Genetics and Genetic Disorders Quiz

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.