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 PO 4 sugar-phosphate backbone + bases Joined nucleotides 7

PO 4 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 AdenineThymine Cytosine Guanine

PO 4 thymine PO 4 adenine cytosine PO 4 guanine Bonding 2 11

Before a cell divides, the DNA strands unwind and separate Each strand makes a new partner by adding the 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

PO 4 The strands separate 17

PO 4 Each strand builds up its partner by adding the appropriate nucleotides 18

How your cell makes very important proteins 3 phases: 1.Transcription 2.RNA processing 3.Translation DNA  RNA  Protein

14 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)

15 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

UCAG U C A G G A C U G A C U G A C U G A C U UUUUUU UUCUUC UUAUUA UUGUUG CUUCUU CUCCUC CUACUA CUGCUG AUUAUU AUCAUC AUAAUA AUGAUG GUUGUU GUCGUC GUAGUA GUGGUG phe leu ile met (start) val UCUUCU UCCUCC UCAUCA UCGUCG CCUCCU CCCCCC CCACCA CCGCCG ACUACU ACCACC ACAACA ACGACG GCUGCU GCCGCC GCAGCA GCGGCG ser pro thr ala UAUUAU UACUAC UAAUAA UAGUAG CAUCAU CACCAC CAACAA CAGCAG AAUAAU AACAAC AAGAAG AAAAAA GAUGAU GACGAC GAAGAA GAGGAG tyr stop his gln asn lys asp glu UGUUGU UGCUGC UGAUGA UGGUGG CGUCGU CGCCGC CGACGA CGGCGG AGUAGU AGCAGC AGAAGA AGGAGG GGUGGU GGCGGC GGAGGA GGGGGG cys stop trp arg ser arg gly First Base 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 a gene There may be a thousand or more bases in one gene Genes 24