last minute q.

[monika.s]

Hi guys!! I have question:

I know there is a genus of bacteria that does not have a cell wall (i think) but does VCAA say that all bacteria have a cell wall because the NOB textbook says "Bacteria have a cell wall and a single major chromosome."? Seems like a generalisation to me but is it correct for vce bio?

[yidazhou]

Yup, stick with all bacteria having a cell wall. Though, it's probably not going to be tested in the exam

[alondouek]

For the purposes of VCE bio, all bacteria have cell walls.

Spoiler

The genus Mycoplasma doesn't though

[monika.s]

Also, why do the lymph nodes swell up during an infection?

Is it because antigen presenting cells rush to where the B and T cells are .. "chilling" in the lymph nodes? Does that trigger the B cells to differentiate and undergo clonal expansion? (- I am a bit confused with the terms because I dont think they are interchangeable.)

[yidazhou]

Pretty much. Most of the clonal expansion occurs there, and also pathogens can also enter and trigger quickly - macrophages engulf, and T cells destroy/ B cells make antibodies. According to some teachers notes, its the site of lymphocyte action, and which results in enlarged lymph nodes.
And clearing up your definitions of differentiate, and clonal expansion.
Differentiate is when you either turn into memory or plasma cells.
Clonal Expansion is when you have many B cells in the body, and only one B cells have the correct antibody. The B cell then undergoes clonal expansion, where it replicates and replicates. So - clonal expansion occurs, and then while that happens, the cells differentiate into B mem or B plas