DNA Replication And Cell Division

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DNA Replication And Cell Division

By: Dr. Richard Waller

DNA replication basically means creating two entire DNA strands for each daughter cell in place of the single parent cell. Prior to the cell division, its DNA within the nucleus is released by an enzyme to break the hydrogen bonds between the bases, resulting in two halves of the DNA. The uninhibited nucleotides within the nucleus bonds with the bases of both strands. Bonds with T alone while C with G, leading to exact matches for both strands.

There are four phases in cell division, or mitosis (normal cell division, meiosis forms sex cells).

Prophase: Pairing of chromosomes occurs and following replication, the parent cell has two complete sets. Two poles are formed as the nucleus disappears.

Metaphase: Alignment of the chromosomes is at the equator between the two poles.

Anaphase: The chromosomes split up towards each pole. Cell membrane division begins.

Telophase: Appearance of nuclei is at each pole and membrane divides. Two cells possess identical chromosomes.

DNA Replication

The DNA composition where two separate strands store all genetic information, replicate easily. A DNA molecule has a polymer opposite of the other, like a photonegative. One side enables the other to be recreated. This duality simplifies copying a DNA molecule remarkably.

Replication causes synthesization of DNA molecules. First a helicase enzyme unwinds the double helix, at any point on the strand, progressing to two replication forks by enzymes extending the helix release in both directions. With unwinding and straightening out of the DNA, DNA polymerase, another enzyme functions. It matches the exposed nitrogenous bases with new nucleotides from the surrounding nuclear fluid. The nucleotides and separated polymers fuse as per the regular Watson-Crick pairing rules. The completion of the separation and re-matching of the DNA molecule makes two perfect copies.

DNA replication remains partially unknown. Signals that start the process, the reason some cells don't replicate and the cause of uncontrollable replication of cancerous cells remain unexplained.

Replication in Prokaryotes

Prokaryotes or bacteria store almost the entire genetic information of an organism in a single large circular DNA ring and not in multiple chromosomes of DNA strings with unconnected ends. This replication is almost identical to eukaryotic DNA except in the use of only two replication forks. Eukaryotes and prokaryotes differ, with multiple replication sites active simultaneously in the former and the speed of the latter requiring only two, one for each direction The rate of replicating bacterial DNA is almost one million base pairs per minute whereas the average is 500 to 5000 pairs for other organisms.

DNA Replication is Semi-Conservative

On completion of the replication process, two DNA molecules result, which are identical both to each other as well as to the original. There is not the slightest alteration in each strand of the original molecule due to its role as the template for the synthesis of a complementary strand. This replication method has been termed semi-conservative; as one half of each new DNA molecule is old while the other half is new.

Finally...

The need for DNA replication or cell genome duplication is created by each cell division. As with all cellular activities, specialized proteins are needed for the purpose of replication. DNA replication is surprising as a process in all organisms except in the case of humans where comprehension can prove very complex.

Learn more about Cell Biology and DNA replecation, visit www.biology-online.org

About The Author

Dr. Richard Waller has been helping thousands of infetile couples and gave hope to childless women since 1999 through the process of in-vitro fertilization. He is based in England. http://www.biology-online.org.

biologyonlineorg@yahoo.co.uk

Comments

Sandra L. 22.07.2013. 22:07

What is one of the differences between cell division in plant cells and cell division in animal cells? A) There is no DNA replication before cell division in plant cells.
B) Plant cells do not use a mitotic spindle to seperate chromosomes.
C) Plant cells seperate chromosomes by attachment to the plasma membrane.
D) Plant cells seperate by growth of a call wall and membrane in the middle of the cell.

Sandra L.

Admin 22.07.2013. 22:07

D) Plant cells seperate by growth of a cell wall and membrane in the middle of the cell.

Admin

Jere 17.02.2013. 17:01

What is one of the differences between cell division in plant cells and cell division in animal cells? Plant cells do not use a mitotic spindle to separate chromosomes.

Plant cells separate by the formation of a new plasma membrane and cell wall in the middle of the cell.

There is no DNA replication before cell division in plant cells.

Plant cells separate chromosomes by attachment to the plasma membrane.
.

Jere

Admin 17.02.2013. 17:01

Plant cells separate by the formation of a new plasma membrane and cell wall in the middle of the cell.

For further reading
cell plate

Admin

Aaron 26.06.2009. 18:34

What is one of the differences between cell division in plant cells and cell division in animal cells? What is one of the differences between cell division in plant cells and cell division in animal cells?
A) Plant cells do not use a mitotic spindle to separate chromosomes.
B) Plant cells separate chromosomes by attachment to the plasma membrane.
C) In a plant cell, there is no nucleus around the chromosomes.
D) There is no DNA replication before cell division in plant cells.
E) Plant cells separate by growth of a cell wall and membrane in the middle of the cell.

Aaron

Admin 26.06.2009. 18:34

E is the correct answers. After the last phase of mitosis, animal cells undergo cytokinesis - a pinching of the cytoplasm and cell membrane into two separate entities. However, plant cells simply grow a new wall in the middle of the cell once chromosomes and organelles have separated from the metaphase plate.

Admin

The name Jin 14.01.2008. 22:58

how is this different in eukaryotes and prokaryotes? how is dna replication and cell division different in prokaryotes vs eukaryotes?? thanks
also please tell me more things than just talk about the nucleus, i need some specifics.

The name Jin

Admin 14.01.2008. 22:58

well eukaryotes have a nucleus...

prokaryotes do not.

therefore from there... it depends on whether dna replication or cell division takes place in the nucleus...

Admin

Jane 09.12.2012. 00:44

DNA replication produces copies of DNA molecules. What happens to these DNA molecules during cell division? DNA replication produces copies of DNA molecules. What happens to these DNA molecules during cell division (mitosis or meiosis)?

A.When sister chromatids separate, the two (double-stranded) copies of a DNA molecule are separated.

B. When sister chromatids separate, the two strands of each DNA molecule are separated.

C. When homologous chromosomes separate, the two (double-stranded) copies of a DNA molecule are separated.

D. When homologous chromosomes separate, the two strands of each DNA molecule are separated.

I think it's A, but I want to make sure....

Jane

Admin 09.12.2012. 00:44

A.

Each chromatid is composed of one really long double strand of DNA, and a chromosome is two really long double strands. Homologues only form in meiosis.

Admin

sallu 30.05.2011. 02:57

The role of a tumour suppressor protein in a cell is to? The role of a tumour suppressor protein in a cell is to
Choose one answer.
a. trigger DNA replication in preparation for cell division.
b. allow cancerous cells to spread to other tissues.
c. slow or halt cell division.
d. promote cell division.

sallu

Admin 30.05.2011. 02:57

c. slow or halt cell division.

Admin

no thank you 19.06.2012. 11:52

Why are high levels of radiation fatal to humans? a.
Radiation leads to permanent increases in the activity of DNA repair proteins.
b.
Radioactive atoms act as mutagens.
c.
Radiation increases the rate of DNA replication.
d.
Radiation inhibits cell division so that dead cells cannot be replaced.

no thank you

Admin 19.06.2012. 11:52

Should be b

Admin

C H 03.12.2007. 01:56

How do you compare and contrast the organization of genetic material in prokaryotic and eukaryotic organisms?. What are some specific examples.

How are DNA replication, Transcription and translation of the genome and gene regulation carried out in prokaryotes and eukaryotes?

What about Cell Division???

C H

Admin 03.12.2007. 01:56

Prokaryotes: Well, most obviously, THEY DON'T HAVE A NUCLEUS. Meaning, of course, that they don't have their own genetic structure (DNA) and can't contain ribosomes, meaning they can't produce proteins.

Eukaryotes: Complex. (Plant/animal cells.) Contain deoxyribonucleic acid. Have FAR more organelles than prokaryotic cells do (ie: lysosomes, RER/SER, chloroplast (plant cells), etc.).

Cell Division: I guess that you're specifically referring to binary fission. Prokaryotes usually reproduce through binary fission, and it's sort of rare for eukaryotes to. DNA replication occurs, forming a 'replication bubble'. The strands then separate and attach to different ends of the cell membrane. The cell elongates, and the opposing pressure makes it divide equally. Ta-da!

Admin

C H 03.12.2007. 02:09

How do you compare and contrast the organization of genetic material in prokaryotic and eukaryotic organisms?. What are some specific examples.

How are DNA replication, Transcription and translation of the genome and gene regulation carried out in prokaryotes and eukaryotes?

What about Cell Division???

C H

Admin 03.12.2007. 02:09

A good way to go about it is to look at the spelling of these two materials, they are very different, once starts with an "E" the other with a "P", aside from how they are spelled, look at their colors under an electron microscope, they have different colors. You may also try drinking the two and compare their tastes. I hope I have helped! Thanks for the 10 Points!!!

Admin

Gene Expression 25.10.2007. 16:58

About of all Americans will develop cancer. Which of the following is one possible cause of cancer? -Cancer results from errors in mitosis where anaphase occurs before prophase.
-Cancer results from errors in transcription were terminators fail to trigger transcriptional termination.
-Cancer results from errors in DNA replication where the DNA polymerase inserts the wrong nucleotide in the growing DNA chain.
-Cancer results from errors in cell division where meiosis occurs instead of the normal mitosis.
-Cancer results from errors in translation where the wrong tRNA gets inserted in the ribosome.

Gene Expression

Admin 25.10.2007. 16:58

Cancer results from errors in DNA replication where the DNA polymerase inserts the wrong nucleotide in the growing DNA chain.

Admin

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