When polymerase binding causes transition to the open complex and initiates transcription. This gives a low level of constitutive expression called the basal level.  Binding of RNA polymerase is the rate-limiting step in this case.

TLS Online TPP Program

#Id: 934

#Unit 5. Developmental Biology

The shoot apical and root apical meristems provide a continuous source of totipotent stem cells for a plant to generate a majority of its aerial and ground tissues throughout life.

TLS Online TPP Program

#Id: 935

#Unit 5. Developmental Biology

When a multipotent stem cell divides asymmetrically, its maturing daughter cell often goes through a transition stage as a progenitor or transit-amplifying cell.

TLS Online TPP Program

#Id: 936

#Unit 5. Developmental Biology

Precursor cell (or simply precursors), is widely used to denote any ancestral cell type (either stem cell or progenitor cell) of a particular lineage.

TLS Online TPP Program

#Id: 937

#Unit 5. Developmental Biology

Inner cell mass (ICM) cells of the mouse blastocyst are maintained in a pluripotent state through E-cadherin interactions with trophectoderm cells that activate the Hippo kinase cascade and repress the function of Yap/Taz as transcriptional regulators of Cdx2.

TLS Online TPP Program

#Id: 938

#Unit 5. Developmental Biology

Induced pluripotent stem cell (iPSC) with the pluripotency of an embryonic stem cell. These genes were 

a. Sox2 and Oct4 (Oct3, Oct3/4, and Pou5f1) -which activated Nanog and other transcription factors that   established pluripotency and blocked differentiation

b. c-Myc which opened up chromatin and made the genes accessible to Sox2, Oct4, and Nanog

c. Klf4 -which prevents cell death

TLS Online TPP Program

#Id: 939

#Unit 5. Developmental Biology

In drosophila, the stem cells for sperm reside in a regulatory microenvironment called the hub.