1. Atoms, Molecules, and Life
Chapter 2
Atoms, Molecules, and Life

2. 2.4 Why Is Carbon So Important To Life?
Carbon can combine with other atoms in many ways to form a huge number of different molecules.
This is possible because carbon has _______________ in its outermost shell, leaving room for four more electrons from other atoms.
Therefore, carbon can form many bonds with other atoms.

3. 2.4 Why Is Carbon So Important To Life?
The great variety of substances found in nature is therefore constructed from a limited pool of atoms.
Organic molecules have a ____________ and some __________________.
Much of the diversity of organic molecules is due to the presence of functional groups.

4. 2.4 Why Is Carbon So Important To Life?

5. 2.4 Why Is Carbon So Important To Life?
PLAY
Animation—Functional Groups

6. 2.5 How Are Biological Molecules Joined Together Or Broken Apart?
Dehydration synthesis
The construction of large molecules yields ___________.
Small molecules are joined together to form large molecules.
During the joining of small molecules, water is released.
This water-releasing reaction is called ____________________.

7. 2.5 How Are Biological Molecules Joined Together Or Broken Apart?
Dehydration synthesis
dehydration synthesis + O HO O H HO OH HO OH O H H
(a)
Dehydration synthesis
Fig. 2-12a

8. 2.5 How Are Biological Molecules Joined Together Or Broken Apart?
Hydrolysis reactions
During the breakdown of large molecules, __________________ bonds are broken, separating the subunits

9. 2.5 How Are Biological Molecules Joined Together Or Broken Apart?
Hydrolysis
hydrolysis + O HO OH HO O H HO OH O H H
(b)
___________________________________
Fig. 2-12b

10. 2.5 How Are Biological Molecules Joined Together Or Broken Apart?
PLAY
Animation—Dehydration Synthesis and Hydrolysis

11. 2.6 What Are Carbohydrates?
Carbohydrates are molecules composed of_________,___________, and ___________ in the ratio of 1:2:1.
They can be small single sugar molecules or long chains of single sugar molecules strung together.

12. 2.6 What Are Carbohydrates?
A simple sugar
CH2OH H O H H H O H H H H 6 5 4 3 2 1 H C C C C C C H HO OH H OH O O O H O O H H H H H OH
(a)
Glucose, linear form
(b)
Glucose, ring form
Fig. 2-13

13. 2.6 What Are Carbohydrates?
___________________ : a carbohydrate consisting of one sugar molecule
Disaccharide: _________ sugars linked together
Polysaccharide: three or more sugars linked together

14. 2.6 What Are Carbohydrates?
Simple sugars, such as glucose, provide important _________ sources for organisms.
Sucrose, such as table sugar, is a disaccharide containing one __________ molecule attached to a ___________ molecule.

15. 2.6 What Are Carbohydrates?
Manufacture of a disaccharide
glucose
fructose
sucrose
CH2OH
CH2OH O
HOCH2 O O
HOCH2 O H H H H H H H H +
dehydration synthesis OH H H HO OH H O H HO HO O H HO
CH2OH HO
CH2OH H OH OH H H OH OH H O H H
Fig. 2-14

16. 2.6 What Are Carbohydrates?
PLAY
Animation—Carbohydrates

17. 2.6 What Are Carbohydrates?
Some complex sugars, such as _____________, provide support for cells or even the entire bodies of organisms.
Complex sugars are made by the dehydration synthesis of simple sugars.
Cellulose is the most _________________ on Earth because it provides support for plants in fields and forests.
Cellulose is made of long chains of ____________ subunits.

18. 2.6 What Are Carbohydrates?
Cellulose structure
wood is mostly cellulose
plant cell with cell wall
close-up of cell wall
Hydrogen bonds cross-linking cellulose molecules
CH2OH H OH
CH2OH H OH O O H H H H H O OH H H O OH H O OH H H O OH H H O H H H H
individual cellulose molecules
bundle of cellulose molecules
cellulose fiber O O H OH
CH2OH H OH
CH2OH
Fig. 2-15

19. 2.6 What Are Carbohydrates?
PLAY
Animation—Carbohydrate Functions
PLAY
Animation—Structure Determines Function

20. Molecular characteristics of lipids
2.7 What Are Lipids?
Molecular characteristics of lipids
Lipids are molecules with long regions composed almost entirely of ___________ and __________________.
The ______________ regions of carbon and hydrogen bonds make lipids hydrophobic and insoluble in water.

21. 2.7 What Are Lipids? Lipid classification
Group 1: Oils,__________, and waxes
Group 2:_______________
Group 3: Steroids

22. Group 1: Oils, fats, and waxes
2.7 What Are Lipids?
Group 1: Oils, fats, and waxes
Contain only carbon, hydrogen, and oxygen
Contain one or more fatty acid subunits—long chains of C and H with a ________________ (–COOH)
They usually ____________ have a ring structure.

23. Group 1: Oils, fats, and waxes (continued)
2.7 What Are Lipids?
Group 1: Oils, fats, and waxes (continued)
Fats and oils form by dehydration synthesis from three fatty acid subunits and one molecule of __________________.
etc.
CH2
CH2
CH2 H O CH H C OH HO C
CH2
CH2
CH2
CH2
CH2
CH2
CH2 CH O H C OH + HO C
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
etc. O H C OH HO C
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
etc. H
glycerol
fatty acids
Fig. 2-16

24. Group 1: Oils, fats, and waxes (continued)
2.7 What Are Lipids?
Group 1: Oils, fats, and waxes (continued)
Fats and oils formed by dehydration synthesis are called______________.
Triglycerides are used for ___________________ energy storage in both plants and animals.
etc.
CH2
CH2
CH2 O H O CH + H H H C O C
CH2
CH2
CH2
CH2
CH2
CH2
CH2 CH O O + H H H C O C
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
etc. O O H C O C
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
etc. + H H H
3 water molecules
triglyceride
Fig. 2-16

25. 2.7 What Are Lipids?
PLAY
Animation—Lipids

26. Group 1: Oils, fats, and waxes (continued)
2.7 What Are Lipids?
Group 1: Oils, fats, and waxes (continued)
Characteristics of fats
Fats are ___________ at room temperature.
Fats have all carbons joined by single covalent bonds.
The remaining bond positions on the carbons are occupied by hydrogen atoms.

27. Group 1: Oils, fats, and waxes (continued)
2.7 What Are Lipids?
Group 1: Oils, fats, and waxes (continued)
Fatty acids of fats are said to be saturated and are straight molecules that can be stacked.
(a)
Beef fat (saturated)
Fig. 2-18a

28. Group 1: Oils, fats, and waxes (continued)
2.7 What Are Lipids?
Group 1: Oils, fats, and waxes (continued)
Characteristics of oils
Oils are ____________ at room temperature.
Some of the carbons in fatty acids have double covalent bonds.
There are fewer attached hydrogen atoms, and the fatty acid is said to be________________.

29. Group 1: Oils, fats, and waxes (continued)
2.7 What Are Lipids?
Group 1: Oils, fats, and waxes (continued)
Unsaturated fatty acids have bends and kinks in fatty acid chains and can’t be stacked.
(b)
Peanut oil (unsaturated)
Fig. 2-18b

30. Group 1: Oils, fats, and waxes (continued)
2.7 What Are Lipids?
Group 1: Oils, fats, and waxes (continued)
Characteristics of waxes
Waxes are _________ at room temperature.
Waxes are highly________________.
Waxes are not a food source.
Waxes form _________________ over plant leaves and stems.

31. Group 1: Oils, fats, and waxes (continued)
2.7 What Are Lipids?
Group 1: Oils, fats, and waxes (continued)
Bees use waxes to store food and honey.
Fig. 2-17b

32. 2.7 What Are Lipids?
PLAY
Animation—Lipid Function

33. 2.7 What Are Lipids? Group 2: Phospholipids
Phospholipids have _____________ heads and _________________ tails.
They are found in cell membranes in a double layer.
They are like ____________ except one fatty acid is replaced by a phosphate group attached to glycerol.

34. Group 2: Phospholipids (continued)
2.7 What Are Lipids?
Group 2: Phospholipids (continued)
The _______________ end of the molecule is water soluble; the fatty acid end of the molecule is water insoluble.
CH3
CH2
CH2
CH3 O–
CH2
CH2
CH2
H3C - N+ -
CH2 -
CH2 - O - P - O -
CH2 O
CH2
CH2 CH
CH3 O HC - O - C -
CH2 -
CH2 -
CH2 -
CH2 -
CH2 -
CH2 -
CH2 - CH O
H2C - O - C -
CH2 -
CH2 -
CH2 -
CH2 -
CH2 -
CH2 -
CH2 -
CH2 -
CH2 -
CH2 -
CH2 -
CH2 -
CH2 -
CH2 -
CH2 -
CH3
polar head
glycerol
fatty acid tails
(hydrophilic)
(hydrophobic)
Fig. 2-19

35. 2.7 What Are Lipids? Group 3: Steroids
Steroids contain _____________ carbon rings fused together.
Various functional groups protrude from the basic steroid “skeleton”.
_________________________ is a steroid found in cell membranes.

36. 2.7 What Are Lipids? Group 3: Steroids
_____________________ and estrogen are male and female reproductive hormones, respectively, and are steroids. OH
CH3
CH3 HC
CH3
CH2 HO
CH2
(b)
Estrogen
CH2 HC
CH3 OH
CH3
CH3
CH3
CH3 HO O
(a)
Cholesterol
(c)
Testosterone
Fig. 2-20

37. 2.8 What Are Proteins? Functions of proteins
Proteins act as _______________ to catalyze many biochemical reactions.
They can act as energy______________.
They are involved in ______________ around the body.
They are involved in muscle______________.

38. 2.8 What Are Proteins?
Some proteins are ______________ and provide support in hair, horns, spider webs, etc.
Fig. 2-21

39. Proteins are formed from chains of _________________.
2.8 What Are Proteins?
Proteins are formed from chains of _________________.
All amino acids have the same basic structure:
A central _____________
An attached ________________
An attached carboxyl group
An attached variable side group

40. 2.8 What Are Proteins? Amino acid structure variable group R H O
amino group
carboxylic acid group N C C H O H H
hydrogen
Fig. 2-22

41. Amino acids join to form chains by dehydration synthesis.
2.8 What Are Proteins?
Amino acids join to form chains by dehydration synthesis.
Proteins are formed by ____________ reactions between individual amino acids.
The –NH2 group of one amino acid is joined to the –COOH group of another, with the release of H2O and the formation of a new peptide (two or more amino acids).

42. 2.8 What Are Proteins?
More and more individual amino acids are added to the peptide until a ___________________ (protein) is formed.
amino acid
amino acid
peptide
water H R O H R O H R O H R O N C C + N C C N C C N C C + O H H O H H H O H H H H O H H H
amino group
carboxylic acid group
amino group
peptide bond
Fig. 2-23

43. 2.8 What Are Proteins?
PLAY
Animation—Proteins

44. Three-dimensional shapes give proteins their functions.
2.8 What Are Proteins?
Three-dimensional shapes give proteins their functions.
Long chains of amino acids fold into __________________ in cells, which allows the protein to perform its specific functions.
When a protein is denatured, its shape has been disrupted and it may not be able to __________________ its function.

45. 2.8 What Are Proteins?
(a) Primary structure: The sequence of amino acids linked by peptide bonds
(b) Secondary structure: Folding usually maintained by hydrogen bonds
leu H R H N C C N
val H C O H C H
lys C N O N C O C
lys H H C C N
gly C N O C O H
his C H C O C N N
hydrogen bond O
ala C H H C C
lys N C N O C O
(c) Tertiary structure: Folding results from bonds with surrounding water molecules and between amino acids
val C H C O N O
lys
helix
(d) Quaternary structure: Individual polypeptides are linked to one another
pro
Fig. 2-24

46. 2.8 What Are Proteins?
PLAY
Animation—Protein Function

47. Structure of nucleic acids
2.9 What Are Nucleic Acids?
Structure of nucleic acids
Nucleic acids are long chains of similar, but__________________ , subunits called________________________.

48. Structure of nucleic acids (continued)
2.9 What Are Nucleic Acids?
Structure of nucleic acids (continued)
All nucleotides have three parts.
A five-________ sugar (ribose or deoxyribose)
A _____________ group
A nitrogen-containing molecule called a base

49. Deoxyribose nucleotide
2.9 What Are Nucleic Acids?
Deoxyribose nucleotide
base
NH2
phosphate C N C N OH HC O C CH N HO P O
CH2 N O
sugar H H H H OH H
Fig. 2-25

50. 2.9 What Are Nucleic Acids? Types of nucleotides
Those that contain the sugar____________.
Those that contain the sugar_____________.
Nucleotides string together in long chains as nucleic acids with the phosphate group of one nucleotide bonded to the sugar group of another.

51. 2.9 What Are Nucleic Acids? Nucleotide chain base sugar phosphate
Fig. 2-26

52. DNA and RNA, the molecules of ____________, are nucleic acids.
2.9 What Are Nucleic Acids?
DNA and RNA, the molecules of ____________, are nucleic acids.
There are two types of nucleic acids.
______________________(DNA): contains the genetic code of cell
Ribonucleic acid (RNA): is used in the synthesis of________________

53. 2.9 What Are Nucleic Acids? Animation—Nucleic Acids
PLAY
Animation—Nucleic Acids
PLAY
Animation—Nucleic Acids

54. Other nucleotides perform other functions.
2.9 What Are Nucleic Acids?
Other nucleotides perform other functions.
Adenosine monophosphate: acts as a _____________ in the cell, carrying information to other molecules
Adenosine triphosphate: carries ______________ from place to place in the cell