Factors Affecting Gene Expression Flashcards
What is cell differentiation?
The process by which cells become specialised
What are transcription factors?
Proteins that bind to DNA in the nucleus and affect the process of transcription
What are promoter sequences?
Specfific areas in DNA that transcription factors bind to and stimulate transcription
What are enhancer sequences?
Areas of DNA that transcription factors bind to and regulate the activity of DNA by making it more or less avaliable to RNA polymerase so stimulating or preventing transcription
What is premRNA?
MRNA that has been transcribed directly from DNA but still needs to be modifyed and introns removed
What are spliceosomes?
Enzymes that join exons together after the introns have been removed in mRNA
What is epigenetics?
The way gene expression is controlled
What systems interact to control gene expression?
DNA methalation
Histone modification
non-coding RNA
What is DNA methalation?
The addition of a methyl group to a C base which prevents the transcription of a gene
Does DNA methalation turn a gene on or off?
Off
What is DNA demethalation?
The removal of a methyl group from C which enables a gene to be expressed
What are histones?
Positively charged proteins that DNA winds around to form chromatin
What are heterochromatin?
When the DNA is coiled tightly around histones so unable to be transcribed
How does the tightness of DNA coils around histones affect gene expression?
The tighter the DNA is coiled, the less the gene is expressed as the enzymes can’t bind to it to transcribe
What is histone acetylation?
An acetyl group is added which losens the coil of DNA arund the histones and allows genes to be transcribed
What is histone methylation?
When a methyl group is added which tightens the coil of DNA arund the histones and stops genes from being transcribed and expressed
What is the first stage of embryonic stem cell development?
Cleavage
What is cleavage?
The first stage of embryonic development where cells divide repeatedly by mitosis without normal interphase which results in a uniform, undifferentiated mass of cells known as a blastocyst
What is a blastocyst?
A small mass of uniform, undifferentiated cells
What is a totipotent cell?
An undifferentiated cell that can form into any of the cells needed to form an entirely new organism
What is an embryonic stem cell?
Undifferentiated cells in the early human embryo that can develop into many different types of specialised tissues
Are embryonic stem cells totipotent or pluripotent?
At first totipotent but later Pluripotent
Are ambilical cord stem cells totipotent or pluripotent
Pluripotent
What is another term for adult stem cells?
Stomatic stem cells
What are stomatic stem cells?
Undifferntiated cells found in adults that can differentiate into any of the major types of cell in the body
What are multipotent cells?
A cell that can form a limited number of differentiated cells
Found in adults.
Why has stem cell therapy had limited sucess?
It’s difficult to control how the cells differentiate
What is theraputic cloning?
An experimental technique where scientists hope to produce large quantities of healthy tissue to treat people with diseases caused by faulty cells
What is the process of theraputic cloning?
The nucleus from a normal cell is removed and put in the empty ovum cell. An electric shock is given to trigger development. The cell divides to produce stem cells with the same DNA as the patient
What are the criticizms of stem cell therapy?
We have limited understanding of differentiation
Could cause cancer
What are the advantages of using stem cell therapy?
Can cure illness
Less change of people rejecting organs
What are induced pluripotent stem cells?
Adult cells that have been reprogrammed by the introduction of new genes to become pluripotent again
What are the advantages of using induced pluripotent stem cells?
Overcomes the ethical objections of embryonic stem cells
In what ways can stem cell therapy help people?
Parkinsons
Type 1 diabetes
Damaged nerves
Organ transplants
