Biology (Holt)

The Bubble Model
In 1986, the geophysicist Louis Lerman suggested that the key
processes that formed the chemicals needed for life took place
within bubbles on the ocean’s surface. Lerman’s hypothesis,
also known as the bubble model, is summarized in Figure 3.

Step Ammonia, methane, and other gases resulting from

the numerous eruptions of undersea volcanoes were

trapped in underwater bubbles.

Step Inside the bubbles, the methane and ammonia needed

to make amino acids might have been protected from

damaging ultraviolet radiation. Chemical reactions

would take place much faster in bubbles (where reac-

tants would be concentrated) than in the primordial

soup proposed by Oparin and Haldane.

Step Bubbles rose to the surface and burst, releasing simple

organic molecules into the air.

Step Carried upward by winds, the simple organic mol-

ecules were exposed to ultraviolet radiation and light-

ning, which provided energy for further reactions.

Step More complex organic molecules that formed by fur-

ther reactions fell into the ocean with rain, starting
another cycle.
Thus, the molecules of life could have appeared more quickly
than is accounted for by the primordial soup model alone.

SECTION 1How Did Life Begin? 255

Reading Effectively

Before reading this chapter,

write the Objectives for each

section on a sheet of paper.

Rewrite each Objective as a

question, and answer these

questions as you read the

section.

BIO

graphic

Gases were trapped in

underwater bubbles.

Lerman proposed that gases formed simple organic molecules.

Lerman’s Bubble Model

1

Gases underwent

(^2) chemical reactions.
Gases were ejected
(^3) into the atmosphere.
Simple and complex
compounds fell into
the oceans.

5

Gases underwent

(^4) further reactions.
Figure 3