1. 6.4 Atoms: KEY CONCEPT All living things are based on atoms and their interactions.

2. Living things consist of atoms of different elements.
An atom is the smallest basic unit of matter.
An element is a pure substance of one type of atom.
Hydrogen atom (H) H O
Oxygen atom (O)

3. An atom has a nucleus and electrons.
The nucleus has protons (+) and neutrons (no charge).
Electrons (-) are in energy levels outside nucleus.
Oxygen atom (O)
Nucleus: 8 protons (+) 8 neutrons
outermost energy level: 6 electrons (-)
inner energy level: 2 electrons (-)

4. O A compound is made of atoms of different elements bonded together.
water (H2O) O H _ +

5. A compound is made of atoms of different elements bonded together.
water (H2O)
carbon dioxide (CO2)

6. A compound is made of atoms of different elements bonded together.
water (H2O)
carbon dioxide (CO2)
many other carbon-based compounds in living things

7. Ions form when atoms gain or lose electrons.
An ion is an atom that has gained or lost one or more electrons.
positive ions attracted to negative ions (ionic bonds)
Ions carry an electric current
Ions are usually soluble in water (dissolve)
Sodium atom (Na)
Chlorine atom (CI)
Sodium ion (Na+)
Chloride ion (CI-)
Na loses an electron to CI
ionic bond
gained electron

8. Atoms share pairs of electrons in covalent bonds.
A covalent bond forms when atoms share a pair of electrons (usually between nonmetals)
multiple covalent bonds
diatomic molecules
covalent bonds
Oxygen atom (O)
Carbon atom (C)
Carbon dioxide (CO2 )

9. 6.5 Water -KEY CONCEPT Water’s unique properties allow life to exist on Earth.
Water is in cells- Water makes up 2/3 or nearly 70% of your body’s cells.

10. Life depends on hydrogen bonds in water.
Water is a polar molecule.
Polar molecules have slightly charged regions due to unequal distribution of electrons. O H _ +
One side positively charged & one side negatively charged
Hydrogen bonds form between slightly positive hydrogen atoms and slightly negative atoms.
Water molecule is shaped like Mickey Mouse (upside down) .

11. Polar vs Nonpolar Molecules:
-Uneven distribution of electrons (charged)
-Even distribution of electrons (uncharged)
-Soluble in water (dissolve in water)
-insoluble in water (do not dissolve in water)
-“Hydrophillic” = (“water-loving”
-“Hydrophobic” = (“Water-Fearing”)

12. Hydrogen bonds are responsible for three important properties of water.
high specific heat
Cohesion
adhesion

13. **Important Properties of Water:
**Cohesion: like molecules attracted to like molecules (water attracted to other water molecules)
Explains why water beads up on a surface.
causes surface tension, which prevents water from stretching or breaking easily
Surface tension explains how bugs walk on water’s surface.
**Adhesion: water molecules attracted to different molecules
- Examples: Adhesion allows for Capillary Action in which water molecules move upward through a narrow tube like a plant stem.
-Demo: Colored water will move up a celery stalk.
** Water dissolves many substances in the body (dissolved substances transported in blood).

14. Many compounds dissolve in water.
A solution is a uniform mixture in which one or more substances is evenly distributed in another substance.
Solvents dissolve other substances (more solvent) .
Solutes dissolve in a solvent (less solute in solution)
solution

15. “Like dissolves like.”
Polar solvents dissolve polar solutes.
Nonpolar solvents dissolve nonpolar solutes.
Polar substances and nonpolar substances generally remain separate (do not mix)
Ex: Oil (nonpolar) and Water (polar) do not mix .

16. Some compounds form acids or bases.
An acid releases a hydrogen ion when it dissolves in water.
high H+ concentration
Acids have a pH less than 7
more acidic
stomach acid pH between 1 and 3

17. A base removes hydrogen ions from a solution.
low H+ concentration
Bases have a pH greater than 7
bile pH between 8 and 9
more basic

18. A neutral solution has a pH equal to 7.
pure water pH 7

19. Ch 2 Section 3- KEY CONCEPT Carbon-based molecules are the foundation of life
Organic molecules contain CARBON .

20. Carbon atoms have unique bonding properties.
Carbon forms covalent bonds with up to four other atoms, including other carbon atoms.
Carbon-based molecules have three general types of structures.
straight chain
branched chain
ring

21. Many carbon-based molecules are made of many small subunits bonded together.
Monomers are the individual subunits.
Polymers are made of many monomers.

22. 4 types of Carbon-based molecules in living things:
Four main types of carbon-based molecules are found in living things:
1) Carbohydrates
2) Lipids
3) Proteins
4) Nucleic Acids.

23. CARBOHYDRATES:
Carbohydrates are made of carbon, hydrogen, and oxygen.
Carbohydrates include sugars and starches
Monosaccharides are simple sugars, like glucose.
Polysaccharides include starches, cellulose, and glycogen

24. Carbohydrates can be broken down to provide energy for cells.
Some carbohydrates are part of cell structure.
Polymer (starch)
Starch is a polymer of glucose monomers that often has a branched structure.
Polymer (cellulose)
Cellulose is a polymer of glucose monomers that has a straight, rigid structure
monomer

25. Many contain carbon chains called fatty acids.
Lipids are nonpolar molecules that include fats, oils, and cholesterol.
Many contain carbon chains called fatty acids.
Fats and oils contain fatty acids bonded to glycerol.
Triglyceride (Fat)

26. Lipids have several different functions.
broken down as an energy source
make up cell membranes
used to make hormones

27. Fats and oils have different types of fatty acids.
saturated fatty acids (all carbon-carbon bonds are single bonds)
unsaturated fatty acids (at least one carbon-cabon double bond)

28. Saturated vs Unsaturated Fats
All single bonds (many hydrogen atoms)
Double bonds between carbons (fewer hydrogen atoms)
Solids at room temperature
Less healthy to consume
Liquids at Room temperature
More healthy to consume

29. Phospholipids make up all cell membranes.
Like a “phospholipid sandwich”
Polar phosphate “head”
Nonpolar fatty acid “tails”
Phospholipid

30. 3) Proteins are polymers of amino acid monomers.
Twenty different amino acids are used to build proteins in organisms.

31. Proteins are polymers of amino acid monomers.
Twenty different amino acids are used to build proteins in organisms.
Amino acids differ in side groups, or R groups.

32. Proteins are polymers of amino acid monomers.
Twenty different amino acids are used to build proteins in organisms.
Amino acids differ in side groups, or R groups.
Amino acids are linked by peptide bonds (contain a nitrogen group) .

33. Proteins differ in the number and order of amino acids.
Amino acids interact to give a protein its shape.
hydrogen bond
Hemoglobin
Incorrect amino acids change a protein’s structure and function.

34. 4) Nucleic acids are polymers of monomers called nucleotides.

35. Nucleic acids are polymers of monomers called nucleotides.
Nucleotides are made of a sugar, phosphate group, and a nitrogen base.
A phosphate group
nitrogen-containing molecule, called a base
deoxyribose (sugar)

36. Nucleic acids are polymers of monomers called nucleotides.
Nucleotides are made of a sugar, phosphate group, and a nitrogen base.
-Two nucleotides are DNA and RNA.
DNA
DNA stores genetic information.
RNA builds proteins.
RNA

37. QUIZ
1) In what type of bond do atoms share electrons?
2) Describe Cohesion of water & give an example.
3) Describe Adhesion of water & give example.
4) What are the building blocks of a protien?
5) List the parts of a Nucleotide AND draw a picture.

38. Ch 2 Section 4: KEY CONCEPT Life depends on chemical reactions.

39. Bonds break and form during chemical reactions.
Chemical reactions change substances into different ones by breaking and forming chemical bonds.
Reactants are changed during a chemical reaction.
Products are made by a chemical reaction.

40. Bond energy is the amount of energy that breaks a bond.
Energy is added to break bonds.
Energy is released when bonds form.
A reaction is at equilibrium when reactants and products form at the same rate.
CO2 + H2O H2CO3

41. Chemical reactions release or absorb energy.
Activation energy is the amount of energy that needs to be absorbed to start a chemical reaction.

42. Exothermic reactions release more energy than they absorb.
Reactants have higher bond energies than products.
Excess energy is released by the reaction.

43. Endothermic reactions absorb or take in more energy than they release.
Reactants have lower bond energies than products.
Energy is absorbed by the reaction to make up the difference.

44. Ch 2 Section 5 KEY CONCEPT Enzymes are catalysts for chemical reactions in living things.

45. A catalyst lowers the activation energy to start a reaction
Catalysts are substances that speed up chemical reactions.
decrease activation energy & increase reaction rate

46. Enzymes allow chemical reactions to occur under tightly controlled conditions.
Enzymes are catalysts in living things.
Enzymes are needed for almost all processes.
Most enzymes are proteins.

47. Disruptions in homeostasis can prevent enzymes from functioning.
Enzymes function best in a small range of conditions.
Changes in temperature and pH can break hydrogen bonds.
An enzyme’s function depends on its structure.

48. An enzyme’s structure allows only certain reactants to bind to the enzyme.
substrates
active site
substrates (reactants)
enzyme
Substrates bind to an enzyme at certain places called active sites.

49. The lock-and-key model helps illustrate how enzymes function.
substrates brought together
bonds in substrates weakened
The structure of the enzyme itself is NOT changed during the reaction.
Substrates bind to an enzyme at certain places called active sites.
The enzyme brings substrates together and weakens their bonds.
The catalyzed reaction forms a product that is released from the enzyme.