1. Nucleic Acids
DNA & RNA

2. What are they ? The 4th type of biomolecule
The chemical link between generations
The source of genetic information in chromosomes

3. What do they do ? Dictate amino-acid sequence in proteins
Give information to chromosomes, which is then passed from parent to offspring

4. What are they made of ?
Simple units called nucleotides, connected in long chains
Nucleotides have 3 parts:
1- 5-Carbon sugar (pentose)
2- Nitrogen containing base
(made of C, H and N)
3- A phosphate group ( P )
The P groups make the links that unite the sugars (hence a “sugar-phosphate backbone”

5. Two types of Nucleotides (depending on the sugar they contain)
1- Ribonucleic acids (RNA)
The pentose sugar is Ribose (has a hydroxyl group in the 3rd carbon---OH)
2- Deoxyribonucleic acids (DNA)
The pentose sugar is Deoxyribose (has just an hydrogen in the same place--- H) Deoxy = “minus oxygen”

6. DNA Nucleotides Composition (3 parts):
1- Deoxyribose sugar (no O in 3rd carbon)
2- Phosphate group
3- One of 4 types of bases (all containing nitrogen):
- Adenine
- Thymine (Only in DNA)
- Cytosine
- Guanine

7. RNA Nucleotides Composition ( 3 parts):
1- Ribose sugar (with O in 3rd carbon)
2- Phosphate group
3- One of 4 types of bases (all containing nitrogen):
- Adenine
- Uracyl (only in RNA)
- Cytosine
- Guanine

8. DNA vs RNA DNA 1- Deoxyribose sugar
2- Bases: Adenine, Thymine, Cytosine, Guanine
3- Double-stranded helix arrangement
RNA
1- Ribose sugar
2- Bases: Adenine, Uracyl, Cytosine, Guanine
4- Single stranded

9. The Double Helix (DNA) Structural model:
Model proposed by Watson & Crick, 1953
Two sugar-phosphate strands, next to each other, but running in opposite directions.
Specific Hydrogen bonds occur among bases from one chain to the other:
A---T , C---G
Due to this specificity, a certain base on one strand indicates a certain base in the other.
The 2 strands intertwine, forming a double-helix that winds around a central axis

10. How DNA Works
1- DNA stores genetic information in segments called genes
2- The DNA code is in Triplet Codons (short sequences of 3 nucleotides each)
3- Certain codons are translated by the cell into certain Amino
acids.
4. Thus, the sequence of nucleotides in DNA indicate a sequence of Amino acids in a protein.

11. Properties of Water

12. Polar covalent bond – unequal sharing of electrons
Properties of Water
Covalent bonding
Polar covalent bond – unequal sharing of electrons
A great example of a molecule with polar covalent bonds is water. Why is water considered polar?
What is a partial positive and partial negative charge?

13. Covalent bonding vs. Hydrogen bonding
Properties of Water
Covalent bonding vs. Hydrogen bonding
Hydrogen Bond
Covalent Bond

14. Water is the solvent of Life!
Properties of Water
Universal Solvent
Water is the solvent of Life!
Solute – substance dissolved in a solvent to form a solution
Solvent – fluid that dissolves solutes
Example: Ice Tea – water is the solvent and tea and sugar the solutes

15. Cohesion, Adhesion and Surface Tension
Properties of Water
Cohesion, Adhesion and Surface Tension
cohesion = water attracted to other water
molecules because of polar properties
adhesion = water attracted to other materials
surface tension = water is pulled together creating
the smallest surface area possible

16. Properties of Water Capillary Action
Because water has both adhesive and cohesive properties, capillary action is present.
Capillary Action = water’s adhesive property is the cause of capillary action. Water is attracted to some other material and then through cohesion, other water molecules move too as a result of the original adhesion.
Ex: Think water in a straw
Ex: Water moves through trees this way

17. Properties of Water High Heat Capacity
In order to raise the temperature of water, the average molecular speed has to increase.
It takes much more energy to raise the temperature of water compared to other solvents because hydrogen bonds hold the water molecules together!
Water has a high heat capacity.
“The specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius.”
High Heat Capacity

18. Properties of Water Density
Water is less dense as a solid! This is because the hydrogen bonds are stable in ice – each molecule of water is bound to four of its neighbors.
Solid – water molecules are bonded together – space between fixed
Liquid – water molecules are constantly bonding and rebonding – space is always changing

19. Properties of Water So, can you name all of the properties of water?
Adhesion
Cohesion
Capillary action
High surface tension
Holds heat to regulate temperature (High heat capacity)
Less dense as a solid than a liquid

20. Acids and Bases
Strength compared using pH scale
Ranges from 0 – 14
Logarithmic Scale (gets 10x bigger/smaller)
Acid – donates H+ when added to aqueous solutions
Ranges from pH 0-6.9
Base – breaks up into hydroxide (OH-) ions and
another compound when placed in an aqueous
solution
Ranges from pH 7.1 – 14
Distilled water is pH 7.0 or neutral. Why?
H2O H OH-

22. Acids and Bases
Buffers – compounds used to maintain a contant pH within a system
H2CO3 H HCO3-
Carbonic acid bicarbonate ion

23. Acids and Bases

24. Making Biological Molecules
and H2O
Condensation Reaction
H2O
Hydrolysis Reaction