Explore BrainMass
Share

DNA Synthesis

This content was STOLEN from BrainMass.com - View the original, and get the already-completed solution here!

Write an equation that describes the synthesis of DNA.

A chemical equation that describes the synthesis of DNA can be:

(DNA)n + dNTPs + DNAPol <--------> (DNA)n+1 + PPi (2)

DNAPol = DNA polymerase
(DNA)n = template DNA
(DNA)n+1 = growing new DNA strand
PPi = two pyrophosphate released

dNTPs is an abbreviation for the four deoxyribonucleoside triphosphates that can be added to the template strand. There are four different kinds of deoxyribonucleoside triphosphate (dNTPs) that contain four different bases. (1) The four different bases are adenine, thymine, guanine, and cytosine. The four different deoxyribonucleoside triphosphates are dTTP, dATP, dGTP, dCTP. (1) The deoxyribonucleoside triphosphate's tails have unstable negative charges. As each deoxyribonucleoside triphosphate join the new DNA strand by reacting with the 3'-hydroxyl end of the growing DNA strand, it loses two phosphate groups (PPi). (1) The hydrolysis of the triphosphate group on the deoxyribonucleoside triphosphate will release energy that drives the synthesis of new nucleotide to form DNA. (1) DNA polymerase is an enzyme that help join new deoxyribonucleoside triphosphate into the 3'- OH end of the growing DNA strand. The substrate for DNA polymerase is really the free 3'-OH end and the dNTPs. (3) The product is the dNMP (deoxyribonucleotide monophosphate) that covalently bound to 3' carbon on DNA , and lengthened the DNA with the release of the two pyrophosphate (PPi). (3)

If you do not understand this equation, then I can summarize the overall process of DNA synthesis or replication.

Step1: DNA synthesis begin when special enzyme called DNA helicase bind to specific sequence of DNA known as the origins of replication and unwind the double strand DNA into two strands. RNA primer is needed to initiate the elongation of the DNA on both unwound strands.
Step 2: DNA polymerase is needed to add new DNA nucleotide ( adenine, thymine, guanine, and cytosine) into the free hydroxyl group of the growing DNA strand. DNA polymerase can only add nucleotide to the free 3' OH end of a growing DNA strand. Therefore, new DNA strand can only grow in the 5'-->3' directions. (2) The energy that drive DNA synthesis to form new DNA come from the hydrolysis of the nucleoside triphosphate (dNTPs). The two DNA strand are antiparallel because one strand have the 5'---> 3' orientation, whereas the other strand have the 3'-----> 5' orientation.
Step 3: After DNA polymerase reaches the end of the template strand, it stop replication. Proofreading enzymes are used to check if the nucleotides are correctly paired to the template strand. (1) If there is errors in pairing, a nuclease enzyme will remove the mistake nucleotide. (1)

References -
1. Campbell. Biology. Third Edition
2. http://www.molecularstation.com/wiki/DNA_replication
3. http://wiki.cstl.semo.edu/agathman/DNA%20synthesis%20reaction.ashx

© BrainMass Inc. brainmass.com October 25, 2018, 8:15 am ad1c9bdddf
https://brainmass.com/biology/dna-chromosomes-and-genomes/dna-synthesis-532763

Solution Preview

A chemical equation that describes the synthesis of DNA can be:

(DNA)n + dNTPs + DNAPol <--------> (DNA)n+1 + PPi (2)

DNAPol = DNA polymerase
(DNA)n = template DNA
(DNA)n+1 = growing new DNA strand
PPi = two pyrophosphate released

dNTPs is an abbreviation for the four deoxyribonucleoside triphosphates that can be added to the template strand. There are four different kinds of deoxyribonucleoside triphosphate (dNTPs) that contain four different bases. (1) The four different bases are adenine, thymine, guanine, and cytosine. The four different deoxyribonucleoside triphosphates are dTTP, dATP, dGTP, dCTP. (1) The deoxyribonucleoside triphosphate's tails have unstable ...

Solution Summary

dNTPs is an abbreviation for the four deoxyribonucleoside triphosphates that can be added to the template strand. There are four different kinds of deoxyribonucleoside triphosphate (dNTPs) that contain four different bases. (1) The four different bases are adenine, thymine, guanine, and cytosine. The four different deoxyribonucleoside triphosphates are dTTP, dATP, dGTP, dCTP. (1) The deoxyribonucleoside triphosphate's tails have unstable negative charges. As each deoxyribonucleoside triphosphate join the new DNA strand by reacting with the 3'-hydroxyl end of the growing DNA strand, it loses two phosphate groups (PPi). (1) The hydrolysis of the triphosphate group on the deoxyribonucleoside triphosphate will release energy that drives the synthesis of new nucleotide to form DNA. (1) DNA polymerase is an enzyme that help join new deoxyribonucleoside triphosphate into the 3'- OH end of the growing DNA strand. The substrate for DNA polymerase is really the free 3'-OH end and the dNTPs. (3) The product is the dNMP (deoxyribonucleotide monophosphate) that covalently bound to 3' carbon on DNA , and lengthened the DNA with the release of the two pyrophosphate (PPi). (3)

$2.19
See Also This Related BrainMass Solution

Synthesis/RNA/DNA

1.The basic differences between RNA and DNA are:
a.The organic bases only
b.Bases, ribose units, and the phosphodiester linkage
c.Bases, ribose units, and the glycosidic bond type
d.Bases and the ribose units only.

2.The solubility characteristics of the pyrimidine or purine bases and the corresponding nucleosides differ greatly. Which of the following statements is not true?
a.purine bases are quite soluble in water.
b.Nucleosides are much more soluble than the corresponding bases.
c.Nucleosides and nucleotides are quite soluble in water.
d.Ribose units are very soluble in water.

3.Adenosine and guanosine are found predominantly in which tautomeric forms, respectively?
a.Amino & keto, respectively
b.Imino & keto, respectively
c.Amino & enol, respectively
d.Imino & enol, respectively

4.The component(s) of DNA which is (are) responsible for the absorbance band at 250-270 nmis:
a.Bases, pentoses. and phosphates all contribute
b.Only bases
c.Only bases and pentoses
d.Only pentoses and phosphates

5.AMP has three relevant ionizable groups. NI of adenine has pKa 4.0 and the phosphomonoester has pKas at 1.0 and 6.0 the net charge on AMP at pH 7.0 is approximately:
a.-3
b.-2
c.-1
d. 0

6.The thermodynamically most favorable form for pyrimidine nucleotides is:
a.Syn conformation
b.Anti conformation
c.Both are equally favored
d.Cannot be predicted

7.Which molecule contains an acid anhydride bond?
a. DNA
b.ATP
c.AMP
d. CAMP

8.All the NTPs are essential for RNA synthesis but GTP is also essential in:
a.Protein biosynthesis
b.Glycogen biosynthesis
c.Phospholipid biosynthesis
d.Fatty acid biosynthesis

9.The oligonucleotide, AUGGp, has all these properties except
a.Composed of ribonucleotides
b.Contains a 3' phosphate
c.Has a net charge pf -2 at pH 8.5
d.Contains three phosphodiester bonds.

10.To what target sequence on DNA is the oligonucleotide pAATTCCGG complementary?
a.TIAAGGCC
b.CCGGAATT
c.UUAAGGCC
d.CCGGAAUU

11.Which of the following characterizes the DNA in human cells?
a.DNA is located at a mesosome.
b.DNA is complexed with nonhistone proteins to form a nucleosome.
c.DNA is complexed with histone proteins with the DNA residing in the interior of the nucleosome.
d.DNA is complexed with the basic histone proteins and winds around the exterior of the histone protein "core".

12.An individual heterogeneous nuclear RNA (hnRNA):
a.Contains intron sequences not found in the final mature mRNA.
b.Contains exon sequences which are removed prior to translation.
c.Encodes more than one protein.
d.Can be found in the cytoplasm.

13.The RNA molecules which are involved in processing the hnRNA are:
a.mRNA
b.tRNA
c.rRNA
d.snRNA

14.RNA is hydrolyzed in basic solution but DNA is not. This occurs because:
a.Thymine is found in DNA, but uracil is not.
b.DNA is double stranded. while RNA is single stranded.
c.DNA contains a 2'-deoxyribose, while RNA does not.
d.RNA has modified bases, while DNA does not

15. What statement is incorrect about the different RNA molecules?
a.tRNA contain numerous intramolecular hydrogen bonds between bases.
b.There are more distinct tRNA molecules than there are rRNA molecules.
c.rRNA are complexed to proteins in the ribosomes.
d.The most abundant RNA molecule in the cell is mRNA.

View Full Posting Details