Genetics and Genetic Disorders Quiz

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Questions and Answers

Which statement best describes the molecular basis of most cystic fibrosis cases?

No protein is produced from mutant alleles

Patients’ cells cannot export chloride (correct)

Patients’ cells cannot export fibrillin

Patients’ cells cannot metabolise phenylalanine

Which is composed of linear DNA?

A human X chromosome (correct)

A plasmid

A prokaryotic chromosome

An E.coli chromosome

How might the amplification of the HER-2 gene impact treatment of a patient?

Decreased dosage with anti-depressant medication

Increased dosage with Herceptin (correct)

Decreased dosage with Herceptin

Increased dosage with anti-depressant medication

Which mutation would be most likely to cause a dominant phenotype?

A mutation that increases the number of repeats at an STR locus Signup and view all the answers

Which viral vector used in gene therapy inserts the therapeutic gene into the host genome?

Lentivirus Signup and view all the answers

When might a patient with a genetic disease be effectively treated by a drug that promotes exon-skipping?

When the patient has Becker Muscular Dystrophy Signup and view all the answers

When is a mutation most likely to be inherited by future generations?

A single-strand break in a germ-line cell is repaired by homologous recombination Signup and view all the answers

What symptom is most commonly associated with Down syndrome?

Intellectual disability Signup and view all the answers

What genetic alteration is primarily responsible for the symptoms of individuals with Down syndrome?

Three separate copies of a chromosome Signup and view all the answers

Which mechanism most commonly leads to the development of Down syndrome?

Non-disjunction of an autosome Signup and view all the answers

Which of the following is NOT a genetic approach to treating disease?

Encouraging lifestyle changes to improve overall health Signup and view all the answers

What does a LOD score of one indicate about a genetic marker?

The marker is close to the gene Signup and view all the answers

Which gene associated with Tibetans has an allele inherited from Denisovans?

EPAS-1 Signup and view all the answers

Which statement is true regarding lactose tolerance?

Lactose tolerance is dominant Signup and view all the answers

Which of the following is a typical symptom of Down syndrome?

Short stature Signup and view all the answers

What is the starting biomolecule in the transcription process?

DNA Signup and view all the answers

Which molecule is produced as a result of transcription?

Messenger RNA (mRNA) Signup and view all the answers

What is one common way to boost eukaryotic transcription?

Activating transcription factors Signup and view all the answers

Which is true of the X-linked recessive mode of inheritance?

Almost all affected individuals are male Signup and view all the answers

During which phase of the cell cycle does DNA replication occur?

S phase Signup and view all the answers

Which disease can be prevented by avoiding foods containing a particular amino acid?

Phenylketonuria Signup and view all the answers

What enzyme is responsible for extending a new strand of DNA during replication?

DNA polymerase Signup and view all the answers

Which end of the new DNA chain is extended during replication?

3' end Signup and view all the answers

What is X inactivation?

The silencing of one X chromosome in females Signup and view all the answers

What symptom would be most likely to be experienced by a hypothetical woman who is heterozygous for null mutations in her CFTR and OCA2 genes?

Pale skin Signup and view all the answers

What is the mode of inheritance of Marfan syndrome?

Autosomal dominant Signup and view all the answers

Which of the following describes a situation that could complicate accurate identification using STR analysis?

Presence of multiple alleles at a locus Signup and view all the answers

How many STR loci have been used to create the profile?

16 Signup and view all the answers

How many STR loci are heterozygous in this profile?

4 Signup and view all the answers

Which is a piece of evidence that helped to identify the first self-replicating biomolecule on earth?

Specific DNA sequences can create copies of themselves Signup and view all the answers

What molecular process is disrupted in oculocutaneous albinism type 2?

An inability to convert tyrosine into melanin Signup and view all the answers

Which of the following is not a method for generating forensic DNA profiles?

Spectral karyotyping Signup and view all the answers

What genotype would most likely describe the mother of a boy with Fragile-X syndrome?

One FMR1 allele has 300 repeats, the other has 40 repeats Signup and view all the answers

Which characteristic is shared by plasmids and eukaryotic chromosomes?

Their replication starts at multiple sites Signup and view all the answers

Which technique is specifically used to change the nucleotide sequence of a gene?

CRISPR-Cas9 Signup and view all the answers

How do mutations in the mitochondrial genome primarily affect cellular energy generation?

By impacting the function of the electron transport chain and oxidative phosphorylation Signup and view all the answers

What would likely be true of a tetraploid plant?

It could not interbreed with diploid relatives to produce fertile offspring Signup and view all the answers

What is the most likely consequence of mutations in mitochondrial DNA?

Reduced capacity for cellular respiration Signup and view all the answers

Study Notes

Cystic Fibrosis

Most cystic fibrosis cases arise from a mutation that affects chloride transport across cell membranes.

DNA Structure

Eukaryotic chromosomes are composed of linear DNA.

HER-2 Gene Amplification

HER-2 gene amplification can lead to increased dosage of Herceptin therapy.

Dominant Mutations

Dominantly inherited phenotypes are most likely caused by mutations that lead to a gain of function, such as a protease that cleaves different proteins.

Viral Vectors in Gene Therapy

Lentiviruses are viral vectors used in gene therapy that integrate the therapeutic gene into the host genome.

Exon-Skipping

Exon-skipping therapy can be effective for treating diseases caused by mutations that lead to frameshift mutations, such as Becker Muscular Dystrophy.

Mutations and Inheritance

Mutations that are most likely to be inherited by future generations are those that occur in germ-line cells.

Down Syndrome

Down syndrome is most commonly caused by non-disjunction of an autosome, resulting in three copies of chromosome 21.

Genetic Approaches to Disease Treatment

Genetic approaches to disease treatment include genetic screening to select appropriate drugs and dosages, and engineering an artificial aid to restore bodily function impaired by genetic mutation.

LOD Scores

A LOD score of 1 indicates that the marker is distant from the gene.

Tibetans and Denisovans

Many Tibetans carry an EPAS-1 allele that they inherited from Denisovans.

Lactose Tolerance

Lactose tolerance is caused by a change in the amino acid sequence of Lactase, enabling the continued production of the enzyme into adulthood.

Oculocutaneous Albinism Type 2

Oculocutaneous albinism type 2 is caused by an inability to import tyrosine into melanosomes.

Forensic DNA Profiling

Spectral karyotyping is not used in the process of generating forensic DNA profiles.

Fragile-X Syndrome

Fragile-X syndrome can be inherited from an unaffected mother if she carries a premutation on one of her FMR1 alleles.

Plasmids and Eukaryotic Chromosomes

Plasmids and eukaryotic chromosomes both replicate their DNA in a semi-conservative manner, meaning that one strand is copied in short stretches.

CRISPR-Cas9

CRISPR-Cas9 is a technique that can change the nucleotide sequence of a gene.

Mitochondrial Mutations

Mutations in the mitochondrial genome often affect the ability of cells to generate energy by impacting the function of the electron transport chain and oxidative phosphorylation.

Polyploidy

Tetraploid plants can result from mating between diploid and tetraploid plants.

X-Linked Recessive Inheritance

X-linked recessive inheritance is characterized by a higher frequency of affected males, as they only have one X chromosome.

Phenylketonuria

Phenylketonuria can be prevented by avoiding foods containing phenylalanine.

Amino-acyl tRNA Synthetase

A homozygous deletion that removes a gene encoding an amino-acyl tRNA synthetase would result in one amino acid not being attached to any tRNAs.

CFTR and OCA2 Mutations

A woman heterozygous for null mutations in her CFTR and OCA2 genes would experience pale skin.

Marfan Syndrome

Marfan syndrome is inherited in an autosomal dominant manner.

STR Profiles

STR profiles are created using 16 STR loci, and individuals are identified based on the unique combination of alleles at each locus.

Self-Replicating Biomolecules

Evidence suggesting that RNA was the first self-replicating biomolecule includes modern RNAs having enzymatic activities and encoding proteins.

Transcription

Transcription uses DNA as the starting biomolecule to create a molecule of RNA.

Eukaryotic Transcription

Eukaryotic transcription can be boosted or suppressed through the use of transcription factors that bind to regulatory sequences in the DNA.

RNA Modifications

Eukaryotic RNA undergoes several modifications, these include:
- Capping
- Splicing
- Polyadenylation

DNA Replication

DNA is replicated during the S phase of the cell cycle.

DNA Synthesis

DNA synthesis uses DNA polymerase and deoxynucleoside triphosphates to extend a new strand of DNA.

DNA Polymerase

DNA polymerase adds nucleotides to the 3' end of the new DNA strand.

Sanger Sequencing

Sanger sequencing uses dideoxy-nucleotides, which terminate chain elongation when incorporated into the new DNA strand.

STR Profiling

STR profiling involves amplifying DNA using PCR and then separating the amplified fragments using electrophoresis.

STR Profile Identification

An individual is identified using an STR profile based on the unique combination of alleles at each locus.

STR Profile Complications

Issues that can complicate accurate identification of an individual using STR analysis include:
- DNA degradation
- Contamination
- Mixed samples

X-Inactivation

X-inactivation is the process in which one of the two X chromosomes in a female is randomly inactivated during embryonic development.

Skewed X-Inactivation

Skewed X-inactivation occurs when one X chromosome is inactivated more frequently than the other, potentially resulting in an individual experiencing symptoms not expected based on their genotype.

Molecularly Targeted Treatments

Cystic fibrosis is an inherited disease for which molecularly-targeted therapy has been developed.

Cystic fibrosis

Cystic fibrosis is caused by mutations in the CFTR gene.

CFTR

CFTR is inherited in an autosomal recessive manner.

CFTR Treatments

Targeted drugs for cystic fibrosis work by restoring CFTR function.

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Description

This quiz covers crucial topics in genetics, including cystic fibrosis, DNA structure, dominant mutations, and gene therapy techniques. It also addresses genetic disorders like Down syndrome and the role of mutations in inheritance. Test your knowledge on these fundamental concepts in genetics!