TOPIC 8 - gene expression is controlled by a number of features ( continue ) Flashcards
what is a stem cell?
undifferentiated cells, that can divide indefinitely and turn into other specific cell types
what are the 3 different types of stem cells? define them.
TOTIPOTENT = can develop into any type of cell type including placenta and embryo
PLURIPOTENT = can develop into any cell type excluding placenta and embryo
MULTIPOTENT = can only develop into a few different types of cell
what happens to totipotent cells during embryonic development?
- certain parts of the DNA are selectively translated so that only some genes are ‘switched on’ in order to differentiate the cell into a specific type and form tissues that make up the foetus.
give a unique feature of the pluripotent cells and the use of this feature.
- they can divide in unlimited numbers = used to repair or replace damaged tissue
what is unipotent cell?
- cell that can develop into one type of cell
- happens at the end of specialisation when the cell can only propagate its own type.
eg cardiomyocytes
which type of stem cells are found in embryos?
totipotent and pluripotent
multipotent and unipotent are only found in mature mammals
give some uses of stem cells
medical therapies eg bone marrow transplants, treating blood disorders
drug testing on artificially grown tissues
research eg formation of organs and embryos
how are induced pluripotent stem cells produced?
- unipotent stem cells are treated with transcription factors to make them pluripotent
-modified virus (vector) inserts transcription factor gene from pluripotent cells into DNA of unipotent stem cells - transcription factors are expressed
what is a transcription factor?
- protein that controls the transcription of genes so only certain parts of the DNA are expressed. = allows a cell to specialise
