Gene expression Flashcards
(27 cards)
Inversion
A group of bases becomes separated from the DNA sequence and rejoins, but in the reverse order
Duplication
One or more bases are repeated. This creates a frameshift downstream.
Translocation of bases
A group of bases becomes separated from the DNA sequence of one chromosomes and becomes inserted into the DNA sequence of a different one
Mutation
change in the DNA base sequence
Rate of mutation creases on exposure to mutagenic agents:
-ionising radiation
-viruses
substitution
one base is replaced by another
Deletion
Cause a frameshift downtsream f the mutation resulting in a adiiferent primary structure
Addition
The addition of a new base into the sequence results in aframeshift downstream of the mutation resulting in a different primary sturcture
Stem cells
-undifferentiated cells that can differentiate into any type of specialised cell and can regenerate an infinite number of times
Totipotent cells
Can divide into any type of cell rom embryonic stem cells including placenta cells
Pluripotent cells
In animals have the potential to differentiate into any body cell except placenta cells
Multipotent cells
Ault stem cells that differentiated further can only give rise to a limited number of different types of cells
Unipotent cells
Can only differetiate into a single type of cell made in adult tissue
Induced pluripotent stem cells
-Derivied from unipotent cells
-Genetically altered to behave like embryo cells
-Turns on genes that were turned off
-Shows that adult cells still contain genes present in the embryo
-Can self renew so could replace embryos cells in research
Cardiomyocytes
A type of unipotent stem cell in the heart
Cells can replicate and replace damanged or aged cells
How are genes transcribed
-Transcipitional factors move from the cytoplasm to the DNA where they bind to a specific DNA base sequence called the promotor region
This then allows RNA polymerase to bind and transcribe the gene, this can then be translated into protein therefore the gene is expressed
How does oestrogen enter the cell
its lipid soluable so simply diffuses through the phospholipid bilayer of target cell
Binds to complementry receptor forming a receptor-oestrogen complex that behaves as a transciription factor
Oestrogen and breast cancer
-Post menopuase the fat cells in the breasts produce more oestrogen
-Oestrogen can control cell division by production of the proteins responsible
-If cell division becomes uncontrollable then this becomes malignant tumour
-This then produces more oestrogen so cancer can grow faster
What does siRNA do
Prvents translation
What does proto ocogenes do
Stimuates the cell cycle by producing proteins to increase cell dicision
What does mutated ocogenes do
Increases the speed of the cell cycle so its less regulated and less well checked for abnormal cells
What does a tumour supressor gene do
Slows the cell cyle in order to regulate it and prevent uncontrolled cell division hence the formation of abnormal cells
What does a mutated tumour supressor gene do
Cell ivision is not regulated and checked also abnormal cells are not killed it apoptosis
Epigenetics
Inheritable change to gene function without a change in the DNA base sequence
