Which strand does RNA polymerase bind to?
During transcription, RNA Pol II binds the non-coding strand, reads the anti-codons, and transcribes their sequence to synthesize an RNA transcript with complementary bases. By convention, the coding strand is the strand used when displaying a DNA sequence. It is presented in the 5' to 3' direction.
Hence, DNA polymerase moves along the template strand in a 3'-5' direction, and the daughter strand is formed in a 5'-3' direction. This difference enables the resultant double-strand DNA formed to be composed of two DNA strands that are antiparallel to each other.
- DNA polymerase 3 is essential for the replication of the leading and the lagging strands whereas DNA polymerase 1 is essential for removing of the RNA primers from the fragments and replacing it with the required nucleotides. These enzymes cannot replace each other as both have different functions to be performed.
- In the replication process, RNase H removes the RNA primer (created by primase) from the lagging strand and then polymerase I fills in the necessary nucleotides between the Okazaki fragments (see DNA replication) in a 5'→3' direction, proofreading for mistakes as it goes.
- 2.A. Where and in what form is prokaryotic DNA found? Where is eukaryotic DNA found? DNA in prokaryotic cells is found in the form of a single circular chromosome in the cytoplasm; DNA in eukaryotic cells is found in the nucleus, packaged into bigger, individual chromosomes.
Since DNA polymerase requires a free 3' OH group for initiation of synthesis, it can synthesize in only one direction by extending the 3' end of the preexisting nucleotide chain. Hence, DNA polymerase moves along the template strand in a 3'–5' direction, and the daughter strand is formed in a 5'–3' direction.
- DNA ligases close nicks in the phosphodiester backbone of DNA. Biologically, DNA ligases are essential for the joining of Okazaki fragments during replication, and for completing short-patch DNA synthesis occurring in DNA repair process. There are two classes of DNA ligases.
- Since DNA polymerase requires a free 3' OH group for initiation of synthesis, it can synthesize in only one direction by extending the 3' end of the preexisting nucleotide chain. Hence, DNA polymerase moves along the template strand in a 3'–5' direction, and the daughter strand is formed in a 5'–3' direction.
- DNA ligase is an enzyme that repairs irregularities or breaks in the backbone of double-stranded DNA molecules. It has three general functions: It seals repairs in the DNA, it seals recombination fragments, and it connects Okazaki fragments (small DNA fragments formed during the replication of double-stranded DNA).
The antisense strand of DNA is read by RNA polymerase from the 3' end to the 5' end during transcription (3' → 5'). The complementary RNA is created in the opposite direction, in the 5' → 3' direction, matching the sequence of the sense strand with the exception of switching uracil for thymine.
- The RNA transcription process occurs in three stages: initiation, chain elongation, and termination. The first stage occurs when the RNA Polymerase-Promoter Complex binds to the promoter gene in the DNA. This also allows for the finding of the start sequence for the RNA polymerase.
- The mRNA formed will be complimentary to the DNA strand. Replace the C with G, G with C, A with U, T with A. this mRNA is sandwiched between the ribosomal sub units, and the long process of translation takes place. Now you need to know that 1 amino acid = 3 base pairs = 1 codon.
- These signals are special sequences in DNA that are recognized by the RNA polymerase or by proteins that help RNA polymerase determine where it should bind the DNA to start transcription. A DNA sequence at which the RNA polymerase binds to start transcription is called a promoter.
Updated: 21st October 2019