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1. factor that determine the form of fat (solid and liquid)

• effect of structure

if the structure of the fatty acid is a mess, that is bent molecule, then the structure will be a liguid, whereas if the structure is straight and regular, then the shape will be a solid

• bonding (saturated n non saturated)

Saturated and unsaturated fats differ in their energy content and melting point. Since unsaturated fats contain fewer carbon-hydrogen bonds than saturated fats with the same number of carbon atoms, unsaturated fats will yield slightly less energy during metabolism than saturated fats with the same number of carbon atoms. Saturated fats can stack themselves in a closely packed arrangement, so they can freeze easily and are typically solid at room temperature. For example, animal fats tallow and lard are high in saturated fatty acid content and are solids. Olive and linseed oils on the other hand are highly unsaturated and are oily.

• long of chain

if chain of fatty acid longer the melting poin is high, so in normal temperature form of this fat is solid. but if chain is shorter, the melting point is lower then in room temperature form of this fat is liquid 

2. convert from primary metabolisme to secondari metabolisme

The building blocks for secondary metabolites are derived from primary metabolism as indicated ( Figure in bottom) This scheme outlines how metabolites from the fundamental processes of photosynthesis, glycolysis, and the Krebs cycle are tapped off from energy-generating processes to provide biosynthetic intermediates.

from this picture, special significance is the appreciation that secondary metabolites can be synthesized by combining several building blocks of the same type, or by using a mixture of different building blocks. This expands structural diversity and, consequently, makes subdivisions based entirely on biosynthetic pathways rather more difficult. A typical natural product might be produced by combining elements from the acetate, shikimate, and methylerythritol phosphate pathways, for example. Many secondary metabolites also contain one or more sugar units in their structure, either simple primary metabolites, such as glucose or ribose, or alternatively substantially modified and unusual sugars. To appreciate how a natural product is elaborated, it is of value to be able to dissect its structure into the basic building blocks from which it is made up and to use fundamental chemical mechanisms to propose how these are joined together. With a little experience and practice, this becomes a relatively simple process and it allows the molecule to be rationalized, thus exposing logical relationships between apparently quite different structures. In this way, similarities become much more meaningful than differences, and an understanding of biosynthetic pathways allows rational connecting links to be established.

3. BIOSYNTHESIS PROGESTERONE

progesterone  like all other steroid hormones, is synthesized from pregnenolone , which in turn is derived from cholesterol. This is  step reactions to formation progesterone 

1. Cholesterol  undergoes double oxidation to produce 20,22-dihydroxycholesterol.
2. This vicinal  diol is then further oxidized with loss of the side chain starting at position C-22 to produce pregnenolone. This reaction is catalyzed by cytochrome P450scc.
3. The conversion of pregnenolone to progesterone takes place in two steps. 

• First, the 3-  hydroxyl group is oxidized to a keto group  
•  second, the  double bond is moved to C-4, from C-5 through a keto/enol tautomerization reaction. This reaction is catalyzed by 3beta-hydroxysteroid dehydrogenase/delta(5)-delta(4)isomerase.

Progesterone in turn  is the precursor of the mineralocorticoid aldosterone, and after conversion to 17-hydroxyprogesterone (another natural progestogen) of cortisol and androstenedione. Androstenedione can be converted totestosterone, estrone and estradiol.


4. biosynthesis of Cocaine (an Alkaloid)
Additional carbon atoms required for the synthesis of cocaine derived from acetyl-CoA, with the addition of two units of acetyl-CoA for the cation N-methyl-Δ1-pyrrolinium.



The first is the Mannich reaction Addisi, namely enolate anion of acetyl-CoA acts as a nucleophile to the cation pyrrolinium. Addisi second place through Claisen condensation produces a racemic mixture of 2-substituted pyrrolidine.
On the formation of racemic tropinone ethyl [2,3-13C2] 4 (Nmethyl-2-pyrrolidinyl)-3-oxobutanoate no particular stereoisomer specificity. However, the biosynthesis of cocaine, only (S)-enantiomer that can perform the cyclization to form a ring system tropan cocaine. Then the oxidation reaction, which regenerates pyrrolinium cations and the formation of enolate anion, and the intramolecular Mannich reaction. Ring system having tropan hydrolysis, SAM-dependent methylation, and reduction of NADPH for the formation of methylecgonine. Benzoyl group of cocaine is required for the formation of diester synthesized from phenylalanine via cinnamic acid. Benzoyl-CoA and then combine the two units to form coke.


functional group which play an important biological activity

functional group which active is carbonil.