DOH133 Lecture Notes - Lecture 11: Arthropod, Asexual Reproduction, Protozoa
Summary – outcomes of lytic and lysogenic life cycles
Lytic cycle
The bacteriophage enters the host cell, produces new particles and lyses the
bacterial cell, causing death of the bacterium.
Lysogenic cycle
- Can form a prophage: this word means that the viral DNA is incorporated
into host chromosome
- The prophage can excise from the host and undergo the lytic cycle, or can
remain and multiply with the host genome
Phage conversion – sometimes the prophage can change the bacterial
phenotype – can bring in toxins for example
The above can be caused by specialized or generalized transduction, which
means the virus packages bacterial DNA too.
Animal viruses
Attachment: Viruses attach to cell membrane
Penetration: by endocytosis or fusion
Uncoating: by viral or host enzymes
Biosynthesis: Production of nucleic acid and proteins
Maturation: Nucleic acid and capsid proteins assemble
Release: by budding (enveloped viruses) or rupture
Describe the different types of parasitism
- If a symbiont either harms or lives at the expense of another organism, it is
called a parasitic organism and the relationship is termed parasitism
- Parasitism always involves two species, the parasite and the host.
- Many of these parasitic associations produce pathological changes in
hosts that may result in disease.
- Successful treatment and control of parasitic diseases requires
comprehensive information about the parasite and its life cycle.
- The parasite is always the beneficiary and the host is always the provider
in any host-parasite relationship.
Document Summary
Summary outcomes of lytic and lysogenic life cycles. The bacteriophage enters the host cell, produces new particles and lyses the bacterial cell, causing death of the bacterium. Can form a prophage: this word means that the viral dna is incorporated into host chromosome. The prophage can excise from the host and undergo the lytic cycle, or can remain and multiply with the host genome. Phage conversion sometimes the prophage can change the bacterial phenotype can bring in toxins for example. The above can be caused by specialized or generalized transduction, which means the virus packages bacterial dna too. If a symbiont either harms or lives at the expense of another organism, it is called a parasitic organism and the relationship is termed parasitism. Parasitism always involves two species, the parasite and the host. Many of these parasitic associations produce pathological changes in hosts that may result in disease.
