أسئلة المحاضرة الـ 11 جينتكس (قبل التعديل)

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Questions and Answers

What role do tumor suppressor genes play in the body?

They generate energy for cellular processes.

They promote the rapid division of cells.

They repair damaged DNA and control cell death. (correct)

They increase the mutation rate of oncogenes.

Which gene is commonly associated with an increased risk of breast and ovarian cancer due to mutations?

RAS

p53

BRCA1 (correct)

HER2

What is a proto-oncogene?

A normal gene involved in regulating cell division. (correct)

A gene that repairs DNA damage.

A mutated gene that causes cancer.

A gene that suppresses tumor growth.

How does the HER2 gene function in cancer cells?

It produces a protein that controls cancer growth. Signup and view all the answers

What is the consequence of mutations in genes from the RAS family?

Promotion of cancer cell proliferation. Signup and view all the answers

Which of the following conditions is an example of a benign disorder related to hemoglobin synthesis?

Anemia Signup and view all the answers

What type of mutation is primarily illustrated by sickle cell disease?

Point mutation Signup and view all the answers

What is the result of a deletion mutation in DNA?

A protein with fewer amino acids than normal Signup and view all the answers

What is the most common tumor suppressor gene associated with cancer mutations?

p53 Signup and view all the answers

Which type of mutation involves the reversal of the orientation of a DNA segment?

Inversion Signup and view all the answers

How does gene amplification typically affect cancer cells?

It results in an overproduction of mRNA and protein Signup and view all the answers

What is a common clinical significance of translocations in cancer?

Deregulated cell growth Signup and view all the answers

What role does the MDR gene play in drug resistance in tumors?

It pumps chemotherapy drugs out of the cells Signup and view all the answers

In the case of duplication mutations, what happens to a portion of a chromosome?

It is repeated within the same chromosome Signup and view all the answers

How can gene amplification contribute to chemotherapy resistance in cancer cells?

By promoting the expression of multiple drug resistance proteins Signup and view all the answers

What significant problem in cancer treatment is associated with gene amplification?

Ongoing growth and spread of resistant tumors Signup and view all the answers

What is the inheritance pattern of Sickle Cell Disease (SCD)?

Autosomal recessive Signup and view all the answers

What type of mutation is primarily associated with Sickle Cell Disease?

Missense point mutation Signup and view all the answers

Which amino acid change occurs in the beta-globin chain due to the mutation in Sickle Cell Disease?

Glutamic Acid to Valine Signup and view all the answers

What is a characteristic feature of Chronic Hemolytic Anemia associated with Sickle Cell Disease?

Presence of abnormal insoluble hemoglobin S Signup and view all the answers

What type of anemia is characterized by microcytic hypochromic features?

β-Thalassemia Signup and view all the answers

Which chromosome is affected by mutations leading to β-Thalassemia?

Chromosome 11 Signup and view all the answers

What happens to the synthesis of hemoglobin beta chain in Sickle Cell Disease?

Decreased synthesis Signup and view all the answers

What is formed from excess beta chains in Beta-Thalassemia?

Hemoglobin H Signup and view all the answers

What occurs as a result of gene amplification in cancer cells?

Production of many copies of genes Signup and view all the answers

Which type of mutation involves a portion of a chromosome being repeated?

Duplication Signup and view all the answers

How does the MDR gene contribute to cancer treatment challenges?

By selectively ejecting chemotherapy drugs from cells Signup and view all the answers

What is a significant outcome of translocations in cancer cells?

New gene combinations leading to abnormal protein production Signup and view all the answers

What is one implication of gene amplification on cell behavior in cancer?

Deregulated cell growth Signup and view all the answers

What happens to the protein production as a result of gene amplification?

There is an overproduction of corresponding proteins Signup and view all the answers

Which mutation type is characterized by a significant exchange of DNA segments between chromosomes?

Translocation Signup and view all the answers

Which phenomenon can lead to inefficacy in chemotherapy treatment?

Gene amplification Signup and view all the answers

What can result from mutations in tumor suppressor genes?

Cells divide uncontrollably Signup and view all the answers

Which of the following genes is most frequently associated with mutations in cancer development?

TP53 Signup and view all the answers

What is the primary role of proto-oncogenes before they become mutated?

To regulate normal cell division Signup and view all the answers

In which type of cancer cells is the HER2 gene overexpressed?

Breast cancer Signup and view all the answers

What does a mutation in the RAS gene family typically cause in healthy cells?

Increased cell division Signup and view all the answers

Which condition is an example of a condition caused by a point mutation affecting hemoglobin synthesis?

Sickle Cell Disease Signup and view all the answers

Which gene involvement is least likely associated with hereditary breast cancer?

RAS Signup and view all the answers

What is the consequence of an ineffective tumor suppressor gene?

Increased cancer risk Signup and view all the answers

What type of mutation is primarily responsible for β-Thalassemia?

Large deletion mutation Signup and view all the answers

What is the primary consequence of the mutation in the beta globin gene associated with Sickle Cell Disease?

Decreased solubility of hemoglobin Signup and view all the answers

Which statement accurately describes the inheritance pattern of Alpha Thalassemia?

Autosomal recessive Signup and view all the answers

What is a defining characteristic of the hemoglobin present in patients with Sickle Cell Disease?

Presence of hemoglobin S Signup and view all the answers

What describes the changes in hemoglobin fractions typically seen in β-Thalassemia?

Increase in hemoglobin A2 and hemoglobin F Signup and view all the answers

What pathological condition is characterized by the presence of hemoglobin H?

Alpha Thalassemia Signup and view all the answers

Which of the following best explains the mechanism behind chronic hemolytic anemia in Sickle Cell Disease?

Hemolysis of sickle-shaped red blood cells Signup and view all the answers

What is the genetic basis for sickle cell anemia's mutation at codon 6 of the beta globin gene?

Missense mutation changing glutamic acid to valine Signup and view all the answers

Study Notes

Large Scale Mutations

Large-scale mutations involve changes in a significant portion of a chromosome, rather than single bases.
Deletion: Removal of a section of DNA, leading to a protein missing some amino acids.
Duplication: Repetition of a section of DNA.
Inversions: Reversal of a DNA segment's orientation.
Translocations: Movement of a DNA segment to a new location. This is frequent in some cancers (e.g., chromosome 9 and 22 exchange in 90% of chronic myelogenous leukemia).

Gene Amplification

Gene amplification produces multiple copies of a chromosomal region's genes.
This leads to overproduction of the corresponding mRNA and proteins.
Amplified genes frequently occur in cancer cells, causing overexpressed oncogenes, abnormal cell regulation, and tumor growth.
Examples of genes involved in amplification frequently found in various tumors are the myc oncogenes.
Amplified genes also often contribute to drug resistance in cancer, as the increased gene copies produce more drug-resistant protein pumps, making chemotherapy less effective.

Tumor Suppressor Genes

Tumor suppressor genes typically protect against cancer by regulating cell growth.
These genes control cell division, fix DNA errors, and signal cell death when needed.
Mutations in tumor suppressor genes can lead to uncontrolled cellular growth, potentially resulting in cancer development.
BRCA1/2: Mutated in inherited breast, ovarian, pancreatic, and prostate cancer risk.
p53 (TP53): The most common mutated tumor suppressor gene, frequently occurring in multiple cancer types. Mutations can cause an increased risk of many different types of cancer. Inherited p53 mutations are less common but dangerous.

Oncogenes

Oncogenes, in their normal, non-mutated state, are called proto-oncogenes and play a role in regulating normal cell division.
When a proto-oncogene mutates, it becomes an oncogene.
Oncogenes promote cellular growth and/or survival without normal controls, potentially leading to cancer.
HER2: This gene produces a protein that controls growth, and its mutation occurs in breast and ovarian cancers.
RAS family: These genes produce proteins vital for communication between cells, growth, and death responses. Mutations can lead to uncontrolled cell growth, contributing to cancer.

Molecular Hematology

Molecular hematology studies the molecular basis of blood disorders, both normal and cancerous.
Hemoglobinopathies, in which abnormal hemoglobin synthesis is involved, are an example.
Examples include sickle cell disease, beta thalassemia, and alpha thalassemia. These disorders involve deficiencies in hemoglobin production or quality by mutations, insertions or deletions.
Point mutations, deletions, or additions lead to hemoglobin deficiencies and related disorders.

Sickle Cell Disease (SCD)

SCD is a genetic disorder caused by a missense mutation in the beta-globin gene.
The mutation within the beta-globin gene changes glutamine to valine in the produced hemoglobin.
This change in hemoglobin leads to red blood cell clumping, causing a variety of serious symptoms like pain crises, fatigue, swelling of hands/feet, stroke, and organ failure.
This disease is frequently accompanied by hemolytic anemia and vaso-occlusive crises.
Treatment often involves bone marrow transplant.

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