1. Deoxyribonucleic Acid
Structure of DNA
Deoxyribonucleic Acid

2. DNA DNA in in the shape of a double helix
DNA is made up of nucleotides
A nucleotide is:
A Sugar
A Phosphate
And one of four bases

3. Deoxyribose Sugar The carbon atoms are numbered 1', 2', 3', 4', and 5'
The hydroxyl groups on the 5'- and 3'- carbons link to the phosphate groups to form the DNA backbone.
The DNA backbone is a polymer with an alternating sugar-phosphate sequence

5. G C The Bases A is for Adenine G is for Guanine C is for Cytosine
T is for Thymine
A T
G C

6. Purine VS Pyrimidine Adenine and Guanine Larger Cytosine and Thymine
Smaller

8. How Many Scientists Does it Take to Discover a Molecule?

9. Erwin Chargaff (Born 1905) Russian
Moved to the U.S.
Discovered that there was always an equal number of A’s to T’s and C’s to G’s.
There could be different amounts of these two groupings.

10. Rosalind Franklin (1920 – 1958) British
Worked under Maurice Wilkins
Used X-ray diffraction to get images of DNA
Her work was passed along to Watson and Crick by Wilkins.
She did not get recognized for her work possibly because she was a woman in science when it was not fully acceptable

12. Watson and Crick Crick (Born 1916) British Watson (Born 1928) American
Used images and papers produced by Franklin
Discovered double helix shape
They got the
Nobel Prize in
1953 along with
Wilkins

13. DNA Replication
DNA replicates when the cells divide and when the sex cells are formed
Groups of proteins guide the process, but DNA polymerase is the major functioning enzyme.

14. Three major events to begin DNA replication
The two nucleotide chains must separate forming a replication fork.
The chains are separated by enzymes called helicases
DNA polymerase binds to the separated chains of DNA and assembles complimentary nucleotides to the old strand
The new strand of DNA hydrogen bonds with the old strand and winds back to form a helix

16. Checking the System
Incoming nucleotides bind to the DNA polymerase and the polymerase checks to see if the incoming nucleotide pairs correctly with the DNA template.
Error rate is about 1 error in base pairs (108)

17. Direction of Replication
Replication takes place in both directions.
DNA polymerase begins replication simultaneously at many points along the separated nucleotide.

18. The Other Nucleic Acid Remember that:
DNA is located in the nucleus and under no circumstances can leave the nucleus.
Proteins are manufactured in the cytoplasm at the ribsomes.
DNA is the instructions for making those proteins.

19. RNA: Ribonucleic Acid Sugar: Ribose Phosphate group Nitrogen bases
Single Stranded
Made of nucleotides
Sugar: Ribose
Phosphate group
Nitrogen bases
The nitrogen bases in RNA have one difference.
Thymine is replace by uracil
So A pairs to U; G pairs to C

21. Three Types of RNA Messenger RNA (mRNA) Transfer RNA (tRNA)
Carries the code from DNA to the ribosome
Transfer RNA (tRNA)
Picks up individual amino acids in the cytoplasm and carries them to the ribosome to be delivered
Ribosomal RNA (rRNA)
Helps bind mRNA and tRNA together during protein synthesis

22. RNA Transcription
DNA transcribes a copy of mRNA in the nucleus of the cell. The mRNA takes the DNA code out of the nucleus and to the ribosomes.

23. Steps of Transcription
RNA polymerase makes RNA copies of specific segments of DNA.
This begins at a promotor site on DNA
Only the DNA template is used for transcription

24. Steps of Transcription
RNA polymerase adds complimentary RNA nucleotides to form a new RNA molecule.
Complimentary base pairing determines the nucleotide sequence

25. Steps of Transcription
Transcription ends at the DNA terminator. Both DNA and RNA are released by the RNA polymerase.
All three types of RNA molecules are transcribed by this process.

27. Protein Synthesis – Structure and Composition
Proteins are polymers made of amino acids bonded by peptide bonds
Proteins are made up of specific sequences of amino acids
There are 20 kinds of amino acids

28. Protein assembly
Codon AUG means “Start” or can code for the amino acid methinone
MRNA codon is paired with tRNA anticodon
Amino acids are bonded with peptide bonds and the polypeptide chain grows into a protein
At the stop codon (UAA, UAG, UGA) translation ends and the protein is finished
The protein folds up
Several ribosomes can translate the same mRNA transcript at the same time

30. A mutation is any change in the DNA sequence
Genetic Changes
A mutation is any change in the DNA sequence

32. Mutations
Mutations are caused by spontaneous mistakes during replication
They are influenced by mutagens.
Radiation
Chemicals
High temperatures
Mutations in body cells can cause individuals to become ill, Cancer

33. Types of Gene Mutations
Frame Shift – addition of deletion of a base, altering the whole sequence
More harmful because it effects more base sequences
Point - Change in a single base

36. Types of Chromosomal Mutations
Deletion
Duplication
Inversion
Insertion
Translocation