Genetics Final Exam Study Guide – Step-by-Step Guidance

Study Guide - Smart Notes

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Q1. Mutant versions of genes that are normally involved in promoting the cell cycle are known as ________.

Background

Topic: Cancer Genetics – Oncogenes

This question tests your understanding of the terminology used to describe genes that, when mutated, can drive uncontrolled cell division and contribute to cancer development.

Key Terms:

Proto-oncogene: A normal gene that promotes cell growth and division.
Oncogene: A mutated or abnormally expressed proto-oncogene that contributes to cancer.

Step-by-Step Guidance

Recall the normal function of proto-oncogenes in the cell cycle.
Consider what happens when these genes are mutated or overexpressed.
Think about the term used for the mutated, cancer-promoting form of these genes.

Try solving on your own before revealing the answer!

Q2. A mother presents with her 8-year-old child to establish care. She is concerned because the child's father died of colon cancer in his forties. She would like her child to be tested for Familial Adenomatous Polyposis (FAP). She would like to know what her child's lifetime cancer risk is for developing colon cancer if his screening is positive for FAP. What is the correct answer?

Background

Topic: Inherited Cancer Syndromes – Familial Adenomatous Polyposis (FAP)

This question tests your knowledge of the lifetime risk of colon cancer in individuals who test positive for FAP, an autosomal dominant disorder caused by mutations in the APC gene.

Key Terms:

FAP (Familial Adenomatous Polyposis): An inherited condition with a high risk of colon cancer.
APC gene: Tumor suppressor gene mutated in FAP.
Lifetime risk: The probability of developing a disease over the course of a lifetime.

Step-by-Step Guidance

Recall the inheritance pattern and penetrance of FAP.
Think about the typical age of onset and risk of colon cancer in FAP patients.
Review the answer choices and eliminate those inconsistent with what you know about FAP risk.
Focus on the answer that reflects the nearly certain risk associated with untreated FAP.

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Q3. What type of tumor originates from hematopoietic organs?

Background

Topic: Tumor Classification

This question tests your understanding of the terminology used to describe tumors based on their tissue of origin, specifically those arising from blood-forming (hematopoietic) tissues.

Key Terms:

Hematopoietic organs: Organs involved in blood cell formation (e.g., bone marrow, lymph nodes).
Leukemia: Cancer of blood-forming tissues.
Lymphoma: Cancer of lymphatic tissue.

Step-by-Step Guidance

Recall the main types of tumors and their tissue origins (carcinoma, sarcoma, leukemia, lymphoma).
Identify which types are associated with hematopoietic (blood-forming) tissues.
Consider examples of cancers that arise from these tissues.

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Q4. A 2-year-old child is diagnosed with retinoblastoma in one eye. What can you assume about this child's retinoblastoma?

Background

Topic: Retinoblastoma – Hereditary vs. Sporadic Forms

This question tests your understanding of the genetic basis of retinoblastoma, including the difference between hereditary (germline) and sporadic (somatic) cases.

Key Terms:

Retinoblastoma: A rare childhood eye cancer.
Knudson's two-hit hypothesis: Both alleles of the RB1 gene must be inactivated for tumor development.
Unilateral vs. bilateral: One eye vs. both eyes affected.

Step-by-Step Guidance

Recall the difference between hereditary and sporadic retinoblastoma (age of onset, laterality).
Consider what is more likely in a very young child: hereditary or sporadic form?
Think about what the diagnosis in one eye suggests about the underlying genetics.

Try solving on your own before revealing the answer!

Q5. What is the significance of CDK/cyclin interactions with respect to cancer cell proliferation?

Background

Topic: Cell Cycle Regulation

This question tests your understanding of how cyclin-dependent kinases (CDKs) and cyclins regulate the cell cycle and how their dysregulation can contribute to cancer.

Key Terms:

CDK (Cyclin-Dependent Kinase): Enzymes that, when bound to cyclins, regulate cell cycle progression.
Cyclin: Regulatory proteins that control CDK activity.
Cell cycle checkpoints: Control mechanisms that ensure proper cell division.

Step-by-Step Guidance

Recall the role of CDK/cyclin complexes in cell cycle transitions (e.g., G1/S, G2/M).
Consider how abnormal CDK/cyclin activity could affect cell proliferation.
Think about how this dysregulation might contribute to uncontrolled cell division in cancer.

Try solving on your own before revealing the answer!

Q6. Which of the following factors is typically monitored during the M checkpoint?

Background

Topic: Cell Cycle Checkpoints

This question tests your knowledge of the specific events monitored at the M (mitotic) checkpoint, which ensures proper chromosome segregation.

Key Terms:

M checkpoint (Spindle Assembly Checkpoint): Ensures chromosomes are properly attached to spindle fibers before anaphase.
Kinetochores: Protein structures on chromosomes where spindle fibers attach.

Step-by-Step Guidance

Review the main events that occur during mitosis, especially metaphase and anaphase.
Recall what the cell checks for before proceeding from metaphase to anaphase.
Match the answer choices to the event monitored at the M checkpoint.

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Q7. Which of the following genes is an example of a tumor-suppressor?

Background

Topic: Tumor Suppressor Genes vs. Oncogenes

This question tests your ability to distinguish between genes that suppress tumor formation and those that promote cell growth.

Key Terms:

Tumor suppressor gene: A gene that protects a cell from one step on the path to cancer.
Oncogene: A gene that has the potential to cause cancer when mutated or overexpressed.

Step-by-Step Guidance

Recall examples of well-known tumor suppressor genes (e.g., BRCA1, p53, RB1).
Review the function of each gene listed in the answer choices.
Identify which gene acts to prevent uncontrolled cell growth.

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Q8. Which statement best describes an example of a mutation in a tumor-suppressor gene?

Background

Topic: Tumor Suppressor Gene Mutations

This question tests your understanding of the consequences of mutations in tumor suppressor genes, which typically result in loss of function.

Key Terms:

Loss-of-function mutation: Mutation that results in reduced or abolished protein function.
Programmed cell death (apoptosis): A process that eliminates damaged or unnecessary cells.

Step-by-Step Guidance

Recall the normal role of tumor suppressor genes in regulating cell growth and apoptosis.
Consider what happens when these genes are mutated (loss of function).
Identify which answer choice describes a loss of tumor suppressor function.

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Q9. The following events occur when p53 regulates the cell cycle. Place these events in the correct sequence:

p53 is activated by posttranslational modifications.
The cell cycle is arrested, and apoptosis is initiated.
p53 regulates the transcription of multiple target genes.
DNA damage causes MDM2 to dissociate from p53.

Background

Topic: p53 Pathway in Cell Cycle Regulation

This question tests your understanding of the sequence of molecular events by which p53 responds to DNA damage.

Key Terms:

p53: Tumor suppressor protein that regulates the cell cycle and apoptosis.
MDM2: Protein that inhibits p53 under normal conditions.
Posttranslational modification: Chemical changes to a protein after it is made.

Step-by-Step Guidance

Recall what triggers p53 activation (DNA damage).
Think about the role of MDM2 in regulating p53 activity.
Consider the order in which p53 is activated, regulates gene expression, and leads to cell cycle arrest/apoptosis.
Match the sequence to the answer choices provided.

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Q10. Mutation in which gene is the first step in the development of colorectal cancer?

Background

Topic: Colorectal Cancer Genetics

This question tests your knowledge of the sequence of genetic events in colorectal cancer, particularly the gene most commonly mutated first.

Key Terms:

APC gene: Tumor suppressor gene mutated early in colorectal cancer.
KRAS, PI3K, TGF-β: Other genes mutated later in progression.

Step-by-Step Guidance

Recall the multistep model of colorectal cancer development (Vogelstein model).
Identify which gene is typically mutated first in this sequence.
Review the functions of each gene listed in the answer choices.

Try solving on your own before revealing the answer!

Q11. Why are oncogenes usually dominant in their action, whereas tumor suppressor genes are recessive?

Background

Topic: Cancer Gene Function – Dominance vs. Recessiveness

This question tests your understanding of the genetic mechanisms underlying oncogene and tumor suppressor gene mutations.

Key Terms:

Oncogene: Gain-of-function mutation; one mutated allele is sufficient for effect.
Tumor suppressor gene: Loss-of-function mutation; both alleles must be inactivated.

Step-by-Step Guidance

Recall the difference between gain-of-function and loss-of-function mutations.
Consider why a single mutated oncogene allele can drive cancer, but both tumor suppressor alleles must be lost.
Think about the implications for inheritance and cancer risk.

Try solving on your own before revealing the answer!

Q12. A couple has one child with bilateral retinoblastoma. The mother is free from cancer, but the father has unilateral retinoblastoma, and he has a brother who has bilateral retinoblastoma. If the next child has retinoblastoma, is it likely to be bilateral or unilateral?

Background

Topic: Retinoblastoma Inheritance Patterns

This question tests your understanding of the inheritance and expression of retinoblastoma, including the difference between bilateral and unilateral cases.

Key Terms:

Bilateral retinoblastoma: Both eyes affected; usually hereditary.
Unilateral retinoblastoma: One eye affected; can be hereditary or sporadic.
Penetrance: Proportion of individuals with a mutation who exhibit clinical symptoms.

Step-by-Step Guidance

Review the family history and inheritance pattern described.
Recall the typical presentation of hereditary vs. sporadic retinoblastoma.
Consider the likelihood of bilateral vs. unilateral disease in the context of this pedigree.