Set Fill to 0% for this layer and click on Add a layer style icon from bottom part of the Layers panel to Inner Shadow.

We’ve got the next result:

Now it’s time to draw a highlight on the made molecule, applying the same Ellipse Tool (U).

Set Fill to 0% for this layer and click on Add a layer style icon from bottom part of the Layers panel to Gradient Overlay.

Click in the color bar to open the Gradient Editor and set the color stops as shown. Click OK to close the Gradient Editor dialog box.

We’ve got the next result:

Use the last tool to create the next layer belonging to the same earlier made bubble.

Set Fill to 0% for this layer and click on Add a layer style icon from bottom part of the Layers panel to Gradient Overlay.

Click in the color bar to open the Gradient Editor and set the color stops as shown. Click OK to close the Gradient Editor dialog box.

We’ve got the next result:

Insert the mask on the layer by choosing Add layer mask on the bottom part of the Layers panel and choose the Soft Round brush of black color.

Paint in the mask using this brush to hide easily a part of the molecule’s surface.

Using the Ellipse Tool (U), try to make another highlight on the molecule’s surface.

Set Fill to 0% for this layer and click on Add a layer style icon from bottom part of the Layers panel to Gradient Overlay.

Click in the color bar to open the Gradient Editor and set the color stops as shown. Click OK to close the Gradient Editor dialog box.

We’ve got the next result:

Combine in a group all layers composing the molecule (press CTRL button to select the necessary layers and hold on the left mouse’s button while dragging the selected layers on Create a new group icon from bottom part of the Layers panel). Make many copies of this last made group and select again the Free Transform (Ctrl+T) command to change the copies’ sizes and place them on the picture the same way demonstrated below.

The Colorful Abstract DNA background is finished!

View full size here.

Download free Layered PSD file.