1. Chapter 3
The Molecules of Cells

2. Standards By the end of the unit you should be able to:
Model synthesis and hydrolysis reactions and relate the reactions to the human body
Recognize carbs, lipids, proteins and nucleic acids in formula & skeleton form, chemical structure and describe their function in the human body
Recognize monosaccharides, disaccharides and polysaccharides and relate the molecules to how they function in the body
Recognize, describe the location of, and explain the importance of the following in the human body: neutral fats, steroids and phospholipids
I can list the major functions of nucleic acids (RNA & DNA), describe their structure with accurate detail and compare these 2 molecules
I can compare the following pairs: saturated and unsaturated fats, DNA & RNA
I can differentiate among the primary, secondary, tertiary and quaternary structure of proteins and explain how these levels of structure relate to protein functions
I can relate protein structure to protein specific examples from the human body
I ca draw the general structure of the ATP molecule in its role as the “energy currency” of cells

3. Biological Molecules
3.1 Life’s molecular diversity is based on the properties of carbon
A carbon atom can form four covalent bonds allowing it to build large and diverse organic compounds
Organic Molecules – contain carbon atom and a hydrogen atom
C can bond with up to 4 other atoms

4. Carbon chains vary in many ways
Hydrocarbons are composed of only hydrogen and carbon
Some carbon compounds are isomers: molecules with the same molecular formula but different structures H H H H H 1 2 3 4. H C C H H C C C H H H H H H
Ethane
Propane
Carbon skeletons vary in length. H H C H H H H H H H H C C C C H H C C C H H H H H H H H
Butane
Isobutane
Skeletons may be unbranched or branched. H H H H H H H H H C H H C C C C C C C H H H H H
1-Butene
2-Butene
Skeletons may have double bonds, which can vary in location. H H H H C H H C H H C C C C H H C C H C C H C H H C H H H H
Figure 3.1A
Cyclohexane
Benzene
Skeletons may be arranged in rings.

5. 3.2 Functional groups help determine the properties of organic compounds
Some examples of functional groups:
Table 3.2

6. Functional groups are particular groupings of atoms that give organic molecules particular properties OH
Estradiol HO
Female lion OH O
Figure 3.2
Male lion
Testosterone

7. Basic Vocab.
Monomer –is a small molecule that may become chemically bonded to other monomers to form a polymer.
Polymer – a large molecule that is made of several monomers bonded to each other

8. Reactions that form polymers & monomers
Hydrolysis and Synthesis Reactions
Reactions we will see for all biological molecules

9. Cells link monomers to form polymers by a dehydration reaction
Cells make most of their large molecules by joining smaller organic molecules into chains called polymers
Cells link monomers to form polymers by a dehydration reaction H OH
Unlinked monomer
Dehydration reaction
Longer polymer
Short polymer
H2O
Figure 3.3A

10. Polymers are broken down to monomers by the reverse process, hydrolysis H
H2O OH
Hydrolysis
Figure 3.3B

11. 3.3 Cells make a huge number of large molecules from a small set of small molecules
The four main classes of biological molecules are carbohydrates, lipids, proteins, and nucleic acids
Many of the molecules are gigantic and are called macromolecules

12. CARBOHYDRATES 3.4 Monosaccharides are the simplest carbohydrates
3.4 Monosaccharides are the simplest carbohydrates
The carbohydrate monomers are monosaccharides
A monosaccharide has a formula that is a multiple of CH2O and contains hydroxyl groups and a carbonyl group
Figure 3.4A

13. Carb Info:
Function of carbs for humans– source of energy for the cell (cellular respiration)
CARBS contains carbon, hydrogen, and oxygen in the ratio of 1:2:1. (empirical formula)

14. The monosaccharides glucose and fructose are isomers that contain the same atoms but in different arrangements C H HO O OH
Glucose
Fructose
Figure 3.4B

15. Abbreviated structure
Monosaccharides can also occur as ring structures H O C OH HO
CH2OH
Structural formula
Abbreviated structure
Simplified structure 6 5 4 3 2 1
Figure 3.4C

16. 3.5 Cells link two single sugars to form disaccharides
3.5 Cells link two single sugars to form disaccharides
Monosaccharides can join to form disaccharides such as sucrose (table sugar) and maltose (brewing sugar) H OH HO O
CH2OH
H2O
Glucose
Maltose
Figure 3.5

17. CONNECTION 3.6 How sweet is sweet?
3.6 How sweet is sweet?
Various types of molecules, including nonsugars taste sweet because they bind to “sweet” receptors on the tongue
Table 3.6

18. 3.7 Polysaccharides are long chains of sugar units
Polysaccharides are polymers of monosaccharides linked together by dehydration reactions
Starch and glycogen are polysaccharides that store sugar for later use
Cellulose is a polysaccharide found in plant cell walls
Starch granules in potato tuber cells
Glycogen granules in muscle tissue
Cellulose fibrils in a plant cell wall
Glucose monomer
Cellulose molecules
STARCH
GLYCOGEN
CELLULOSE O OH
Figure 3.7

19. LIPIDS 3.8 Fats are lipids that are mostly energy-storage molecules
3.8 Fats are lipids that are mostly energy-storage molecules
Lipids are diverse compounds that consist mainly of carbon and hydrogen atoms linked by nonpolar covalent bonds
Lipids are grouped together because they are hydrophobic
Figure 3.8A

20. Consist of glycerol linked to three fatty acids
Fats, also called triglycerides (neutral fats) are lipids whose main function is energy storage
Consist of glycerol linked to three fatty acids
CH2
CH3
H2O H OH HO C O
Fatty acid
Glycerol H
CH2 O
CH3 CH C
Figure 3.8B
Figure 3.8C

21. 3.9 Phospholipids, waxes, and steroids are lipids with a variety of functions
Phospholipids are a major component of cell membranes
Waxes form waterproof coatings
Steroids are often hormones HO
CH3
H3C
Figure 3.9

22. CONNECTION 3.10 Anabolic steroids pose health risks
3.10 Anabolic steroids pose health risks
Anabolic steroids are synthetic variants of testosterone that can cause serious health problems

23. 3rd group of Bio Cules - Proteins
2 types
Functional
Structural
Enzymes – hydrolytic- (lysosomes, digestive)
Found in ligaments, bones, tendons, skin
Ex – keratin, collagen

24. PROTEINS
3.11 Proteins are essential to the structures and activities of life
A protein is a polymer constructed from amino acid monomers
Proteins are involved in almost all of a cell’s activities
As enzymes they regulate chemical reactions.
Figure 3.11

25. Each amino acid contains
3.12 Proteins are made from amino acids linked by peptide bonds
Protein diversity is based on different arrangements of a common set of 20 amino acid monomers
Each amino acid contains
An amino group
A carboxyl group
An R group, which distinguishes each of the 20 different amino acids H N C R O OH
Amino
group
Carboxyl (acid)
Figure 3.12A

26. Each amino acid has specific properties based on its structure
Each amino acid has specific properties based on its structure H N C
CH2 CH
CH3 O OH
Leucine (Leu)
Serine (Ser)
Aspartic acid (Asp)
Hydrophobic
Hydrophilic
Figure 3.12B

27. Cells link amino acids together by dehydration synthesis
Cells link amino acids together by dehydration synthesis
The bonds between amino acid monomers are called peptide bonds H N C O OH + R
H2O
Peptide
bond
Dipeptide
Amino acid
Dehydration
reaction
Amino
group
Carboxyl
Figure 3.12C

28. Peptide Bonds The N of one a.a. bonds to C of carboxyl of another a.a.
Dipeptide – has 1 peptide bond & 2 a.a.
Tripeptide – has 2 bonds & 3 a.a
Polypeptides – many amino acids

29. 3.13 A protein’s specific shape determines its function
3.13 A protein’s specific shape determines its function
A protein consists of one or more polypeptide chains folded into a unique shape that determines the protein’s function
Groove
Groove
Figure 3.13A
Figure 3.13B

30. Levels of Protein Structure
3.14 A protein’s shape (and therefore its function!) depends on four levels of structure
Primary Structure
A protein’s primary structure is the sequence of amino acids forming its polypeptide chains
Levels of Protein Structure
Primary structure
Gly
Thr
Glu
Ser
Lys
Cys
Pro
Leu
Met
Val
Asp
Ala
Arg
Ile
Asn
His
Amino acids
Phe
Figure 3.14A

31. Secondary structure
A protein’s secondary structure is the coiling or folding of the chain, stabilized by hydrogen bonding between a.a. on different parts of the strand
Figure 3.14B
Secondary structure C N O H
Hydrogen
bond R
Alpha helix
Pleated sheet
Amino acids

32. Tertiary Structure
A protein’s tertiary structure is the overall three-dimensional shape of a polypeptide
This 3D shape is the result of interactions between the R groups of the a.a.s
Tertiary structure
Polypeptide
(single subunit
of transthyretin)
Figure 3.14C

33. Quaternary Structure
A protein’s quaternary structure results from the association of two or more polypeptide chains
EX: hemoglobin
Polypeptide
chain
Collagen
Quaternary structure
Transthyretin, with
four identical
polypeptide subunits
Figure 3.14D

34. TALKING ABOUT SCIENCE
3.19 Linus Pauling contributed to our understanding of the chemistry of life
Linus Pauling made important contributions to our understanding of protein structure and function
Discovered the alpha helical structure in proteins (secondary level) and also the difference in the structure of hemoglobin in regular blood vs sickle cell anemia blood
Figure 3.15

36. NUCLEIC ACIDS
3.20 Nucleic acids are information-rich or energy carrying polymers of nucleotides
There are 3 ex: DNA, RNA, ATP
Nucleic acids such as DNA and RNA serve as the blueprints for proteins and thus control the life of a cell
ATP serves as the energy currency of the cell

37. The monomers of nucleic acids are nucleotides
The monomers of nucleic acids are nucleotides
Composed of a 5 carbon sugar, phosphate, and nitrogenous base (ATCGU)
Sugar OH O P O
CH2 H N
Phosphate
group
Nitrogenous
base (A)
Figure 3.16A

38. Different Nucleotides: Note same basic shape!

39. The sugar and phosphate form the backbone for the nucleic acid or polynucleotide
Sugar-phosphate
backbone T G C A
Nucleotide
Figure 3.16B

40. DNA consists of two polynucleotides twisted around each other in a double helix, the two strands run antiparallel to each other
Stretches of a DNA molecule called genes program the amino acid sequences of proteins C T A G
Base
pair
Figure 3.16C

41. RNA, by contrast is a single-stranded polynucleotide
RNA, by contrast is a single-stranded polynucleotide
RNA, when compared to DNA, is:
Shorter
Single stranded
Has a U base (uracil) instead of a T base (thymine)
Has MANY more types/jobs, ex: messenger, transfer, ribosomal etc

42. ATP – Adenosine Triphosphate
Produced by cellular respiration
Glucose + oxygen -
Carbon dioxide + water + ATP
ATP – needed for active transport
Notice – 2 high energy bonds
Synthesis of –
ADP + Pi → ATP + H2O

43. Nucleic Acids Comparison
Molecule
ATP
DNA
RNA
Structure
Nucleotide
Double stranded molecule
Single
Stranded molecule
Sugar
Ribose
Deoxyribose
BASES A
A,C,T,G
A. C, U,G
Uses
Energy
Information
Information,
many others