Introduction to Oncology

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Questions and Answers

What is cancer defined as?

The uncontrolled division of cells in a specific tissue or organ, forming a tumor (mass of altered cells) impeding the good functioning of the system and that can invade nearby tissues and be fatal.

What are the earliest recorded instances of tumors?

  • Ancient Egyptian hieroglyphics
  • The Edwin Smith Papyrus (correct)
  • The writings of Hippocrates
  • A bone tumor found in a Neanderthal skeleton

Cancer incidence is generally higher in males than in females.

False (B)

Cancer mortality is generally higher in northern and richer countries.

<p>True (A)</p> Signup and view all the answers

Which of the following is NOT a category of cancer causes?

<p>Astrological Factors (E)</p> Signup and view all the answers

Which of these is NOT a lifestyle factor that can contribute to cancer development?

<p>Regular exercise (D)</p> Signup and view all the answers

The G1/S checkpoint ensures that the cell has enough nutrients to replicate DNA.

<p>True (A)</p> Signup and view all the answers

The G1/S checkpoint checks for DNA damage.

<p>True (A)</p> Signup and view all the answers

What external signals can stimulate cell growth?

<p>All of the above (D)</p> Signup and view all the answers

What is the role of Rb protein in the G1 to S phase transition?

<p>Rb is phosphorylated by Cdk4-6/Cyclin D, which releases the transcription factor, E2F, allowing the cell to proceed to the S phase.</p> Signup and view all the answers

The genes associated with DNA replication are not produced until the S-phase of the cell cycle.

<p>False (B)</p> Signup and view all the answers

What is the primary purpose of DNA replication during the S phase?

<p>To ensure two complete sets of DNA for daughter cells.</p> Signup and view all the answers

The initiation of DNA replication in the S phase is solely controlled by DNA polymerase.

<p>False (B)</p> Signup and view all the answers

Which DNA repair mechanism is responsible for correcting mismatches that occur during DNA replication?

<p>Mismatch Repair (A)</p> Signup and view all the answers

Describe the role of MutS and MutL proteins in Mismatch Repair (MMR).

<p>MutS proteins recognize DNA errors, and MutL proteins bind and recruit the DNA repair process.</p> Signup and view all the answers

Homologous Recombination (HR) is an error-prone repair process.

<p>False (B)</p> Signup and view all the answers

Non-Homologous End Joining (NHEJ) is a high-fidelity repair process.

<p>False (B)</p> Signup and view all the answers

The G2 checkpoint ensures that all DNA has been correctly replicated without damage, including the removal of transcription factors.

<p>False (B)</p> Signup and view all the answers

What is the role of ATM/ATR in the G2 checkpoint?

<p>They detect DNA damage and activate Chk proteins (D)</p> Signup and view all the answers

The Cdk1/Cyclin B complex is activated by phosphorylation.

<p>True (A)</p> Signup and view all the answers

The activation of Cdk1/Cyclin B complex is referred to as 'Mitosis Promoting Factor' (MPF).

<p>True (A)</p> Signup and view all the answers

Which of these removes inhibitory phosphates from Cdk1/Cyclin B complex?

<p>Cdc25 (B)</p> Signup and view all the answers

The Wee1 kinase adds an inhibitory phosphate to the Cdk1/Cyclin B complex.

<p>True (A)</p> Signup and view all the answers

What is the primary outcome of mitosis?

<p>The division of a cell into two daughter cells with identical genetic material.</p> Signup and view all the answers

During which stage of mitosis do the chromosomes line up at the cell's equator?

<p>Metaphase (C)</p> Signup and view all the answers

The Anaphase-Promoting Complex (APC/C) plays a crucial role in regulating the separation of chromosomes during anaphase.

<p>True (A)</p> Signup and view all the answers

What is the function of Mad2 in the metaphase to anaphase checkpoint?

<p>It inhibits APC/C (C)</p> Signup and view all the answers

The separation of sister chromatids occurs during telophase.

<p>False (B)</p> Signup and view all the answers

Proto-oncogenes are normally involved in inhibiting the cell cycle, cell growth, and differentiation.

<p>True (A)</p> Signup and view all the answers

Tumor suppressor genes promote the activation and progression of the cell cycle, cell growth, and differentiation.

<p>True (A)</p> Signup and view all the answers

Mutations in proto-oncogenes are typically hyperactivated in cancer.

<p>True (A)</p> Signup and view all the answers

Which of these is NOT a characteristic of the tumor microenvironment?

<p>Neurons (C)</p> Signup and view all the answers

What is the role of angiogenesis in cancer?

<p>Formation of new blood vessels (C)</p> Signup and view all the answers

Metastasis refers to the spread of cancer cells through blood and lymphatic systems, but not directly to other organs.

<p>False (B)</p> Signup and view all the answers

The 'seed and soil' hypothesis proposes that cancer cells spread to organs with compatible microenvironments.

<p>True (A)</p> Signup and view all the answers

Which migration mode is characterized by amoeboid movement?

<p>Amoeboid (B)</p> Signup and view all the answers

Cancer cells can spread via hematogenous, lymphatic, and transcoelomic routes, but not through the nervous system.

<p>False (B)</p> Signup and view all the answers

Organotropism refers to the tendency of cancer cells to metastasize to organs with distinct microenvironments.

<p>True (A)</p> Signup and view all the answers

Flashcards

Cancer Definition

Uncontrolled cell division forming a tumor that invades and can be fatal.

Cancer Origins

Earliest records date back to ancient Egypt (Edwin Smith Papyrus).

Cancer Incidence Trends

Increased incidence worldwide, higher in wealthier, northern countries.

Chemical Carcinogens

Substances like tobacco, benzene, and asbestos that cause cancer.

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Biological Carcinogens

Viruses, bacteria, and parasites that can cause cancer.

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Lifestyle Cancer Factors

Diet, alcohol, inactivity, and obesity affect cancer risk.

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Internal Cancer Factors

Genetics, hormones, immune issues, and aging increase cancer risk.

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G1 Phase

Cell growth and preparation for DNA replication.

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G1/S Checkpoint

Ensures cell is ready to replicate DNA; checks size, nutrients, and damage.

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Rb Protein

Protein whose phosphorylation releases E2F, allowing DNA replication.

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S Phase

DNA replication; crucial for creating two identical copies.

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DNA Replication Initiation

Cdk2-Cyclin A starts DNA unwinding to allow replication.

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Mismatch Repair

Fixes mistakes during DNA copying, a high-fidelity process.

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Homologous Recombination

Fixes DNA breaks using a matching template, highly accurate.

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Non-Homologous End Joining

Fixes DNA breaks without a template, less precise.

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G2 Phase

Cell growth and DNA damage check before mitosis.

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G2/M Checkpoint

Final check of DNA before mitosis; verifies full replication.

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Mitosis

Cell division into two identical daughter cells.

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Metaphase Checkpoint

Ensures chromosomes are correctly attached before separation.

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Proto-oncogenes

Normal genes controlling cell growth and division.

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Tumor Suppressor Genes

Genes that inhibit cell growth.

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Tumor Microenvironment

Surrounding cells (immune, fibroblasts).

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Apoptosis Avoidance

Cancer cells preventing programmed cell death.

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Angiogenesis

Tumor's formation of new blood vessels.

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Metastasis

Cancer spreading to different parts of the body.

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Study Notes

Introduction to Oncology

  • Cancer is uncontrolled cell division forming a tumor that disrupts normal bodily functions. It can invade nearby tissues and potentially be fatal
  • Evidence of tumors dates back 1.7 million years (Edwin Smith Papyrus, 3000BC)
  • Cancer incidence is increasing globally, more common in wealthier northern countries
  • Median age of cancer diagnosis is 66 years

Causes of Cancer

  • Chemical & Physical Carcinogens: Tobacco, benzene, asbestos, ionizing radiation, UV rays, radon
  • Biological Carcinogens: Viruses (e.g., Epstein-Barr Virus (EBV)), bacteria, and parasites
  • Lifestyle Factors: Western diet, alcohol, lack of exercise, obesity, and chronic inflammation
  • Internal Factors: Genetics, hormones, immune dysfunction, aging, and epigenetic changes

Cell Cycle and Cancer

  • G1 Phase (Gap 1): Primarily focused on cell growth and protein/organelle synthesis in preparation for DNA replication. This phase can last 22-23 hours.
  • G1/S Checkpoint: Checks cell size, nutrient availability, and DNA integrity. External signals (e.g., epidermal growth factor (EGF), fibroblast growth factor (FGF), Sonic hedgehog) stimulate growth through specific pathways.
  • Restriction point: If these checks are satisfactory, the cell progresses to DNA replication (S phase).
  • S Phase (Synthesis): DNA replication occurs to produce two identical copies of each chromosome, essential for cell division. Various DNA repair mechanisms, such as mismatch repair (MMR) and homologous recombination (HR), are essential during this phase to correct replication errors, preventing mutations.
  • G2 Phase (Gap 2): Cell growth and preparation for mitosis, verifies DNA replication integrity. This is controlled by checkpoints (G2/M).
  • M Phase (Mitosis): The cell divides into two daughter cells with identical genetic material. This phase includes phases like prophase, metaphase, anaphase, and telophase. The Metaphase and Anaphase checkpoints guarantee proper chromosome alignment and separation before cell division.

Tumor Suppressor Genes and Proto-oncogenes

  • Proto-oncogenes: Genes that regulate cell growth, differentiation, and division to maintain bodily function. In cancer they are inactive or under-functioning
  • Tumor suppressor genes: Genes that inhibit cell growth and division. In cancer they are over-active
  • Example: BRCA1/2 mutations are associated with hereditary breast and ovarian cancers.

Tumor Microenvironment

  • Composed of immune cells, fibroblasts, extracellular matrix (ECM), and blood vessels
  • Cancer cells exhibit characteristics of self-sufficiency in growth, insensitivity to anti-growth signals, apoptosis resistance, limitless replication, sustained angiogenesis (blood vessel formation), and tissue invasion

Cancer Cell Traits and Survival Mechanisms

  • Evading Apoptosis: Cancer cells avoid programmed cell death, potentially immortalizing them
  • Angiogenesis: Cancer cells promote the growth of new blood vessels to supply themselves with nutrients
  • Metastasis: Cancer cells spread to other parts of the body via blood and lymph systems.

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