Viruses And Subviral Particles 1.5

Question 1

Virus

Answer 1

Composed of genetic material, a protein coat, and sometimes an envelope containing lipids. The genetic information may be circular or linear, or double-stranded, and composed of either DNA or RNA. The protein coat is known as a capsid. Because viruses cannot reproduce independently, they are considered obligate intracellular parasites.

Question 2

Virion

Answer 2

Viruses replicate in a host cell and produce virions which can be released to infect additional cells. A virion is a fully assembled infectious virus.

Question 3

Positive sense viral genome

Answer 3

Single-stranded RNA viruses may be Positive sense. Positive sense implies that the genome may be directly translated to functional proteins by the ribosomes of the host cell, just like mRNA.

Positive sense means it can serve as mRNA. This term is reserved for RNA viruses.

Question 4

Negative sense viral genome

Answer 4

Negative sense single-stranded RNA viruses contain RNA strands that act as a template for synthesis of a complimentary strand, which can then used as a template for protein synthesis. Must have RNA replicase to ensure synthesis of complementary strand.

Negative sense refers to it not being able to serve directly as mRNA. This term is reserved for RNA viruses.

Question 5

Retroviruses

Answer 5

Enveloped, single stranded RNA viruses containing two identical RNA molecules. Contain reverse transcriptase that synthesizes DNA from straight single-stranded RNA. This synthesized DNA can integrate (using integrase) into the hosts genome and be replicated and transcribed as if it were the hosts own DNA.

Question 6

Lifecycle of the human immuno deficiency virus

Answer 6

HIV is a positive sense, single stranded RNA virus.

Question 7

CCR5 and CD4

Answer 7

CCR5 and CD4 is the receptor required on white blood cells in order to be infected with HIV. No receptor no HIV.

Question 8

Virulent, regarding virus life cycle.

Also general definition of virulent.

Answer 8

A virus in its lytic phase.

Severe or harmful in its effects, disease or poison.

Question 9

Viroid

Answer 9

Small pathogens consisting of a very short circular single-stranded RNA that mostly infect plants.

There are a few known viroids known to infect humans such as hepatitis D virus.