Topic 7C

T lymphocytes produce different types of cytokine. Some of these cytokines activate T killer cells and some activate B cells. Explain why different cytokines can activate different cells.


[3marks]

cytokines have a specific/ different shape

cytokines bind to specific receptors / protein molecule on cell membrane

therefore these cytokines initiate gene transcription / protein synthesis in T killer/B cells

Explain how cytokine genes can be expressed in an activated T lymphocyte.
[3marks]

activation results in production of / activation of transcription factors

transcription factors binds to the promotor region of cytokine genes

cytokine genes are transcribed

CD45 is a protein found on the surface of lymphocytes.
Different forms of the CD45 protein are found on the surface of different lymphocytes.

Describe how different forms of the CD45 protein can be produced from a single CD45 gene

[3marks]

gene for CD45 protein transcribed into pre mRNA

spliceosome / enzyme remove non coding regions / introns from pre-mRNA

translation of (different) mRNA molecules

to produce CD45 protein with a different primary structure

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