Homologous Recombination, CRISPR Gene Editing, and SCAR-TRACE Flashcards | Quizlet

What is homologous recombination?

A mechanism of DNA repair that uses a homologous sequence as a template for accurate repair.

Why are point mutations problematic?

They can alter protein function and lead to diseases.

What is a consequence of a deletion mutation?

It causes a frameshift, changing the amino acid sequence.

What might happen if a mutation alters the amino acid sequence?

It could change protein properties, function, or lead to early termination of the peptide.

When might a mutation have no impact on function?

When it is synonymous, the biochemical properties are similar, or it does not occur in a functional site.

Why is double-stranded DNA damage significant?

It can lead to chromosomal breaks that must be repaired to maintain genomic integrity.

What is the downside of Non-Homologous End Joining (NHEJ)?

It is a clumsy repair method that can create numerous mutations, including deletions and frameshifts.

How does homologous recombination differ from NHEJ?

Homologous recombination is more accurate and uses a homologous template for repair.

What occurs during the initial step of homologous recombination?

A double-stranded DNA break is created.

What happens to the broken DNA strands during homologous recombination?

Nuclease activity digests the 5' end, resulting in overhangs.

What is the role of DNA polymerase in homologous recombination?

It extends the invading strand using the undamaged DNA as a template.

What is the final outcome of homologous recombination?

The ends of the newly synthesized DNA strands are ligated together, completing the repair.

What is the significance of homologous recombination in meiosis?

It is essential for meiotic crossing over and generating genetic variation.

What are CRISPR and its role in DNA editing?

A versatile tool for DNA editing that utilizes a mechanism of phage immunity in bacteria.

How does CRISPR create targeted DNA breaks?

By using a guide RNA that targets homologous DNA, leading to double-stranded breaks.

What are the two repair mechanisms following CRISPR-induced breaks?

Non-Homologous End Joining (NHEJ) and Homologous Recombination.

What is the purpose of using synthetic guide RNA in CRISPR?

To create a dsDNA break that can be repaired using a plasmid as a template.

What is SCAR-TRACE?

A method using zebrafish embryos to trace cell lineages through CRISPR-induced mutations.

How does SCAR-TRACE help in developmental biology?

It allows researchers to understand how cells develop from a single cell to a complex organism.

What happens to gRNAs during SCAR-TRACE?

They are unstable, leading to a mosaic of edits in the early embryo.

How are cell relationships determined using SCAR-TRACE?

By organizing cells into trees based on shared barcode mutations.

What does a high number of shared barcodes indicate?

It suggests that the cells are closely related.

What is a potential experimental benefit of using NHEJ?

It can create mutations that are useful for studying loss of function phenotypes.

What is a targeted mutation in the context of homologous recombination?

A specific alteration made to the DNA sequence, such as inserting a tag to a protein.

What is the role of Cas proteins in CRISPR?

They bind to guide RNA and target homologous DNA for cleavage.

What is the significance of the double-stranded break in CRISPR applications?

It initiates the repair process that can lead to desired genetic modifications.