monster creation decoding dna triplets codes and codons
TRANSCRIPT
Monster Creation
• Decoding DNA
Triplets Codes and Codons
The most common organic bases are
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
The bases 5
A molecule of DNA is formed by millions of nucleotides joined together in a long chain
PO4
PO4
PO4
PO4
sugar-phosphate backbone
+ bases
Joined nucleotides 7
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
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2-stranded DNA 9
One strand bonds with another strand,creating the double-helix shape
Adenine forms a bond with Thymine
and Cytosine bonds with Guanine
Bonding 1 10
Adenine Thymine
Cytosine Guanine
PO4
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thymine
PO4
PO4
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adenine
cytosine
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guanine
Bonding 2 11
Before a cell divides, the DNA strands unwind and separate
Each strand makes a new partner by addingthe appropriate nucleotides
The result is that there are now two double-stranded DNA molecules in the nucleus
So that when the cell divides, each nucleus contains identical DNA
This process is called replication
replication 16
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The strands separate
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PO4
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PO4
Each strand builds up its partner by adding the appropriate nucleotides
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How your cell makes very important proteins
• 3 phases:
1. Transcription
2. RNA processing
3. Translation
• DNA RNA Protein
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RNA (ribonucleic acid)
3 forms of RNA– mRNA (messenger)– tRNA (transfer)– rRNA (ribosomal)
RNA is used to take the information in DNA and make proteins (gene expression)
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During gene expression, the info in DNA is first transcribed as mRNA (messenger RNA) and then translated via tRNA (transfer RNA) and used to build a protein.
The Big Idea…
– The DNA is transcribed into RNA, which is translated into the polypeptide
Figure 10.6A
DNA
RNA
Protein
TRANSCRIPTION
TRANSLATION
• The information constituting an organism’s genotype is carried in its sequence of bases
The Big Idea…
• In transcription, DNA helix unzips
– RNA nucleotides line up along one strand of DNA, following the base-pairing rules
– single-stranded messenger RNA peels away and DNA strands rejoin
Figure 10.9B
• The “words” of the DNA “language” are triplets of bases called codons– The codons in a gene specify the amino acid
sequence of a polypeptide
Translation of nucleic acids into amino acids
For example
Cytosine
Adenine Codes for Valine
Cytosine (C)
Guanine (G)
Adenine (A)
Codes for Alanine
Thymine
Coding 21
U C A G
U
C
A
G
GACU
GACU
GACU
GACU
UUUUUCUUAUUG
CUUCUCCUACUG
AUUAUCAUAAUG
GUUGUCGUAGUG
phe
leu
leu
ile
met (start)
val
UCUUCCUCAUCG
CCUCCCCCACCG
ACUACCACAACG
GCUGCCGCAGCG
ser
pro
thr
ala
UAUUACUAAUAG
CAUCACCAACAG
AAUAAC
AAGAAA
GAUGACGAAGAG
tyr
stopstop
his
gln
asn
lys
asp
glu
UGUUGCUGAUGG
CGUCGCCGACGG
AGUAGCAGAAGG
GGUGGCGGAGGG
cys
stoptrp
arg
ser
arg
gly
Firs
t B
ase
Third
Base
Second Base
Virtually all organisms share the same genetic code “unity of life”
When a sequence of triplets in the DNA molecule code for a complete protein, the sequence forms agene
There may be a thousand or more bases in one gene
Genes 24