DNA polymerases add nucleotides to the 3′ end of a polynucleotide chain. ... To initiate this reaction, DNA polymerases require a primer with a free 3′-hydroxyl group already base-paired to the template. They cannot start from scratch by adding nucleotides to a free single-stranded DNA template.

How is DNA replicated? Replication occurs in three major steps: the opening of the double helix and separation of the DNA strands, the priming of the template strand, and the assembly of the new DNA segment. During separation, the two strands of the DNA double helix uncoil at a specific location called the origin.

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3 years ago

Suppose that a strain of bacteria lacks a key biochemical used in purine synthesis. Complete all the statements about purine syn

olga55 [171]

Answer:

1. Phosphoribosyl amine

2. glycinamide ribonucleotide (GAR), a formyl group

3. Formylglycinamide ribonucleotide (FGAR), an amino group

4. Carboxyaminoimidazole ribonucleotide (CAIR), an amino group.

Explanation:

1. Phosphoribosyl amine will accumulate in bacteria that lack glycine.

2. The intermediate glycinamide ribonucleotide (GAR) will build up in the absence of tetrahydrofolate.

N10‑Formyltetrahydrofolate donates a formyl group to the substrate

3. Formylglycinamide ribonucleotide (FGAR) will accumulate in the absence of glutamine.

Glutamine donates an amino group

4. The intermediate carboxyaminoimidazole ribonucleotide (CAIR) will accumulate when aspartate is lacking.

Aspartate donates an amino group.

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3 years ago