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Chapter 11 Study Guide
What is a nucleotide? Draw a picture.
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A nucleotide is the monomer to the polymer DNA or
RNA. The nucleotide is like the subunit or smaller unit of of
the DNA/RNA strand. It is made up of three parts: a simple
sugar, a phosphate, and a nitrogen base.
What are the functional differences between RNA and DNA?
What are the structural differences?
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DNA has the function of storing all the genes (or codes to make proteins) in itʼs
molecules. That is the entirety of DNAʼs job, to protect the information it stores,
therefore, DNA sits in the nucleus and does not allow other materials to come in and it
does not leave so that the DNA is not damaged or changed in any way. RNA has the
function of using this code to actually make the protein that the gene from the DNA tells
it to make. There are three types of RNA that work together to accomplish this goal.
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DNA and RNA have three basic structural differences, these structural changes
come about because RNA has to travel outside the nucleus and therefore needs to
become more stable to withstand those changes. The first is that DNA has two strands,
it is double-stranded, while RNA only has one strand, so it is called single-stranded.
Next, DNA has a deoxyribose sugar, while RNA has a ribose sugar. Finally, DNA has the
nitrogen base thymine. RNA cannot have that base because it is not stable enough to
go outside the nucleus, therefore it is changed slightly on RNA to become the nitrogen
base we call Uracil.
What are the three types of RNA and what do they do?
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The three types of RNA are mRNA, rRNA, and tRNA.
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mRNA is called messenger RNA and it brings the message from the DNA out into
the cytoplasm to a ribosome so the gene can be made into a protein.
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rRNA is ribosomal RNA, and it works at the ribosome checking to make sure the
animo acids are the correct amino acid for the codons that the mRNA has in the
message. Codons are a set of three nucleotides that code for a particular amino acids
and codons are in the mRNA.
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tRNA is transfer RNA and it is the RNA that delivers the amino acid to the
ribosome for the building of the protein. tRNA has an anticodon which is opposite of the
codon on mRNA, if the opposite letters can bind then the rRNA is sure that the amino
acid attached to the anticodon is the correct amino acid.
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Together all of these three types of RNA work together to build a protein from the
gene found in the DNA.
Explain transcription and translation. What are the steps? Why is this also called protein
synthesis or gene expression? Use all of the following terms: tRNA, rRNA, ribosome,
mRNA, DNA, gene, protein, nitrogen base, nucleotide, uracil, ribose, single-stranded,
double-stranded, nucleus, peptide bond, and amino acids.
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Transcription and translation are two steps in protein synthesis. The first step you
have all the pieces needed to make mRNA enter the nucleus with the DNA, which is
made out of nucleotides. The cell needs to make a specific protein so the DNA finds the
gene that has the code for that protein. DNA is double stranded so it splits open and
allows the mRNA to start making a copy of the gene. The mRNA just copies the gene by
using the code and finding the corresponding nitrogen base (Aʼs go with Tʼs and Cʼs go
with Gʼs). However, RNA cannot have the nitrogen base thymine, so in RNA, where
there would be a Thymine, it is now switched to a Uracil (U). Another difference is that
RNA has a ribose sugar and is only single stranded. Once the mRNA is made it leaves
the nucleus and goes into the cytoplasm and finds a ribosome. The ribosome is the
organelle that assembles proteins and ribosome has little rRNA molecules inside it that
work to read the code from the mRNA and assemble the protein. The mRNA is read by
using things called codons, which is a set of three nitrogen bases that code for a
specific amino acid. Once the rRNA figures out which amino acid it needs, it sends the
tRNA to go get that amino acid and bring it to the protein to be attached to the other
amino acids through a peptide bond. Once all the gene has been read through codons
and put into a protein, the mRNA has a stop codon which tells the cell the protein is
finished and the job is now complete.
What are the different types of mutations, what does each one do to the DNA? Which
one is the most severe? Least severe?
Point mutation: one nitrogen base or base pair is changed. It could change the amino
acid that it codes for. This is typically the least severe kind of mutation.
Frameshift mutation: this is when an insertion or deletion causes a shift in how you read
the codons. This typically results in a malfunctioning gene or protein.
Chromosomal mutations: this is when pieces or an entire chromosome has been added
or deleted to your karyotype. This is typically the most severe because we are now
dealing with multiple genes that are affected as opposed to just one gene/protein that is
affected.
Using this DNA sequence give me the following information:
A) Complimentary DNA Sequence
B) mRNA Sequence
C) Amino Acid Sequence (Gene/protein this codes for)
AA G C C TA C G AAT T C C C AT T G G C G C AAT TA G G G C T TAT T G C TA
A)
T T C G G AT G C T TAA G G G TAA C C G C G T TAAT C C C G AATAA C G AT
B)
U U C G G A U G C U U A A G G G U A A C C G C G U U A A U C C C GA A U A A C G
AU
C)
U U C G G A U G C U U AA G G G U AA C C G C G U U AA U C C C G AA U AA C G
AU
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