Finals Flashcards
(30 cards)
What is the main difference between forward and reverse genetics?
Forward genetics starts with a phenotype and identifies the gene; reverse genetics starts with a gene and studies the resulting phenotype after modification.
Name three applications of PCR in genetics.
Genetic mapping, genotype detection, diagnosis of diseases (e.g., Huntington’s disease).
What is the role of Dicer in RNA interference?
Dicer processes double-stranded RNA into short interfering RNAs (siRNAs) that guide the RISC complex for gene silencing.
How does CRISPR-Cas9 achieve gene targeting?
CRISPR uses guide RNA (gRNA) and Cas9 to create targeted DNA double-strand breaks, repaired by NHEJ or HR to introduce edits.
Describe a method to introduce a transgene into C. elegans.
By injecting DNA into the syncytial gonad region of C. elegans, where it may form extrachromosomal arrays or integrate.
What is positional cloning and what are its key steps?
A method using DNA linkage markers to locate and clone a gene. Key steps: mapping, narrowing region, identifying candidates, and confirming gene function.
Which mutagen introduces G:C to A:T transitions?
EMS (ethyl methanesulfonate).
How are chimeric mice used to generate gene knockouts?
ES cells with a knockout allele are injected into a blastocyst, which is implanted into a surrogate. Chimeric mice are bred to transmit the KO allele.
List two reasons Drosophila is an excellent model organism.
Short life cycle and many available genetic tools; 61% of human disease genes have homologs.
What makes Arabidopsis suitable for genetic studies?
Small genome, self-fertilizing, easy to grow, short generation time, large seed yield.
What is a plasmid?
A small circular DNA molecule used to carry inserted genes in molecular cloning.
What is the function of gel electrophoresis?
To separate DNA fragments by size through an electric field.
What are restriction enzymes used for in cloning?
To cut DNA at specific sequences to allow cloning or analysis.
What is the role of the neoR and tk+ markers in gene targeting?
neoR allows positive selection (resistance to G418); tk+ allows negative selection (sensitivity to ganciclovir).
What type of gene disruption do ZFN or TALEN introduce?
They introduce double-strand breaks in DNA, which can lead to knockouts via NHEJ or targeted insertions via HR.
What is siRNA?
A small RNA molecule that directs RISC to degrade complementary mRNA.
Which model organism led to the discovery of RNAi?
Caenorhabditis elegans.
What year did RNAi-based drugs first receive FDA approval?
2018 (e.g., Patisiran for hereditary transthyretin-mediated amyloidosis).
What is a conditional lethal mutant?
A mutant that survives under normal conditions but is lethal under restrictive conditions (e.g., temperature-sensitive).
What is a suppressor screen?
A screen that finds secondary mutations that restore the original mutant phenotype.
What is the purpose of a balancer chromosome in Drosophila genetics?
To maintain lethal/sterile mutations and suppress recombination in Drosophila.
What makes C. elegans useful for cell lineage studies?
Transparent body and invariant cell lineage make it easy to trace every cell during development.
What is an imaginal disc in Drosophila?
A larval structure that gives rise to adult tissues during metamorphosis.
Why is Mus musculus (mouse) important for studying human diseases?
It closely resembles humans genetically and physiologically, making it ideal for modeling diseases.
