1. Resurrecting the Extinct
DNA Structure
Amoeba Sisters
Resurrecting the Extinct

2. DNA is…
A macromolecule found in cells that contains the codes (like a recipe) for making proteins for the organism.
Chromosomes are your DNA, only coiled up
What is DNA?

4. Sugar-Phosphate Backbone
The sides of the DNA ‘ladder’ are made of alternating sugars and phosphates held together by strong covalent bonds. It is referred to as the sugar-phosphate backbone.
Deoxyribose (sugar)
phosphate
nitrogen base

5. Base Pairing Rules
The steps of the “ladder” are made up of pairs of nitrogen bases held together by weak hydrogen bonds.

6. Base Pairing Rules
A always bonds with T
G always bonds with C

7. DNA vs RNA (ribonucleic acid)
3 main differences from DNA
RNA contains ribose as its 5-carbon sugar
RNA is single stranded
RNA has Uracil instead of Thymine (A pairs with U)

8. RNA vs. DNA

9. Protein Synthesis
What is a protein?

10. Protein synthesis=using DNA codes to make proteins Your DNA contains codes for making proteins. Proteins are the basis of your traits, so that is why your DNA determines your traits.

11. The basics of protein synthesis-
Two steps of protein synthesis:
Transcription-DNA codes are copied onto mRNA
Translation-the ribosome ‘reads’ the codes on the mRNA to build a protein.

12. Part I: Transcription
DNA contains codes that the ribosome needs to make proteins (the codes are like a recipe for protein). DNA can’t leave the nucleus, so mRNA is built from DNA, which makes a copy of the DNA codes. mRNA leaves the nucleus and delivers the codes to the ribosome.

13. A-C-G-T-C-G-T-A-C-A-T-G-T-C-T-A-C-G-A-C-C-T-A-C
DNA  mRNA
What would be the mRNA sequence for the following template strand of DNA?
A-C-G-T-C-G-T-A-C-A-T-G-T-C-T-A-C-G-A-C-C-T-A-C

14. AGT CTA TAT GTA ATC CAT GGC
Codons
Codons=a group of three mRNA nitrogen bases is a code for an amino acid (remember, amino acids combine to make proteins!)
What would be the mRNA codons for the following DNA sequence?
AGT CTA TAT GTA ATC CAT GGC

15. Part II: Translation The ribosome ‘reads’ the codons on the mRNA to build a protein ***Remember, a protein is a macromolecule made of a chain of amino acids!!!
After transcription, the mRNA molecule attaches to a ribosome
2. ribosome ‘reads’ the codons (each codon is a code for an amino acid)
3. tRNA carries the
amino acid to the ribosome.

16. Genetic Code

17. Genetic Code Template strand of DNA TAC GGA CTG AAG TTC mRNA
Amino Acids

18. The BIG Picture

19. Mutations

20. Mutation: a change in the DNA sequence Causes
High energy radiation (UV & X-rays)
Chemicals
High temperatures
Mistakes in DNA replication
Viruses
Other environmental factors

21. Mutations ‘Normal’ Sequence: THE FAT CAT ATE THE RAT Mutation:
THE FAT HAT ATE THE RAT
THE FFA TCA TAT ETH ERA T

22. Significance of Mutations
Most mutations are neutral (neither good or bad) because they don’t affect proteins being made and used by the body.
Bad mutations – associated with cancer and many genetic disorders
Good mutations - source of genetic variation, help organisms adapt to changing environments