0
What is the function of a ddNTP in DNA sequencing and how does it impact the sequencing process?
A ddNTP (dideoxynucleotide triphosphate) is used in DNA sequencing to terminate the DNA strand during replication. When a ddNTP is incorporated into the growing DNA strand, it prevents further elongation, resulting in fragments of varying lengths. These fragments are then separated by size to determine the sequence of the original DNA strand.
What else can I help you with?
What is the ratio of ddNTP to dNTP in the nucleotide mixture used for the Sanger sequencing reaction?
The ratio of ddNTP to dNTP in the nucleotide mixture for Sanger sequencing is typically 1:10.
Why are ddNTPs used for DNA sequencing?
ddNTPs (dideoxynucleotide triphosphates) are used in DNA sequencing because they lack the 3'-OH group required for the formation of phosphodiester bonds with the next nucleotide, causing DNA polymerase to terminate the DNA strand synthesis upon ddNTP incorporation. This results in the production of a series of DNA fragments with varying lengths that can be separated by size to determine the sequence of the original DNA template.
What is dideoxyribonucleoside triphosphate when we sequence DNA?
They are ddNTPs (ddATP, ddGTP, ddTTP, ddCTP) that also lack a 3' hydroxyl (OH) group in their deoxyribose sugar. This allows them to terminate the complementary nucleotide sequence (forming antiparallel to the template strand) that starts with the oligonucleotide (primer) and continues with dNTPs (deoxynucleoside triphosphate) attached by DNA polymerase. ddNTPs terminate the sequence at different positions which results in sequences of different lengths that each end with a different ddNTP. As these sequences are ran through a capillary electrophoresis gel, they are sorted by length, with the shortest sequence exiting the capillary tube first, and so on. Since each ddNTP is dyed a different color and fluoresces differently, the sequencing machine reads the ddNTP at the end of each sequence, determines its nucleotide (A, G, T, or C), and writes out the sequence one nucleotide at a time. Below is a link to a wonderful interactive animation that teaches about this method of sequencing.
Why are four reactions needed in Sanger sequencing?
In Sanger sequencing, four reactions are needed to determine the sequence of nucleotides because each reaction incorporates a different dideoxynucleotide (ddNTP) corresponding to one of the four bases (A, T, C, G). This allows for the termination of DNA synthesis at each base position, creating fragments of varying lengths that can be separated by gel electrophoresis. The resulting pattern of fragments reveals the order of nucleotides in the original DNA template, as each terminated fragment corresponds to a specific base. Thus, the four reactions collectively provide the complete sequence information.
In dideoxy sequencing of DNA isn't it so that in each test tube containing a separate ddNTP apart from getting fragments ending at ddNTPs you shall also get the full fragments in each case?
http://wiki.answers.com/Q/In_dideoxy_sequencing_of_dna_isn%27t_it_so_that_in_each_test_tube_containing_a_separate_ddNTP_apart_from_getting_fragments_ending_at_ddNTPs_you_shall_also_get_the_full_fragments_in_each_case" "http://wiki.answers.com/Q/In_dideoxy_sequencing_of_dna_isn%27t_it_so_that_in_each_test_tube_containing_a_separate_ddNTP_apart_from_getting_fragments_ending_at_ddNTPs_you_shall_also_get_the_full_fragments_in_each_case"
