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Transcription, Translation, and Replication
Jennifer Kitchen
May 1, 2011
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The Nucleic Acid Pairs
There are two nucleic acids; ribonucleic acid (RNA) and deoxyribonucleic acid (DNA).
They are made up of units called nucleotides, chemical building blocks, that each includes a
phosphate, a five-carbon sugar, and a nitrogen base (Thibodeau & Patton, 2008). DNA is
molecule consisting of an extremely long chain of nucleotides in the form of a double helix
(Nuland, 1997). This looks like a twisted ladder. DNA is found in the nucleus and is the genetic
material of the cell that carries the chemical “blueprint” of the body (Thibodeau & Patton, 2008).
The cells of the body keep this information and can copy it whenever needed. RNA is a linear
molecule composed of a single chain of nucleotides for which synthesis DNA is the template
(Nuland, 1997). This means it is half of the twisted ladder. RNA is found in the in the
cytoplasm and is crucial to protein synthesis (Thibodeau & Patton, 2008). DNA makes RNA
and RNA, in turn, makes protein.
Transcription, Translation, and DNA Replication
Transcription and translation are important in the production of protein. Transcription
occurs when the double-stranded DNA molecules unwind and form messenger RNA (mRNA)
(Thibodeau & Patton, 2008). RNA transcription happens in the nucleus of a cell and occurs
when a message, for needed amino acids, is received from outside the cell. A strand of RNA is
constructed using DNA as a template (Nuland, 1997). This means the genetic information from
the DNA is transferred to the RNA. The mRNA strand will travel to the ribosome where the
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RNA sequence will be read and translated (Kwpitcairn, 2007). Translation is the synthesis of
protein by the ribosomes in the cytoplasm of the cell (Thibodeau & Patton, 2008). A polypeptide
chain is constructed after the assembling of a sequence of amino acids on a strand of RNA
(Nuland, 1997). Where RNA needs DNA in order to make proteins, DNA replication is the
unique ability of the DNA molecules to make copies of themselves (Thibodeau & Patton, 2008).
Replication is the process that creates new DNA. The DNA strand splits and the two halves
become their own strands. Next a portion of DNA is transcribed onto a strand of RNA. Then
the RNA nucleotides join up with the template strands of DNA (Kwpitcairn, 2007). This makes
a new DNA chain and is used in the building and maintaining of the cells of the body.
A Little about the Functioning of Organelles
Organelles are structures inside of a cell which have specific functions. These structures
help maintain homeostasis in a cell much as organs maintain homeostasis in the body. A few of
the organelles are mitochondria, ribosomes, endoplasmic reticulum, and the Golgi apparatus.
Some organelles, such as mitochondria, have their own genetic material separate from that found
in the nucleus of the cell. Mitochondria are the “power plants” of the cell, involved in chemical
reactions that release energy to be used by the cells for production and maintenance (Thibodeau
& Patton, 2008). These reactions are caused by enzymes breaking down glucose and other
nutrients and the energy is used throughout the body. This energy is what keeps the heart
beating and the nerves transmitting and receiving. Ribosomes are the “protein factories” of the
cell because their function is to make enzymes and other protein compounds (Thibodeau &
Patton, 2008). They are tiny dots found throughout the entire cell and may be free in the
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cytoplasm or attached to the membrane of the endoplasmic reticulum. Each dot or particle is
made up of two tiny subunits, which are constructed of a special RNA called ribosomal RNA
(rRNA) and protein and are the site of protein synthesis. Enzymes and proteins are used
throughout the body for many purposes, such as forming tissue and in the synthesis of hormones.
Endoplasmic reticulum is networks of connecting sacs and canals within the cytoplasm of a cell,
occurring either with a smooth surface (smooth endoplasmic reticulum) or studded with
ribosomes (rough endoplasmic reticulum). Smooth endoplasmic reticulum synthesis chemicals
to maintain the plasma membrane. Rough endoplasmic reticulum collects and transport proteins
made by ribosomes (Thibodeau & Patton, 2008). If the ER did not perform its function, “a cell
would not be able to produce the proteins and lipids necessary for basic functions, and would die.
It would be like our body losing the function of the liver” (Kitchen, 2011). Golgi apparatus can
be called the cell’s “chemical processing and packaging center”. The primary function of the
Golgi apparatus is to process and package the proteins and lipids that are synthesized by a cell
(Thibodeau & Patton, 2008). This organelle stores and modifies these products for specific
functions and prepares them for transport to other parts of the cell.
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References
Kitchen, J., (2011). Response to discussion post ‘Topic #3- organelles’ by Michelle Goble.
HS120-01 Anatomy and Physiology I; Kaplan University.
Kwpitcairn, (2007). Replication, Transcription, and Translation. Retrieved from
http://www.youtube.com/watch?v=3aVT2DTbtA8 .
Nuland, S., (1997). How we live. New York; Vintage.
Thibodeau, G. and Patton, K., (2008). Structure and function of the body. Missouri; Mosby
Elsevier.
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