1. The correct answer is: The viral envelope proteins interact with CD4 and a co-receptor on the cell membrane.
Binding and entering the host cell are the first steps of the HIV virus infection. So, these steps play a major role in determining the ability of HIV to degrade the human immune system. Binding of HIV to CD4+ T lymphocytes (express chemokine receptors CCR5 and CXCR4 called co-receptors) triggers the fusion of the viral and host cell membranes, initiating infection (viral core gets into the cytoplasm).
Attachment of the virion can be:
• Nonspecific-envelop protein of the virus (Env) binds to cell-surface heparan sulfate proteoglycans
• Specific-Env binds to integrin.
2. The correct answer is: Activation of the host cell by cytokines, growth factors, or antigens.
After the viral capsid enters the cell, single-stranded RNA genome is released from the attached viral proteins and copied it into a complementary DNA (cDNA) molecule thanks to an enzyme called reverse transcriptase. Next step is the integration of the viral DNA into the host cell's genome. This process is done by another viral enzyme called integrase. The integrated DNA is transcribed into RNA and then translated into proteins that will help the package of new viruse particles.
3. The answer is: false
Reverse transcriptase is an enzyme that catalyzes the formation of DNA from an RNA template. Since the genome of the virus (HIV) is single stranded RNA, reverse transcriptase copies it into a complementary DNA (cDNA) molecule. Thanks to this enzyme, formed cDNA can be integrated into host’s genome. Because of this proprety, antiretroviral drugs used to treat HIV infection work as reverse-transcriptase inhibitors.
Answer:
3 materials
Explanation:
The jacket and trousers worn by a firefighter have to be constructed from materials that will withstand intense heat. Aramid fiber is a synthetic fiber that is highly regarded for its strength and heat resistance. Nomex is the trade name for arimid fiber clothing, and this type of material is used in the construction of a firefighter jacket and trousers. Nomex is often combined with Kevlar to increase the strength of the material.
Here is an article that can help.
https://healthblog.uofmhealth.org/heart-health/anatomy-of-a-human-heart
Answer: D) cAMP
Explanation:
In the absence of glucose cell can make use of other sources of carbohydrates such as lactose. In E. Coli and other bacteria utilization of lactose depends on the availability of cAMP. Bacteria accumulate cAMP only when starved. When glucose is exhausted, cAMP is available in plenty.
cAMP is necessary for the gene expression because it binds catabolite repressor protein (CAP) to form CAP-cAMP complex. CAP is a lac repressor the binds to the operator site of the lac operon preventing RNAP From binding to the promoter.
RNA polymerase can bind to the promoter site only when CAP-cAMP formed
Method 1:1. Start with your equation and determine which variables you know.
2. Use the lens equation to get d.
3. Sovle for h.
4. Solve for M.
5. Interpret your M value.
6. For diverging lenses, use a negative focal length value.
