exam questions Flashcards
For some patients hsct stem cells from bone marrow is a treatment for MDS how?
- produce healthy cells
-no MDS
-stem cells divide
Sickle cell disease (SCD) is a group of inherited disorders. People with SCD
have sickle-shaped red blood cells. A single base substitution mutation can
cause one type of SCD. This mutation causes a change in the structure of the
beta polypeptide chains in haemoglobin.
(a) Explain how a single base substitution causes a change in the structure of
this polypeptide
-change in the amino acid sequqence so primary struc changes
- change in hydrogen bonds
-so alters tertiary structure.
Scientists have found that a chemical in green tea, called EGCG, is a
competitive inhibitor of DNMT. EGCG enables daughter cells to produce
messenger RNA (mRNA) from the tumour suppressor gene.
(b) Suggest how EGCG allows the production of mRNA in daughter cells.
-EGCG binds to actve site of DNMT
- decreased methylation
- allows transcriptional factor to bind to promoter region
- allowing rna polymerase to be stimulated
when is RNA polymerase stimulated
- when the transcriptional factor binds to the promoter region
- this allows rna nucleotides to bind to make mRNA
-so the protein is made in translaton
Describe how alterations to tumour suppressor genes can lead to the
development of tumours.
____________________________
-increased methylation
-mutation in gene
-so methyl binds to cytosine groups
-so tf factor cant bind to the dna
-so tumour s genes cant be transcribed
-so cells divide uncrontrolably
Define what is meant by epigenetics
Heritable changes in gene function;
2. Without changes to the base sequence of DNA
explain how methylation causes tumours
Methyl groups (could be) added to (both copies of) a tumour
suppressor gene;( methyl to cytosine)
2. The transcription of tumour suppressor genes is inhibited;
3. Leading to uncontrolled cell division
