why is cholesterol needed by the body?

Question

also can u describe the structure of amino acids and proteins

Answer 1

To transport certain proteins.

2 types HDL and LDL

LDL leaves residue which can cause Atherosclerosis.

Answer 2

Cholesterol is required to build and maintain cell membranes; it makes the membrane's fluidity - degree of viscosity - stable over wider temperature intervals (the hydroxyl group on cholesterol interacts with the phosphate head of the membrane, and the bulky steroid and the hydrocarbon chain is embedded in the membrane). Some research indicates that cholesterol may act as an antioxidant. Cholesterol also aids in the manufacture of bile (which helps digest fats), and is also important for the metabolism of fat soluble vitamins, including vitamins A, D, E and K. It is the major precursor for the synthesis of vitamin D and of the various steroid hormones (which include cortisol an aldosterone in the adrenal glands, and the sex hormones progesterone, the various estrogens, testosterone, and derivatives ).

Protein structure:
Proteins are amino acid chains, made up from 20 different L-α-amino acids, also referred to as residues, that fold into unique three-dimensional protein structures. The shape into a which a protein naturally folds is known as its native state, which is determined by its sequence of amino acids. Below about 40 residues the term peptide is frequently used. A certain number of residues is necessary to perform a particular biochemical function, and around 40-50 residues appears to be the lower limit for a functional domain size. Protein sizes range from this lower limit to several thousand residues in multi-functional or structural proteins. However, the current estimate for the average protein length is around 300 residues. Very large aggregates can be formed from protein subunits, for example many thousand actin molecules assemble into an actin filament. Large protein complexes with RNA are found in the ribosome particles, which are in fact 'ribozymes'.

Amino Acids Structure:
R
|
+H3N-Cα-COO-
|
H

The general structure of proteinogenic alpha amino acids at a physiologically relevant pH, Where R represents a side chain specific to each amino acid, and Cα the central carbon atom to which the two termini and the R-group are attached. Amino acids are usually classified by the properties of the side chain into four groups. The side chain can make them behave like a weak acid, a weak base, a hydrophile, if they are polar, and hydrophobe if they are nonpolar. The chemical structures of the 20 standard amino acids, along with their chemical properties, are cataloged in the list of standard amino acids.

The phrase "branched-chain amino acids" is sometimes used to refer to the amino acids having aliphatic side-chains that are non-linear: leucine, isoleucine and valine.