Gene Expression Flashcards
Inversion Mutation
A group of bases become separated from the DNA and join in the reverse order
Duplication Mutation
One or more bases are repeated which causes a frameshift to the right
Translocation Mutation
A group of bases become separated from the DNA sequence and join on a DNA sequence in a different chromosome
Stem Cell
Undifferentiated cells that can divide indefinitely and differentiate.
Totipotent, pluripotent, multipotent and unipotent
Pluripotent Stem Cells
Pluripotent cells can divide in unlimited numbers and can therefore be sued to repair or replace damaged tissue
Unipotent Stem Cells
Can only differentiate into one type of cell, e.g. cardiomyocytes (heart cells)
Uses of Stem Cells
Medicine, treating blood disorders, bone marrow transplants, tissue repair.
Research
Induced Pluripotent Stem Cells
Unipotent body cells that have been genetically altered into pluripotent stem cells through the use of transcription factors
Transcription Factor
Protein that controls the transcription of genes so only certain parts of the DNA are expressed by binding to promoter regions of target genes which stimulates RNA polymerase and the transcription of that gene
Effect of Oestrogen on Transcription Factors
Oestrogen binds to oestrogen receptor on the transcription factor which causes the transcription factor to be activated and to change shape so it is now complementary to the promotor region, it enters the nucleus and binds to the promotor region and activates RNA polymerase which causes the transcription of the gene and so the gene is expressed
Epigenetics
A heritable change caused by environment factors, in gene function without altering the base sequence of the DNA
Increased Methylation of DNA
CH3 group is added to the cytosine bases in the DNA, this alters the promoter region so it is no longer complementary to the transcription factors so they can no longer bind preventing the gene from expressed.
Decreased Acetylation of Associated Histones
Decreased acetylation makes the positive charge on the histones stronger, so they are more attracted to the DNA, this increases the association of the histones to the DNA making the DNA promoter region is inaccessible to transcription factors, so gene expression is prevented
Impact of Epigenetic Changes
Cause disease, by over activating a gene such as in cancer or supressing it
Epigenetic Uses
Treatments of various disease
Development of ways to reverse epigenetic changes e.g. drugs that prevent methylation.
RNA Interference
siRNA, small interfering RNA, molecules causes the break down of mRNA which prevents it from being translated, thus preventing gene expression
Tumour Suppressor Genes
Controls cell division by slowing it down and repairing mistakes in DNA.
Programs cell death through apoptosis.
Mutations to tumour suppressor genes that result in them being inactivated can lead to uncontrolled cell division and thus tumours and cancer
Proto-oncogenes
Controls cell division by stimulating it to divide when proto-oncogenes are activated by a growth factor binding to it.
Opposite of tumour suppressor genes.
Oncogenes
Mutated proto-oncogenes.
Can result in them being permanently activated which results in uncontrolled cell division.
This can be due to excessive production of growth factors by oncogenes.
Or the growth factor receptor being activated in absence of growth factors
Abnormal Methylation of Genes
Hypermethylation of promotor region of tumour suppressor genes prevent them from being expressed leading to uncontrolled cell division
Hypomethylation of promotor region of oncogenes resulting in over expression which also leads to uncontrolled cell division
Oestrogen and Breast Cancer
Increased oestrogen concentration, oestrogen binds to oestrogen receptor on transcription factor, activating transcription factor which goes into nucleus and binds to promotor region of proto-oncogenes activating RNA polymerase, expressing proto-oncogenes and causing uncontrolled cell division
