Parasitic Life Cycles Flashcards
How many hosts do parasites require?
Some require only one host to complete their life cycle however many parasites require more than one host to complete their life cycle
What is the definition of a definitive host?
The organism on or in which a parasite reaches sexual maturity
What is definition of an intermediate host?
The host that the parasite might require in order to complete its life cycle
What is a vector?
A vector plays an active role in the transmission of the parasite and may also be a host
What is the human disease malaria caused by?
Plasmodium
What is the pathway of malaria?
1.An infected mosquito, acting as a vector, bites a human
2.The plasmodium enters the human blood stream
3.Asexual reproduction occurs in the liver and then in the red blood cells
4.When the red blood cells burst gametocytes are released into the bloodstream
5.Another mosquito bites an infected human and the gametoctes enter the mosquito, maturing into male and female gametes allowing sexual reproduction to now occur. The mosquito can then infect another human host.
What causes the human disease schistosomiasis?
Schistosomes
What is the pathway of schistosomiasis?
1.schiatosomes reproduce sexually in the human intestine.
2.The fertilised eggs pass out via faeces into water where they develop into larvae
3.The larvae then infect water snails, where asexually reproduction occurs
4.This produces another type of motile larvae, which escape the snail and penetrate the skin of a human entering the bloodstream
What is a virus?
Parasites that can only replicate inside a host cell
What do viruses contain?
Genetic material in the form of DNA or RNA, packaged in a protective protein coat.
What are some viruses surrounded by?
A phospholipid membrane derived from host cell material
What does the outer surface of a virus contain?
Antigens that a host cell may or may not be able to detect as foregin
What is the viral life cycle?
Stage 1- Infection of a host cell with genetic material
Stage 2- Host cell enzymes replicate viral genome
Stage 3- Transcription of viral proteins
Stage 4- Assembly and release of new viral particles
What does RNA retrovirus use the enzyme reverse transcriptase to form?
DNA which is then inserted into the genome of the host cell. Viral genes can then be expressed to form new viral particles
