1. Briefly describe the steps of DNA Replication.
Agenda
Replication Math
Transcription: Making RNA

3. DNA Info DNA never ever leaves the nucleus
DNA is the master copy of the directions a cell needs to live so it needs to be protected
DNA in the nucleus is safe
But DNA in the cytoplasm can be destroyed

4. RNA
RNA is a copy of DNA that goes out into the cytoplasm to tell the cell what to do in order to stay alive
RNA: ribonucleic acid
RNA is similar to DNA
Sugar is ribose not deoxyribose
Nitrogen Base thymine is replaced with Uracil
Single stranded

5. RNA DNA RNA How many strands? 2 1 Nucleotide subunit Bases Thymine (T)
Adenine (A)
Guanine (G)
Cytosine (C)
Uracil (U)
Phos-phate Group
Deoxyribose
Sugar
Nitro- gen
Base
Phos-phate Group
Ribose Sugar
Nitro- gen
Base
U – A
G – C
T – A
G – C

6. 3 types of RNA Messenger RNA (mRNA) – complementary to DNA
C=G, A=U
Travel from nucleus to ribosome
Direct synthesis of protein
Ribosomal RNA (rRNA) – associates with proteins to form ribosomes
Transfer RNA (tRNA) – transport amino acids to ribosome

8. Transcription RNA is made from 1 gene in DNA
Specifically mRNA (messenger RNA) because it sends a message from DNA to the cytoplasm
DNA safe in the nucleus
To send a message to the cytoplasm
Uses mRNA

9. Transcription Unzip DNA RNA Polymerase binds to synthesize RNA
Match up bases to one side of a gene in DNA in the 5’ to 3’ direction (adds to 3’ end)
Use Uracil instead of thymine
mRNA detaches from the DNA
mRNA moves out of the nucleus and into the cytoplasm

10. Transcription happens in the nucleus. An RNA copy of a gene is made.
Then the mRNA that has been made moves out of the nucleus into the cytoplasm
Once in the cytoplasm, the mRNA is used to make a protein
Cytoplasm of cell
Nucleus
DNA
mRNA

12. Transcribe your DNA (get your paper from replicating DNA)
1. Does the mRNA model more closely resemble the DNA strand from which it was transcribed or the complementary strand that wasn’t used? Explain 2. Explain how the structure of DNA enables the molecule to be easily transcribed. Whys is this important for genetic information? 3. Whys is RNA important to the cell? How does an mRNA molecule carry information from DNA? 4. If DNA strand read AAC GTC GCG TAC, what would the mRNA strand be?

13. Briefly describe transcription.
Agenda
Finish Transcribing DNA
Translation

14. A little more about RNA RNA is shorter than DNA
DNA is interrupted by short sequences that are not in the final mRNA
These are called introns
Sequences that are kept in the final mRNA sequence are called exons

16. Translation

17. The Code 20 amino acids (AA) used to make proteins
DNA provides at least 20 different codes
If each base coded for an AA then we could only get 4 AA
If a pair of bases coded for an AA then we could get 16 (4x4)
If 3 bases coded for an AA then we could get 64 (4x4x4)

18. The Code We find that every 3 bases codes for an amino acid sequence
Some amino acids are repeated
Three base code is called a codon
All but 3 codons code for an amino acid
A chart was made to show each AA that DNA/mRNA codes for

20. Translation mRNA is synthesized and moves to the ribosomes
Located on the Rough ER
mRNA then attaches to the ribosome
tRNA interprets the mRNA codon sequence and brings the appropriate amino acid
Several amino acids make proteins
Continues until a stop codon is reached (3)

21. tRNA 3 base sequence at the bottom – anticodon
Matches the codon on the mRNA strand

22. Ribosome 2 subunits – only together during translation
Attach the to mRNA strand
3 grooves, E site, P site, and A site
Each groove holds a tRNA
E site – exit
P site – add amino acid to polypeptide chain
A site – new tRNA arrives

24. Translate your DNA Questions Write your Amino Acid Sequence
Would you make a complete protein? Explain.
Transcribe the following DNA sequence into mRNA. Draw a line separating each codon:
A T C G T C C A A A ….

25. Briefly describe translation
Agenda for Thursday Nov 4th
Review Replication, transcription, and translation
Practice

26. Replication DNA Helicase unzips DNA Primers bind to DNA strands
Proteins bind to keep it apart
Primers bind to DNA strands
DNA Polymerase adds nucleotides to DNA
Leading – continuous adding of bases
Lagging – Okazaki fragments
DNA Ligase fills in gaps

27. Transcription DNA Helicase unzips DNA
RNA Polymerase adds bases to the template strand of DNA
Only 1 strand of DNA gets copied
RNA detaches from DNA strand
RNA moves into cytoplasm

28. Translation mRNA attaches to ribosomes tRNA moves into ribosome
Anitcodon matches with mRNA strand and adds and amino acid
tRNA leaves ribosome
Stop codon is reached the amino acid chain (polypeptide) detaches from ribosome
Folds and creates a protein

29. DNA vs. RNA DNA RNA 2 Strands 1 Strand Deoxyribose sugar Ribose Sugar
A-T
C-G
A-U

32. How is RNA different from DNA
Agenda for Friday Nov. 5th
Quiz
Practice with transcription and translation

33. Which RNA gets translated (mRNA, tRNA, rRNA)?
Agenda for Monday Nov 8th
Replication, transcription, translation (one last time)
Questions 2 and 3 on page 335
Questions 1 – 4 on page 341
Practice
Gene Regulation