The document outlines antibody production, the effects of HIV on the immune system, and two experiments. It describes how lymphocytes recognize antigens and clone themselves to produce antibodies, and how HIV attacks T-helper cells, weakening the immune system. It also summarizes Florey and Chain's experiment showing penicillin cured mice infected with Streptococcus bacteria within 24 hours, and notes bacteria can evolve genes for antibiotic resistance.

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

2. Outline Antibody production
Many different lymphocytes exist.
Each type recognize one specific antigen
When 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 cloned
Some clone cells remain as memory cell, ready for a
second invasion by the pathogen. This is immunity

3. Effects of HIV on the immune system and methods of transmission
Effect 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

4. 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.

5. 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.