1. DNA, RNA, and Protein Replication Transcription Translation

2. Semi-conservative Replication Occurs during S phase of cell cycle DNA unwinds, at replication fork, via helicase DNA polymerase makes 2 copies of DNA – Complementary base pairing: A=T, G=C A & G are purines; T & C are pyrimidines Purines are double rings; pyrimidines are single – Leading strand has continuous replication – Lagging strand done in Okazaki fragments DNA ligase joins fragments on lagging strand

3. Replication Forks & ORE

4. Prokaryotic Replication Prokaryotes have no internal membranes. They have 1 circular chromosome. Replication starts at 1 site. Two replication forks form; replication moves in opposite directions. Replication continues until forks meet & entire chromosome is copied.

5. http://www.wiley.com/college/pratt/0471393 878/student/animations/dna_replication/inde x.html

6. Making copies of DNA 5’TACCGACTTGATCATTTAGGTAGACATATT …3’ 3’ATGGCTGAACTAGTAAATCCATCTGTATAA …5’ DNA splits into leading (5’) & lagging (3’) strands Each strand does complementary base pairing. 5’TACCGACTTGATCATTTAGGTAGACATATT …3’ 3’ATGGCTGAACTAGTAAATCCATCTGTATAA …5’ and 3’ATGGCTGAACTAGTAAATCCATCTGTATAA…5’ 5’TACCGACTTGATCATTTAGGTAGACATATT …3’

7. Transcription Makes RNA copy of DNA via RNA polymerase Makes mRNA, tRNA, or rRNA RNA polymerase binds to DNA promoter DNA strands unwind & separate RNA polymerase adds free RNA nucleotides to complement 1 strand of DNA bases. G =C; C=G; T=A; A=U RNA polymerase releases DNA & new RNA when reaches a termination signal.

8. Transcription & Translation DNA:5’TACCGACTTGATCATTTAGGTAGACAT…3’ mRNA:AUGGCUGAACUAGUAAAUCCAUCUGUA… mRNA exits nucleus after processing cap & tail mRNA on ribosome is translated via tRNAs. tRNA anticodons pair with mRNA codons (UAA, UAG, UGA). Each tRNA carries a specific amino acid or a stop signal. Genetic code is maintained universally. mRNA: AUGGCUGAACUAGUAAAUCCAUCUGUA polypeptide: met-ala-glt-leu-val-ast-pro-ser-val-

9. Translation Involves all 3 types of RNA: mRNA, tRNA, rRNA Produces polypeptides which form proteins Peptide bonds link amino acids together There are 20 essential amino acids found in all living things. Some have modifications. Amino acids form 1 o, 2 o & 3 o protein structures – Structures are essential to protein function

10. Steps of Translation mRNA docks on ribosome. Its 1 st codon is AUG tRNA with met binds via its anticodon UAC. tRNA with its amino binds to 2 nd codon. Ribosome detaches met from 1 st tRNA. Peptide bond forms between met & 2 nd amino acid. First tRNA exits the ribosome & 3 rd tRNA enters. Elongation continues until reaches stop codon Ribosome separates from mRNA with last tRNA Translation machinery then translates same or new mRNA

11. Human Genome The entire gene sequence of human DNA 3.2 billion base pairs in our 23 chromosomes Use computers to analyze DNA sequences – Bioinformatics, a new field, compares these. Help predict loci of genes Don’t know yet what our 30,000 genes encode Field of proteomics links gene to protein made