Gene Regulation

Stem cell

Stem cells are unspecialized cells that have the ability to become specialized

Differentiation

The process of stem cells becoming specialized

Types of stem cells

• Totipotent

• Multipotent

• Unipotent

Totipotent stem cell

Can differentiate into any type of cell

Multipotent stem cell

Can differentiate into a handful of different cell types

Unipotent stem cell

Can only differentiate into one type of cell

How is specialization achieved?

when certain genes are activated or inactivated

Gene Activation

the process of switching a gene from an inactive to an active state, allowing it to maintain homeostasis

Housekeeping genes

• Genes that are always activated

• The same in every cell

Cell-identity genes

• Genes that are activated or inactivated in response to environment

• will differ between each type of cell

TATA Box / Promoter

• A DNA sequence where RNA polymerase and transcription factors bind to start transcription

TATA Box sequence

TATAA

Activators

Turns gene on by signaling RNA polymerase to begin transcription

Silencer / Enhancer

Enhancer

• Region where transcription factors can bind to speed up transcription

Silencer

• Region where transcription factors can bind to block transcription

Repressors (eukaryotes)

Transcription factors that will bind to silencer to prevent other transcription factors from binding to TATA box

Enhancer transcription factor

Transcription factors that will bind to enhancer to recruit more activators

Operator

site of transcription factor binding to block or activate transcription

prokaryote

Inducer

• Transcription factor that will bind to operator to turn gene on

• RNA Polymerase will bind to promoter, move through operator, and start transcription

Repressor ( prokaryotes )

• Transcription factor that will bind to operator to turn gene off

• RNA polymerase will bind to promoter but will not be able to move through operator to reach gene for transcription