Gene Expression Flashcards
Universal
Same triplet codes for the same amnio acids in all organisms
Non overlapping
Each base is read once in a triplet
Degenerate
More than one triplet codes for each amino acid
3 types of mutagenic agents and examples and what they do
- High energy radiation which damage DNA molecule and chemicals alter DNA structure/ effect DNA replication= x rats, gamma rays
- DNA reactive chemicals= nitrous oxide removes a NH2 from cytosine converting it into uracil
- Biological Agents = Viruses and bacteria
Stem cell definition
They are undifferentiate that can divide into any type of cell continually and become specialised
4 types of stem cells
Pluripotent
Totipotent
Multipotent
Unipotent
Stem cell
Cells that can differentiate by mitosis into two genetically identical cells one remains of the stem cell on the other differentiate into a specialised cell by translating part of the DNA.
Totipotent
They can divide and differentiate into any type in cell and produce a whole new organism found up to 8 cell stages in early mammalian embryo for a limited time
Pluripotent
Divide unlimited times and differentiate into any type of cell found in an embryo
Multi potent
Divide a limited number of times and differentiate into a limited number of different type types of cell found in mature mammal tissues e.g. bone marrow
Uni potent
Divide a limited number of times and differentiate into one cell type found in hard as cardiomycocytes
Applicational stem cells to medical research
- Producing tissues for skin graft.
- Research introduce an organs for transplant.
- Research into how cells become specialised.
- Use of stem cells to cure diseases such as Parkinson’s disease.
Ethical concerns about using stem cells in IPC
- Not right to use stem cells from embryos as embryos are human.
- Embryos have no moral rights
- Donors consent.
- Animal testing.
- Cancer
Promoter region
One or more basic sequence is found before a gene that control the expression of that gene
Transcription factors
Proteins which when activated by to the promoter region of a gene stimulating RNA polymerase to begin transcription of that target gene
Oestrogen acting as a transcription factor
- Oestrogen diffuses through the phospholipid cell membrane as its lipid soluble.
- Diffuses through the nuclear envelope.
- Binds to the oestrogen receptor protein.
- Changes the tertiary structure.
- Releases the transcription factor.
- Transcription factor by to the DNA.
- At the promoter region.
- This allows stimulation of RNA to transcribe the gene.
- This increases transcription or mRNA is produced.
How does interfering RNA work?
- Enzyme cuts mRNA into SI RNA.
- One strand of SI RNA combines with another enzyme.
- The sRNA enzyme complex will bind via complementary base pairing to named gene proteins mRNA.
- Once abound the enzyme will cut up the mRNA so it could no longer be transcribed or no ribosome can bind
- So reduction of translation of name protein.
- So reduces name protein in cell cell less name protein function.
Why can’t some protein still be made even if there is interfering RNA
More mRNA has been transcribed and there is interfering RNA so not all mRNA is bound to RNAi
So not Emma, all of mRNA is destroyed
Epigenetic definition
Heritable changes in gene function
Without changes to the base sequence of DNA
What is methylation?
Addition of methyl groups added to DNA which tightens the DNA so no RNA polymerase can translate the DNA
What is acetylation
Addition off acetal groups to histones proteins which results in them becoming loosely packed so DNA is less coiled
Gene switched off
No translation or transcription
Gene switched on
There is transcription and translation
Describe and explain the epigenetic modification that keeps the gene switched off
- Increase methylation means name transcription factor cannot bind to promotor a region of DNA.
- Decrease acetylation of his protein tails results in DNA more tightly packed.
- Less expression of gene.
- So RNA polymerase cannot bind to DNA next promoter.
- So less mRNA of named gene produced
- So less named protein function.
Describe and explain the Epigenetics modification that keep the genes turned on
- Decrease methylation means transcription factor binds to promote a region of DNA.
- Increased acetylation of his stone protein tales means DNA more loosely packed.
- More expression of gene.
- More RNA by a DNA promoter region.
- Scribes names protein producing more mRNA.
- More protein.
- More name protein function.
Tumour suppressor gene
Genes that code for a protein that stops cell division
Proto-oncogene
Gene that code for a protein that starts cell division
Cancer
Uncontrolled rapid mitosis
Tumour
Mass of abnormal cells from uncontrolled mitosis
Malignant tumour
Cells that have metastasised and can spread around the body
Benign tumours
Cells that are metastasised and will not spread around other parts of the body
Does tumour suppressor gene need to be turned off or on?
No, a cell cycle needs to start
Describe how tumor could form because of epigenetic modifications to Tumor suppressor genes
- More methylation of a suppressor gene DNA promoter region
- Less acetylation of histones proteins around humans oppressed genes.
- Less expression of named tumour suppressor gene.
- Less transcription of gene.
- Less mRNA formed.
- Less translation.
- Less named protein that stop cell cycle.
- Leads to uncontrolled cell division.
Describe how humours could form because of epigenetic modifications to proto-oncogenes
- Needs to be expressed cell cycle starts.
- Less methylation of Proto onco DNA at promoter region.
- More acetylation of histone proteins around named Proto onco gene
- More expression of named proton once gene .
- More transcription of gene
- More mRNA formed.
- More translation of its mRNA.
- More name protein that starts cell cycle.
- Lead to uncontrolled cell division.
Describe the result of mutations to promote a regions of tumour suppressed genes and proto-oncogenes
- Mutation in promoter regions for both tumour suppressor gene and proton onco genes
- Transcription factor cannot bind.
- So RNA polymerase is not stimulated.
- So no transcription of gene.
- So no mRNA formed.
- So no translation.
- Less protein.
- Can’t start or uncontrolled cell division.
Describe the result of mutations to exons in tumour suppressed genes or proto-oncogenes
- Change in amino acid sequence.
- Change in structure due to different placement of hydrogen ionic and Dulfi bonds between all groups of amino acids.
- Protein cannot do its function.
- Faulty protein leads to increase or decrease in cell division.
Gene
A base sequence of nucleotides that form a polypeptide chain
A observed ratio is distinctly different to
expected phenotype ratios. The data
showed two phenotypes with a large
number of individuals and two
phenotypes with very low number of
individuals. . Explain this data
Genes are linked
