1. THIS IS A STUDY GUIDE, NOT AN ALL INCLUSIVE REVIEW. THERE MIGHT BE THINGS NOT COVERED BY THIS STUDY GUIDE THAT MIGHT BE ASKED IN YOUR QUIZZES and TESTS. STUDENTS ARE RESPONSIBLE FOR STUDYING THEIR TEXT BOOKS AS PER THE COURSE SYLLABUS

2. LESSON # 5

3. MOLECULE OF WATER + + 8 +   POLAR MOLECULE _ _ _ _ _ __ _ _ _ O H H

4. + + + + - + + HYDROGEN BONDING links an already covalently bonded hydrogen atom with an electronegative atom (oxygen or nitrogen) in other molecule HYDROGEN BONDING Hydrogen bond O O O HH H H H H

6. Covalent Bond It links two or more atoms to form molecules (polar or nonpolar) Hydrogen Bond 1- It links different molecules in a given compound 2- It maintains the shape of macromolecules 3- It makes some ionic compounds soluble in other ionic compounds Ionic Bond It links two or more atoms to form ionic compounds HYDROGEN BONDING

7. Secondary Structure of Proteins: The way that aminoacid chains are arranged in the space due to hydrogen bonds between the aminoacids next or near to each other  O -  H +  H +  H +  O -  O -  H +  O -

8. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings. nitrogenous base sugar (deoxyribose) DNA double helix DNA consists of two strands of nucleotides linked by hydrogen bonds The rungs consist of bases hydrogen- bonded together The outer “rails” of the double helix are composed of sugar and phosphate components of the molecule A computer-generated model of DNA phosphate group (b)

9. ENZYME SUBSTRATE Molecular shape determines the capacity of molecules to bind with another. When molecular shape is modified the molecule can lose its function. DNA REPRESSOR(protein)

10. Molecular shape is a critical element in the functioning of most proteins Protein of influenza virus Antibody The antibody helps disable the virus by binding with it. The antibody is able to carry out this binding because it has a shape that is com- plementary to that of the virus molecule

11. The three-dimensional molecular shape is important in biology because it determines the capacity molecules have to bind with one another.

12. 2- Water and Life

13. 1- Water is the most important constituent of the body. Two thirds (66%) of the human body is water. Ex: If a person weighs 128 pounds, about 85 pounds of his body is water. 2- A change in the body’s water content can have fatal consequences to the organism. 3- Most chemicals reactions that support life in the organism occur in an aqueous solution.

15. UNUSUAL PROPERTIES OF WATER 1- Solvent properties. Over the range of substances, nothing can match water as a solvent. It can dissolve more compound in greater amounts than can any other liquid. 2- The solid form of water is less dense than the liquid form. Therefore, ice floats in water. 3- Water has a great capacity to absorb and store heat. 4- Water molecule cohesion gives water surface tension

16. SOLVENT PROPERTIES OF WATER SOLUTES, SOLVENTS, AND SOLUTIONS

17. SOLVENT SOLUTE SOLUTION When we pour a small amount of table salt into water, the salt crystals dissolve into the water yielding a solution.

18. SOLUTION: A homogeneous mixture of two or more kinds of molecules, atoms or ions. SOLUTE: The substance that is being dissolved SOLVENT: The substance that is doing the dissolving

19. An aqueous solution is one in which water is the solvent, acting to break down the compounds (solutes) that have been put in it. Ex: An aqueous solution of sodium chloride. SOLVENT O H + _ H + SOLUTE ClNa + _ Sodium chloride dissolves in water in three steps:

20. Cl -Na +Cl -Na +Cl -Na + Cl - HYDRATION ESPHERE SODIUM CHLORIDE SOLUTION IN WATER + + + + + + ++ + + ++ + + + + + + + + + + + + + ++ + + + + + ++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ __ _ _ _

21. Cl - Na + Cl - + + + + + + + + ++ + + + ++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ __ _ _ _ 1- Water works as a solvent of ionic compounds because they dissociate and bind to water molecules through electro- static charges. Ex: Sodium chloride.

22. 2- Water can dissolve other compounds because water molecules can form hydrogen bonding with other molecules. Ex: Ammonia is a gas that is soluble in water. It is a polar molecule due to the electronegativity of nitrogen atoms.  N H H H Ammonia

23. N H H H + + + - N H H H + + + - N H H H + + + - O H H + + - O H H + + - N H H H + + + - O H H + + - Water can dissolve ammonia because water molecules form hydrogen bonds with ammonia molecules

24. Water can acts as a solvent by two mechanisms: 1- Ionic compounds dissociate and bind to water molecules through electrostatic charges Ex: Sodium chloride solution in water Cl - Na + 2- Polar molecules form hydrogen bonds with water molecules N H H H + + + - O H H + + - N H H H + + + - Ex: Ammonia solution in water

25. Sodium chloride and ammonia are both polar compounds. Water is also a polar compound, that is why sodium chloride and ammonia dissolve easily in water. Substances that are polar (ex: salts) dissolve best in polar solvents (ex: water, alcohol). Substances that are nonpolar (ex: hydrocarbons, fats) dissolve better in nonpolar solvents (ex: acetone).

26. P O L A R I T Y

27. Compounds that have the ability to interact with water. Usually they are polar and soluble in water. Ex: Sodium chloride, alcohol. Compounds that do not interact with water. Usually they are nonpolar compounds. Ex: oil, methane An oil spill in the ocean Hydrophilic compounds Hydrophobic compounds

28. PHOSPHOLIPID Many molecules are not completely hydrophilic or completely hydrophobic, but they can have hydrophilic portions and hydrophobic portions Hydrophobic tail Hydrophilic head Polar headNonpolar tails

29. CELL MEMBRANE STRUCTURE Polar attracts polar Nonpolar attracts nonpolar Phospholipid Orientation