1. Chapter 12-2 Chromosomes and DNA Replication

2. Remember? The DNA double helix is coiled up to make chromosomes.The DNA double helix is coiled up to make chromosomes. Chromosomes contain all the genetic information that makes an organism what it is.Chromosomes contain all the genetic information that makes an organism what it is.

3. 12-2 How long is DNA? The chromosome of the bacteria E. coli, which lives in your large intestine, has 4,639,221 base pairs. That’s over 4.6 million of these!

4. This means that if you counted 1 base pair per second, it would take you 54 days to count them all.

5. How is DNA organized into chromosomes? ? 12-2

6. 12-2

7. 12-2

8. Before a cell divides, it must copy its DNA. Remember ? So how is DNA copied (replicated)?

9. How is DNA copied (replicated)? The complementary strands of the DNA double helix allow it to be copied.The complementary strands of the DNA double helix allow it to be copied. Each strand can be used to make another strand because of the rules of base pairing.Each strand can be used to make another strand because of the rules of base pairing. Each strand of the double helix serves as a template, or model for the new strand.Each strand of the double helix serves as a template, or model for the new strand.

10. DNA Replication replication cbp-4122  Draw some form of this on the DNA Structure tab of your flip book. 

11. DNA Replication activity: www.phschool.comwww.phschool.com, find online textbook. Go to page 298. Click on

12. 12-3: RNA and Protein Synthesis We know that DNA is the genetic code and that it can copy itself. But how does the gene work? California content standards: Genetics 4 a,b,e; 5 a,b

13. Dude, we’re seriously low on burgers!!!!! NUCLEUS CYTOPLASM Burger Factory Messenger DNA Ribosome mRNA

14. RNA DNA message must first be copied to RNA RNA sugar is Ribose (vs. deoxyribose)RNA sugar is Ribose (vs. deoxyribose) RNA usually single-stranded (not double)RNA usually single-stranded (not double) RNA contains Uracil in place of ThymineRNA contains Uracil in place of Thymine RNA is similar to DNA, but has these differences: 12-3 DNA: A T C C G A A T C G RNA: U A G G C U U A G C

15. 1) Messenger RNA (mRNA)1) Messenger RNA (mRNA) 2) Ribosomal RNA (rRNA)2) Ribosomal RNA (rRNA) 3) Transfer RNA (tRNA)3) Transfer RNA (tRNA) 12-3 There are 3 types of RNA: These are all involved in making PROTEINS

16. 1. mRNA carries a copy of DNA instructions to the rest of the cell (a “messenger”)

17. 2. rRNA combined with protein makes a ribosome. This is where proteins are assembled. 12-3 Located in the cytoplasm

18. 3. tRNA transfers amino acids to the ribosome, based on the code in mRNA. Bases (just like DNA) Amino acid attaches here

19. Transfer RNA

20. Protein Synthesis 12-3 Remember: the genetic code is instructions for producing _________ ? Proteins

21. There are 2 steps in Protein Synthesis: 1. 2.

22. 1. Transcription (DNA strand transcribed) 2. Translation: Polypeptide assembled.

23. Step 1: transcription DNA code copied to messenger RNA. mRNA bases are complimentary to the DNA strand.DNA code copied to messenger RNA. mRNA bases are complimentary to the DNA strand. DNA:TCGCATA RNA: 12-3 Remember the base-pairing rules?

24. Checkpoint 1. The genetic code is a set of instructions or a “recipe” for the production of _________. 2. The first step in protein synthesis is ? 3. Which type of RNA is the DNA message copied to in the nucleus?

25. Each group of 3 bases on mRNA is a code “word.” Each “word” is called a codon and specifies an amino acid to be added to a polypeptide. 12-3

26. DNA strand : TACCCAATC Complementary mRNA strand: AUGGGUUAG CODONCODON CODON methionine (start) Glycine (stop) Polypeptide - - Amino Acids

27. How do you tell what amino acid a codon specifies? You use a codon table: 

28. 1st 3rd 2nd

29. Step 2: translation mRNA strand moves through nuclear pore into cytoplasm.mRNA strand moves through nuclear pore into cytoplasm. Here it joins up with the 2 other kinds of RNA: rRNA, tRNAHere it joins up with the 2 other kinds of RNA: rRNA, tRNA 12-3

30. Transfer RNA (tRNA) Holds amino acid to be added to growing polypeptide chain.Holds amino acid to be added to growing polypeptide chain. Each tRNA will pick up only 1 kind of amino acid.Each tRNA will pick up only 1 kind of amino acid. Anticodon loop is on bottom.Anticodon loop is on bottom. 12-3

31. Transfer RNA U C A Approximately 80 nucleotides long. This anticodon is complementary to codon on mRNA Amino acid attachment site

32. Translation

33. Put it all together

36. Recap

37. Gene 1 Gene 2 polypeptide 1 polypeptide 2 26-3

38. What is the DNA double helix composed of? What bases pair together? What is transcribed from the DNA strand? Where does this occur? What are the 3-base triplets on mRNA called? What is translation and where does it occur? What are the 3-base codes on tRNA called? What is the final outcome of all this?