1. Central Dogma

2. Semiconservative Replication = each strand has 1 parent and 1 new strand

3. Replication DNA Helicase unzips DNA RNA Primers bind to DNA strands
DNA Polymerase adds nucleotides to DNA
Leading – continuous adding of bases
Lagging – Okazaki fragments
DNA Ligase fills in gaps

4. DNA Replication
Two strands open forming Replication Forks (Y-shaped region)
New strands grow at the forks
Replication
Fork
Parental DNA Molecule 3’ 5’

5. Unwinding DNA Helicase unwinds/unzips DNA strand
Hydrogen bonds are broken

6. Base Pairing Steps DNA Polymerase adds nucleotides
only adds to the 3’ end of the DNA
NEW strand is built in a 5’ to 3’ direction
Adds a 5’
Q: Will the strands be identical?
Parental DNA Molecule 3’ 5’

7. Leading Strand Replicated as the DNA unwinds
New nucleotides are added continuously

9. Lagging Strand Replicated away from replication fork
Create fragments - Okazaki Fragment
Fragments later connected

11. Joining
DNA Ligase – links two sections of DNA together

12. Replication DNA Helicase unzips DNA RNA Primers bind to DNA strands
DNA Polymerase adds nucleotides to DNA
Leading – continuous adding of bases
Lagging – Okazaki fragments
DNA Ligase fills in gaps

13. Prokaryote vs. Eukaryote
Prokaryotes
1 origin
Eukaryote
Many origins

15. DNA Info DNA in the nucleus is safe
But DNA in the cytoplasm can be destroyed

16. RNA – Ribonucleic Acid Copy of DNA that goes into cytoplasm DNA RNA
guides synthesis of proteins
DNA
RNA
# of strands
2 Strands
1 Strand
Type of Sugar
Deoxyribose sugar
Ribose Sugar
Nucleotide Base pairs
A-T
C-G
A-U

17. 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) –forms ribosomes
Transfer RNA (tRNA) – brings amino acids

19. Transcription RNA is made from 1 strand of DNA
Specifically mRNA is made
DNA safe in the nucleus
To send a message to the cytoplasm
Uses mRNA

20. Transcription Unzip DNA (helicase)
RNA Polymerase binds to synthesize RNA
Match up bases to one strand of DNA
Uracil instead of thymine
mRNA gets modified
mRNA moves out of nucleus and into cytoplasm

21. 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

23. A little more about RNA
DNA is interrupted by short sequences that are not in the final mRNA
Called introns
Exons = RNA kept in the final sequence

24. The Code Every 3 bases codes for amino acid sequence
Three base code is called a codon
All but 3 codons code for an amino acid
AUG = start codon

25. Anticodon - 3 base sequence at the bottom
Ribosomes
2 subunits – only together during translation
Attaches to mRNA strand
tRNA
Anticodon - 3 base sequence at the bottom
Matches the codon on mRNA strand

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

30. Proteins
Chains of amino acids fold into a specific 3-D shape to perform their biological function
Shape depends on interactions among amino acids
Hydrogen bonding

31. What would be the complementary DNA strand for the following DNA sequence?
Which direction (right to left or left to right)
DNA 5’-CGTATG-3’

32. Translate mRNA Write the Amino Acid Sequence for the following mRNA
UUG CAG CGC AUG
Would you make a complete protein? Explain.
Transcribe and translate the following DNA sequence. Draw a line separating each codon:
A T C G T C C A A

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

34. SWEET VID!!

35. Questions: put on a separate sheet of paper.
1. Replicate this strand of DNA: ATGCAGTCGATG TACGTCAGCTAC 2. If a DNA strand were to replicate, would they be the same or different? Why? 3. How does the structure of a DNA molecule help account for the great variety of life that exists on earth?

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