A single molecule is the one that is responsible for initiating a signal transduction pathway. The answer in this question is a single molecule. Molecule is defined as an electrically neutral group of two atoms or more held together by a chemical bonds.
Each chromosome (replicated or not) contains 2 chromatids.
The earliest modern humans in Australia, dating to 50 - 40,000 yBP, were found at Lake Mungo. Early modern humans moved into North and South America because of population increase, competition for food and climate change. Modern humans likely migrated to the Americas via walking across the Being land bridge.
Endosymbiosis is important because it is a theory that explains the origin of chloroplast and mitochondria. It is also a theory that explains how eukaryotic cells came to be.
The answer: Ventricles.
There are four ventricles in the brain all connected between them,
where the cerebrospinal fluid is produced. There is a choroid plexus in each ventricle that produce the fluid.
The four ventricles:
<span><span>- 2 lateral ventricles right and left (one for each hemisphere)</span>
-third ventricle<span>
- fourth ventricle</span></span>
