10

contractile vacuole

Answer 10

contraction of vacuole expels water from cell

vacuole becomes full as canals take up water from cytoplasm and move it to vacuole

ciliates are hypotonic

Question 11

protist ‘eyespot’

Answer 11

photoreceptive organelle which through photoreceptor proteins causes flagellar to move through signal transduction.

Question 12

do all protists have mitochondria

Answer 12

no

energy is generated through alternative routes

Question 13

diarrhoea symptoms

Answer 13

A loose or watery stool at least three times a day,.

Results in fluid loss and dehydration

Question 14

diarrhoea causes

Answer 14

viruses/bacteria/protists

rotavirus

Question 15

3 types of diarrhoea

Answer 15

osmotic

• impaired absorption
• excessive solutes
• enhanced excretion
• enterocyte malfunction

inflammatory

• mucosal invasion
• leukocytes in stool

secretory

• toxin associated
• excessively watery

Question 16

solutions to high child mortality rates from diarrhoea

Answer 16

Delivery of life-saving treatment of low-
osmolarity oral rehydration salts (ORS)
and zinc tablets.

Vaccination.

Provision of safe drinking water and sanitation.

Improved hygiene

Question 17

zinc deficiency

Answer 17

reduces the number of B and T lymphocytes (CD4+ lymphocytes in particular) through increased apoptosis, and reduces their functional capacity

disrupts the intestinal mucosa

reduces brush border enzymes

increases mucosal permeability and the intestinal secretion of water

Question 18

importance of zinc

Answer 18

stabilises cell membrane

acts as a potassium channel blocker, inhibiting cyclic adenosine monophosphate-mediated chlorine

Question 19

faecal-oral transmission

Answer 19

when bacteria or viruses found in the stool of one child (or animal) are swallowed by another child

Question 20

encystment

Answer 20

helps the microbe to disperse easily, from one host to another or to a more favourable environment

Question 21

excystation

Answer 21

cyst wall breaks down when the encysted microbe reaches an environment favourable to its growth and survival

Question 22

microbial cyst

Answer 22

a state of suspended animation in which the metabolic processes of the cell are slowed down and the cell ceases all activities like feeding and locomotion

excreted in faeces
infectious
resistant

Question 23

trophozoite

Answer 23

a growing stage, where nutrients are absorbed from the host

inhabits intestinal tract
not infectious
motile

becomes a cyst

Question 24

dysentry

Answer 24

infection of large intestine

blood and mucous in stool

Question 25

gastrointestinal tract infections

Answer 25

nausea, vomiting, diarrhoea, abdominal distress

Question 26

gastroenteritis

Answer 26

disease of small intestine and indicates excessive secretion relative to absorption. Results in fluid and electrolyte loss

Question 27

layers of gi tract

Answer 27

``` mucosa submucosa muscle serosa lumen ```

Question 28

functions/features of intestinal structure

Answer 28

Large surface area: 200x skin. Protect rest of body from intestinal content. Take up nutrients from food.

Question 29

effect of parasite damage to gi tract

Answer 29

Water absorption impaired due to epithelial damage. Crypt cells produce new cells but excrete water and Cl-. Water not reabsorbed with Na+

Question 30

amoebiasis

Answer 30

3rd leading cause of parasitic death

Question 31

where do trophozoites replicate

Answer 31

large intestine

Question 32

entamoeba histolytica

Answer 32

anaerobic parasite causes amoebiasis lyses cells in contact dependent manner eats its way into epithelium

Question 33

how do entamoeba histolytica get access to circulatory system

Answer 33

erode mucous layer break down extracellular matrix kill neutrophils Perforation of serous layers leading to peritonitis (inflammation of peritoneum)

Question 34

virulence factors of entamoeba

Answer 34

1. Adhesion – Gal/GalNAc lectin 2. Mucous breakdown – Cysteine proteases 3. Cytotoxicity – Pore forming peptides (Amebapore)

Question 35

giardia

Answer 35

Most common parasite isolated from human stool. Colonises upper portions of the small intestine Often results in asymptomatic infections rarely penetrates cell wall produces resistant cysts

Question 36

giardia adhesive disk

Answer 36

Important for adhesion to intestinal epithelium. Made from cytoskeleton and contractile proteins. Unique cytoskeletal element called a microribbon

Question 37

symptoms of acute giardisis

Answer 37

``` diarrhoea bloating nausea weight loss malaise flatulence ```

Question 38

giardia pathogenesis

Answer 38

Attachment could cause irritation and mucosal injury. Villus blunting, enterocyte apoptosis. Increased crypt cell activity: hyperplasia with hypersecretion of Cl- and water.

Question 39

treatment of giardisis

Answer 39

nitroimidazole | e.g. metronidazole

Question 40

balantidium coli

Answer 40

infectious ciliate. Rare: <1% - common in people that work with pigs. Fecal-oral route of transmission. When symptomatic: diarrhoea or dysentery. (if invades intestinal epithelium shows diarrhoea similar to Entamoeba dysentery with blood and mucus) Nuclear dimorphism Asymmetric division

Question 41

blastocystis

Answer 41

Only known mammalian pathogen within the stramenopiles linked to irritable bowel syndrome

Question 42

cryptosporidium

Answer 42

apicomplexan parasite | diarrhoea

Question 43

extracytoplasic association - crytosporidium

Answer 43

Sporozoites do not invade enterocytes but attach to epithelial cells. Induce fusion of microvilli: parasite encapsulated by host membrane. Hidden from immune system

Question 44

sexual reproduction - cryptosporidium

Answer 44

Two rounds of asexual reproduction of zygote to generate oocyst Thick-walled ones thought to be excreted and thin-walled cysts reinfect. Healthy individuals suppress merozoite release.

Question 45

transmission cycles- crytposporidium

Answer 45

Although typical fecal-oral route, Cryptosporidium notorious for waterborne outbreaks. Drinking water problems from surface water reservoirs. Oocysts resistant to routine chlorine treatment. Zoonotic C. parvum from animal waste. Up to 100 billion oocysts excreted by calves