Topic 1 review
Name __________________________________
1. Explain the difference in mass and weight.
The quantity of matter contained in a body, while weight is the force by which the body is pulled to the earth’s
surface
2. What is the relationship between elements and compounds?
An element is a substance that cannot be broken down to other substances by chemical reactions
A compound is a substance consisting of two or more elements in a fixed ratio
3. What elements are essential to life? Why are these different than trace elements?
About 25 of the 92 elements are essential to life. Carbon, hydrogen, oxygen, and nitrogen make up 96% of
living matter. Most of the remaining 4% consists of calcium, phosphorus, potassium, and sulfur. Trace
elements are those required by an organism in minute quantities
4. Draw or explain the structure and arrangement of particles in an atom. Include charges of particles.
Atoms are composed of subatomic particles
Relevant subatomic particles include:
a. Neutrons (no electrical charge)
b. Protons (positive charge)
c. Electrons (negative charge)
Cloud of negative
charge (2
electrons)
5. What is the difference in atomic mass and atomic number?
An element’s atomic number is the number of protons in its nucleus
An element’s mass number is the sum of protons plus neutrons in the nucleus
Atomic mass, the atom’s total mass, can be approximated by the mass number
6. How do isotopes differ from one another?
Isotopes are two atoms of an element that differ in number of neutrons
7. List the types of bonds from strongest to weakest.
a. Strongest chemical bonds—covalent and ionic (weaker of the two)
b. Weakest—hydrogen, and Van der Waals
8. How is a covalent bond different from an ionic bond?
Covalent Bond
• Forms by the sharing of a pair of valence electrons
• May share one, two, or three pairs of electrons
• H-H
• O=O
• NN
• Maybe polar or nonpolar depending on the electronegativity of atoms involved
Ionic Bond
-Involves the complete transfer of electrons between atoms
9. A hydrogen bond forms between what elements?
Hydrogen atom covalently bonded to one electronegative atom is attracted to another electronegative atom.
Weak, readily formed and broken
Hold water molecules together
Usually involves O or N
10. Explain the difference in polar covalent and nonpolar covalent bonds.
• Nonpolar—electrons are shared equally between atoms
-molecules made of one element usually have this type of covalent bond (H2, N2, Cl2)
• Polar—sharing of electrons is not equal
-electrons spend more time around more electronegative element
-water: O is more electronegative than H
11. What element in water is highly electronegative?
O
12. Explain how water molecules form hydrogen bonds.
• Has polar bonds
• Water has polar covalent bonds
• Oxygen is more electronegative than H
• Electrons of covalent bonds spend more time closer to Oxygen than to H
• Creates a polar molecule
• O region is partially negative
• H regions are partially positive
• Causes the anomalous properties of water
13. What other polymer in the human body is held together by hydrogen bonds? Ammonia
14. Ionic bonds result in forming __neutral charge______________.
15. Describe the placement of products and reactants in a chemical equation.
a. Reactants = Substances existing before the reaction
b. Products = Substances existing after the reaction
16. What does a double arrow mean? Reversible reaction.
17. Explain how water is polar. How many hydrogen bonds can it form?
Polar molecule (opposite charges on opposite sides)
H bonded to O by polar covalent bonds
Polarity allows water molecules to form hydrogen bonds with each other
Each water molecule can form 4 hydrogen bonds with 4 other water molecules
18. What are the four emergent properties of water?
a. Cohesive behavior
b. Ability to moderate temperature
c. Expansion upon freezing
d. Versatility as a solvent
19. What is the difference in cohesion and adhesion?
Collectively, hydrogen bonds hold water molecules together, a phenomenon called cohesion
Cohesion helps the transport of water against gravity in plants
Adhesion is an attraction between different substances, for example, between water and plant cell walls
Both of the above qualities can cause water to move upward through narrow tubes, which is an action know as
______capillary action_______________________.
20. Explain how these properties allow transpiration to occur.
21. Why does ice float?
Ice floats in liquid water because hydrogen bonds in ice are more “ordered,” making ice less dense
Water reaches its greatest density at 4°C
Therefore, water expands when it freezes
22. What is the relationship between solute, solvent, and solution?
A solution is a liquid that is a homogeneous mixture of substances
A solvent is the dissolving agent of a solution
The solute is the substance that is dissolved
23. What does hydrophobic and hydrophilic mean in terms of solubility?
A hydrophilic (water-loving)substance is one that has an affinity for water
A hydrophobic substance is one that does not have an affinity for water
24. Explain the pH scale in terms of where neutral, acidic and alkaline substances are found.
An acid is any substance that increases the H+ concentration of a solution
A base is any substance that reduces the H+ concentration of a solution
 In any aqueous solution at 25°C the product of H+ and OH– is constant and can be written as
[H+][OH–] = 10–14
 The pH of a solution is defined by the negative logarithm of H+ concentration, written as
pH = –log [H+]
 For a neutral aqueous solution
[H+] is 10–7 = –(–7) = 7
• hydroxide ion –
OHThe water molecule that lost the proton
Has a charge of 1-
• Hydronium ion –
0+
H3
Occurs when the proton binds to another water molecule
This reaction is reversible
• Acids
Acidic
When dissolve in water, donate additional H+ to solution
Substance that increases the hydrogen ion concentration of a solution
25. In each of the above solutions, what is the ratio of hydrogen to hydroxide ions?
26. What do buffers do?
Buffers are substances that minimize changes in concentrations of H+ and OH– in a solution
27. What is an organic compound? Who proposed that they could spontaneously arise? Describe that
experiment.
Organic compounds range from simple molecules to colossal ones
Most organic compounds contain hydrogen atoms in addition to carbon atoms
Stanley Miller - Experimented to see if complex organic molecules could arise spontaneously under conditions
thought to have existed on the early Earth. His experiment supported the idea that abiotic synthesis of organic
compounds could have been an early stage in the origin of life
28. Why is carbon perfectly suited to form large molecules?
Carbon atom
• Atomic number 6 (6 protons, 6 electrons, 6 neutrons)
• 4 valance electrons
• Forms 4 covalent bonds usually with H, O, N, C
• Can form large, complex molecules
29. What are isomers? Give an example.
. Isomers are compounds with the same molecular formula but different structures and properties.
Three types of isomers:
Structural Isomers
• Have different covalent arrangements of their atoms
• Number of possible isomers increases as C skeleton size increases
• Ex:
C5 H13—3 isomers
C8 H18—18 isomers
C20 H42—366,319 isomers
• May differ in location of double bonds
Geometric isomers
• Have the same covalent arrangements but differ in spatial arrangements
• Result from the fact that double bonds will not allow the atoms they join to rotate freely about the axis
of the bonds
• Subtle differences between isomers affects their biological activity
. Enantiomers
• Are isomers that are mirror images of each other
•
•
•
•
Can occur when 4 different atoms or groups of atoms are bonded to the same carbon (asymmetric
carbon)
Usually one form is biologically active and its mirror image is not
Important in the pharmaceutical industry
Two enantiomers of a drug may have different effects
30. Identify the functional groups.
Functional groups are the components of organic molecules that are most commonly involved in chemical
reactions
The seven functional groups that are most important in the chemistry of life:
 Hydroxyl group
 R—OH
 Consists of a hydrogen atom bonded to an oxygen atom, which is bonded to carbon
 Carbonyl group
 (-CO)
 Carboxyl group
 (-COOH)
 Amino group
 (-NH2)
 Sulfhydryl group
 (-SH)
 Phosphate group
 (H3PO4)
 Methyl group
 (-CH3)
31. What is the relationship between dehydrations reactions and hydrolysis?
Monomers are connected by covalent bonds that form through the loss of a water molecule by condensation
reaction or more specifically a dehydration reaction
Polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the reverse of the
dehydration reaction
32. What is the relationship between polymers and monomers?
A polymer is a long molecule consisting of many similar building blocks
These small building-block molecules are called monomers
33. List the four organic compounds required for life and the building blocks of each one.
1. Carbohydrates
The simplest carbohydrates are monosaccharides, or single sugars
Carbohydrate macromolecules are polysaccharides, polymers composed of many sugar building blocks . have
molecular formulas that are usually multiples of CH2O. A disaccharide is formed when a dehydration reaction
joins two monosaccharides. This covalent bond is called a glycosidic linkage
2. Lipids
Lipids are the one class of large biological molecules that do not form polymers. The unifying feature of lipids
is having little or no affinity for water. Lipids are hydrophobic because they consist mostly of hydrocarbons,
which form nonpolar covalent bonds. The most biologically important lipids are fats, phospholipids, and
steroids. Fats are constructed from two types of smaller molecules: glycerol and fatty acids. The glycerol is
linked to the fatty acids by an ester linkage (bond formed between a hydroxyl group and a carboxyl group)
creating a triacylglycerol, or triglyceride. In a phospholipid, two fatty acids and a phosphate group are
attached to glycerol. Steroids are lipids characterized by a carbon skeleton consisting of four fused rings
3. Proteins
Proteins are the most structurally complex molecules known. A protein consists of one or more polypeptides.
Amino Acid Monomers - Amino acids are organic molecules with carboxyl and amino groups.
Amino Acid Polymers
• Amino acids are linked by peptide bonds
• A polypeptide is a polymer of amino acids
• Polypeptides range in length from a few to more than a thousand monomers
• Each polypeptide has a unique linear sequence of amino acids
4. Nucleic acids
There are two types of nucleic acids:
a. Deoxyribonucleic acid (DNA)
b. Ribonucleic acid (RNA)
DNA provides directions for its own replication
DNA directs synthesis of messenger RNA (mRNA) and, through mRNA, controls protein synthesis
Protein synthesis occurs in ribosomes
34. What are carbs used as in the body? Sugar. Storage.
Glucose (C6H12O6) is the most common monosaccharide
Monosaccharides are classified by
a. The location of the carbonyl group (as aldose or ketose)
b. The number of carbons in the carbon skeleton
-triose—3C—glyceraldehyde
-pentose—5C—ribose
-hexose—6C—glucose
35. Identify starch, glucose, cellulose, ribose, and glycogen as mono or polysaccharide.
Storage Polysaccharides
a. Starch, a storage polysaccharide of plants, consists entirely of glucose monomers. Plants store surplus
starch as granules within chloroplasts and other plastids
Glycogen is a storage polysaccharide in animals
• Humans and other vertebrates store glycogen mainly in liver and muscle cells
The polysaccharide cellulose is a major component of the tough wall of plant cells
• Like starch, cellulose is a polymer of glucose, but the glycosidic linkages differ
• The difference is based on two ring forms for glucose: alpha () and beta ()
Glucose and fructose are hexoses and have six carbons
Disaccharide
Monomers
Maltose
glucose + glucose
Sucrose (table sugar)
glucose + fructose
Lactose (milk sugar)
glucose + galactose
36. What is the difference between starch and glycogen?
Starch - Plant polysaccharide
• Two forms
Amylose (unbranched)
Amylopectin (branched)
• Plants store starch as granules within cellular plastids
Include chloroplasts
Glycogen - Humans store this in liver and muscle cells
• Hydrolysis releases glucose when the demand for sugar increases
• Cannot sustain an animal for long
• Stores are depleted in about a day unless they are replenished by consumption of food
37. What is the difference between cellulose and chitin?
The polysaccharide cellulose is a major component of the tough wall of plant cells
• Like starch, cellulose is a polymer of glucose, but the glycosidic linkages differ
• The difference is based on two ring forms for glucose: alpha () and beta ()
Chitin, another structural polysaccharide, is found in the exoskeleton of arthropods
• Chitin also provides structural support for the cell walls of many fungi
38. Why aren’t lipids polymers? What are some examples?
Fats, phospholipids, and steroids
39. Explain the difference in saturated and unsaturated fats.
Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds
i. Solid at room temperature
ii. Most are animal fats
iii. Bad health wise
Single carbon to carbon bonds
Unsaturated fatty acids have one or more double bonds
• Fatty acids vary in number and location of double bonds
• Tail kinks at CC so molecules do not pack closely enough to solidify at room
temperature
• Usually liquid at room temperature
• Plant fats and fish fats are usually
40. Why are they also known as triglycerides?
Fats are constructed from two types of smaller molecules: glycerol and fatty acids
Glycerol is a three-carbon alcohol with a hydroxyl group attached to each carbon
A fatty acid consists of a carboxyl group attached to a long carbon skeleton
The glycerol is linked to the fatty acids by an ester linkage (bond formed between a hydroxyl group and a
carboxyl group) creating a triacylglycerol, or triglyceride
41. What is the function of lipids in the body?
The major function of fats is energy storage
• Humans and other mammals store their fat in adipose cells
• Adipose tissue also cushions vital organs and insulates the body
The structure of phospholipids results in a bilayer arrangement found in cell membranes
• Phospholipids are the major component of all cell membranes
42. What are phospholipids? Why are they important?
In a phospholipid, two fatty acids and a phosphate group are attached to glycerol. The structure of
phospholipids results in a bilayer arrangement found in cell membranes
• Phospholipids are the major component of all cell membranes
43. What is the structure of steroids? What are examples of steroids?
Steroids are lipids characterized by a carbon skeleton consisting of four fused rings
Cholesterol, an important steroid, is a component in animal cell membranes and is also the precursor for
steroids like estrogen and testosterone
Although cholesterol is essential in animals, high levels in the blood may contribute to cardiovascular disease
44. What constitutes an amino acid?
Amino Acid Monomers
•
•
Amino acids are organic molecules with carboxyl and amino groups
Amino acids differ in their properties due to differing side chains, called R groups
45. What does a peptide bond do?
Amino Acid Polymers
• Amino acids are linked by peptide bonds
• A polypeptide is a polymer of amino acids
• Polypeptides range in length from a few to more than a thousand monomers
• Each polypeptide has a unique linear sequence of amino acids
46. Explain the four levels of protein structure.
 The primary structure of a protein is its unique sequence of amino acids
 Secondary structure, found in most proteins, consists of coils and folds in the polypeptide chain
 The coils and folds of secondary structure result from hydrogen bonds between repeating
constituents of the polypeptide backbone
 Typical secondary structures are a coil called an  helix and a folded structure called a 
pleated sheet


Tertiary structure is determined by interactions among various side chains (R groups)
 Is determined by interactions between R groups, rather than interactions between backbone
constituents
 These interactions between R groups include hydrogen bonds, ionic bonds, hydrophobic
interactions, and van der Waals interactions
 Strong covalent bonds called disulfide bridges may reinforce the protein’s structure
Quaternary structure results when a protein consists of multiple polypeptide chains
 Results when two or more polypeptide chains form one macromolecule
 Collagen is a fibrous protein consisting of three polypeptides coiled like a rope
 Hemoglobin is a globular protein consisting of four polypeptides: two alpha and two beta chains
47. Why is the shape of a protein important?
A slight change in primary structure can affect a protein’s structure and ability to function
48. What is the conformation of a protein? How is that changed? And what do we call it when that
happens?
Protein conformation—3-D shape of a protein
In addition to primary structure, physical and chemical conditions can affect structure
Alterations in pH, salt concentration, temperature, or other environmental factors can cause a protein to
unravel
This loss of a protein’s native structure is called denaturation
A denatured protein is biologically inactive
A protein’s function depends on it’s unique conformation which is determined by the order of aa.
It is hard to predict a protein’s structure from its primary structure
Most proteins probably go through several states on their way to a stable structure
Chaperonins are protein molecules that assist the proper folding of other proteins and keep new
polypeptides segregated from “bad environmental influences” while it folds
49. What are the common nucleic acids?
There are two types of nucleic acids:
a. Deoxyribonucleic acid (DNA)
b. Ribonucleic acid (RNA)
DNA provides directions for its own replication
DNA directs synthesis of messenger RNA (mRNA) and, through mRNA, controls protein synthesis
Protein synthesis occurs in ribosomes
50. How are the different from one another? (4 ways)
1 - Nucleic acids are polymers called polynucleotides
2 - Each polynucleotide is made of monomers called nucleotides
3 - Each nucleotide consists of a nitrogenous base, a pentose sugar, and a phosphate group
4 - The portion of a nucleotide without the phosphate group is called a nucleoside
RNA – single stranded, contains sugar ribose, directs synthesis of protein
DNA – double stranded, contains sugar deoxyribose, resides in the nucleus
51. What are the three parts to a nucleotide?
Three parts:
a. Nitrogenous base
b. 5-Carbon Sugar (pentose)
c. Phosphate group
52. Make sure to know the summary table on p.42.
53. Answer the multiple choice and free response questions on p.42-46. Then check your answers in the
back.