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Questions and Answers
What is the basic functional unit of heredity that consists of a distinct DNA sequence within a chromosome?
What is the basic functional unit of heredity that consists of a distinct DNA sequence within a chromosome?
Which of the following components is NOT a target of gene mutation in carcinogenesis?
Which of the following components is NOT a target of gene mutation in carcinogenesis?
What term describes the variations of a single gene that contribute to an individual's physical features?
What term describes the variations of a single gene that contribute to an individual's physical features?
How many chromosomes are present in most human cells?
How many chromosomes are present in most human cells?
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Which process occurs before cell division and involves the replication of DNA?
Which process occurs before cell division and involves the replication of DNA?
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What percentage of genes do people have that are slightly different from one another?
What percentage of genes do people have that are slightly different from one another?
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What does the sequence of bases in DNA determine?
What does the sequence of bases in DNA determine?
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What component of a chromosome is responsible for its efficient condensation and organization?
What component of a chromosome is responsible for its efficient condensation and organization?
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What is the primary function of proto-oncogenes?
What is the primary function of proto-oncogenes?
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What characterizes the BRAFV600E mutation?
What characterizes the BRAFV600E mutation?
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Which oncogene is most commonly mutated?
Which oncogene is most commonly mutated?
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What role does telomerase play in cancer cells?
What role does telomerase play in cancer cells?
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Which of the following is NOT considered oncogenic?
Which of the following is NOT considered oncogenic?
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What does the mutation in the BRAF gene lead to?
What does the mutation in the BRAF gene lead to?
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What is the primary consequence of MYC gene activation?
What is the primary consequence of MYC gene activation?
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Which process is directly influenced by oncogenes?
Which process is directly influenced by oncogenes?
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What is the definition of an allele?
What is the definition of an allele?
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What structure contains tightly packed DNA?
What structure contains tightly packed DNA?
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Which of the following describes the basic unit of DNA?
Which of the following describes the basic unit of DNA?
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What is primarily contained in a gene?
What is primarily contained in a gene?
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How many chromosomes are typically found in human cells?
How many chromosomes are typically found in human cells?
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How many chromatids does a standard human chromosome have during mitosis?
How many chromatids does a standard human chromosome have during mitosis?
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What role do cyclins play in the cell cycle?
What role do cyclins play in the cell cycle?
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What is the primary result of the cell signaling pathway involving genes?
What is the primary result of the cell signaling pathway involving genes?
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What is the primary function of the Bcl-2 family of genes?
What is the primary function of the Bcl-2 family of genes?
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Which statement about the Philadelphia chromosome is accurate?
Which statement about the Philadelphia chromosome is accurate?
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What outcome is typically the result of overexpression of Bcl-2 in cells?
What outcome is typically the result of overexpression of Bcl-2 in cells?
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Which mechanism is NOT commonly associated with genetic damage in cancer?
Which mechanism is NOT commonly associated with genetic damage in cancer?
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What is a consequence of erroneous repair of DNA double-strand breaks?
What is a consequence of erroneous repair of DNA double-strand breaks?
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What is the primary cause of microsatellite instability in Lynch syndrome colorectal carcinoma?
What is the primary cause of microsatellite instability in Lynch syndrome colorectal carcinoma?
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Which factor is associated with hereditary breast cancer in relation to BRCA mutations?
Which factor is associated with hereditary breast cancer in relation to BRCA mutations?
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Which of the following gene types primarily promotes tumor cell growth?
Which of the following gene types primarily promotes tumor cell growth?
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What is the role of BRCA proteins in cellular functions?
What is the role of BRCA proteins in cellular functions?
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How does the accumulation of mutations contribute to carcinogenesis?
How does the accumulation of mutations contribute to carcinogenesis?
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Study Notes
Genetics
- A gene is a distinct DNA sequence within a chromosome that acts as instructions for creating proteins.
- Humans have 20,000-25,000 genes, each with two copies – one from each parent.
- Alleles are variations of a single gene that contribute to an individual’s unique physical features.
- A chromosome is a condensed packaging of DNA, with most human cells containing 46 chromosomes in 23 pairs.
- DNA is comprised of four chemical bases (adenine, thymine, guanine, cytosine) arranged in a specific sequence that determines protein structure.
- A chromatid is one of two identical copies of DNA within a chromosome during cell division.
Cell Cycle
- The cell cycle is a series of events that allow a cell to prepare for division and eventually divide into two daughter cells.
- The cell cycle includes the G0 (resting) phase, where the cell spends most of its time, and the active cell division phases.
- Cyclins are proteins that activate cyclin-dependent kinases (CDKs), which drive progression through the cell cycle.
- CDK inhibitors inhibit CDK function and help to regulate the cell cycle.
Neoplasia and Genetics
- Neoplasia is a genetic disease, caused by mutations in four classes of normal regulatory genes:
- Proto-oncogenes
- Tumor suppressor genes
- Apoptosis-regulating genes
- DNA repair genes
Proto-oncogenes
- Proto-oncogenes are normal genes that promote cell growth.
- Oncogenes are mutated proto-oncogenes that contribute to autonomous cell growth in cancer cells.
- Oncoproteins are the mutant proteins encoded by oncogenes that promote uncontrolled cell growth.
- The MAPK pathway, which is involved in cell signaling, is often altered in ameloblastomas, with BRAF mutations being the most common.
- The BRAFV600E mutation, which occurs in 90% of BRAF mutations in neoplasia, results in a gain-of-function mutation in the BRAF protein, leading to uncontrolled activation of the MAPK pathway.
Evasion of Apoptosis
- Apoptosis is programmed cell death that eliminates cells with damaged or abnormal DNA.
- The Bcl-2 family of proteins, which includes both pro- and anti-apoptotic members, regulates apoptosis.
- Follicular lymphoma can evade apoptosis by overexpressing Bcl-2 through chromosomal translocation, a process where a segment of one chromosome moves to a different chromosome.
Chromosomal Translocations
- Chromosomal translocations are often caused by errors in DNA double-strand break repair.
- The Philadelphia chromosome, a characteristic translocation in chronic myelogenous leukemia, is an example of a translocation that can contribute to cancer development.
- Translocations can also involve the fusion of two genes, as seen in mucoepidermoid carcinoma of the hard palate with the CRTC1-MAML2 translocation.
Mechanisms of Genetic Damage
- Common mechanisms of genetic damage include:
- Point mutations: single nucleotide changes.
- Gene deletions: loss of a segment of DNA.
- Gene amplifications: duplications of a segment of DNA.
- Chromosomal translocations: exchanges or attachments of chromosomal segments.
Lynch Syndrome
- Lynch syndrome, a hereditary cancer syndrome, is associated with a high risk of colorectal cancer.
- Lynch syndrome involves a dysfunction in the mismatch repair (MMR) system, which is responsible for correcting errors in DNA replication.
- Colorectal cancer in Lynch syndrome is often characterized by microsatellite instability, which occurs when the MMR system is deficient and results in increased mutation rates in repetitive DNA sequences.
BRCA1/BRCA2 and Familial Breast Cancer
- Hereditary mutations in BRCA1 and BRCA2 genes are common in familial breast cancer.
- BRCA1 and BRCA2 are involved in DNA repair, specifically homologous recombination, which uses a sister chromatid as a template to repair DNA breaks during replication.
- Cells lacking functional BRCA1 and BRCA2 are prone to chromosomal breaks and aneuploidy (abnormal chromosome number).
Carcinogenesis
- Carcinogenesis is a multi-step process that involves the accumulation of multiple genetic mutations over time.
- These mutations can occur in proto-oncogenes, tumor suppressor genes, apoptosis-regulating genes, and DNA repair genes.
- The combination of these mutations leads to uncontrolled cell growth, evasion of apoptosis, and tumor development.
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Description
Explore the fundamental concepts of genetics and the cell cycle in this informative quiz. Learn about DNA, genes, chromosomes, and the stages of cell division. This quiz will test your understanding of the basic biological processes that govern life.
