the making of a protein!
DESCRIPTION
The Making of a Protein!. Transcription. DNA holds the instructions. When proteins are produced in the body, the instructions for how to make it comes from the DNA (deoxyribonucleic acid) BUT, there are many steps between a strand of DNA and a protein. Let’s review DNA first. - PowerPoint PPT PresentationTRANSCRIPT
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The Making of a Protein!
Transcription
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DNA holds the instructions
When proteins are produced in the body, the instructions for how to make it comes from the DNA (deoxyribonucleic acid)
BUT, there are many steps between a strand of DNA and a protein
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Let’s review DNA first• DNA is double-stranded• Adenine is always across from Thymine• Cytosine is always across from Guanine• bases are held across from each other by weak
hydrogen bonds
A--TC--G
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Making Proteins•Making proteins involves another step as you saw on the first slide•First, a molecule called RNA is produced•This process is called TRANSCRIPTION
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RNARibonucleic acidsingle strandedalso made of nucleotides
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The nucleotides of RNAThey are slightly different than DNAThey have a sugar and a phosphate group like
DNA does
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The differenceThree of the nitrogenous
bases are the same: Adenine (A) Cytosine (C) Guanine (G)
The last one is different: Uracil (U)
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Instructions for a ProteinThe instructions to make a certain protein are
coded by the sequence of nucleotides in a strand of DNA (a gene)
These instructions get transferred from the DNA strand to an RNA strand through transcription
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So how does this happen?
There are a number of steps in the process of making a protein
The first involves two different parts: RNA polymerase the gene’s promoter
A promoter is a certain order of DNA that acts as a “start” signal for transcription
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RNA polymeraseRNA polymerase is an enzyme It binds to the promoter of a geneThis enzyme helps unwind and separate the
two strands of DNA
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The templateOne strand of the DNA acts as a “template” for
making the RNAThis means that the nucleotides that will form
the RNA pair up with this strandRNA polymerase helps make this happen
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Base Pairing Rules Just like with DNA, the nucleotides only pair
with certain other nucleotides If there is a Thymine on the DNA strand,
Adenine still pairs with it If there is an Adenine on the DNA strand, it now
pairs with UracilCytosine pairs with Guanine just like before
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Some covalent bonds are involved
As the RNA nucleotides get added to the strand of RNA that is forming, they are forming covalent bonds
The covalent bonds occur between the nucleotides of the RNA
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How it endsTranscription keeps going until RNA polymerase
reaches a “stop” signal on the DNARNA polymerase falls off of the DNA and
releases the RNA moleculeThe DNA then winds
back up
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Animations:http://www.dnalc.org/resources/3d/12-transcript
ion-basic.html
http://www.youtube.com/watch?v=OtYz_3rkvPkTextbook:
http://bcs.whfreeman.com/thelifewire/content/chp12/1202001.html
Nebraska: http://croptechnology.unl.edu/animation/transcription.swf