The Chemistry of Microbiology Flashcards
1
Q
What is matter?
A
Anything that takes up space and has mass
2
Q
What are the smallest chemical units of matter?
A
Atoms
3
Q
Describe the 3 subatomic particles found in an atom
A
- Electrons - negatively charged - found orbiting the nucleus
- Protons - positively charged - found in the nucleus
- Neutrons - no charge - found in the nucleus
4
Q
Which of the subatomic particles are found in the nucleus?
A
Protons and neutrons
5
Q
How is the hydrogen atom an exception with regard to its nucleus?
A
The nucleus is composed of only a single proton and no neutrons
6
Q
Why do electrons determine an atom’s chemical behavior?
A
Only electrons come close enough to interact with another atom
7
Q
What is an electron shell?
A
Allow electrons to orbit the nucleus
8
Q
How many electrons make up the first and second shell of all atoms?
A
- First shell - 2 electrons
- Second shell - 8 electrons
9
Q
What is the valence shell? (2)
A
- The outermost shell
- Holds a specific number of electrons which determines the atom’s reactivity
10
Q
When are atoms most stable?
A
When their valence shell is full
11
Q
When are atoms most unstable? (2)
A
- When an atom has extra protons or neutrons
- When an atom has unfilled shells
12
Q
Describe significance of an unfilled valence shell with respect to chemical bond formation (2)
A
- Atoms with unfilled shells transfer electrons with other atoms to become more stable
- Bonds are formed in order for each atom to fulfill the octet rule (8 electrons)
13
Q
What is a covalent bond?
A
Results from the sharing of a pair of electrons by two atoms
14
Q
What is the relative strength of a covalent bond?
A
Strong
15
Q
What is a molecule?
A
Multiple atoms sharing 2 pairs of electrons to form a covalent bond
16
Q
What is the difference between a single covalent bond and a double covalent bond?
A
- Single covalent bond - atoms share 1 pair of electrons
- Double covalent bond - atoms share 2 pairs of electrons
17
Q
What term is used to refer to the attraction of an atom for electrons?
A
Electronegativity
18
Q
What is a nonpolar covalent bond?
A
Neither nucleus acts as a ‘pole’ to exert an unequal pull
19
Q
What is a polar covalent bond? (3)
A
- Bonds with unequal sharing of electrons
- Atoms with significantly different electronegativities combine
- Electrons will spend more time orbiting the ‘pole’ (nucleus of the atoms with the greater electronegativity)
20
Q
Which type of covalent bond results in partial charges within the molecule?
A
Polar covalent bond
21
Q
How and why do sodium and chlorine atoms form an ionic bond? (3)
A
- Chlorine has 7 electrons and sodium has 1 electrons
- Sodium loses an electron and becomes positively charged
- Chlorine gains an electron and becomes negatively charged
22
Q
What is an ion?
A
A charged atom
23
Q
Differentiate between cations and anions
A
- Cations - positively charged ions
- Anions - negatively charged ions
24
Q
What is an ionic bond?
A
2 atoms with vastly different electronegativities approach each other and the atom with the higher electronegativity will steal one or more electron from the valence shell of the other atom
25
What is the relative strength of an individual ionic bond?
Weak
26
Describe the fundamental difference between a covalent bond and an ionic bond with respect to electron sharing vs transfer of electrons (2)
- Covalent bonding involves the sharing of electrons between atoms
- Ionic bonding involves the transfer of electrons due to the attraction of opposing cations and anions (no sharing of electrons)
27
What are electrolytes?
Cations and anions dissociated in water
28
How are electrolytes formed in an aqueous environment?
Substances dissolve in water to yield ions called electrolytes
29
Define a hydrogen bond
A bond that is essential to life and does not involve the sharing of electrons
30
What is the relative strength of an individual hydrogen bond?
Weak
31
Describe acids
Dissociate into one or more hydrogen ions (H+) and anions (give off protons)
32
Describe bases
Bind with H+ when dissolved in water (accumulate protons)
33
What are the ionic components of water (H2O)?
H+ (hydrogen ions) and OH- (hydroxyl ions)
34
What does the pH scale express (what does it reveal about a given solution)?
The concentration of hydrogen ions in a solution
35
What is the relationship between acidity and the pH values associated with the pH scale? (3)
- Acidity increases as pH value decreases
- Less than 7.0 = acidic (excess protons)
- Greater than 7.0 = basic (excess hydroxyls)
36
Using numerical pH values, differentiate among acidic, neutral, and basic aqueous solutions (ex. lemon juice, with a pH of 2.0, is very acidic)
2 - lemon juice
3 - vinegar
4 - wine
5 - black coffee
6 - milk
7 - pure water
8 - sea water
9 - baking soda
37
What are the 4 classes of organic macromolecules?
- Proteins
- Carbohydrates
- Lipids
- Nucleic acids
38
What is a functional group?
Common arrangements of atoms (organic macromolecules)
39
Identify the functional group
Hydroxyl
40
Identify the functional group
Ether
41
Identify the functional group
Interal carbonyl
42
Identify the functional group
Terminal carbonyl
43
Identify the functional group
Carboxyl
44
Identify the functional group
Amino
45
Identify the functional group
Ester
46
Identify the functional group
Sulfhydryl
47
Identify the functional group
Organic phosphate
48
Briefly describe the chemical composition of a lipid - what is it primarily made of and how are the atoms held together?
Organic macromolecules composed almost entirely of carbon and hydrogen atoms linked by nonpolar covalent bonds
49
Are lipids polar or nonpolar molecules?
Nonpolar
50
What are the 4 major groups of lipids?
- Fats
- Phospholipids
- Waxes
- Steroids
51
What are fats composed of?
Three fatty acid chains and a glycerol molecule joined via dehydration synthesis
52
What are phospholipids composed of?
Two fatty acid chains and a phosphate group attached to a glycerol backbone
53
Describe the characteristics of a fatty acid tail (2)
- Nonpolar
- Hydrophobic
54
Describe the characteristics of a phospholipid head (2)
- Polar
- Hydrophilic
55
What are the 3 elements that make up carbohydrates?
- Carbon
- Hydrogen
- Oxygen
56
What is the chemical structure of carbohydrates?
CH₂O
57
What are the functions of carbohydrates? (3)
- Transient
- Long-term storage of energy
- Structural components of DNA, RNA, and some cell walls
58
What are the 3 basic groups of carbohydrates?
- Monosaccharides
- Disaccharides
- Polysaccharides
59
Describe monosaccharides
Simple sugars that can exist as either linear or cyclic molecules (usually cyclic)
60
Describe disaccharides
Two monosaccharides linked together via dehydration synthesis
61
Describe polysaccharides
Polymers composed of tens, hundreds, or thousands of monosaccharides linked via dehydration synthesis
62
What type of bonds are present in polysaccharides?
Covalent glycosidic bonds
63
What are some examples of monosaccharides? (2)
- Glucose
- Fructose
64
What are some examples of disaccharides? (3)
- Sucrose
- Lactose
- Maltose
65
What are some examples of polysaccharides? (2)
- Cellulose
- Glycogen
66
What is the monomeric subunit of a polysaccharide?
Monosaccharides
67
What do glycosidic bonds create? (2)
- Link glucose and fructose to create sucrose
- Link monosaccharides to create polysaccharides
68
Where are glycosidic bonds found? (2)
- Polysaccharides
- Between cellulose subunits
69
What are the most complex organic macromolecules?
Proteins
70
What are the functions of proteins? (5)
- Structural components of cells
- Enzymatic catalysts
- Activity regulation
- Defense molecules
- Substance transport
71
What is the monomeric subunit of a polypeptide?
Amino acids
72
What are the structural components of an amino acid? (5)
- Central (alpha) carbon
- Carboxyl group
- Amino group
- Side group (varies according to the amino acid)
- Hydrogen atoms
73
What special term is used to describe the covalent bond between amino acids?
Peptide bond
74
Describe the synthesis reaction used in the polymerization of a polypeptide and indicate the functional groups involved (3)
- A covalent bond is formed between the carboxyl group of one amino acid and the amino group on the next amino acid in the chain
- Dehydration synthesis occurs
- Results in a dipeptide molecule composed of two amino acids linked together by a single peptide bond
75
Describe a protein’s primary structure
The linear sequence of amino acids
76
Describe a protein’s secondary structure
Ionic bonds, hydrogen bonds, and hydrophobic / hydrophilic characteristics cause many polypeptide chains to fold into either alpha-helices or beta-pleated sheets
77
Describe a protein’s tertiary structure
The complex, three-dimensional shape of a single polypeptide
78
Describe a protein’s quaternary structure
Two or more polypeptides linked together via disulfide bridges or other bonds
79
What are alpha-helices?
Polypeptide chains folded into coils
80
What are beta-pleated sheets?
Polypeptide chains folded into accordion-like structures
81
At what level of the protein structure are alpha-helices and beta-pleated sheets found?
Secondary structure
82
Describe denaturation (3)
- A protein loses its structure due to physical factors that interfered with hydrogen and ionic bonding
- Disrupts the three-dimensional structure of the protein (reverts to its primary structure)
- Results in loss of function of the protein
83
Indicate physical or chemical factors that can cause proteins to become denatured (3)
- Heat
- Changes in pH
- Salt concentration
