1. The Structure of DNA and RNA
All life on earth uses a chemical called DNA to carry its genetic code or blueprint. In this lesson we be examining the structure of this unique molecule.
{Point out the alligator’s eyes in the first picture.} By the way, can you make out what this is?
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[The goal of this presentation is to introduce high school biology students to the chemical structure of DNA. It is meant to be presented in the classroom while accompanying the teacher’s lecture, under the control of the teacher.]

2. What is genetics and Why do we study it?
Genetics is the study of heredity and the variation of inherited characteristics.
Reasons to study genetics:
its central importance to all life on Earth,
medical benefits such as cures for diseases,
better food crops.
About better food crops, this area is controversial. There is a Dr. Charles Arntzen who is working on bioengineering foods with vaccines in them. People in poor countries could be immunized against diseases just by eating a banana, for instance.

3. There are 2 types of nucleic acids
-DNA
-RNA

4. DNA DNA is often called the blueprint of life.
In simple terms, DNA contains the instructions for making proteins within the cell. (Proteins made by ribosomes!)
Why is DNA called the blueprint of life?
Remember all cells have ribosomes even bacteria

5. RNA present in all living cells
Its role is to act as a messenger carrying instructions from DNA for controlling the synthesis of proteins

6. What are nucleic acids made of?
Nucleic acids (a macromolecule) are made up of long chains of monomers called nucleotides
Each nucleotide is made up of 3 parts
a phosphate group (PO4)
a sugar (deoxyribose or ribose)
a nitrogenous base (GCAT or U)

7. bond bond P base Sugar Nucleotides
A phosphate group bonded to one of the 2 sugars
that is bonded to one of the nitrogenous bases
DRAW THE NUCLEOTIDE
bond
bond
base P
phosphate
Sugar
It is the phosphate group which gives DNA its acidic properties

8. The different sugars Ribose (RNA) is a 5 carbon ring sugar (C5H10O5 )
Deoxyribose (DNA) is also a 5 carbon sugar, but
lacks one oxygen atom C5H10O4
monosaccharide sugars have C:H:O ratio of 1:2:1
sugars typically end in -ose

9. Quick check What are the 2 types of nucleic acids?
What are nucleic acids made of?
What are the 3 parts of a nucleotide??
What are the 2 types of sugars?

10. Our genes are on our chromosomes.
Where is DNA found?
Our genes are on our chromosomes.
floats in the cytoplasm of all prokaryotic cells
{Ask students where the chromosomes are in this picture. Or ask them where the DNA is. Remind them that the mitochondria also have DNA.}

11. The Shape of the Molecule
DNA is a very long polymer.
The basic shape is like a twisted ladder or zipper.
This is called a double helix.
{Show students a model of the double helix. Explain what a spiral is and a helix is.}

12. One Strand of DNA
nucleotide
One strand of DNA is a polymer (multitude) of nucleotides.
The backbone of the molecule is alternating phosphates and deoxyribose sugar
The teeth are nitrogenous bases.

13. Remeber Each DNA nucleotide is made up of…3
Remeber Each DNA nucleotide is made up of…
a phosphate
group
a sugar
deoxyribose
A nitrogenous base
G or C or A or T
base
PO4

14. The nitrogenous bases of DNA and RNA are5
The nitrogenous bases of DNA and RNA are
Guanine G
Cytosine C
Adenine A
Thymine
(DNA only) T
Uracil
(RNA only) U

15. The bases always pair up in the same way10
The bases always pair up in the same way
Guanine always bonds with Cytosine and C with G
Cytosine
Guanine
Adenine forms a bond with Thymine and T with A
Adenine
Thymine
23 seconds
Remember: Gangster CAT has DNA
Soulja Boy likes RNA…why??

16. Quick check
What are the 2 sugars found in nucleic acids?
How many nucleotide bases are there?
Name one possible base.
Which base is only found in DNA? RNA?

17. Chargraff’s Rule: Adenine and Thymine always join together
Cytosine and Guanine always join together

18. What conclusions can you make?
Chargaff’s Rule
What conclusions can you make?
Organism %A %T %G %C
Mycobacterium tuberculosis
15.1
14.6
34.9
35.4
Yeast
31.3
32.9
18.7
17.1
Wheat
27.3
27.1
22.7
22.8
Sea Urchin
32.8
32.1
17.7
17.3
Marine Crab
47.3
2.7
Turtle
29.7
27.9
22.0
21.3
Rat
28.6
28.4
21.4
21.5
Human
30.9
29.4
19.9
19.8

19. Over View of DNA vs. RNA RNA DNA
Made of nucleotide subunits chained together
Single strand of nucleotides
Double strand of nucleotides
5 carbon sugar, ribose
5 carbon sugar, deoxyribose
Nucleotide bases G, C, A, U (uracil)
Nucleotide bases G, C, A, T (thymine)

20. Go to next blank ION page. Turn it sideways
Set up a double bubble map for DNA and RNA
DNA
RNA

21. Double Bubble
DNA
RNA

22. DNA Replication and Protein synthesis

23. DNA Review
Deoxyribonucleic Acid – composed of building blocks called nucleotides
Phosphate
Sugar (deoxyribose)
Nitrogen bases
Adenine – Thymine
Guanine – Cytosine
Right hand twist
Double stranded

24. Quick review Chromosomes: Tightly coiled strands of DNA
Each chromosome contains genes
Characteristics/traits passed down through generations
The genes on a chromosome produce proteins
This is how you see a trait!

25. What’s in a gene?
sequences of nucleotide bases; passed down from parent to offspring
These Genes code for polypeptides (proteins)
All cells require proteins to function, thus they have many genes!

26. More about Proteins!
Proteins are made of amino acids linked together by peptide bonds
20 different amino acids
exist
Amino acid chains are
called polypeptides

27. From DNA to Proteins The major steps: Replication of DNA
Transcribe to RNA
Translate to Protein
DNA is found in the nucleus of a cell
RNA and proteins are found outside of the nucleus
How does this happen?

28. Pathway to Making a Protein
DNA
mRNA
tRNA (ribosomes)
Protein

29. DNA  RNA  Protein Eukaryotic Cell DNA Pre-mRNA mRNA Ribosome Protein
Nuclear
membrane
Transcription
RNA Processing
Translation
DNA
Pre-mRNA
mRNA
Ribosome
Protein
Eukaryotic Cell

30. 16
Step 1: replication
process of producing two identical replicas from one original DNA molecule
First unzip
Next copy
Finally 2 identical strands

31. The strands separate 17
PO4
PO4

32. 18
Each strand builds up its partner by adding the appropriate nucleotides
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
The nucleotides are present in the nucleoplasm. The nuclear equivalent of cytoplasm
PO4
PO4
PO4
PO4
PO4

33. Review What is the copying of DNA into 2 strands called?
How much of the strand created is new material?

34. Steps 2 and 3 Protein synthesis 2 main steps
process by which the genetic code puts together proteins in the ribosomes
2 main steps
Transcription
Translation

35. Step 2: Transcription Double stranded DNA is unzipped
One side is the template (pattern) and the other builds the mRNA
mRNA= messenger RNA
Carries genetic info to ribosmes
This process happens in the nucleus

37. In-between Steps 2 and 3
Once the mRNA has been created it leaves the nucleus and heads to a ribosome

38. Step 3: Translation
Now the mRNA is in the cytoplasm traveling to the ribosome
Once there, it binds to a ribosome

39. The bases of the mRNA strand are read in sets of 3
Step 3: Translation
The bases of the mRNA strand are read in sets of 3
A set of three is known as a codon/triplet
Each codon will specify 1 of the 20 different amino acids

40. Step 3: Translation
Once bound to the ribosome tRNA reads the codons on mRNA and transports the
tRNA=transfer RNA
The anticodons are connected to a specific amino acid

41. Step 3: Translation
The ribosome connects the amino acids together into a chain called a polypeptide chain
Polypeptides chains are just amino acids linked together. This is what makes a protein!

43. POP QUIZ!!!!!!
Take out 1 sheet of paper
Write your name
Number 1-6

44. Question 1 Which of the following are components of nucleotides?
(a) deoxyribose
(b) amino acids
(c) phosphate
(d) enzymes
(e) organic bases

45. Question 2 Which of the following represent a correct
pairing of bases?
(a) adenine with thymine
(b) adenine with guanine
(c) thymine with adenine
(d) guanine with cytosine
(e) thymine with thymine

46. Question 3 DNA molecules are formed from (a) organic bases
(b) amino acids
(c) deoxyribose
(d) nucleotides

47. Question 4 Which of the following are nucleotide bases? (a) Valine
(b) Guanine
(c) Thymine
(d) Serine

48. Question 5 Replication of DNA occurs (a) During cell division
(b) before cell division
(c) at any time

49. Question 6 A codon/triplet codes for (a) a protein (b) an amino acid
(c) an enzyme
(d) an organic base