Genetic Testing and Genetic Disorders

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Questions and Answers

What is the primary cause of mitochondrial disorders?

Inheriting an extra chromosome from the father.

Having parents that are both carriers of a mutated gene.

Mutations in the DNA of mitochondria. (correct)

Environmental factors that affect cell processes.

Which of the following is a characteristic of multifactorial diseases?

They involve a combination of genetic and environmental factors. (correct)

They are caused solely by genetic mutations.

They are the result of mitochondrial DNA mutations.

They involve inherited extra or missing chromosomes.

What is the most common way a person would inherit a mitochondrial disorder?

From both the mother and the father.

Only from the mother. (correct)

Only from the father.

It is the result of random mutations, not inheritance.

What is the cause of Down's syndrome, also known as Trisomy 21?

An extra copy of chromosome 21. Signup and view all the answers

What does a karyotype reveal about an individual's chromosomes?

The presence of missing or extra chromosomes. Signup and view all the answers

What is the primary purpose of carrier screening?

To determine if the parents are carriers of genes for potential genetic diseases. Signup and view all the answers

What is a common factor when a couple seeks carrier screening?

That there is a family history of a specific genetic disease. Signup and view all the answers

What is a distinguishing characteristic of a 'carrier' of a genetic disease?

They have a mutated gene, but don't show symptoms. Signup and view all the answers

What is the primary purpose of Preimplantation Genetic Diagnosis (PGD)?

To select embryos without specific genetic traits for implantation. Signup and view all the answers

Which procedure involves extracting fetal cells from amniotic fluid?

Amniocentesis Signup and view all the answers

At what embryonic stage is a single cell removed for testing in PGD?

8-cell stage Signup and view all the answers

What is the primary source of cells for genetic testing in chorionic villus sampling?

Placental cells Signup and view all the answers

Which procedure is typically performed after 14 weeks of gestation?

Amniocentesis Signup and view all the answers

What is a common method used to amplify DNA in genetic testing?

PCR (Polymerase Chain Reaction) Signup and view all the answers

Which of the following is a risk associated with both amniocentesis and chorionic villus sampling?

Miscarriage Signup and view all the answers

How is DNA obtained for newborn screening?

From a blood sample Signup and view all the answers

What is the primary function of genes within DNA?

To provide instructions for protein synthesis Signup and view all the answers

During which phase are chromosomes typically visible under a light microscope?

During cell division Signup and view all the answers

What does genetic testing primarily involve?

Sampling a person's DNA and examining chromosomes or genes for abnormalities Signup and view all the answers

Besides autosomes, what other type of chromosomes are part of the human genetic material?

Sex chromosomes Signup and view all the answers

What is the role of proteins in the human body as described in the text?

To act as the workers of the body, responsible for various traits Signup and view all the answers

What is a chromosome primarily comprised of?

Tightly coiled DNA Signup and view all the answers

What does genetic testing allow us to ascertain?

If an individual has a genetic disorder, will develop one or is a carrier Signup and view all the answers

What is the primary characteristic of a single-gene disorder?

It is due to a change or mutation in one single gene. Signup and view all the answers

Within a cell, where is DNA primarily located?

In the nucleus Signup and view all the answers

What is the inheritance pattern in which the defective gene must be inherited from both parents to express the trait?

Autosomal recessive Signup and view all the answers

Which of the following is an example of an autosomal dominant genetic disorder?

Huntington's disease Signup and view all the answers

In the context of sex-linked traits, why are males more likely to express an X-linked disorder?

Males only have one X chromosome, so if they inherit a defective one, they don't have a backup. Signup and view all the answers

Which of the following disorders is considered a sex-linked trait?

Duchenne muscular dystrophy Signup and view all the answers

What is the primary difference between single-gene and multifactorial disorders?

Single-gene disorders involve only one gene, while multifactorial result from multiple genetic and environmental factors. Signup and view all the answers

What role do environmental factors play in the development of multifactorial disorders?

They interact with genetic predispositions to increase the likelihood of disease development. Signup and view all the answers

A female is a carrier for an X-linked recessive trait. Which of the following is true regarding her chances of passing on the trait?

She has a 50% chance of passing the trait to her sons, and her daughters will likely be carriers. Signup and view all the answers

During the extension phase of PCR, what is the primary role of Taq polymerase?

To attach to the DNA at the primer site and add complementary nucleotides. Signup and view all the answers

What is the purpose of centrifugation in the process of DNA isolation?

To separate heavy cell components, including DNA, from other waste products. Signup and view all the answers

What is the temperature at which the extension phase of PCR occurs?

72°C Signup and view all the answers

What does the term 'genotype' refer to?

The genetic sequence written in DNA. Signup and view all the answers

Which component is NOT required for the extension phase of PCR?

Primers Signup and view all the answers

After centrifugation in DNA isolation, where is the DNA primarily located?

In the small pellet of cell parts at the bottom of the tube. Signup and view all the answers

What is the primary purpose of PCR in genetic testing?

To create many copies of DNA from an original strand. Signup and view all the answers

What is the purpose of adding Chelex to a DNA sample?

To remove cellular debris from the DNA. Signup and view all the answers

What is the primary purpose of using Chelex in the DNA extraction process?

To separate DNA from cellular waste. Signup and view all the answers

Why is the supernatant, after using Chelex, moved to a new tube?

Because it contains the desired DNA. Signup and view all the answers

What is the purpose of PCR in this context?

To make many copies of a specific DNA sequence. Signup and view all the answers

How do restriction enzymes help to detect genetic differences?

By cutting DNA at specific sequences, revealing variations. Signup and view all the answers

What are single nucleotide polymorphisms (SNPs)?

Tiny, 1-nucleotide differences in DNA. Signup and view all the answers

Why are restriction enzymes described as 'picky'?

They are selective in the DNA sequences they cut. Signup and view all the answers

In gel electrophoresis, what is the purpose of adding 'markers' to the gel?

To act as a size standard for DNA fragment comparison. Signup and view all the answers

What is the next step, after DNA has been copied and cut with restriction enzymes?

Visualizing the results with gel electrophoresis. Signup and view all the answers

Study Notes

Genetic Testing and Screening

Genetic testing examines DNA to diagnose diseases before birth or identify disease carriers.
It uses molecular methods like DNA sequencing and karyotyping.
Genetic testing analyzes chromosomes or genes for abnormalities.
DNA is a tightly coiled structure forming chromosomes (22 pairs of autosomes and 1 pair of sex chromosomes).
Genes provide instructions for building proteins. These proteins determine traits like hair color, and diseases.
Too many or too few chromosomes, or defective DNA can cause diseases.

Types of Genetic Disorders

Single-gene disorders involve mutations in one gene (e.g., cystic fibrosis, sickle cell anemia).
Single gene disorders can be autosomal dominant, autosomal recessive, or sex-linked.
- Dominant traits show up even with one copy of the gene.
- Recessive traits need two copies of the gene to show up.
- X-linked traits are passed on the X chromosome.
Multifactorial disorders arise from a combination of genes and environment (e.g., breast cancer).
Chromosomal disorders involve abnormal chromosome numbers(e.g., Down syndrome).
Mitochondrial disorders result from mutations in mitochondrial DNA, inheriting only from the mother.

Genetic Testing Procedures

Carrier screening: Testing for potential disease carriers in couples planning pregnancy.
Preimplantation genetic diagnosis (PGD): Detecting genetic diseases in embryos before implantation.
Prenatal diagnosis (e.g., amniocentesis, chorionic villus sampling): Testing fetal cells for genetic disorders during pregnancy by analyzing amniotic fluid or chorionic villi.
Newborn screening: Testing newborns for inherited diseases.

DNA Amplification (PCR)

Polymerase chain reaction (PCR) is a lab technique for amplifying DNA.
It involves three steps: denaturation (95°C), annealing (-50°C), and extension (72°C). This process repeatedly doubles the DNA.
Enzymes, primers, and nucleotides are essential components of PCR. Taq polymerase is a heat stable enzyme.
PCR produces multiple copies of a specific DNA sequence to allow large amount of DNA needed for diagnosis

Gel Electrophoresis

Separates DNA fragments based on size using an electrical current and agarose gel.
Smaller fragments move faster through the gel.
Markers (fragments of known sizes) are included to estimate sizes.
Results reveal genetic versions (alleles) and SNPs (single-nucleotide polymorphisms) to diagnose disorders.

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Description

This quiz explores the fundamentals of genetic testing and screening, detailing how DNA analysis can diagnose diseases and identify carriers. It covers various genetic disorders, including single-gene and multifactorial disorders, and the roles of chromosomes and genes in heredity.