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Transcription - is the first stage of __________________ and happens in the _____________.
 RNA molecules are produced by copying part of the nucleotide sequence of
_____________ into a complementary sequence in RNA, a process called
________________.
 Transcription requires an enzyme known as _____________________________ that is
similar to DNA polymerase.
Steps of Transcription:
1. RNA _____________________________ binds to DNA and separates the DNA strands.
Unzipping the ___________________________.
2. RNA polymerase will bind to regions of DNA known as promoters, which have specific
base sequences. In effect, _________________________ are signals in DNA that
indicate to the enzyme where to bind to make RNA
3. RNA _________________________ then uses ___________strand of DNA as a
template from which free ______________________ are assembled into a strand of
mRNA.
4. Nucleotides will form base pairs - Guanine bonds with ____________________ Adenine
bonds with _________________________. (RNA does not have _________________)
5. The transcribing continues until the mRNA reaches a signal on the DNA called a stop
codon that cause transcription to stop when the new RNA molecule is completed.
6. The completed mRNA leaves the _______________________________ and travels to
the_________________________________ located in the cytoplasm.
RNA Editing
1. RNA molecules require editing before they are ready to make proteins. A few,
including some of the rRNAmolecules that make up
________________________, are produced from larger RNA molecules that are
cut and trimmed to their final sizes.
2. Large pieces are removed from the RNA molecules transcribed from many
eukaryotic genes before they become functional. These pieces, known as
___________________ or intervening sequences, are cut out of RNA molecules
while they are still in the cell nucleus.
3. The remaining portions, called __________________________, or expressed
sequences, are then spliced back together to form the final mRNA. This process
is shown below.
RNA Editing Many RNA molecules have sections, called introns, edited out of them
before they become functional. The remaining pieces, called exons, are spliced
together. Then, a cap and tail are added to form the final RNA molecule.
Translation
The decoding of an mRNA message into a polypeptide chain (protein) is known as
translation. Translation takes place on ribosomes. During
_________________________, the cell uses information from messenger RNA to
produce proteins.
Before translation can occur, messenger ______________________ must first be
transcribed from ______________________________ in the nucleus and released into
the cytoplasm.
Translation begins when an mRNA molecule in the cytoplasm attaches to a
________________________________________________ As each
________________ of the mRNA molecule moves through the ribosome, the proper
_____________________ acid is brought into the ribosome and attached to the
growing polypeptide chain. The _________________does not “know” which amino acid
to match to each ________________ That’s the job of transfer RNA. Each
___________________________________ molecule has an amino acid attached to
one end and a region of three unpaired bases at the other. The three bases on the
______________________ molecule, called the anticodon, are complementary to one
of the mRNA _________________________________
In the case of the tRNA molecule for methionine, the anticodon
____________________ are UAC, which pair with the methionine codon,
____________________. The ribosome has a second binding site for a
________________________________molecule for the next codon. If that next codon
is UUC, a tRNA molecule with an _________________________anticodon would fit
against the mRNA molecule held in the ribosome. That second tRNA molecule would
bring the amino acid phenylalanine into the ribosome.
Like an assembly line worker who attaches one part to another, the ribosome forms
a ________________ bond between the first and second amino acids, methionine and
phenylalanine. At the same time, the ribosome breaks the bond that had held the first
___________________________ molecule to its amino acid and releases the tRNA
molecule. The ribosome then moves to the third ______________________, where a
tRNA molecule brings it the amino acid specified by the third codon.
The polypeptide chain continues to grow until the ribosome reaches a stop
_________________ on the mRNA molecule. When the ribosome reaches a stop
codon, it releases the newly formed ___________________________and the mRNA
molecule, completing the process of _________________________________
The Genetic Code
1. Proteins are made by joining amino acids into long chains called
______________________ Each polypeptide contains a combination of any or
all of the 20 different _________________. The properties of proteins are
determined by the order in which different _______________ acids are joined
together to produce ____________
2. The “language” of mRNA instructions is called the ________________code.
3. RNA contains four different bases: ______________, __________________,
______________, and __________________. The genetic code is read three
letters at a time, so that each “word” of the coded message is _________bases
long. Each three-letter “word” in mRNA is known as a codon,.
4. A _______________ consists of three consecutive nucleotides that specify a
single amino acid that is to be added to the polypeptide. For example, consider
the following RNA sequence:
UCGCACGGU
This sequence would be read
three bases at a time as:
UCG-CAC-GGU
The codons represent the
different amino acids:
UCG-CAC-GGU
Serine-Histidine-Glycine
Codons A codon is a group of three nucleotides on messenger RNA that specify a
particular amino acid.
 Because there are four different bases, there are 64 possible three-base codons
(4 × 4 × 4 = 64). 61 are codons for amino acids.
 There is also one codon, AUG, that can either specify methionine or serve as the
initiation, or “_________________" codon for protein synthesis.
 there are three “stop” codons that do not code for any amino acid.
_______________ codons act like the period at the end of a sentence; they
signify the end of a polypeptide.