Download Nucleotides

http://www.math.fsu.edu/~quine/IntroMathBio_04/Proteins/myoglobin_geis.jpg
myoglobin
When DNA copies…..
• It copy's in a very specific order. It copies
5’-3’ from a 3’-5’ Template.
• That means the DNA strand is in the following
order…
DNA
• That means the DNA strand is in the following
order…
• That means the DNA strand is in the following
order…
• That means the DNA strand is in the following
order…
• That means the DNA strand is in the following
order…
• That means the DNA strand is in the following
order…
Double Helix
Nucleotides: basic molecule of
DNA
Pyrimidine
Nucleotides: basic molecule of
DNA
Purine
Pyrimidines and Purines
Made up of a
1. Sugar (5 carbon)
2. Phosphate group
3. Nitric Base
DNA Replication
• http://www.johnkyrk.com/DNAreplication.ht
ml
Differences between RNA and DNA
• RNA has only a SINGLE Strand (DNA is
Double Stranded)
• RNA contains ribose instead of
deoxyribose
• RNA polymerase can start the RNA
transcription without a primer
Differences between RNA and DNA
• RNA uses Uracil(U) instead of Thymine(T)
• More errors occur in an RNA copy than in DNA
copy of nucleotides (103 more than in DNA)
• FACT: DNA has a transcription error
approximately every 107 nucleotides. RNA has an
error approximately every 104 !
Differences between RNA and DNA
• WHY are there more errors in RNA
Transcription?
• One of several reasons is that in rare
instances Uracil can also bond with
Guanine
Is this a Bad thing?
• WHY are there more errors in RNA
Transcription?
• One of several reasons is that in rare
instance Uracil can also bond with
Guanine
• RNA is a temporary copy in Eukaryotes
Types of RNA
• mRNA= messenger RNA
• codes for a protein
Types of RNA
• tRNA= transfer RNA
• central to protein synthesis as adaptors
between mRNA and amino acids
Types of RNA
• rRNA= ribosomal RNA
• form the basic structure of the ribosome
and catalyze protein synthesis
• Transcription- the synthesis of RNA
under DNA (occurs in the nucleus)
• Translation- the actual synthesis of a
polypeptide coded for by the mRNA.
(changing the base sequence of the
mRNA molecule into a chain of amino
acids that form a polypeptide. For our
purposes a protein.)
An mRNA copy is
made from DNA in
the Nucleus
The DNA strand
from which the
mRNA is copied is
the
TEMPLATE
STRAND
The mRNA leaves
the nucleus and
enters a ribosome
(made up of rRNA)
tRNA collects a
specific amino
acids present in
the cell and brings
it to the ribosome
The anticodon of
the tRNA matches
up with its
counterpart codon
on the mRNA
When the mRNA &
the tRNA link up
the amino acid
detaches and is
connected to the
adjacent amino
acid
This chain of
amino acids is a
protein
(polypeptide)
rRNA
Ribosome
rRNA
mRNA
enters the
“A” site of
the ribosome
rRNA
When the first
codon reaches
the “P” site the
tRNA brings
down the amino
acid and links up
with the mRNA
rRNA
The “E” site is
where the amino
acid separates
form the tRNA
and links up to
adjacent amino
acids. This is
where the MRNA
and tRNA leave
the ribosome
ANTICODONS
•Anticodons specify
which amino acid a
tRNA collects
•The anticodon then
pairs up with its
corresponding codon
Anticodon
ANTICODONS
•So for example...
•The anticodon AGU
would pair with the
codon UCA.
Anticodon
•THEY ARE
OPPOSITES OF
EACH OTHER
So What's a codon?
Codon
• This basic unit of genetic code is 3
nucleotides long
• It specifies a specific amino acid
• Each codon only specifies 1 amino acid
(BUT…an amino acid may have several
different codons that code for it)
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THE END
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