Gene Expression Flashcards
What is a gene mutation
A change to the nucleotide bases and their arrangement
When does a chromosome mutation happen
Chromosome number changes
When do gene mutations happen
Occurs spontaneously possibly during meiosis (anaphase 1&2)
Mutation frequency may be increased by mutagenic agents such as high energy ionising radiation or chemicals such as nitrogen dioxide
What is a substitution mutation and its effects
Replace one base with another and form a stop codon or make a different amino acid , but equally degenerate bases means nothing may change
What is a deletition mutation and its effects
Removing a base causing frame shift so different amino acids are coded for
What is an addition mutation and its effects
Adding a base causing frame shift but if 3 bases are added no frame shift happens
What is a duplication mutation and its effects
One or more bases repeated in a sequence causing frame shift to the right
What is an inversion mutation and its effects
Section of dna breaks away and reattaches in the reverse order changing the amino acid sequence
What is a translocation mutation and its effects
Chromosome breaks and fragments re attach to different chromosomes causes an abnormal phenotype
Types of chromosome mutation and their effects
Deletion , duplication , inversion , translocation
Cause change in chromeosome structure for growth and development
What is a zygote
The precursor to all cells in your body containing all genetic information required to produce all cell types
What is a totipotent stem cell
The cell that has all the total possibilities to differentiate into any cell
What is a pluripotent stem cell
Embryo
Can differentiate into almost any type of specialised body cell ( only cell types and tissues )
How do totipotent stem cells differentiate
They translate only part of their dna
What genes are expressed in all cells
Transport proteins
Glycoproteins for cell signalling
What is a multi potent stem cells
Found in the bone marrow and can be used to make blood cells
Can only produce one type of tissue
What is a unipotent stem cells
Makes clones
All they same cell
Three properties of all stem cells
They can divide and renew themselves over a long time period
They are un specialised
They can differentiate into other specialised cell types
What are induced pluripotent stem cells
Can be produced from almost any adult somatic stem cell and they aquaire the characteristics of a pluripotent stem cells by appropriate protein transcription factors
Name the stem cells in a plant
Meristem are the totipotent stem cells
What is a transcriptional factor
Protein complexes with different subunits that diffuse from the cytoplasm to dna through the nuclear pore
They are spesific to a particular gene
How does a transcriptional factor initiate transcription
Hormone binds to the complementary receptor on the transcriptional factor
The inhibitor molecule is released and the transcriptional factor can diffuse through the nuclear pore. It binds to the promoter region on the dna and attracts a co factor
This stimulates rna polymerase to transcribe the gene
What is small interfering RNA and how does it work
A small molecule of double stranded rna regulates gene expression to prevent translation
Enzyme 1 breaks up double stranded rna making single stranded rna by breaking phosphodiester bonds
Enzyme 2 combines with one of the two single stranded rna molecules
Complimentary base pairs between single stranded RNA and target mRNA
mRNA is broken down into fragments
Translation of protein stops
What is epigenetics
environmental factors cause heritable changes in the gene function without changing the genome
Some environmental factors believed to influence epigenetics
Diet , exercise , smoking , alcohol
How does the epigenetics influence gene expression
It is make up of chemical tags which determine the shape of the dna histone complex
The tags respond to environmental change which intern impacts transcription
Why is the rate of expression higher if the dna histone complex is less condensed
Less condensing means that the promoter is more likely to be exposed for the transcription factor to bind to
What is decreased acetylation
Decreased acetylation of histones increase the possitively charge of the histones and increase the attraction of the dna so it is less accessible to transcriptional factors
What is acetylation
Histones moving further apart
What is increased methylation
Prevents binding of transcriptional factors to the dna as it attracts the proteins that condense dna histone complexes to make it inaccessible
Describe how a tumor spreads
The primary tumor moves into the lymph duct and it enlarges to develope blood and lymphatic vessels
Capillaries grow into the tumor to supply it with o2 and glucose
Tumor cell squeezes into the blood and lymphatic system
And circulates around
The tumor cells then adhere to the vessel walls and squeeze through to form distinct metastatis
What is a proto oncogene
Stimulates the cell division
What is an oncogene
A faulty protooncogene which is permantly switched on
