9 Questions
What is the primary function of genes?
To produce proteins necessary for development
What is the purpose of non-homologous end joining in gene editing?
To repair broken DNA strands
What is the structure of DNA?
A double-stranded antiparallel helix
Where are chromosomes located in a cell?
In the nucleus
What is the primary advantage of Homology Directed Repair over Non-Homologous End Joining?
It is less prone to errors and mutations
What is the main limitation of Zinc Finger Endonucleases in gene editing?
They have a high risk of off-target cleavage
What is the key difference between TALENs and ZFNs in gene editing?
The presence of a highly conserved repeated sequence
What is the advantage of CRISPR-Cas9 over previous gene editing methods?
It surpasses previous methods in precision, efficiency, and flexibility
What is the role of the Repeat Variable Diresidue in TALENs?
It has a strong correlation with specific nucleotide recognition
Study Notes
Chromosomes
- Chromosomes are condensed DNA, compacted and located in the nucleus of a cell, carrying the genetic information of an organism.
- Humans have twenty-two (22) chromosome pairs called autosomes, and the twenty-third (23rd) are the sex chromosomes, which differ between males and females.
DNA, RNA, and Genes
- DNA (deoxyribonucleic acid) is an antiparallel double helix structure, serving as the base of genes.
- DNA contains base pairs, specifically Adenine (A), Guanine (G), Thymine (T), and Cytosine (C), with pairings of A-T and G-C.
- RNA (ribonucleic acid) is single-stranded, containing base pairs similar to DNA, but with Uracil (U) instead of Thymine.
- RNA is responsible for various genetic processes in organisms.
- Genes serve as code for producing proteins necessary for development and carry the code for traits like eye color, hair, etc.
Gene Therapy
- Gene therapy involves modifying, cutting, and replacing DNA strands to change the output of genes.
Ways to Edit a Gene
- Non-homologous End Joining (NHEJ) is a type of DNA repair system that directly joins two broken strands of DNA, useful for creating knock-out genes.
- Homology Directed Repair (HDR) is a type of DNA repair system that uses a homologous template to generate the missing parts of a cut sequence, with fewer mutations and nearly error-free.
Gene Editing Tools
- There are three established tools used in gene editing: Zinc Finger Endonucleases (ZFNs), Transcription Activator-like Effector Nucleases (TALENs), and Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR).
ZFNs
- ZFNs are artificial restriction enzymes consisting of zinc finger repeats and type II endonuclease Fok-1.
- Each zinc finger can recognize 9-18 base pairs, but ZFNs have limitations, such as the need to know the exact zinc finger repeats of the target DNA sequence.
TALENs
- TALENs are similar to ZFNs in their cleavage domains, but use a highly conserved repeated sequence of 33-34 amino acids, offering better matching opportunities to find the targeted sequence.
- TALENs have a divergent on the 12th and 13th amino acid known as the Repeat Variable Diresidue (RVD), which has a strong correlation with specific nucleotide recognition.
CRISPR
- CRISPR-Cas9 is a highly advanced gene editing tool that surpasses previous methods like ZFNs and TALENs in precision, efficiency, and flexibility.
Learn about genes, chromosomes, and DNA structure. This quiz covers the basics of chromosomes, including autosomes and sex chromosomes.
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