Mutations and Cancer Flashcards
How can DNA mutations alter gene products?
They can change the sequence of amino acids in the protein, affecting its function.
Where must a mutation occur to impact the final protein?
In the coding region of DNA.
What are the two types of mutations based on their effects?
Germline mutations (affect all cells, inherited) and Somatic mutations (local effects, e.g., cancer).
What are the two main scales of DNA mutations?
Large-scale (chromosomal rearrangements) and Small-scale (one or few nucleotide changes).
What are point mutations?
Mutations where a single nucleotide is altered, including substitutions, insertions, and deletions.
What are the three types of substitution mutations?
Silent (no change in amino acid), Nonsense (stop codon produced), Missense (changes amino acid).
What is a frameshift mutation?
A nucleotide is inserted or deleted, altering the entire protein sequence.
What are the causes of DNA mutations?
Inherited (affect all cells, susceptibility genes) or Acquired (viruses, UV damage, drugs, treatment).
What genes are often affected in cancer?
Proto-oncogenes (promote cell division) and Tumour suppressor genes (inhibit cell division).
What is the role of tumour suppressor genes?
They inhibit uncontrolled cell division.
What happens when tumour suppressor genes are mutated?
They lose function, leading to uncontrolled cell growth and cancer.
What are examples of tumour suppressor genes?
TP53, BRCA1, BRCA2.
What is a proto-oncogene?
A gene that produces proteins promoting cell cycle progression.
What happens when a proto-oncogene mutates?
It can become hyperactive, producing excess growth-stimulating proteins.
What is an oncogene?
A mutated proto-oncogene that leads to uncontrolled cell growth.
How does cancer develop?
Multiple DNA mutations activate proto-oncogenes and deactivate tumour suppressor genes.
What are the stages of colon cancer development?
- Loss of tumour suppressor gene APC → Polyp formation. 2. Activation of Ras + loss of SMAD4 → Adenoma. 3. Additional mutations + loss of p53 → Carcinoma (invasive cancer).
