1. Life’s Instruction Manual or What Genes are Made Of
DNA
Life’s Instruction Manual or
What Genes are Made Of

2. What can DNA do?
1. Can replicate before cell division. Remember MEIOSIS and MITOSIS, chromosomes need to replicate before they divide
2. Can direct protein synthesis. It tells the RIBOSOME to make a protein.

3. Why is the DNA the genetic material
DNA doubles prior to cell division (mitosis)
DNA divides equally between daughter cells
A body cell has 2X the
amount of DNA as a
gamete (egg or sperm)

4. Discovery of DNA
1952 Rosalind Franklin-studies DNA molecule using x-ray diffraction
1953 Watson and Crick- develop double helix model

5. The Shape of the DNA Molecule
DNA is a complex organic molecule with a double helix shape. (a twisted ladder)
It consists of 2 phosphate-sugar backbones connected by a series of nucleotide bases. (colored letters)

6. DNA Nucleotide Bases Adenine A Thymine T Guanine G Cytosine C
These bases are joined together in a specific way…
A with T G with C
We call this base pairing.

7. DNA Structure

8. DNA Replication
The bonds between the base pairs are weak hydrogen bonds and can be broken easily. This means that the molecule can unwind and unzip itself.
Each side of the DNA molecule has all the information necessary to make a complementary (second) side.
Each piece of “old” DNA will act as a template for a “new” piece of DNA.

9. DNA Copies Itself!!
Because of base pairing, each strand of DNA can replicate itself making two new strands of DNA.
It uses extra nucleotide bases (in cell) to create this copy.
All of the work of DNA replication is done by enzymes!!
The main enzyme is called DNA polymerase

10. Semi-Conservative Replication
The result is that each new copy of DNA produced by this process is made up of ½ original DNA molecule and ½ new DNA molecule. This makes the process semi-conservative.

11. RNA RNA is a nucleic acid like DNA RNA is single stranded.
RNA does not contain thymine but instead has the base called uricil which bonds with adenine.
RNA has many functions in the cell, most importantly it is critical in the process of protein synthesis

12. Mutations What happens when a mistake is made in replication of DNA?
Most mutations are NOT helpful!! But every so often, a beneficial mutation occurs (black moths)

13. Types of Mutations
Point Mutations – the change in one single nucleotide base.
substitution – one letter replaces another in the sequence. (ex. A->G)
insertion – one letter is added to the sequence. (ex. a new T is added)
deletion – one letter is removed from the sequence. (ex. a G is removed)

14. Make a substitution in the following DNA
A T T G C G T G T G
A T T A C G T G T G
Make an insertion in the original sequence
A T T G C G A T G T G
Make a deletion in the original sequence
A T G C G T G T G

15. Larger Mutations
Inversions – when 2 or more bases (letters) are switched into reverse order.
Duplications – when bases are repeated in the original order more than one time.
Translocations – when bases are moved from one area of the sequence to another.

16. Make an 3 base inversion mutation in the following DNA sequence…
A T T G C G T G T G
A T C G T G T G T G
Make a duplication of the inversion here
A T C G T C G T G T G T G
Make a translocation of 3 bases from another DNA sequence of T G C C A A to the original DNA
A T T G C C C A A G T G T G

17. Protein Synthesis The Central Dogma
DNA holds the _______ to make Proteins
____ transfers the CODE to the Ribosome
_____________ are strings of amino acids coded for by DNA
Proteins are the “___________” of the cell
Structure, enzymes, communication, etc.

18. Transcription
The DNA message is __________ into an mRNA message by complementary ______ pairing

19. Translation
The mRNA then goes into the _________ to give the code for a protein to the ribosome. ______ (transfer) molecules will bring the correct _______ _____ to the ribosome.

21. DNA

22. Mutations
Sometimes mistakes can be made in the copying process of DNA. Any change in the original sequence of base pairs is called a mutation.

23. Protein Synthesis The Central Dogma
DNA holds the CODE to make Proteins
RNA transfers the CODE to the Ribosome
Proteins are strings of amino acids coded for by DNA
Proteins are the “workhorses” of the cell
Structure, enzymes, communication, etc.

24. Transcription
The DNA message is transcribed into an mRNA message by complementary base pairing

25. Translation
The mRNA then goes into the cytoplasm to give the code for a protein to the ribosome. tRNA molecules will bring the correct amino acid to the ribosome.

27. DNA

28. Mutations
Sometimes mistakes can be made in the copying process of DNA. Any change in the original sequence of base pairs is called a mutation.