How does Shakespeare portray the themes of jealousy and deception in Othello through form, structure, characters, imagery, and language?

Form, structure, and language: When characters such as Othello (later in the play) or Iago (whenever he is alone or with Roderigo) demonstrate jealousy (Othello regarding Desdemona and Cassio and Iago regarding Othello and Cassio), their language changes from verse to prose.  Iago, especially, plots his revenge and betrayal in prose, or the language of the commoner, and when Othello loses control of his etiquette and the charm which won him Desdemona, he too slips into prose rather than using elegant verse.  Shakespeare uses this form and switch in language to demonstrate man's base nature.  He stresses that when man gives into his original sinful state, he regresses in speech and action.

Characters: Shakespeare uses Othello to portray a Garden of Eden allegory.  Iago is the serpent who causes Othello to be jealous of Desdemona and not to trust that good can exist in someone else or in the world. Desdemona is an Eve to Othello's Adam, but she does not wittingly lead him astray; the serpent uses her without her knowledge.  Iago's deceit throughout the play is dependent upon his ability to camouflage his true intentions just as the serpent did in the Garden of Eden.

Imagery: Light and dark imagery dominate the play, along with animalistic images and references. Desdemona, who symbolizes purity, is pale in contrast to the darkness of Iago's plot and Othello's jealousy.  The animalistic imagery mainly represents Othello because Iago refers to him as a ram and uses other degrading terms which demonstrate the extent of his jealousy toward the military leader and his lieutenant (Cassio).