Question

True or False:

1. MicroRNAs that associate with the RISC complex usually have full complementarity to their target RNAs and induce expression by cleaving the target RNAs.

2. Most somatic cell mutations of multicellular organisms do not go completely unnoticed by the organism.

3. Different cell types often respond in different ways to some extracellular signals, contributing to the specialization that gives each cell type its distinctive character.

Answer 1

1.

False

In most animals, only the conserved seed sequence of the microRNA needs to be perfectly complementary to the target gene. The other regions may or may not be exactly complementary.

2.

False

There are many somatic cell mutations that occur daily in multicellular organisms, most of which are point mutations. All mutations are not lethal or disruptive and hence do not require special attention by the cell. Most mutations of this sort in genes show no visible affects are go undeteced.

3.

True

Each cell type is designated to perform certain specific activities. An extracellular signal/stimulus will cause each cell type to react differently, thereby making them specialized for certain functions.