1. GENE
EXPRESSION

2. What is DNA Replication?
DNA Replication – the process of creating copies of DNA molecules
Why is DNA Repliction SEMI CONSERVATIVE?
DNA Replication is SEMI-CONSERVATIVE (each strand of the original DNA molecule serves as a template for the two new DNA molecules)

3. One ring
Thymine and cytosine each have one ring

4. Two rings
Adenine and guanine each have two rings

5. Hydrogen Bonds
When making hydrogen bonds, a double ring always pairs with a single ring
A – T
C – G

6. DNA Replication = 3 steps
DNA Replication: Simplified
DNA Replication = 3 steps

7. DNA Replication = 3 steps
What are the 3 steps of DNA Replication?
DNA Replication = 3 steps
Unzip DNA
Add free nucleotides
Re-zip new strands to old strands

8. Enzymes Play an Important Role!
Many enzymes help DNA replicate
Enzymes are proteins
Enzyme #1 = helicase (unwinds DNA)

9. Enzymes Play an Important Role!
Many enzymes help DNA replicate
Enzymes are proteins
Enzyme #2 = DNA Polymerase (add new nucleotides, “proofreads” for mistakes

10. So...exactly HOW do we use our DNA?
Our DNA sequences serve as a code!
ACTGGGACTACCATTGA
We take this information and make RNA molecules, which help us to make proteins!

11. DNA Review: Try to fill in the blanks:
1. A nucleotide is made of three parts: ______________ , __________________, and one of the _______ pairs. 2. The nucleotides are combined together to create a __________ acid, and ______ is an example of this. 11

12. Review:
1. A nucleotide is made of three parts: DEOXYRIBOSE SUGAR__ , _PHOSPHATE_, and one of the __BASE _ pairs. 2. The nucleotides are combined together to create a _NUCLEIC_ acid, and _DNA_ is an example of this. 12

13. More about Nucleic Acids!
We’ve already learned about one important nucleic acid, DNA. Today, we’ll explore the second nucleic acid…
RNA!! 13

14. RNA NOTES

15. How is RNA different from DNA?
Three differences from DNA:
RNA = one strand (DNA = two strands)
RNA has the sugar ribose (DNA has the sugar deoxyribose)
RNA uses uracil [U] instead of thymine (DNA = A, T, G, C RNA = A, U, G, C )

16. DNA vs. RNA Deoxyribose Sugar Ribose Sugar
Double Stranded Single Stranded
(usually) (usually)
THYMINE base URACIL base
1 type of DNA 3 types of RNA
(mRNA, rRNA, tRNA)
Examples of Nucleic Acids
Made of Nucleotides
Code for Information

17. DNA
RNA

18. What are the 3 types of RNA?
Messenger RNA (mRNA) carries the genetic message
Transfer RNA (tRNA) transfers amino acids
Ribosomal RNA (rRNA) makes ribosomes

19. D N A
Transcription

20. What is Transcription? transcribe = “to copy”
The genetic code on DNA is copied to RNA in
the nucleus
Why does it happen in the nucleus?
Original DNA cannot pass through the nuclear membrane, so a smaller copy is made and transported

21. Where in the cell does transcription happen?
The nucleus!
Why does it happen in the nucleus?
Original DNA cannot pass through the nuclear membrane, so a smaller copy is made and transported

22. How does Transcription happen?
1. RNA polymerase unwinds DNA
2. RNA polymerase adds RNA nucleotides
(A  U, G  C)
3. mRNA is formed! DNA reforms a double helix

23. Transcription recap… RNA polymerase makes RNA using DNA sequence
RNA leaves the nucleus for the cytoplasm

24. Where does it go from there?
Translation
Where does it go from there?
Into the great beyond?

25. To a ribosome! (Floating in cytoplasm)

26. At this point you only knew ribosome's as little dots in the cell… now you will learn their big purpose!
Turning RNA into the proteins that make up your hair, skin, muscles, nails etc!

27. What is translation?
Ribosomes translate mRNA into an amino acid sequence
Amino acids form proteins

28. What is a Codon? How are codons used? Codons = 3 nucleotides in a row
Ribosome recognizes a codon on mRNA and matches to the aniticodon on tRNA
amino acid
anticodon
A C G

29. How do tRNA and anticodons work together?
Transfer RNA transfers amino acids from the cytoplasm to a ribosome
Anticodon = 3 nucleotides on one end of a tRNA
amino acid
anticodon
A C G
Anticodons base pair with complementary bases on mRNA

30. Codon triplets code for 1 of 20 amino acids
Codons
Codon triplets code for 1 of 20 amino acids

31. Codons
1 “start” codon
3 “stop” codons

32. Steps of Translation
mRNA attaches to ribosome
mRNA

33. Steps of Translation
2. tRNAs add amino acids based on how anticodons match to mRNA
mRNA

34. Steps of Translation
2. tRNAs add amino acids based on how anticodons match to mRNA
mRNA

35. Steps of Translation
2. tRNAs add amino acids based on how anticodons match to mRNA
mRNA

36. Steps of Translation
2. tRNAs add amino acids based on how anticodons match to mRNA
mRNA

37. Steps of Translation
2. tRNAs add amino acids based on how anticodons match to mRNA
mRNA

38. Steps of Translation
2. tRNAs add amino acids based on how anticodons match to mRNA
mRNA

39. Steps of Translation
2. tRNAs add amino acids based on how anticodons match to mRNA
mRNA

40. Steps of Translation
2. tRNAs add amino acids based on how anticodons match to mRNA
mRNA

41. Steps of Translation
2. tRNAs add amino acids based on how anticodons match to mRNA
mRNA

42. Steps of Translation
2. tRNAs add amino acids based on how anticodons match to mRNA

43. Steps of Translation 3. Protein is released from ribosomes!
Protein chain
Stop codon

44. Steps of Translation 3. Protein is released from ribosomes!
Protein chain

45. What process turns DNA into RNA?
Transcription!!

46. What process turns RNA into PROTEIN?
Translation!!

47. What do amino acids build?
Protein!!

48. Summary
DNA
(Transcription)
RNA
(Translation)
PROTEIN

49. Gene Expression Practice
DNA sequence: AAC TGA CTG ATT GCA TGC
What is the complementary DNA sequence?
What is the complementary RNA sequence?
What are the amino acids for this sequence? 2.
DNA sequence: TAG CAT TGG GCA TCA CGA
TTG ACT GAC TAA CGT ACG
UUG ACU GAC UAA CGU ACG
ATC GTA ACC CGT AGT GCT
AUC GUA ACC CGU AGU GCU

50. Determine the amino acids for this strand of mRNA:
EXIT QUIZ
Determine the amino acids for this strand of mRNA:
AUG GCA AGU UCU UGA
(Use genetic code table on page 186-Turtle or p. 526)
Met – Ala – Ser – Ser – STOP

51. Determine the amino acids for this strand of mRNA:
Practice
Determine the amino acids for this strand of mRNA:
UGU AGA GAU CUC UAA
Cys – Arg – Asp – Leu – STOP
(Use genetic code table on page 186-Turtle or p. 526)

52. Big Picture Gene Expression Short Essay
Take one of the gene expression pictures and staple or tape it to a piece of paper (you may also choose to draw this out).
Explain in your own words how DNA is used to make proteins including a brief description of DNA replication, transcription, and translation.