Steroid

A steroid is a type of organic compound that contains a

characteristic arrangement of four cycloalkane rings that

are joined to each other

The main feature of steroids is the ring system of three

cyclohexanes and one cyclopentane in a fused ring system

as shown below. There are a variety of functional groups

that may be attached. The main feature, as in all lipids, is

the large number of carbon-hydrogens which make steroids non-polar.
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Phospholipids

Phospholipids are very much like triglycerides but with one

important difference. A phosphate functional group is substituted

for one of the three fatty acids

Phospholipids are a class of lipids and are a major component of

all cell membranes as they can form. Most phospholipids contain

a diglyceride, a phosphate group, and a simple organic molecule

such as choline; one exception to this rule is sphingomyelin, which

is derived from sphingosine instead of glycerol.

Triglycerides are lipid compounds composed of a glycerol esterified to

3 fatty acid chains of varying length and composition. Triglycerides are a

blood lipid that help enable the bidirectional transference of adipose fat

and blood glucose from the liver. These fatty acid chains can be saturated

or unsaturated, and the chemical composition of each chain is different.

Each chain consists of carbon and hydrogen atoms with varying single

or double-bonded chains, depending on the degree of saturation or

unsaturation.

Nucleotides are the basic structural units of nucleic acids, which

control the production of proteins in living organisms. The

nucleotides are made up of a phosphate group, a pentose sugar, and

a nitrogen base.

The simplest of the polynucleotides is a single chain in which the

pentose sugar is always ribose. The name of this polynucleotide

comes from the sugar ribonucleic acid, abbreviated to the three

letters RNA. Adenine, guanine, cytosine and uracil are the four

nitrogenous bases always found in RNA.

Deoxyribose is the pentose sugar found in this type of

polynucleotide, hence its name Deoxyribonucleic Acid, or DNA.

The nitrogenous bases found in DNA are, adenine, guanine,

cytosine and thymine. DNA molecules have two polynucleotide 

chains, held together in a ladderlike structure. The sugar phosphate

backbones of the two chains run parallel to each other in opposite

directions. Each "rung" of the ladder is a pair of nitrogenous bases,

one purine and one pyrimidine extending into the center of the

molecule.

Disaccharides: is one of four groups of Carbohydrates 

(monosaccharide, disaccharide, polysaccharide, 

and oligosaccharide). A disaccharide or biose is the 

carbohydrate formed when two monosaccharides undergo 

a condensation reaction, which involves the elimination of 

a small molecule, such as water, from the functional groups 

only.

Monosaccharides are the simplest form of carbohydrates and may be subcategorized as aldoses or ketoses. They are the simplest form of sugar and are usually colorless, water-soluble, crystalline solids. Some monosaccharides have a sweet taste. Examples of monosaccharides include glucose (dextrose), fructose (levulose), galactose, xylose and ribose. Monosaccharides are the building blocks of disaccharides such as sucrose and polysaccharides (such as cellulose and starch).

Polysaccharides are polymeric carbohydrate structures, formed of repeating units (either mono- or di-saccharides) joined together by glycosidic bonds. Polysaccharides are characterized by the following chemical properties:  not sweet in taste, insoluble in water, do not form crystals when desiccated, compact and not osmotically active inside the cells,  can be extracted to form white powder, and general chemical formula of C_x(H₂O) _y.

Amino Acids

Amino acids play central roles both as building blocks of proteins and as intermediates in metabolism. The 20 amino acids that are found within proteins convey a vast array of chemical versatility. The precise amino acid content, and the sequence of those amino acids, of a specific protein, is determined by the sequence of the bases in the gene that encodes that protein. The chemical properties of the amino acids of proteins determine the biological activity of the protein. Proteins not only catalyze all (or most) of the reactions in living cells, they control virtually all cellular process. In addition, proteins contain within their amino acid sequences the necessary information to determine how that protein will fold into a three dimensional structure, and the stability of the resulting structure. The field of protein folding and stability has been a critically important area of research for years, and remains today one of the great unsolved mysteries. It is, however, being actively investigated, and progress is being made every day. As we learn about amino acids, it is important to keep in mind that one of the more important reasons to understand amino acid structure and properties is to be able to understand protein structure and properties. We will see that the vastly complex characteristics of even a small, relatively simple, protein are a composite of the properties of the amino acids which comprise the protein.

• The other amino acids are polar and hydrophilic ("water loving").
• The eight amino acid orange area are non-polar and hydrophobic.
• The two amino acids are acid magenta box (with groups "carboxy" in the side chain).
• The three aminácidos in pale blue box are basic (groups "amino" in the side chain).

this video review the amino acids

Proteins

Proteins are basically natural polymer molecules formed by amino acid units. They are involved in virtually all cellular functions. each protein from type has a different function, some proteins are involved in structural support, while others are involved in body movement, or in defense against germs. Proteins vary in structure since they are designed for various vital functions. Are constructed from a set of 20 amino acids and have different three-dimensional shapes.

What are macromolecules?

Macromolecules are a long molecules that make almost all functions performed by living matter. There are four types of macromolecules: carbohydrates, lipids, proteins and nucleic acids. Although they have different structures and functions, are all composed of long, complex chains of molecules called polymers, with subunits called monomers. They are joined together in a process known as dehydration synthesis in which a covalent bond is formed between two monomers through the release of a water molecule.
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