Which region of the Ig molecule interacts with the antigen? What makes the region suited for this purpose?

Answer and Explanation:

Immunoglobulins (Ig) are proteins that are composed of 4 polypeptidic chains: 2 heavy chains (H) and two light chains (L). They assemble in a structure with a 'Y' form. This structure has two regions: the Fab region and the Fc region.

The region of Ig which interacts with the antigen is the Fab region. That is possible because the Fab region presents variability in the amino acid sequence which determines the specific complementary shape with the antigen structure (like a lock and the key).

answer: - few nutrients

high pressure

low temperatures

explanation: 1. few nutrients:   open-ocean zone is located way far from the land, which is the main source of the essential nutrients.2. high pressure: pressure increases by 1 atmosphere for every 10 meters increase in depth.3. ample sunlight: a large fraction of the sunlight is reflected back to the atmosphere from the sea surface. 4. varying salinity: below the thermocline, the water is isolated from the atmosphere so the salinity remains stable over the year.5. low temperatures:   the temperature of open-ocean zone ranges from a low of -2°c to an average of 17°c

the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.