Genetics

Questions and Answers

What is the main function of telomerase in cells?

To extend telomeres in rapidly dividing cells. (correct)

To repair damaged DNA sequences.

To add microsatellite DNA sequences.

To facilitate the movement of transposons.

What characterizes microsatellite DNA sequences?

They are always the same length in every individual.

They serve solely as a source of genetic variation.

They consist of short, repeated base pair sequences. (correct)

They are exclusively found in embryonic cells.

Which types of cells contain significant quantities of telomerase?

Only cancer cells.

Embryonic cells and white blood cell precursors. (correct)

Mature neurons exclusively.

Most somatic cells.

How do retrotransposons move within the genome?

By utilizing an RNA intermediate. Signup and view all the answers

What is a significant application of microsatellites in forensic science?

To identify relationships and crime scene profiles. Signup and view all the answers

Which statement is true regarding most transposons in the genome?

Most have become inactive due to mutations. Signup and view all the answers

Which of the following statements about transposable elements is correct?

They can move to different genome positions. Signup and view all the answers

What is the origin of retrotransposons in the genetic sequence?

They arise from RNAs that are reverse-transcribed. Signup and view all the answers

What is the haploid human nuclear genome comprised of?

3.2 billion base pairs distributed on 23 chromosomes Signup and view all the answers

What defines aneuploidy in human cells?

Having an abnormal number of chromosomes Signup and view all the answers

Which of the following cells are considered haploid?

Spermatozoa and oocytes Signup and view all the answers

What is indicated by the term polyploid?

The presence of multiple complete sets of chromosomes Signup and view all the answers

What is the primary purpose of karyotyping?

Identifying chromosomal abnormalities associated with diseases Signup and view all the answers

Which of the following statements about maternal family history and breast cancer risk is accurate?

Having a family history of breast cancer increases the chances of being a carrier of genetic mutations. Signup and view all the answers

What distinguishes somatic cells from spermatozoa and oocytes?

Somatic cells are diploid, containing two sets of chromosomes. Signup and view all the answers

What is a common result of aberrant chromosome duplication in cancer cells?

Aneuploidy leading to abnormal chromosome numbers Signup and view all the answers

What is the primary reason mitochondrial DNA is maternally inherited?

Sperm mitochondria are destroyed upon fertilization. Signup and view all the answers

Which type of microorganisms are included in the human microbiome?

Bacteria, fungi, and protozoa Signup and view all the answers

How many genes are encoded in the mitochondrial genome?

37 Signup and view all the answers

What is the estimated weight of the human microbiome for an average adult?

2-5 pounds Signup and view all the answers

Which statement about the mitochondrial DNA is true?

It represents only a small fraction of the total mitochondrial information. Signup and view all the answers

How does the nuclear genome relate to mitochondrial function?

It encodes most mitochondrial proteins and RNAs. Signup and view all the answers

What is one unique aspect of the microbial composition in the human body?

Each body part has a unique microbial composition. Signup and view all the answers

What is the estimated ratio of microbiome cells to human cells in the body?

2:1 Signup and view all the answers

What is the primary purpose of microarray genotyping in DNA testing?

To automatically identify all protein encoding genes in the human genome. Signup and view all the answers

What methodology allows for the rapid diagnosis of genetic diseases in clinical laboratories?

Targeted and Gene Panel Sequencing. Signup and view all the answers

Which characterization describes Whole Exome Sequencing (WES)?

It targets only the coding regions of the genome. Signup and view all the answers

What role do fluorescent dyes play in the microarray process?

They allow visualization of hybridization events. Signup and view all the answers

What advantage do predesigned gene panels offer in genetic testing?

They focus on the most relevant genes, conserving resources. Signup and view all the answers

Which statement is true regarding the application of microarrays?

They can be designed for specific disease mutations. Signup and view all the answers

Which DNA testing companies are known to utilize microarray genotyping?

23andMe and Ancestry.com. Signup and view all the answers

What makes Whole Genome Sequencing (WGS) considered the gold standard?

It provides comprehensive analysis of all genomic variations. Signup and view all the answers

What percentage of disease-associated mutations are typically found in regions outside of protein-coding areas?

50% Signup and view all the answers

Which of the following statements about whole exome sequencing (WES) is true?

WES analyzes only the mRNA transcribed into cDNA. Signup and view all the answers

What is a significant factor affecting the validity of a genome-wide association study (GWAS)?

The ethnic and racial backgrounds of the individuals involved. Signup and view all the answers

Which of the following is NOT a recognized risk factor for breast cancer?

Being male Signup and view all the answers

What role does high throughput DNA sequencing play in whole exome sequencing (WES)?

It sequences the complementary DNA produced from isolated mRNA. Signup and view all the answers

Which of the following statements about WGS is true regarding its amount of information?

The information from WGS can be overwhelming due to its quantity. Signup and view all the answers

Which common genes are typically associated with inherited breast cancer risk?

BRCA1 and BRCA2 Signup and view all the answers

What is a primary characteristic of mRNA that differentiates it from other types of RNA?

It carries the genetic information for protein synthesis. Signup and view all the answers

Study Notes

Familial Breast Cancer Risk

Family history of breast cancer increases risk, particularly if close relatives are diagnosed at young ages.
Direct-to-consumer (DTC) genetic tests, such as those from 23andMe and Ancestry.com, may indicate breast cancer risk but can lack clinical accuracy.
Negative results from DTC tests do not fully rule out genetic predisposition, especially with familial histories.

The Nuclear Genome

Human nuclear genome consists of approximately 3.2 billion base pairs and is organized into 23 chromosomes.
Somatic cells are typically diploid with 22 pairs of autosomes and one pair of sex chromosomes.
Haploid cells (sperm and oocytes) contain 23 single chromosomes; variation in chromosome number occurs in certain tissues due to genetic syndromes or cancer.
Karyotyping detects chromosomal abnormalities linked to diseases, while aneuploidy indicates abnormal chromosome counts.
Telomerase is an enzyme that extends telomeres, prominent in rapidly dividing cells, influencing genetic stability.

Microsatellite DNA

Unique profiles of microsatellite sequences (2-13 base pair repeats) are distinctive to each individual, aiding in forensic science and paternity testing.
Microsatellites can expand or contract during replication, contributing to genetic variability among cells.

Transposable Elements

Three different kinds of transposable elements exist: DNA transposons, retrotransposons, and non-autonomous transposons.
Retrotransposons move within the genome through an RNA intermediate, emphasizing evolutionary processes.
Mitochondrial DNA is maternally inherited, crucial for tracing human evolutionary lineage.

The Microbiome

Composed of microorganisms like bacteria and fungi, the human microbiome has a higher cell count than human cells, weighing 2-5 pounds on average.
Unique microbial compositions characterize different body parts, influencing health and disease.

Microarray Genotyping

Utilizes automated techniques with microarrays of DNA fragments to identify genetic sequences by hybridization.
Commonly employed by DTC testing services, microarrays can also target specific diseases for clinical genetic diagnosis.

Targeted and Gene Panel Sequencing

Preset gene panels focus on significant genes associated with specific diseases, optimizing resources and data analysis.
Whole Exome Sequencing (WES) provides insights into protein-coding regions; however, many disease mutations are located outside these regions.

Genome-Wide Association Studies (GWAS)

GWAS is used to identify genetic associations with diseases by comparing genomic sequences of affected and unaffected individuals.
Validity relies on comparing subjects from similar ethnic and racial backgrounds to improve relevance and accuracy.

Risk Factors for Breast Cancer

Key risk factors include being female, advancing age, family history, and specific inherited gene variants (e.g., BRCA1/2).
Reproductive history, such as early menstruation and late menopause, correlates with prolonged estrogen exposure, potentially increasing cancer risk.

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Description

Explore the complexities of familial breast cancer risk and the implications of DTC genetic testing. This quiz covers the structure of the human nuclear genome, chromosome organization, and the significance of chromosomal abnormalities. Test your knowledge on how genetics plays a crucial role in cancer predisposition.