Cancer biochemistry Exam QUESTIONS WITH
COMPLETE SOLUTIONS (ANSWERS VERIFIED 100%
CORRECT)
What are microsatellites and what is microsatellite instability? - ✔✔Microsatellites
are a sequence of repetitive nucleotides typically occurring 5-50 times and can be seen
in various locations of an organism's genome.
Microsatellite instability (MSI) is a condition of genetic hypermutability that results from
impaired DNA mismatch repair (MMR). Microsatellites are regions of repeated DNA that
change in length when MMR is not working properly. The presence of MSI represents
phenotypic evidence that MMR is not functioning normally.
What are BRACA 1 and BRACA 2 and why are they called tumor suppressor genes? -
✔✔They stand for Breast cancer genes. They are called tumor suppressor genes
because they play a role in regulating and halting cell growth and division.
A fault (or mutation) in the BRCA1 or BRCA2 gene means that the cells can grow out of
control. This can lead to cancer developing.
Faulty BRCA1 and BRCA2 genes are rare. Only around 1 in every 400 people have a
faulty BRCA1 or BRCA2 gene. - ✔✔
It is important to remember that breast cancer is not the only type of cancer that can
manifest due to mutations in BRACA genes. What are some other possible cancers that
can arise in both men and women? - ✔✔Ovarian, prostate, and pancreatic cancers.
What is Lynch syndrome?
, Up to 70 in every 100 people (70%) with Lynch syndrome will develop bowel cancer.
Most people will develop bowel cancer before the age of 50. - ✔✔Hereditary non-
polyposis colorectal cancer . Autosomal dominant condition. Bowel polyps are small
growths on the lining of the large intestine (colon) or rectum. They're very common and
not usually serious, but sometimes they can lead to bowel cancer.
Autosomal dominant changes in ONE of which of the following genes can cause Lynch
syndrome? - ✔✔MLH1, MSH2, MSH3, MSH6 or PMS2
What can microsatellite instability cause? - ✔✔Strand slippage- It involves
denaturation and displacement of the DNA strands, resulting in mispairing of the
complementary bases.
Around 70% and 45% of women with a BRCA1/BRCA2 mutated gene will develop breast
cancer or ovarian cancer by the age of 80 - ✔✔
A few things that BRACA genes do: - ✔✔1- Cell cycle checkpoint activation
2- Transcriptional regulation
3- Apoptosis
4- DNA double strand break repair
What 8 genes have a strong association with increased risk of breast cancer? -
✔✔BRCA1, BRCA2, PALB2, BARD1, RAD51C, RAD51D, ATM and CHEK2.
We have seen previously that there are 2 main pathways for double strand break repair
which are HRR ( homologous recombination repair ) and NHEJ ( Non-homologous end
joining ). Explain both of them: - ✔✔HRR: The complementary strand is used as a
template to removed the damaged part of the other strand, and reattach appropriate
base pairs to match the complementary strand. THIS METHOD IS ERROR FREE.
COMPLETE SOLUTIONS (ANSWERS VERIFIED 100%
CORRECT)
What are microsatellites and what is microsatellite instability? - ✔✔Microsatellites
are a sequence of repetitive nucleotides typically occurring 5-50 times and can be seen
in various locations of an organism's genome.
Microsatellite instability (MSI) is a condition of genetic hypermutability that results from
impaired DNA mismatch repair (MMR). Microsatellites are regions of repeated DNA that
change in length when MMR is not working properly. The presence of MSI represents
phenotypic evidence that MMR is not functioning normally.
What are BRACA 1 and BRACA 2 and why are they called tumor suppressor genes? -
✔✔They stand for Breast cancer genes. They are called tumor suppressor genes
because they play a role in regulating and halting cell growth and division.
A fault (or mutation) in the BRCA1 or BRCA2 gene means that the cells can grow out of
control. This can lead to cancer developing.
Faulty BRCA1 and BRCA2 genes are rare. Only around 1 in every 400 people have a
faulty BRCA1 or BRCA2 gene. - ✔✔
It is important to remember that breast cancer is not the only type of cancer that can
manifest due to mutations in BRACA genes. What are some other possible cancers that
can arise in both men and women? - ✔✔Ovarian, prostate, and pancreatic cancers.
What is Lynch syndrome?
, Up to 70 in every 100 people (70%) with Lynch syndrome will develop bowel cancer.
Most people will develop bowel cancer before the age of 50. - ✔✔Hereditary non-
polyposis colorectal cancer . Autosomal dominant condition. Bowel polyps are small
growths on the lining of the large intestine (colon) or rectum. They're very common and
not usually serious, but sometimes they can lead to bowel cancer.
Autosomal dominant changes in ONE of which of the following genes can cause Lynch
syndrome? - ✔✔MLH1, MSH2, MSH3, MSH6 or PMS2
What can microsatellite instability cause? - ✔✔Strand slippage- It involves
denaturation and displacement of the DNA strands, resulting in mispairing of the
complementary bases.
Around 70% and 45% of women with a BRCA1/BRCA2 mutated gene will develop breast
cancer or ovarian cancer by the age of 80 - ✔✔
A few things that BRACA genes do: - ✔✔1- Cell cycle checkpoint activation
2- Transcriptional regulation
3- Apoptosis
4- DNA double strand break repair
What 8 genes have a strong association with increased risk of breast cancer? -
✔✔BRCA1, BRCA2, PALB2, BARD1, RAD51C, RAD51D, ATM and CHEK2.
We have seen previously that there are 2 main pathways for double strand break repair
which are HRR ( homologous recombination repair ) and NHEJ ( Non-homologous end
joining ). Explain both of them: - ✔✔HRR: The complementary strand is used as a
template to removed the damaged part of the other strand, and reattach appropriate
base pairs to match the complementary strand. THIS METHOD IS ERROR FREE.
