أسئلة المحاضرة العاشرة جينتكس (قبل التعديل)

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Questions and Answers

What type of radiation is known to induce mutations?

Microwave radiation

Gamma and X-rays (correct)

Ultraviolet radiation

Radio waves

Which of the following is NOT a type of mutagen listed?

Nuclear force (correct)

Biological agent

Physical agent

Chemical agent

Which category does ionizing radiation belong to?

Physical agents (correct)

Environmental toxins

Only biological agents

Only chemical agents

What is a common effect of exposure to mutagens?

Induced mutations Signup and view all the answers

Which of the following options best describes a mutagen?

An agent that causes genetic mutations Signup and view all the answers

What type of inheritance pattern is associated with Alpha thalassemia?

Autosomal recessive Signup and view all the answers

Which of the following conditions is classified under β-Thalassemia?

Mediterranean Anemia Signup and view all the answers

Which condition is categorized as autosomal recessive among the following?

Both A and B Signup and view all the answers

What is the correct categorization of Alpha Thalassemia?

An autosomal recessive disorder Signup and view all the answers

Which of the following is true regarding Sickle Cell Disease?

It exhibits autosomal recessive inheritance. Signup and view all the answers

What is the maximum number of bases typically affected by a small scale mutation?

20 bases Signup and view all the answers

Which type of mutation involves a mutation affecting larger segments of DNA?

Large scale mutation Signup and view all the answers

Which of the following best characterizes small scale mutations?

They affect 1-20 base pairs Signup and view all the answers

What distinguishes small scale mutations from large scale mutations?

The number of bases affected Signup and view all the answers

What is the definition of large scale mutations?

Only mutations greater than 20 bases Signup and view all the answers

What is the distinction between germinal and somatic mutations?

Germinal mutations occur in germ cells, somatic mutations occur in somatic cells. Signup and view all the answers

How is the size of mutations understood at different levels?

Mutations are gross at the chromosome level and small at the DNA level. Signup and view all the answers

In which type of cell do germinal mutations occur?

Germ cells Signup and view all the answers

Which statement is true regarding somatic mutations?

Somatic mutations occur in somatic cells. Signup and view all the answers

Which of the following statements about mutations is correct?

Mutations can vary in size at chromosome and DNA levels. Signup and view all the answers

What is a missense point mutation?

A mutation that changes one amino acid in the protein sequence. Signup and view all the answers

What can be a result of having more than 200 different gene mutations?

Potential for genetic disorders or diseases. Signup and view all the answers

Which of the following best describes a large exon deletion mutation?

The removal of one or more entire exons from a gene. Signup and view all the answers

What is one consequence of a genetic mutation?

It can sometimes result in harmful or beneficial effects. Signup and view all the answers

Which virus is associated with hepatocellular carcinoma (HCC)?

Hepatitis C Virus (HCV) Signup and view all the answers

What type of cancer is caused by human papilloma virus (HPV)?

Cancer of the Cervix Signup and view all the answers

Which of the following is NOT caused by a virus?

Breast Cancer Signup and view all the answers

Which of the following pairs correctly identifies a virus and the type of cancer it is associated with?

Hepatitis C Virus (HCV) → Heptocellular Carcinoma Signup and view all the answers

What consequence can result from a chronic infection with the Hepatitis C virus?

Cirrhosis and Liver Cancer Signup and view all the answers

Which type of defect is associated with a mutation that can be transmitted to future generations?

Defect in mRNA Signup and view all the answers

Which of the following types of mutations cannot be transmitted to offspring?

Defects in somatic cells Signup and view all the answers

What is an example of an effect caused by a defect in a defect in mRNA?

Loss of enzymatic function Signup and view all the answers

Which consequence is most likely related to a defect in the polypeptide chain?

Impaired protein function Signup and view all the answers

Which statement correctly differentiates the types of defects related to genetic mutations?

Defect in mRNA impacts protein synthesis; defect in polypeptide chain impacts protein function. Signup and view all the answers

What is the primary effect of certain DNA damage on nucleotide sequences?

Alters the nucleotide structure making them unreadable. Signup and view all the answers

Which statement best represents the consequence of modified nucleotides on genetic expression?

They can halt transcription entirely. Signup and view all the answers

What aspect of RNA polymerase activity is primarily affected by certain types of DNA damage?

The capability to synthesize mRNA from a DNA template. Signup and view all the answers

How would RNA polymerase specifically react to a segment of DNA with damaged nucleotides?

It will likely stall or fail to transcribe that segment. Signup and view all the answers

What type of nucleotide changes are most likely to disrupt RNA polymerase binding?

Modified nucleotide bases or groups. Signup and view all the answers

What effect do additions or deletions of nucleotides have on the genetic code?

They alter the reading frame of the sequence. Signup and view all the answers

Which of the following accurately describes the outcome of a mutation that alters the reading frame?

The amino acid sequence may become entirely different from the wild type. Signup and view all the answers

What is a common consequence of both additions and deletions in nucleotide sequences?

Potential production of nonfunctional proteins. Signup and view all the answers

When a reading frame is altered by a mutation, what potential impact can this have on an organism?

It can result in severe consequences for the organism's phenotype. Signup and view all the answers

How does a mutation that alters the reading frame differ from other types of mutations?

It can change all subsequent amino acids in a protein. Signup and view all the answers

What is a primary health risk associated with aflatoxin exposure?

Liver cancer Signup and view all the answers

Which of the following substances is classified as a heterocyclic amine?

Compounds in over-cooked food Signup and view all the answers

Which group of substances is primarily responsible for inducing mutations through their chemical properties?

All of the above Signup and view all the answers

What is a common source of heterocyclic amines that could affect human health?

Overcooked meat or fish Signup and view all the answers

Which type of cancer has been linked to the inhalation of certain chemicals present in cigarette smoke?

Lung cancer Signup and view all the answers

Which virus is specifically linked to the development of cervical cancer?

Human papiloma virus (HPV) Signup and view all the answers

Which of the following cancers is NOT associated with a virus?

Squamous cell carcinoma of the skin Signup and view all the answers

What type of cancer is correlated with the Hepatitis C virus (HCV)?

Hepatocellular carcinoma (HCC) Signup and view all the answers

Which of these viruses is primarily associated with causing cancer in the liver?

Hepatitis C virus (HCV) Signup and view all the answers

What effect does a mutation in a regulatory element typically have on gene expression?

It leads to an expression level that can range from abnormally low to abnormally high. Signup and view all the answers

Which of the following statements accurately describes the impact of mutations in regulatory elements?

They may cause an expression level that is either excessively high, low, or entirely absent. Signup and view all the answers

How can the expression level of a gene be affected by regulatory mutations?

By either increasing, decreasing, or eliminating the expression level. Signup and view all the answers

What range of effects can regulatory mutations have on gene expression levels?

From complete inactivity to extremely high levels of expression. Signup and view all the answers

In general, what is the consequence of a mutation occurring in a regulatory element of DNA?

It can cause a variety of changes, including both increases and complete losses of expression. Signup and view all the answers

Which virus is correctly associated with the development of a specific type of cancer?

Hepatitis C virus → hepatocellular carcinoma Signup and view all the answers

What cancer is primarily linked to persistent infection with human papilloma virus?

Cervical cancer Signup and view all the answers

Which virus is NOT depicted as causing any type of cancer in the provided information?

Varicella zoster virus Signup and view all the answers

What is the main type of cancer associated with chronic infection from Hepatitis C virus?

Hepatocellular carcinoma Signup and view all the answers

Which of the following statements about viruses causing cancer is accurate?

Human papilloma virus is linked to cervical cancer. Signup and view all the answers

Study Notes

DNA Mutations

DNA mutations are permanent changes to the base sequence of nucleotides.
Mutations can be classified by size: gross changes at the chromosome level, or smaller changes at the DNA level.
Mutations can be classified by cell type: germline or somatic.
- Germline mutations occur in germ cells (sperm or egg) and can be transmitted to future generations.
- Somatic mutations occur in somatic cells and cannot be passed on to offspring.

Types of Mutations

Germline mutations affect the entire organism, as all cells inherit the mutation.
Somatic mutations only affect the specific cells where the mutation occurs and its immediate area of the organism.

Causes of Mutations

Uncorrected replication errors: Errors that arise during DNA replication can lead to mutations.
Transcription errors: RNA polymerase may make errors in copying DNA, potentially leading to mutations.
Spontaneous mutations: These occur naturally, including depurination (loss of a purine base) and oxidative deamination (conversion of a cytosine to uracil).
Induced mutations: These are caused by external factors (mutagens). Examples include:
- Physical mutagens: ionizing radiation (e.g., gamma rays, X-rays) and UV radiation. Electromagnetic radiation from mobile phones, satellites, and computers
- Chemical mutagens: free radicals, aflatoxin, heterocyclic amines (found in overcooked food), certain drugs (chemotherapy), cigarette smoke, and others.
- Biological mutagens: viruses (e.g., Hepatitis C virus, Human papilloma virus, Human Herpes virus), bacteria (e.g., H.pylori)), and other biological agents.

Effects of Mutations

Mutations can cause defects in mRNA, polypeptide chains, and protein function.
Mutations can lead to noticeable phenotypic changes (e.g., sickle cell disease)
- Some mutations can result in a silent phenotypic effect with no protein production changes.
- Other mutations lead to:
  - Missense mutations: substitutions that change the amino acid, with results that can be acceptable, partially acceptable, or non-acceptable.
  - Nonsense mutations: change a normal codon to a termination codon, resulting in a non-functioning protein.
  - Sense mutations: change a termination codon to one that codes for an amino acid.

Large-Scale Mutations

Deletions: Loss of a segment of DNA.
Duplications: Repetition of a segment of DNA.
Inversions: A segment of DNA is reversed.
Translocations: Movement of a DNA segment to a different location in the genome.

Molecular Hematology

Molecular hematology is the study of the molecular basis of hematological disorders, both benign (e.g., anemia) and malignant (e.g., leukemia).
Hemoglobinopathies are a group of diseases related to abnormal hemoglobin synthesis.
Examples of hemoglobinopathies (diseases caused by point mutations): sickle cell disease, beta-thalassemia, and alpha-thalassemia.

Sickle Cell Disease (SCD)

Characterized by chronic hemolytic anemia and abnormal hemoglobin S.
Caused by a missense point mutation in the beta-globin gene, changing the 6th amino acid from glutamic acid to valine.
This results in a change in the shape of red blood cells, making them sickle-shaped.

Beta-Thalassemia

A group of autosomal recessive diseases related to reduced synthesis or absence of beta-globin chains.
Caused by various gene mutations on chromosome 11, resulting in abnormal hemoglobin and anemia.

Alpha-Thalassemia

Caused by large (exon or gene) deletion mutations in the alpha-globin gene on chromosome 16, resulting in decreased or absent alpha-globin production.

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