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2021-05-14

How does the mismatch repair machinery of E coli determine which of the bases is incorrect?

How does the mismatch repair machinery of E coli determine which of the bases is incorrect?

How Does The Mismatch Repair Pathway Identify The Incorrect Base In E. Coli? The Error Is Found On The DNA Strand Identified By The Absence Of Nicks. The Error Is Found On The DNA Strand Identified By The Presence Of Nicks.

What is the function of the MutS MutL MutH protein complex in E coli?

MutS, MutL, and MutH initiate MMR and play specialized biological roles in MMR in E. coli. MutS recognizes base-base mismatches and small nucleotide insertion/deletion (ID) mispairs, and thus MutS has been called the “mismatch recognition” protein 3.

How do repair proteins fix DNA mismatch problems?

Mismatch repair

  1. A mismatch is detected in newly synthesized DNA.
  2. The new DNA strand is cut, and a patch of DNA containing the mispaired nucleotide and its neighbors is removed.
  3. The missing patch is replaced with correct nucleotides by a DNA polymerase.
  4. A DNA ligase seals the remaining gap in the DNA backbone.

How does MutS recognize mismatched base pairs?

All of the MutS mismatched DNA structures show DNA kinked with a 45-60° bend angle. The conserved Phe stacks with a mismatched or inserted base, which is rotated out into the minor groove by ∼3 Å, and the Glu forms a hydrogen bond with the N-3 of a mismatched thymine or the N-7 of mismatched purines (11, 12, 16).

What type of bond holds base pairs together?

hydrogen bonds

How do the 4 nitrogen bases pair up?

The Four Bases Cytosine pairs with guanine, and adenine pairs with thymine. These are the base pairing rules that allow DNA replication and protein synthesis to happen. A and T are connected by two hydrogen bonds, while C and G are connected by three hydrogen bonds.

What will pair with adenine?

In DNA, the code letters are A, T, G, and C, which stand for the chemicals adenine, thymine, guanine, and cytosine, respectively. In base pairing, adenine always pairs with thymine, and guanine always pairs with cytosine.

What is the number of base pairs in E coli?

4 million

Why do base pairs pair up?

Attached to each sugar ring is a nucleotide base, one of the four bases Adenine (A), Guanine (G), Cytosine (C), and Thymine (T). The nucleotides in a base pair are complementary which means their shape allows them to bond together with hydrogen bonds. The A-T pair forms two hydrogen bonds.

How are base pairs formed?

Each base pair is formed from two complementary nucleotides (purine with pyrimidine) bound together by hydrogen bonds. The base pairs in DNA are adenine with thymine and cytosine with guanine. DNA has a spiral staircase-like structure.

Does RNA have base pairs?

RNA consists of four nitrogenous bases: adenine, cytosine, uracil, and guanine. Uracil is a pyrimidine that is structurally similar to the thymine, another pyrimidine that is found in DNA. Like thymine, uracil can base-pair with adenine (Figure 2).

How do we measure length in base pairs?

The following abbreviations are commonly used to describe the length of a D/RNA molecule:

  1. bp = base pair(s)—one bp corresponds to approximately 3.4 Å (340 pm) of length along the strand, and to roughly 618 or 643 daltons for DNA and RNA respectively.
  2. kb (= kbp) = kilo base pairs = 1,000 bp.

What is the third step in the translation process?

  1. The third step of translation is when the ribosome runs into a stop codon.
  2. A stop codon is either UAA, UAG or UGA.
  3. The ribosome places the last amino acid and severs the protein. It is now as long as it needs to be and will go into the cytoplasm for modification.
  4. The ribosome breaks off from the mRNA strand.