1. Bonding A covalent bond is stronger and holds the atoms in a molecule together. A Hydrogen bond is weaker and it attracts molecules to one another.

2. Covalent bonds are strong bonds that hold atoms in a molecule together. The electrons orbit around both nuclei, holding the atoms together. A covalent bond happens between atoms that share electrons.

3. Which of these molecules will bond? 1 2 3

4. DNA Deoxyribonucleic Acid

5. DNA is in every Cell of living things DNA Why is DNA important Chromosome

8. DNA is shaped like a double helix.

9. DNA structure This is what DNA looks like. The white parts represent the two different strands. These strands can be separated.

10. DNA STRANDS can be represented differently DNA structure

11. Nucleotides DNA

12. Nucleotides or Bases GuanineThymineAdenineCytosine The 4 molecules in DNA are called bases... Each base has physical properties and they’re so small (0.33 nanometres) nothing can see them

13. Base Pairing Cytosine

14. Base Pairing Adenine Guanine Cytosine

15. Base Pairing Thymine Adenine Guanine Cytosine

16. Bonding in DNA Hydrogen bonds (Weaker & can be separated) Covalent bonds (stronger & difficult to break)

17. Uniqueness The sequence..... Each sequence provides unique information about living organisms

18. Base pairing

19. Next: Self-Assembly & Viruses

20. What is self- assembly? What does it mean to “assemble” something? Then what would “self-assembly” mean?

21. Self-assembly at very small scales Patterns self-assembled from the interactions of molecules. Scientist don’t put the particles right next to each other or bond them by hand; the particles do this themselves. The scientist just creates the right environment.

22. Virus examples Influenza Chickenpox Measles

23. Viruses (say: vy-rus-iz) Virus means toxin or poison Viruses are made of genetic material (DNA) They need to be inside living cells to grow and reproduce.

24. Base Pairing Guanine Cytosine

25. Virus Structure a Virus consists of two parts: 1. Genetic material: single OR double DNA strand 2. Capsid: A coat that protects this genetic material

26. Finding a Virus So far we know..... C - G A - T Viruses are a long chain of nucleotides (A A T G C T A C T A C T A T......)

27. Help find the Virus! ? Your job: Catch the virus with 4 nucleotides Important: Make sure your catcher isn’t going to catch the non-viral DNA strand! ???

28. Virus: C T G T G T G G T C A A T T C T GG T T G G C T A C T G T G T G G T C A A T T C T A T A C T G C T ANon Virus: