Cell Division and Cancer

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Questions and Answers

What is the role of KRAS in normal cell growth?

It inhibits external growth signals to the cell nucleus

It transmits external growth signals to the cell nucleus (correct)

It regulates cell division

It causes apoptosis

What is the result of the chromosome translocation between the long arms of chromosomes 9 and 22?

Activation of a variety of intracellular signaling pathways (correct)

Deletion of a chromosome

Inhibition of cell growth

Formation of a tumor-suppressor gene

What is the effect of activating the Ras oncogene?

Apoptosis

Uncontrolled cell proliferation (correct)

Regulation of cell division

Inhibition of cell growth

What is the role of the tumor-suppressor gene p53?

It inhibits cell growth and proliferation Signup and view all the answers

What is the result of losing the tumor-suppressor gene APC?

Uncontrolled cell proliferation Signup and view all the answers

What is the characteristic of CML cells?

They are mutated and proliferate uncontrollably Signup and view all the answers

What is the effect of ultraviolet radiation on cells?

It causes DNA mutations and cancer Signup and view all the answers

What is the Philadelphia chromosome?

A chromosome translocation between the long arms of chromosomes 9 and 22 Signup and view all the answers

What is the main function of oncogenes in a normal cell?

To promote cell growth/division in a controlled manner Signup and view all the answers

What is the effect of activating an oncogene?

Uncontrolled cell growth and division Signup and view all the answers

What is the role of tumor suppressor genes?

To inhibit cell growth and division Signup and view all the answers

What is the result of inactivating a tumor suppressor gene?

Uncontrolled cell growth and division Signup and view all the answers

What is the name of the catalogue that provides information on somatic mutations found in cancer genes in human tumors?

COSMIC Signup and view all the answers

How many somatic 'cancer genes' have been identified to date?

Approximately 400 Signup and view all the answers

What is the name of the gene that acts as a switch within signal transduction pathways, including the regulation of cell division?

ras Signup and view all the answers

What is the result of losing/damaging DNA repair genes?

Decreased DNA repair Signup and view all the answers

What is the outcome when a receptor protein receives a signal for cell division?

Activation of genes involved in cell division Signup and view all the answers

What is a result of certain mutations in the ras sequence?

Constitutive activation of the cell cycle Signup and view all the answers

What is the normal function of tumor suppressor genes?

To prevent cell growth and division Signup and view all the answers

What type of mutations are commonly found in tumor suppressor genes?

Loss-of-function mutations Signup and view all the answers

What is the role of the BRCA1 gene?

To repair DNA damage Signup and view all the answers

What is a characteristic of immortalized cancer cells?

They can grow and divide indefinitely Signup and view all the answers

What is required for tumor growth and survival?

Development of new blood vessels through angiogenesis Signup and view all the answers

What is the process by which cancer cells travel to other parts of the body?

Metastasis Signup and view all the answers

Study Notes

Cell Signaling and Cancer

Receptor proteins receive signals for cell division, activating ras, which leads to gene activation and cell division.
Mutations in ras cause permanent activation, leading to constitutive activation of the cell cycle.

Tumor Suppressor Genes

Over 30 genes are classified as tumor suppressors, involved in DNA repair, apoptosis, and preventing abnormal cell division.
Loss-of-function mutations in tumor suppressor genes contribute to cancer progression.
Examples include BRCA1, which is involved in DNA repair, and inherited mutations increase the risk of breast cancer.

Characteristics of Cancer Cells

Cancer cells are resistant to apoptosis and have uncontrolled ability to divide.
They are insensitive to antigrowth factors and can invade neighboring tissues.
They can form new tumors (metastases) at distant sites and secrete chemical signals for angiogenesis.

Tumorigenesis

Genetic changes in tumorigenesis involve gain of function (oncogenes) and loss of function (tumor suppressor genes).
Non-lethal genetic damage is central to carcinogenesis.

Cancer Genes

There are two types of cancer genes: tumor suppressor genes and oncogenes.
Approximately 400 somatic "cancer genes" have been identified, with many more to be discovered.

Oncogenes

Oncogenes are genes that promote cell growth and division in a controlled manner.
Examples include ras, which acts as a switch in signal transduction pathways, regulating cell division.

External Causes of Cancer

Ultraviolet radiation and tobacco smoke and diet are external causes of cancer.

Chronic Myelogenous Leukemia (CML)

CML is a cancer of white blood cells, characterized by a consistent chromosome translocation (t(9:22)(q34;q11)) known as the Philadelphia chromosome (Ph+).
This mutation leads to unregulated expression of a gene and its kinase product, causing activation of intracellular signaling pathways and uncontrolled proliferation of CML cells.

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Description

Learn about the role of receptor proteins, ras, and tumor suppressor genes in cell division and their impact on cancer development.