F4 biology about protein

Structure of protein:
It contains an amino group,NH2 and a carboxylic group COOH attached to the central carbon.

Kinds of protein:
There are two kinds of proteins: one can be made by ourselves called NON-ESSENTIAL protein such as aspartic acid, alanine and glycine. While the other cannot be made by ourselves called ESSENTIAL such as iso-leucine ,lysine and leucine. For essential proteins, they must be absorbed from our daily food. There are total 20 kinds of protein we required (the sum of essential and non-essential ones).

Different structure of protein:
they have PRIMARY STRUCTURE, SECONDARY STRUCTURE , TERITARY STRUCTURE and QUATERNARY STRUCTURE. You can find them more detailed in web.

Functions of protein
(i)It helps us to grow and repair.
(ii)It make red blood cell and haemoglobin for carrying oxygen, carbon dioxide and metabolic wastes produced inside our cells.
(iii)It makes hormones acting on the receptors located in different parts of organs such as in pancreas containing some insulin receptors for insulin to act on them.
(iv)Body defence
(a)It produces white blood cells including lymphocytes and phagocytes to produce anti-body and to engulf microbes respectively when bacterial or viral infection occurs.
(b)It forms fibrin from fibrinogen for blood clotting to carry out. This prevents further blood loss and invasion of virus and bacteria.
(c)It makes anti-body called immunoglobulin ,Ig to act against viral infection. There are several types of anti-bodies including IgA, IgM, IgE, IgG and IgD
(v)It forms muscles including actin and myosin for muscle contraction to carry out.'
(vi)It forms enzymes to speed up the bio-chemical reaction during digestion process. Those enzymes can be found in mouth(amylase), stomach(pepsin and rennin), pancreas (lipase, amylase, nuclease and trypsin) and intestine (peptidase, sucrase, maltase and nucleotidase).
(vii)In enzyme, protein also forms an active site for substrate to attach to so that the enzyme-substrate complex will be formed.
(viii)It forms channel proteins and carrier proteins for active transport and selective permeability to carry out.
( ix)It forms a light sensitive pigment called rhodopsin in the rod cells for night vision in our eyes' retina.
and finally
(x)It acts as a buffer to resist any change in pH in blood and change in the osmotic potential of our body fluid.

SUGGEST SOME METHOD HOW TO STUDY
The methods for the study can be:
(i)chromatograhy
To separate a compound contains different types of protein by using an organic solvent placed inside the flask. Since different proteins have different solubility towards this solvent, they will travel at different speed and different distance travelled resulted. At the end of the experiment, spray ninhydrin on the paper so that different proteins can be seen.

This technique shows that different types of proteins have different solubility in an organic solvent.

(ii)electrophoresis
to separate those charged molecules (DNA, RNA or protein) under the action of an electrical field, usually in agarose or polyacrylamide gel.
(iii)Gel electrophoresis for the study of DNA

Base on technique used in (ii) and (iii), protein is a charged molecule which will migrate under the electric field.

(iv)Infra-red Spectroscopy This method suitale for all organic compounds.

I hope my writing can help you.

2007-03-02 20:22:35 補充：
This essay is self-made and just for reference only.

2007-03-02 20:24:27 補充：
它出不到巨噬細胞的英文即macrophage