Mutations and cancer Flashcards
Gene mutation
change in base sequences of DNA
occurs during DNA replication
includes addition, deletion, substitution, inversion, duplication, and translocation of bases
mutagenic agents
Chemical or radiation that increases mutation rate
Addition mutation
one extra base is added to the DNA sequence
causes all subsequent codons to be altered (frameshift)
Deletion mutation
one base is deleted in the DNA sequence
causes all subsequent codons to be altered
substitution mutation
One base in the DNA sequence is changed
no frameshift
only one codon changes
may have no impact due to degenerate genetic code
Frameshift
A change in all codons after the point of mutation
each base shifts left or right one position
inversion mutation
A section of bases detach from the DNA sequence and re-join inverted
results in different amino acids being coded for in this region
duplication mutation
One base is duplicated at least once in the sequence
causes a frameshift to right
Translocation of bases mutation
A section of bases on one chromosome detaches and attaches to a different chromosome
non-functioning protein
a protein with a different primary and tertiary structure
Therefore, the shape is changed
it cannot carry out its function
Tumour
a mass of cells as a result of uncontrolled cell division
can be benign or malignant
Benign tumour
non-cancerous tumour
grows large but at a slow rate
produce adhesive and are surrounded by a capsule so they cannot spread
malignant tumour
cancerous tumour
grows rapidly
can become unspecialised
can metastasise
grow projections
develop own blood supply
cancer
malignant tumours that form due to uncontrolled cell division
metastasis
cancer cells breaking off from the tumour
spreading to form secondary tumours in different tissues or organs
oncogene
a mutated version of a proto-oncogene
results in constant initiation of DNA replication and mitotic cell division
causes tumour formation
tumour suppressor genes
genes that produce proteins to slow down cell division and cause cell death if DNA copying errors are detected
epigenetics
The heritable change in gene function
without changing the DNA base sequence
caused by changes in the environment
can inhibit transcription
hypermethylation
an increased number of methyl groups attached to a gene
results in the gene being deactivated
results in cancer if happens to a tumour suppressor gene
methylation of DNA
inhibits transcription
methyl groups attach to the cytosine base on DNA
prevents transcriptional factors from binding
condenses the DNA-histone complex
how can oestrogen increase the risk of breast cancer
Oestrogen is a steroid hormone
it binds to a receptor site on a transcriptional factor
causing a change in shape
so it can bind to the DNA to initiate transcription
can result in uncontrolled cell division
