Use the Paragraph and Accompanying Figure to Answer the Following

question 34

Multiple Choice

Use the paragraph and accompanying figure to answer the following questions.
Human immunodeficiency virus (HIV) infects cells that have both CD4 and CCR5 cell surface molecules. The viral nucleic acid molecules are enclosed in a protein capsid, and the protein capsid is itself contained inside an envelope consisting of a lipid bilayer membrane and viral glycoproteins. One hypothesis for viral entry into cells is that binding of HIV membrane glycoproteins to CD4 and CCR5 initiates fusion of the HIV membrane with the plasma membrane, releasing the viral capsid into the cytoplasm. An alternative hypothesis is that HIV gains entry into the cell via receptor-mediated endocytosis, and membrane fusion occurs in the endocytotic vesicle. To test these alternative hypotheses for HIV entry, researchers labeled the lipids on the HIV membrane with a red fluorescent dye.

-What would be observed by live-cell fluorescence microscopy immediately after HIV entry if HIV is endocytosed first, and then later fuses with the endocytotic vesicle membrane?

• A) A spot of red fluorescence will be visible on the infected cell's plasma membrane, marking the site of membrane fusion and HIV entry.
• B) The red fluorescent dye-labeled lipids will appear in the infected cell's interior.
• C) A spot of red fluorescence will diffuse in the infected cell's cytoplasm.
• D) A spot of red fluorescence will remain outside the cell after delivering the viral capsid.

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Definitions:

Elderly

A term referring to individuals who are significantly beyond the middle age, often considered to be 65 years and older.

Secure Attachments

A type of attachment characterized by feelings of safety and security in relationships, often resulting from consistent and caring responses from caregivers in early childhood.

Siblings

Brothers or sisters; individuals having one or both parents in common.

Preoperational Stage

A stage in Piaget's theory of cognitive development, occurring roughly between the ages of 2 and 7, characterized by the development of language and symbolic thinking but limited in logical reasoning.