Question

QUESTION 12 The first step in the infection cycle of a virus is replication of its genome degradation of the host genome lysis of the host cell attachment to the host cell surface QUESTION 13 Which of the following is NOT a true statement about regulons? Regulons are known to be under positive and negative control Regulons are only known to be under positive control. A regulon describes two or more operons that are under the control of the same regulatory protein. The maltose activator protein controls the transcription of more than one operon Click Save and Submit to save and submit Chicks o ch 16 PAT AP n...pptx Ch. 17 PPTP no pot < @ Ch 18 PPT AP noppbi a DELL

Answer 1

Answer 12: The first step in the infection of a virus is:

The correct option is attachment to the host cell surface.

Reason:

1. Attachment, in which phage or the virus attaches itself with the surface of bacteria.

2. Penetration, in this the DNA of the virus or phage goes inside the host cell body.

3. Degradation of host genome occurs after its entry into the host body.

4. Synthesis of DNA, in this phage replicates and forms new DNA and proteins.

5. Maturation, in this the phage matures and assembles it’s all parts.

6. Lysis: the newly formed phages or viruses are ready and now, release or burst out from the host cell body.

Answer13: The wrong option is: Regulons are known only to be under positive controls.

Reason:

Regulons:

1. It contains a group of genes that are under positive control and also can be under negative control. They can also be called as a transcriptional activator (+ regulon) and transcriptional repressor (- regulon).

2. These are a group of genes or operons that are controlled by the same or common regulatory mechanisms.

3. Maltose activator proteins are global regulators that enhance RNAP binding and are under positive control and they can control multiple operons.

Answer 14: The correct option is: Retroviruses

Reason:

· Retroviruses are viruses whose genetic material is RNA. This possesses an enzyme called reverse transcriptase, which first forms and transcribes mRNA and then turns itself into DNA in the host cell.

· double-stranded DNA viruses are the viruses encapsulated in viral capsules. They work as vectors and binds to target cells using penton protein and, thus gets its entry. For example Adenoviruses

· positive-sense single-stranded RNA virus (or (+) ssRNA virus are viruses that contain positive-sense single-stranded RNA as its genetic material.

· Negative-sense single-stranded RNA virus (or (-) ssRNA virus are viruses that contain negative sense or polarity single-stranded RNA as its genetic material.

· Both vary as positive or negative that depends on its sense or polarity to the RNA.

Answer 15: The correct option is the viral genome when enters a living host cell.

Reason: In order to initiate viral replication to initiate firstly, the virus must attach itself to the host cell body and then penetrates inside to use host machinery. This proceeds and then replication of phage DNA takes place.

No, the viruses do not receive any signals to work.

There are a couple of incidences where viruses are seen to mutate this is detrimental for humans but if it successfully kills the host before infection transmits. This mutation can be lost.

Viruses are crystalline structures. It has always been in contradictions that whether they are living or not. As when it enters in the host body then only it starts functioning and replicating.