Dna Mutations Flashcards
Explain the difference between necrosis and apoptosis
Necrosis could be cell injury. The well would burst and the conformational shape of the cell changed.
Apoptosis is cell suicide and can be reversed and organised. Tails, fingers, cell proliferation, Cell differentiation
What is spontaneous DNA damage
dna damage that would occur due to the instability and chemical changes
What is spontaneous base loss
When the covalent bond in the base and the sugar would break, due to the weakness in the covalent bonds. This would then damage the dna and would lead to mutations
What is spontaneous deamination
When the cytosine base in dna is converted to uracil. This is bad as this is not a dna a base. Would change the sequence and effect proteins or cause cancer.
THIS IS CAUSED BY A CHEMICAL MUTAGEN NITROUS ACID
What does smoking tobacco do to the dna
Would have a covalent adduct. The benzo[a]pyrene in the DNA would be lost. Old lead to cancer
What does UV light do to the DNA
Cross links would form between the groups on the DNA stand. There can be one or two cross links formed
Where do the radicals come from in the body and what would they do to the DNA
Radical come from the mitocondtia due to the processing of Oxygen.
Could add the O, OH or HOOH groups, this would then cause the double strand in DNA to break leading to mutations, cancer and ageing
What does ionising radiation do to the DNA strand
Double strand breaks
Damage of the bases
Damage in many areas
Cross links would form
What genetic effects can cause DNA damage
DNA replication
Recombination of the DNA between the homologous chromosomes
What is photo-reactivation
Repairs the DNA.
Would use the photolyase enzyme that would absorb the photon from the sun and would fix the cross link formed in the DNA
What is Excision repair
Enzyme would move across the DNA strand and would detect the damage
Signals a protein that would locate the damage
Protein would cut out the damaged part of the DNA
Polymerase and nucleotides to fix
What is non-homologous repair of the DNA
DNA placed into a complex.
Would force the dna strands together for them to be fixed.
Would cause more damage
Happens in the non-coding areas, so this would be a compromise
What is homologous repair of dna
Repair that would fix the back bone of the dna
This would need the homologous series And therefore would occur after the s-phase of the cell cycle
What causes radiation sickness
The damage of the organs and the cells
What happens to the body in the high and the low dose of radiation exposure
High doses: immediate and serious damage that would cause the damage to the cells and cause the cell death. This would then cause the damage to the organs and give radiation sickness
Low doses: delayed but serious effects
What occurs in the recombinant repair of DNA.
The dna would be fixed using a different pathway
What are the ways in which the mutations can abolish or damage the DNA
Frameshift
Insertions
Duplications of parts of the chromosome
Stops transcription from occurring
Decrease the mRNA stability
What is the difference between transition and transversion of the dna
Transition would be when the individual base changes, e.g. A to T (point mutation)
Transversion would be when the purine would be converted to the pyramidine or visa versa.
Describe what occurs in phenylketonuria
Point mutation where the phenylalanine would be converted to the tyrosine
Would then cause the neurological issues and would not be able to eat: milk, dairy, meat and fish
What causes sickle cell anemia
A point mutation that would cause a nucleotide to change which would then cause the amino acid. A to T
What mutation would cause common Down syndrome
A transitional mutation that would change glycine to arginine. Would then cause a change in the FRGR3 chromosome.
The change from glycine to arginine would enhance the FRGR3 and would then allow lower amounts of proliferation. Would not allow bone growth
What mutation would cause cystic fibrosis
CFTR gene
Deletion in the phenylalanine amino acid
F508del
What are the treatments for cystic fibrosis
Aerosols, that would contain lipids would treat the symptoms
Digesting enzymes
Drainage of the lungs from when it gets full of liquid
What are the biological effects caused by ionising radiation
Necrosis of the cells
Increased chance of leukaemia
Eye irritation
Erythema (skin redness)
What are the direct and the indirect effects radiation has on bio molecules
Directs: through the direct interaction with the radiation and the bio molecules
Indirect caused through ionising water or even the radioactive radicals that would then go onto interact with the bio-molecules
What are the advantages of using a physical map to map gene defects
Allows a more precise location to be viewed
Allows identification of new defects
What is the mutation of the HD gene (Huntington’s disease)
A triplet repeat of CAG
What are the conditions for an X-linked dominant disorder
Both men an women effected
If have an effected man would have all daughters effected but none of the sons would be effected
Fragile X syndrome (large head, large ears long face)
What are the conditions for an X linked recessive disorder
Only males would be effected
No male to male transmission
Haemophilia A, duchennes muscular distrophy, red and green colour blindness
What conditions would be autosomal dominant
Huntingtons
Common Down syndrome (Achondroplasia mutation in the FGFR3 gene)
What conditions would be autosomal recessive
Cystic fibrosis (CFTR gene mutation)
Phenylketonuria (the defective phenylalanine hydroxylase that would normally convert phenylalanine to tyrosine)
What causes phenylketonuria
The defective phenylalanine hydroxylase (PAH) that would allow the phenylalanine to be converted to tyrosine
There would also be a g to a point mutation that would lead to a premature stop codon (so a nonsense mutation)
What can you use to treat phenylketonuria
The polyribsomes
Since enzyme deficiency would wand to synthesis the PAH from an RNA.
Shear the ribosome and isolate the complex using an enzyme that would be complementary to the PAH
Make a cDNA.
What mutation causes sickle cell anemia
A mutation in the persons HBB gene (haemoglobin gene)
A GAG to GTG mutation
What chromosome would be effected by Huntington’s disease
Chromosome 4
The triplet CAG CAG CAG (when have the disease would have the increased length of the CAG so would allow this triplet to form)
What would it mean if a cell is mis-repaired
Mutation would occur
What can cause free radical damage
Ionising radiation or UV
Translocation of what chromosomes would lead to myeloid leukaemia
9 and 22
