1. DNA, RNA Replication, Transcription, Translation

2. What is DNA? Deoxyribonucleic acid Subunits: nucleotides
Contains: genetic code
Structure: double helix.

3. NUCLEOTIDES - the subunits of DNA
Parts of a nucleotide:
Phosphate group
Sugar (ribose or deoxyribose)
Nitrogen base

4. DNA’4 Nitrogen Bases Adenine (A) Thymine (T) Guanine (G) Cytosine (C)
Thymine and Cytosine are PYRIMIDINES
(one-ring base)
Adenine and Guanine are PURINES
(two-ring bases)

5. BASE PAIRING RULES: A binds with T G binds with C
There are 3 hydrogen bonds holding G and C together
There are 2 hydrogen bonds holding A and T together.

6. DNA STRUCTURE: DOUBLE HELIX
DNA is like a twisted ladder
Rails of the ladder: alternating deoxyribose and phosphate.
Rungs of the ladder: base pairs (cytosine–guanine or thymine– adenine)

7. 3-D Animation of DNA
DNA Video

8. Stop & Review What is the smallest subunit of DNA? List 3 parts to #1?
What are the side chains of DNA made of?
What are the “rungs” of DNA made of?
What are the base pairing rules of DNA?
Describe the structure of DNA in 2 words.

9. ANSWERS Nucleotide Sugar, phosphate and a nitrogen base
Sugar and phosphate
Nitrogen base
A-T, C-G
Double Helix

10. Comparing eukaryote & prokaryote DNA
Circular
Linear

11. How are genes, chromosomes and DNA related?
Genes: portions of DNA that code for proteins.
DNA: Contains the genetic code, tightly packed into chromosomes

12. How are genes, chromosomes and DNA related?
Think of chromosomes as socks and genes as stripes on the socks.

13. Place in order from smallest to largest.
1. Chromosomes
2. Genes
3. DNA
Smallest to Largest:
Genes -> DNA -> Chromosomes

14. DNA RNA There are THREE main differences between DNA & RNA NAME
Deoxyribonucleic acid
Ribonucleic acid
SUGAR
Deoxyribose
ribose
NO. OF STRANDS
double
single
NITROGEN BASES
A,T,G,C
A,U,G,C (U = Uracil)
NITROGEN BASE PAIRS
A – T
G – C
A – U
G - C
TRANSPORT IN AND OUT OF NUCLEUS
Stays in nucleus
Goes in and out of nucleus
CONTAINS A CHEMICAL MESSAGE OR CODE
Yes
yes

16. Semi-conservative replication
Part 2

17. DNA Replication Duplication of DNA: DNA copies itself!
Happens during the S-phase of Interphase, before cell division.

18. “Semi-Conservative” Replication
results in 2 new DNA molecules
“Semi-Conservative Replication: Each “new” DNA molecule will contain an “original” DNA strand and a “new” DNA strand, made of added free nucleotides.

19. The Process of Replication
STEP 1:
Enzyme HELICASE unwinds DNA at “replication fork” by breaking hydrogen bonds between two complementary strands of DNA
(It “unzips” the helix)
“Antiparallel”:
DNA strands run
in opposite directions: ”
3’to 5’ and 5’to 3’.

20. RNA primase adds a RNA primer to free 3’ end
STEP 2:
RNA primase adds a RNA primer to free 3’ end
The direction of synthesis is from 5’ to 3’.
Base Pairing Animation

21. STEP 3:
DNA Polymerase attaches to Primer and adds new nucleotides to 3’ end of a growing DNA chain, following base-pair rules:
Adenine - Thymine
Guanine – Cytosine
Forms the LEADING STRAND,
Made continuously from primer.
helicase
polymerase
Leading strand
primer 3”

22. DNA Polymerase can only add new nucleotides to a 3’ end!
Lagging Strand (5’ to 3’): made discontinuously on opposite DNA strand, near replication fork.
DNA Polymerase can only add new nucleotides to a 3’ end!
Contains Okazaki fragments: “pieces of DNA”, later mended by enzyme LIGASE to form new DNA strand
Replication animation 5” 3”
helicase
primer
Lagging
strand
polymerase
Leading 3” 5” 5” 3”

23. Replication fork

24. Protein synthesis

25. Warm-Up Quiz: DNA 101
DNA is a double stranded sequence of ___________ (smallest unit of DNA).
DNA is a code of instructions for building ___________ (molecule).
DNA is stored in the _________ (control center of the cell).
The DNA code must be transmitted to the ___________ where proteins are built. Today we’ll see how this happens.

26. The role of DNA is to store and transmit genetic information
DNA RNA PROTEINS PHENOTYPE YOU

27. What is RNA?? RNA, like DNA, is made up of nucleotides
However, there are 3 differences between DNA and RNA:
RNA has ribose instead of deoxyribose
RNA has uracil instead of thymine
RNA is single-stranded instead of double- stranded

29. How do DNA & RNA compare? Deoxyribose sugar & phosphate “backbone”
N-bases: A, C, G, T
Double helix
RNA
Ribose sugar & phosphate “backbone”
URACIL replaces thymine
Single-stranded, globular, hairpin (huh? Hairpin???)

30. Warm-up
What’s the difference between RNA and DNA?

31. mRNA is written in the form of codons.
Types of RNA
Messenger RNA (mRNA)
The original DNA code is transcribed then carried from the nucleus to the ribosome.
mRNA is written in the form of codons.

32. Transfer RNA (tRNA) Types of RNA
The anticodon that matches the codon found on mRNA.
It transfers an amino acid in order to assemble a protein chain.

33. RNA & proteins that make up ribosomes where proteins are made.
Types of RNA
RibosomalR NA (rRNA)
RNA & proteins that make up ribosomes where proteins are made.

34. Base Pairing in DNA vs. RNA
A - T
C - G
RNA
A - Uracil
C - G

35. Check your understanding… Decide with your partner whether the following describes DNA or RNA or Both:
Involves Uracil
Single-stranded
Double-stranded
Involves codons
Polymerase
Master Plan
Blueprint copy
Stays in nucleus
Goes to ribosome
Involves Thymine

36. Step 1 Transcription Step 2 Translation
PROTEIN SYNTHESIS
Step 1 Transcription Step 2 Translation

37. Why? Because mRNA can leave the nucleus whereas DNA cannot.
Step 1: TRANSCRIPTION
DNA is transcribed to create a strand of nucleic acid called RNA (ribonucleic acid)
The RNA codes are “read” 3 nucleotides at a time called a codon
Occurs in the nucleus
Why? Because mRNA can leave the nucleus whereas DNA cannot.

38. TRANSCRIPTION Enzymes unzip helix
RNA polymerase assembles mRNA nucleotides but base pairing rules changes slightly
Thymine in DNA pairs with Adenine
Adenine in DNA pairs with Uracil
Cytosine still pairs with Guanine

39. T - - A - - C - - G - - DNA A T G C U A C G mRNA - - A - - T - - G
Step 1: Helicase enzyme “unzips” double helix by weakening H-bonds
T - - A - - C - - G - - DNA A T G C U A C G
mRNA
- - A
- - T
- - G
- - C
Write the complementary codon sequence.
Slide 
Copy the following DNA sequence.
Write the complementary nucleotide sequence.
Step 2: RNA polymerase enzyme forms complementary mRNA strand

40. Step 2: TRANSLATION
The language of DNA is translated into the language of amino acids
Occurs in the cytoplasm on a ribosome

41. TRANSLATION The mRNA travels to the ribosome where each codon is read
The codon of mRNA matches an anticodon on tRNA
When the codon and anticodon match the amino acid being carried by the tRNA is transferred to a growing protein chain.

42. Let’s use your foldable from before.
A T G C DNA U A C G
mRNA
 Open the foldable and translate the mRNA code into the correct amino acid sequence.

44. The translation… A T G C
DNA U A C G
mRNA
Tyrosine
Lysine
Leucine
STOP

47. Protein Synthesis Animation

48. YOU NEED TO UNDERSTAND THIS!!!
DNA codes for RNA, which guides the synthesis of proteins.
DNA  RNA  Protein
DNA is unzipped
RNA polymerase uses DNA as a template for making mRNA (Uracil is incorporated instead of thymine)
mRNA moves out of nucleus to ribosome
tRNA carries amino acids to ribosome where they are assembled into a peptide chain
Upon reading a STOP codon, the complete protein chain is released

49. Now consider this… On a sheet of paper, write the word CATS.
Try rearranging the letters to form as many 3- letter words as you can.
Write each word on your paper, and then add a definition for each word.
Did any of the codes you formed have the same meaning?

50. Like CATS, there are only 4 nitrogen bases in the DNA alphabet.
Like the CATS activity, DNA “words” are only 3-letters. These triplet base sequences are called codons.

51. = 64 possible codon combinations.
BRAIN TEASER
How many codons can be made using the four letters of the four different bases?
Hint:
A codon is made up of 3 nucleotides.
So there are 3 spots and a possibility of 4 bases in each.
4 bases x 4 bases x 4 bases
= 64 possible codon combinations.
Since the nitrogen base is the only unit to change, the sequence of bases makes up the code.

52. How is DNA like Morse code?

54. How is DNA like Morse code?
It is a series of single repeating units (sounds or symbols) that make up a message. The repeating units are the nucleotides of the DNA molecule. The message is the final protein that is produced. Proteins can be structural, enzymatic, hormones, etc.