Lecture24- parasites

Question 1

What is parasitism?

Answer 1

It is when an organism lives in or on a host- and the organism benefits while also harming the host

Question 2

Describe the 3 types of parasitism

Answer 2

Ectoparasite- Lives In surface of host INFESTED (fleas, lice, ticks)
Endoparasite- Lives within the host INFECTED (roundworms/tapeworms) in gut
Hyper parasite- parasite living within a parasite ( malarial parasite in mosquito)

Question 3

How are parasites usually got rid of?

Answer 3

Excretion

Question 4

What are the 2 ways parasites can be transmitted from host- host?
1st

Answer 4

• Consumption of contaminated food or putting object in mouth contaminated with feces of an infected animal
• Vector

Question 5

What are the 2ntypes of parasitic vectors?

Answer 5

Biological- transports AND is necessary for life cycle

Mechanical- used just to physically carry the parasite

Question 6

What are Helminths?

Answer 6

Multicellular parasitic worms that can be seen with naked eye

Question 7

What are Protozoa?

Answer 7

Informal grouping of 
-unicellular
-Eukaryotic
-Heterotrophic organisms 
Belonging to the Kingdom Protista

Question 8

Give eg’s of non protozoic Protista that are biologically important

Answer 8

Algae- found in aquatic environments and are photosynthetic

Water & slime molds- Saprophyric like fungi but MOTILE

Question 9

What is the size range of most Protozoa?

Answer 9

Small (2-1000 μm)

Question 10

How do most Protozoa digest food, and what type do Cell wall do they possess?

Answer 10

Most Protozoa ingest food (Halozoic) [not parasites] and are heterotrophs
They LACK a cell wall

Question 11

What is the typical environments that Protozoa live in?

Answer 11

Water
Moist soil
Inside other organisms (as parasites)

Question 12

What are the 2 modes that Protozoa exist in, and which is most common?

Answer 12

-Most exist as Trophozoite- vegetative, reproducing form that feeds and multiplies
-Some exist as Cyst- Dormant, protective form from harsh conditions when cells come together (multinucleated)
Under favorable conditions the cysts can reproduce by Nuclear Organization & cell division

Question 13

What are the common methods of asexual reproduction of Protozoa?

Answer 13

• Binary fission (most common)
• Schizogony (multiple fission) nucleus divides many times & cell separates into several daughter cells
• Budding buds form and daughter cell pinches off

Question 14

Are Protozoa able to reproduce sexually?

Answer 14

Some are, during a part of their life cycle.

Fusion of haploid sex cells (only one of each chromosome pair)

Question 15

What are the 3 types of locomotion that Protozoa May possess? Link them to the type of medically important Protozoa.

Answer 15

-pseudopods (amoeboids)
-Cilia (Ciliates)
-Flagella (Flagellates)
Some do not move (intracellular parasites)

Question 16

Describe pseudopods of Amoeboids

Answer 16

• Used to move & engulf food
• they form when cytoplasm moves in a particular direction
• Phagocytoses organism by surrounding and engulfing it (algae, bacteria, other protists)
• Digestion occurs in food vacuole (contains hydrolytic enzymes)

Question 17

Describe Entamoeba coli- commensals in small intestine

Answer 17

• Acquired by ingestion of food/water contaminated with human feces containing CYSTS
• Infection remains asymptomatic in healthy individuals
• Looks similar to Entamoeba Histolytica

Question 18

Describe Entamoeba Histolytica

Answer 18

It is a pathogenic parasite that causes Amoebic DYSENTRY (infection of intestine with bleeding)
-Traphozoites that live and destroy tissues lining host’s large intestine
-May invade other organs (Extra-intestinal amoebiasis)
-Produces protective cysts that are passed in human feces
Humans infected by ingesting cyst

Question 19

Describe ciliates

Answer 19

They are the most complex protists
Move by cilia through semi rigid outer covering (pellicle) and best in a coordinated rhythmic manner
Most ciliates are holozoic, sweep food particles to oral groove (gullet)
Digested in food vacuoles
After digestion, they are absorbed by cytoplasm
Food that is Indigestible exist via ANAL PORE
Most ciliates are NOT pathogenic

Question 20

Describe Balantidium coli

Answer 20

Pathogenic ciliate fro humans
Causes diarrhea type infection
Macro nucleus is distinctly visible
Infection occurs by ingestion of food or contaminated Water with cysts

Question 21

Describe flagellates

Answer 21

Move by flagellum, and some by Undulating Membrane (UM)
No, or atypical mitochondria (kinetoplast)
Many flagellates are Parhogenic

Question 22

Describe 4 types of flagellates

Answer 22

The further away the kinetoplast is from the anterior end of flagellate, the faster it is
-Trypomastigote- fastest, kinetochore at posterior end (Very long flagella) with long UM
-Epimastigote- kinetochore at Middle of cell (long flagella) short UM
-Promastigote-kinetochore at anterior end of cell (short flagellum) no UM
Amastigote- circular cell with no pronounced flagella

Question 23

Describe Giaedia lamblia

Answer 23

Flagellate that Causes giardiasis (severe diarrhea)

• Trophozoites have 2 nuclei at anterior end
• produces cysts, to be transmitted by contaminated water

Question 24

Describe Trichomonas vaginalis

Answer 24

Flagellate that Infects vagina & make urinary tract
NO cyst formation, 4 free flagella, one with UM
Transmission through Sexual contact
Asymptomatic in most ppl

Question 25

Describe Trypansoma brucei

Answer 25

Flagellate that infects humans & other animals
Causes African sleeping sickness
Transmitted when infected Tsetse fly bites
Also transmitted from animals to humans (zoonotic infection)
Contains kinetoplast
Found as trymastigote in host blood
Found as Epimastigote in vectors intestinal tract

Question 26

Describe leishmania

Answer 26

Flagellate that infects humans, dogs, rodents
Transmitted via sand fly
Contains Kinetoplast
Amastigote in host cell
Promastigote in vectors gut
Causes Localized skin infections (cutaneous leishmaniasis)

Question 27

How many plasmodium Protozoa infects humans and cause malaria and which is the most common one?

Answer 27

4, Plasmodium Vivaldi is most common

Question 28

Describe Malarial disease and corresponding common parasite that causes it

Answer 28

Caused by Plasmodium Vivax
Transmitted via Female Anopheles Mosquito
Reproduces asexually in body cell, sexually in mosquito
SPOROZOITES pass from mosquito glands into blood, and enter Liver cells
In liver sporozoites develop into MEROZOITES
Divide asexually in RBC causing rupture (chills and fever)
Some Merozoites develop into TROPHOZOITE
Others develop into GAMETOCYSTS where next mosquito contracts it -> gametes-> zygote

Question 29

How many humans approx die from malaria, and why is it out of control?

Answer 29

0.5million
Insecticide resistance by Anopheles
Anti malarial drug resistance by Plasmodium