Biology - 2.5 - Part 2 - parasitic life cycles

What is a vector?

An organism responsible for transferring a parasite from one host to another.

What is a definitive host?

The host where the parasite reaches sexual maturity.

What is the intermediate host?

An additional host that the parasite might require to complete its life cycle e.g. reproduction. An intermediate host can also be used for transmission, which would make it a vector.

Can a vector be a host?

Yes.

What parasite causes malaria?

Plasmodium.

What causes the disease Schistosomiasis?

Schistosomes.

What are viruses?

Parasites that can only replicate inside a host cell.

What form does genetic material take inside viruses?

DNA or RNA and is packaged in a protective protein coat.

What are some viruses surrounded by?

A phospholipid membrane derived from host cell materials.

What does the outer surface of a virus contain?

Antigens which may or may not be detected as foreign by the host cell.

What are the four viral life stages?

Host is infected with genetic material, host cell enzymes replicate viral genome, viral genes are transcribed and viral proteins are translated, new viral particles are assembled and released from the cell.

What are retroviruses?

Viruses that contain RNA rather than DNA.

How can retroviruses alter the host cell genome, even though they contain RNA?

They use the enzyme reverse transcriptase to form DNA, which is then inserted into the genome of the host cell.

What can viral genes be expressed to form?

New viral particles.