Biology Activity 2 for Weekend (28/8 -31/8/2015).

Outline Antibody productionMany different lymphocytes exist.Each type recognize one specific antigenWhen the immune system is challenged by the invasion

pathogen the corresponding lymphocyte responds. It makes many clones of itself, each of which produces

antibodies to the pathogen.This process is called clonal selection, as the right

lymphocyte is selected and then clonedSome clone cells remain as memory cell, ready for a

second invasion by the pathogen. This is immunity

Effects of HIV on the immune system and methods of transmissionEffect of HIV on the immune system -HIV is retrovirus: its insert its own RNA into the host cell, which then

incorporates the RNA in its DNA -HIV attacks T-helper cells (CD4+ macrophages), binding to the CD4+

protein on their surface -once inside the cell, the HIV RNA is inserted into the macrophage

genome -Transcription now includes the HIV’s code, resulting an output of more

viral RNA-and subsequent transcription to HIV particles. -as a result, the immune system is weakened and fewer antibodies can

be produced.\

methods of transmission. -child birth -blood transmission -sexual intercourse

Florey and Chain experiments to test penicillin on bacterial infections in mice.Eight mice were deliberately infected with Streptococcus bacteria that cause death from pneumonia. Four of the infected mice were given injections with penicillin. Within 24 hours all the untreated mice were dead but the four given penicillin were healthy.

The resistance of virus to antibiotics Some strains of bacteria have evolved with genes which

confer resistance to antibiotics and some strains of bacteria have multiple resistance.