Final answer:
A T-dependent antigen is a molecule that requires assistance from T helper cells to promote an immune response; single-stranded DNA would be a T-dependent antigen.
Step-by-step explanation:
The question refers to T-dependent antigens, which are molecules that require the assistance of T helper cells to induce an immune response. Such antigens usually contain proteins that are recognized by the T-cell receptors (TCR) when presented by Major Histocompatibility Complex (MHC) molecules on the surface of antigen-presenting cells. The answer to which of the following would be a T-dependent antigen is c) Single-stranded DNA. Unlike lipid molecules and polysaccharide chains, proteins and nucleic acids can be recognized by TCRs when presented with MHC II molecules (indicated by the information given in point 10).
In relation to the other references given:
- HIV brings reverse transcriptase into a cell, not RNA polymerase. Reverse transcriptase is responsible for converting RNA into DNA within the host cell.
- Helper T cells bind antigens presented with MHC II molecules.
- Viruses can be classified by their genetic material; in the Baltimore classification scheme, a single-stranded RNA (-) genome would be indicative of negative polarity viruses.
- Cellulose and starch are examples of polysaccharides, not monosaccharides or lipids.
- All nucleated cells present antigens with MHC I molecules.
- The E. coli polymerase subunit that confers specificity to transcription is the sigma factor, which binds to the DNA promoter region initiating gene transcription.