1. WARM-UP If the DNA sequence is --- AAA TAT CCG TAG CAA ATG
Write the mRNA sequence, tRNA anticodon sequence, and the six amino acids.
DNA: AAA TAT CCG TAG CAA ATG
mRNA:
tRNA:
Amino acids:

2. Review Chromosomes v. Genes v. DNA
Chromosomes contain genetic information
Genes are sections of chromosomes
Segments of genes are called DNA

3. DNA and RNA are examples of what major macromolecule?
Nucleic Acids
What are the other
3 macromolecules?
-Lipids
-Carbohydrates
-Proteins

4. What does DNA stand for? Deoxy-ribo-nucleic acid
DNA is often called the blueprint of life
DNA contains the instructions for what traits (eye/hair color, etc.)
are inherited from
generation to generation
Where is it found? Nucleus

5. DNA Structure Composed of sub-units called Nucleotides
Nucleotides can be broken down into 3 parts
1. Phosphate Group
2. Deoxyribose Sugar (5 carbon sugar)
3. Nitrogenous Base
Cytosine (C)
Guanine (G)
Adenine (A)
Thymine (T)
1. Phosphate
The four nitrogenous bases are abbreviated with the first letter of their names.
Structure of nucleotides
Phosphate group
5-Carbon sugar
Nitrogenous base
3. Nitrogenous Base
(A, T, G, C)
2. Deoxyribose Sugar

6. The Shape of DNA The basic shape is like a twisted ladder or zipper.
This is called a double helix, which means it is double stranded
Nitrogenous
Base (C,G, A or T)
“Rungs of ladder”
“Legs of ladder”
Phosphate &
Sugar Backbone

7. One Strand of DNA One strand of DNA is a polymer of nucleotides.
One strand of DNA has many millions of nucleotides.
phosphate
deoxyribose
{Point to the 3-D mode, if you have one, to show the parts as you discuss them.}
bases

8. Nucleotides
O -P O O
One deoxyribose together with its phosphate and base make a nucleotide.
O -P O O
Nitrogenous
base C O
Phosphate
{Ask students where they have seen a similar molecule before in this class.
Answer: ATP Emphasize that nucleotides are the basic building blocks or units of a DNA molecule and that a single molecule has many millions of nucleotides.} C C C
Deoxyribose O

9. DNA P O 1 2 3 4 5 P O 1 2 3 4 5 G C T A

10. Double Stranded DNA Remember, DNA has 2 strands that fit
together like a zipper.
The teeth are the nitrogenous bases but why do they stick together?

11. Chargaff’s Rule
They stick together because of hydrogen bonds of the nitrogenous bases
Adenine always pairs with Thymine
A T
Cytosine always pairs with Guanine
C G T A G C

12. DNA by the Numbers Each cell has about 2 m of DNA.
The average human has 75 trillion cells.
The average human has enough DNA to go from the earth to the sun more than 400 times.
DNA has a diameter of only m.
The earth is 150 billion m
or 93 million miles from
the sun.
If you unravel all the DNA in the chromosomes of one of your cells, it would stretch out 2 meters. If you did this to the DNA in all your cells, it would stretch from here to sun more than 400 hundred times!

13. What about RNA? Stands for: Ribo-nucleic acid
Structure similar to DNA but different
Nucleotides divided into 3 parts
1. Phosphate Group
2. Ribose Sugar
3. Nitrogenous Base
Adenine (A)
Uracil (U) (Replaces Thymine)
Guanine (G)
Cytosine (C)
Single stranded

14. How are DNA and RNA related?
DNA codes for RNA, which guides protein synthesis
The reading and expression of genes is from DNA to RNA to protein
DNA -> RNA -> Protein = Central Dogma of Biology

15. DNA Structure
Rosalind Franklin took diffraction x-ray photographs of DNA crystals
In the 1950’s, Watson & Crick built the first model of DNA using Franklin’s x-rays

16. DNA Nucleotide O=P-O O N CH2 O C1 C4 C3 C2 Phosphate Group O
Nitrogenous base
(A, G, C, or T) O
CH2 O C1 C4 C3 C2 5
Sugar
(deoxyribose)

17. Pentose Sugar Carbons are numbered clockwise 1’ to 5’ CH2 O C1 C4 C3
(deoxyribose)

18. Antiparallel Strands One strand of DNA goes from 5’ to 3’ (sugars)
The other strand is opposite in direction going 3’ to 5’ (sugars)

19. Nitrogenous Bases Double ring PURINES Adenine (A) Guanine (G)
Single ring PYRIMIDINES
Thymine (T)
Cytosine (C)
A or G
T or C

20. Base-Pairings Purines only pair with Pyrimidines
Three hydrogen bonds required to bond Guanine & Cytosine C G
3 H-bonds

21. Two hydrogen bonds are required to bond Adenine & Thymine

22. DNA Replication

23. 3 Questions about DNA Replication
What is DNA Replication? the process where DNA make a copy of itself
Why does DNA need to copy? Simple: Cells divide for an organism to grow or reproduce, every new cell needs a copy of its DNA or instructions to know how to be a cell.

24. 3 Questions about DNA Replication
3. When does DNA replication occur?
It occurs right before the cell divides
During the S Phase of interphase of the cell cycle

25. Synthesis Phase (S phase)
S Phase during interphase of the cell cycle
Mitosis
-prophase
-metaphase
-anaphase
-telophase G1 G2 S
phase
interphase
DNA replication takes
place in the S phase.

26. DNA Replication is Semiconservative
The two strands of the parental molecule separate, and each acts as a template for a new complementary strand
In other words: when DNA makes a copy, one half of the OLD strand is always kept in the NEW strand.
This helps reduce the number of COPY errors.
New DNA consists of 1 PARENTAL (original) and 1 NEW strand of DNA
DNA Template
New DNA
Parental DNA

27. Semiconservative Replication

28. Question: DNA 5’-CGTATG-3’
What would be the complementary DNA strand for the following DNA sequence?
DNA 5’-CGTATG-3’

29. Answer:
DNA 5’-GCGTATG-3’
DNA 3’-CGCATAC-5’

31. 1. What is the complimentary mRNA sequence to DNA sequence
A-T-T-G-C-A?
T-A-A-C-G-T C. U-A-A-C-G-T
U-A-A-C-G-U D. T-A-A-G-C-U
2. What causes the two sides of the double helix of DNA to stay joined together?
joining of phosphate molecules C. joining of base pairs
joining of sugar molecules D. joining of RNA
3. What the three main parts of a nucleotide of DNA? (Choose all that Apply)
phosphate group C. deoxyribose sugar
ribose sugar D. nitrogenous base
4. The process whereby DNA unzips and makes a strand of mRNA is called?
replication C. translation
transcription D. complementation
5. When does DNA replication occur?
During transcription C. During translation
During mitosis D. During the S phase of interphase
6. Determine the amino acids sequence from this mRNA sequence:
AUG CCC GGA UUA UAG (Use amino acid chart on board)
Met Pro Gly Leu Stop C. Met Leu Pro Gly Stop
Stop Leu Pro Gly Met D. Met Pro Cys Gly Stop

32. Lesson Closure 3 things you learned in class today
2 questions you have about the lesson
1 real-life connection

33. MIND MAPS Create a map using all of the following terms Be sure to link them together
DNA RNA
Nucleotide Thymine
Transcription chromosome
Translation nucleic acid
Uracil deoxyribose sugar
Ribose sugar mRNA
Amino acid Unzipping
Nucleus Protein
Double Helix