Expert: Walter Hintz - 11/14/2007

Question
QUESTION: I was wondering if you could help me out, my teacher hasn't replied to my email asking for help and i was wondering if you could give me some information on the following:
Active transport regarding digestion:
what emulsification of fats means:
Enzymes: Rate of activity:
      : Denaturing
      : PH
      : Temperature
The information on osmosis was really useful and i was hoping could help me out again, i'm sorry to ask so much but i really want to pass my exam

ANSWER: Hi Lauren
 Active transport is involved it moving some digested materials into the blood stream
 Emulsification is reducing large fat molecules into smaller ones.  Bile does this.

I am unsure what you are asking here with the third question Except that enzymes are sensitive to pH and temperature and only operate within an optimum range.

---------- FOLLOW-UP ----------

QUESTION: Could you please go into further detail about Active transport, i still don't understamd. Could you please also explain about enzymes rate of activity

Answer
Active transport is movement of substances across the membrane against the concentration gradient. (from low concentration to higher concentration)  With simple diffusion things move from high to low not low to high.  Assume that digestion has reduced a protein to Amino acids which must be taken into the blood stream.  If there are more Amino acids in the blood then there are the intestine then movement of more into the blood requires Active transport and that requires energy

As to the enzymes;  They are bringing about chemical reactions. How fast this is happening is controlled by temperature and pH.  Lets say that a particular reaction works best pH 7.4  At 7.3 it slows down and at 7.2 it stops.