Micro bio

Why is it advantageous for viruses to possess different shapes?

Why is it advantageous for viruses to possess different shapes?

Different shapes allow viruses to have different functions which enable them to invade immune systems of their hosts

Are viruses specific?

yes, many viruses are species specific and most will target one type of cell

Obligate intracellular parasite life cycle

1. entry and uncoating 2. replication 3.Transcription and manufacture of capsid proteins 4self-assembly of new virus particles and their exit from the cell

How do viruses identify their host cells?

A receptor on the virus (either a peplomer or capsomer) interacts and binds to a receptor on the surface of the host cell.

What are the advantages and disadvantages of the lysogenic cycle?

Advantage: can hide and wait which allows the bacteria to divide before the "mass murder", higher ratio of virus to new phages produced Disadvantage: risk of being detected because bacteria may be able to recognize

What are the advantages and disadvantages of the lytic cycle?

Advantage: little risk of being detected, quick and efficient Disadvantage: only kill one cell at a time, risk of having no more hosts

Temperate phage

λ phage that is used for research and that is capable of reproducing by either a lytic or lysogenic cycle

Why might humans utilize temperate phages?

used as a treatment to kill bacteria, as viral vectors, and to study how viruses work

What are some harmful examples of a bacteria containing prophages?

Vibrio cholerae, E. coli

prophage

before it becomes an actual phage, it is embedded into the host's DNA

Lytic cycle

Virulent or temperate phage, Destruction of host DNA, Production of new phages, Lysis of host cell causes release of progeny phages

Lysogenization

process of infecting bacteria with temperate phage

lysogenic cycle

Temperate phage only, Genome integrates into bacterial chromosome as prophage, which (1) is replicated and passed on to daughter cells and (2) can be induced to leave the chromosome and initiate a lytic cycle

types of viruses

There are single stranded and double stranded viruses containing either DNA or RNA

what does the host cell do to the capsid?

The host cell digests the capsid releasing RNA into the host cell

Why is HIV called a retrovirus?

Retroviruses are RNA viruses that use RNA as their genetic material but the host cell must synthesize a DNA copy of the RNA before it can be transcribed or translated.

Which cells are targeted by HIV?

The primary targets of HIV are activated CD4+ T4 helper lymphocytes (leads to immunosuppression) or helper T cells but the virus can also infect several other cell types including macrophages.

reverse transcriptase

an enzyme encoded by certain viruses (retroviruses) that uses RNA as a template for DNA synthesis