Parasitism (b) Parasitic life cycles Flashcards
1
Q
A vector plays an active role in…
A
The transmission of a parasite and may also be a host
2
Q
Viruses are…
A
Parasites that can only replicate inside a host cell
3
Q
Viruses contain…
A
Genetic material in the form of DNA and RNA, packaged in a protective protein coat.
4
Q
Some viruses are surrounded by…
A
A phospholipid membrane derived from host cell materials
5
Q
The outer surface of a virus contains…
A
Antigens that a host cell may or may not detect as foreign
6
Q
draw virus
A
7
Q
Life cycle of Plasmodium, causing Malaria
A
- An infected mosquito, acting as a vector, bites a human. 2. A plasmodium enters the human bloodstream, and is carried to the liver cells. 3. Asexual reproduction occurs in the liver cells and thousands of daughter parasites are released. 4. Daughter parasites infect red blood cells, where they develop and replicate. 5. As many as 20 gametocytes enter the bloodstream as one blood cell bursts. 6. Another mosquito bites the human and the gametocytes enter the mosquito. 7. Gametocytes mature into male and female gametes and sexual reproduction occurs in the mosquito. 8. The zygotes formed become motile and make their way to the mosquitos salivary glands. 9. The mosquito can then infect another human host.
8
Q
Life cycle of schictosomes, causing schictosomimasis
A
- Schictosomes reproduce sexually in the human intestine. 2. Fertilised eggs pass out via faeces into the water where they develop into larvae. 3. The larvae then infect water snails. where asexual reproduction occurs. 4. This produces another type of motile larvae, which escapes the snail into the surrounding water. 5. The larvae penetrates the skin of a human, entering the bloodstream.
9
Q
Viral life cycle stages:
A
- infection of host cell with genetic material 2. host cell enzymes replicate viral genome 3. Transcription of viral genes and translation of viral proteins. 4. Assembly and release of new viral particles
10
Q
RNA retroviruses use the enzyme reverse transcriptase to…
A
Form DNA, which is then inserted into the genome of the host cell. Viral genes can ten be expressed to form new viral particles.
