Genetics Quiz on CRISPR and Restriction Enzymes

CRISPR-CAS System

• In the acquisition stage of the original prokaryotic CRISPR-CAS system, foreign viral DNA is incorporated as a repeat in the CRISPR locus.
• This statement is TRUE.

Restriction Endonuclease Recognition

• Could 5'CTGCAG3' be the recognition sequence for a restriction endonuclease?
• This statement's answer is FALSE.

EcoRI Restriction Enzyme

• The recognition sequence for the Type II restriction endonuclease EcoRI is 5'G*AATTC3'.
  • The * indicates the location where the DNA sequence is cleaved by the enzyme.
• The following DNA sequence is an example of a sequence cut by the enzyme:
  • 5′...G3′
  • 3'...СТТАA5′
• This statement is TRUE.

Neofunctionalization

• Neofunctionalization can occur following a gene duplication event.
• This statement is TRUE.

Next-Generation Sequencing

• Next-generation sequencing, like Illumina, determines DNA sequences by DNA synthesis involving fluorescently labeled non-reversible terminators.
• This statement is TRUE.

Reverse Transcriptase in cDNA Synthesis

• During cDNA synthesis, reverse transcriptase performs specific actions.

  • It catalyzes the formation of phosphodiester bonds between the 5'-OH and the 3'-phosphate on adjacent nucleotides in the growing DNA polymer. This is the correct function of reverse transcriptase.
  • It does not synthesize a new DNA strand based directly on amino acid sequences.
  • It does not initiate DNA synthesis independently of a primer.
  • It creates a DNA copy of the RNA template and then replaces the RNA strand with a DNA version.

• The correct answer is A

Polyploidy

• Polyploidy is a common phenomenon in plant species, but also occurs in animal species.
• Hybrids of two species with the same number of chromosomes as their parents are fertile because the hybrids have the exact same number of chromosomes as their parent species.
• Mitotic nondisjunction in somatic cells can lead to the production of a polyploid organism.
• Polyploidy plays a major role in plant speciation
• Triploids can be fertile, but not always because they don't always produce balanced gametes.

Down Syndrome

• Down syndrome can be caused by chromosomal translocations.
  • Down syndrome can be caused by aneuploidy. (an incorrect number of chromosomes)
• The most typical cause of Down syndrome is a translocation of chromosome 21 that passes within families.
• Older women are more inclined to give birth to children with Down syndrome.
  • The majority of Down syndrome occurrences stem from a nondisjunction event in the mother.
• The incorrect statement is C.

Chromosomal Mutations

• Reciprocal translocation produces an unbalanced gene dosage.

• Chromosome duplications typically have no effect on the phenotype as long as no genetic material is lost.

• The gain of an extra sex chromosome is generally fatal.

• Chromosome mutations arising in germline cells (sperm or egg-producing cells) will be passed on to the next generation.

• Duplication of chromosome segments can result in pseudogenes, which are non-functional copies of genes.

• The correct statement is E

Single Nucleotide Polymorphisms (SNPs)

• Any two unrelated humans typically differ at several thousand SNPs.

• SNPs occur approximately every million base pairs.

• While SNPs may theoretically have more than two alleles, most SNPs only have two.

• Haplotypes are combinations of SNPs where only one copy of an allele for each SNP is present.

• The correct statement is C

Chromosome Mutation - Monosomy

• Monosomy is a type of chromosomal mutation where an organism loses one copy of each of two non-homologous chromosomes.

Quantitative Polymerase Chain Reaction (qPCR)

• The number of cycles required for the PCR product to become detectable (Cq) provides a method for determining template abundance.

• The linear phase of the reaction can be used to estimate template abundance.

• A double-stranded DNA-binding dye that fluoresces can be utilized to monitor PCR product amplification.

• The lag phase in qPCR refers to the time before any amplification occurs.

• The incorrect statement is B.