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Key Points : 1) Double Helix 2) Sugar-phosphate backbone 3) Nucleotide Rungs 4) Hydrogen bonds.

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Presentation on theme: "Key Points : 1) Double Helix 2) Sugar-phosphate backbone 3) Nucleotide Rungs 4) Hydrogen bonds."— Presentation transcript:

1 http://members.aol.com/wayneheim/dna-w.jpg

2 Key Points : 1) Double Helix 2) Sugar-phosphate backbone 3) Nucleotide Rungs 4) Hydrogen bonds

3 Guanine Adenine Thymine Cytosine DNA Nucleotides:

4 Complementary Base Pairing: DNA GC AT

5 RNA: Ribonucleic Acid 1) Single stranded (usually) 2) Nucleotide Uracil replaces Thymine 3) Four species (for this course): 3.1) messenger RNA (mRNA) 3.2) ribosomal RNA (rRNA) 3.3) transfer RNA (tRNA) 3.4) “interfering” RNA (iRNA)

6 Complementary Base Pairing: RNA GC AU

7 Histone protein complex DNA (a) the nucleosome: DNA wraps around histone proteins. (b) solenoids: loop of nucleosomes. (c): solenoids form a loop. (d): idealized cross section of a chromosome: several solenoid loops. (e): portion of a chromosome without the protein scaffold. DNA Packaging:

8 http://users.ntua.gr/sofial/DNA.jpg

9 T G C A C G A T A T G T C G G A T C C T A A A T G C G C T A C A G C C T A G G A T T (a) DNA replication: strands separate T G C A C G A T A T G T C G G A T T A C G C G T A A T A T A T G C G C T A C A G C C A T T A C G C G T A A T A T (b) Synthesis of new, complementary strands. Replication “Stuff”

10 Terms Amino acid = basic building block of polypeptide chains. Polypeptide chain = series of linked amino acids. AKA peptide chain. Protein = one or more polypeptide chains, folded and taking on a 3 dimensional configuration. Enzyme = a type of protein that speeds up chemical reactions. Try Tyr PheSerPheSerArgAlaPhe Tyr

11 http:// www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPROTSYn.html Genetic Code (mRNA) 1) Triplet 2) Redundant 3) Universal

12 Five Steps in Protein Synthesis (PETAP): 1) Photocopying 2) Editing 3) Transportation 4) Assembly 5) Packaging

13 Five Steps in Protein Synthesis (PETAP): 1) Photocopying 2) Editing 3) Transportation 4) Assembly 5) Packaging = Transcription = Post-transcriptional modification = Transportation = Translation = Post-translational modification Common Sense TermsScientificese

14 I. Photocopying (Transcription) Definition: An RNA strand is synthesized from the DNA using complementary base pairing. Process: 1) “Transcription stuff” binds to a promoter region of the DNA. 2) An enzyme “slices” the DNA, making it single stranded. 3) Another enzyme (polymerase) synthesizes a strand of RNA using one of the DNA strands as a template.

15 DNA RNA transcript T G C A C G A U T T G G G A A C A C T A A A C U U G G U G A G A A C U U C Transcription “Stuff”

16 II. Editing (Post-transcriptional modification) Definition: Nonmessage segments in the newly synthesized RNA strand are edited out. Process: 1) Enzymes excise the introns (nonmessage segments) from the RNA strand. 2) Other enzymes splice together the exons (message segments) giving messenger RNA (mRNA).

17 exon 1intron 1exon 2intron 2exon 3 Punctuation marks Punctuation marks RNA transcript: exon 1intron 1exon 2intron 2exon 3 Editing: exon 1 Punctuation marks exon 2exon 3 Punctuation marks mRNA messemger RNA

18 III. Transportation (Transportation) Definition: mRNA is transported from the nucleus to the cytoplasm and attaches to a ribosome. Process: (same as the definition)

19 IV. Assembly (Translation) Definition: The mRNA codons are “read” and the corresponding amino acid is added to the polypeptide chain. Process: 1) A codon enters the “reading frame” of a ribosome. 3) The amino acid carried by the tRNA molecule is added to the polypeptide chain. 3) Steps 1 to 3 are repeated until all codons are “read.” 2) A transfer RNA (tRNA) molecule with the complementary anticodon binds to the codon of mRNA.

20 Trp CC A anticodon other RNA amino acid Transfer RNA (schematic) “bar code”

21

22 http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPROTSYn.html

23 http://tidepool.st.usm.edu/pix/protsynth.gif

24 Posttranslational Modification: ALWAYS HAPPENS Polypeptide Folding

25 Posttranslational Modification: Sometimes happens Folded polypeptide chains join (e.g., ALDH-2, hemoglobin) add a sugar add a fat

26 Posttranslational Modification: Protein Activation/Deactivation Phosphorylation (add a phoshate group) Acetylation (add an acetyl group) Alkylation (add a ethyl, methyl group) Ubiquitination (add the protein ubiquitin to an existing protein usually instructs the cellular machinery to degrade/destroy the protein)

27  2  1 GG AA    -like gene cluster on chromosome 11: 1020304050600 length in kilobases (kb): Blow up of Exon 1 of the  hemoglobin gene: GTGCACCTGACTCCTGAGGAGAAGTTGGCC..AGG Nucleotides: Val His Leu Thr Pro Glu Glu Lys Ser Ala.. Arg Amino Acids: ACATTG: Start trans- scription here Exon 1Exon 2Exon 3Intron 1Intron 2 Promoters: TATA CAAT ATG: Start Translation Here TAA: Stop Translation Here CATTGC: Stop trans- scription here Attach a tail of multiple adenines here Blow up of the  hemoglobin gene: 1 3031 104 105 146 CodonNumber:

28 5101520250 length in kilobases (kb):  -like gene cluster on chromosome 16:  1  2  1  2  1

29 Open window (A) and fly kite (B). String (C) lifts small door (D) allowing moths (E) to escape and eat red flannel shirt (F). As weight of shirt becomes less, shoe (G) steps on switch (H) which heats electric iron (I) and burns hole in pants (J). Smoke (K) enters hole in tree (L), smoking out opossum (M) which jumps into basket (N), pulling rope (O) and lifting cage (P), allowing woodpecker (Q) to chew wood from pencil (R), exposing lead. Emergency knife (S) is always handy in case opossum or the woodpecker gets sick and can't work.

30 The Self-Operating Napkin: As you raise spoon of soup (A) to your mouth it pulls string (B), thereby jerking ladle (C) which throws cracker (D) past parrot (E). Parrot jumps after cracker and perch (F) tilts, upsetting seeds (G) into pail (H). Extra weight in pail pulls cord (I), which opens and lights automatic cigar lighter (J), setting off sky-rocket (K) which causes sickle (L) to cut string (M) and allow pendulum with attached napkin to swing back and forth thereby wiping off your chin.


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