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MICRB 106 - Exam 1 > The Chemistry of Microbiology > Flashcards

The Chemistry of Microbiology Flashcards

1
Q

What is matter?

A

Anything that takes up space and has mass

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2
Q

What are the smallest chemical units of matter?

A

Atoms

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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
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4
Q

Which of the subatomic particles are found in the nucleus?

A

Protons and neutrons

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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

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6
Q

Why do electrons determine an atom’s chemical behavior?

A

Only electrons come close enough to interact with another atom

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7
Q

What is an electron shell?

A

Allow electrons to orbit the nucleus

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8
Q

How many electrons make up the first and second shell of all atoms?

A
  • First shell - 2 electrons
  • Second shell - 8 electrons
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9
Q

What is the valence shell? (2)

A
  • The outermost shell
  • Holds a specific number of electrons which determines the atom’s reactivity
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10
Q

When are atoms most stable?

A

When their valence shell is full

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11
Q

When are atoms most unstable? (2)

A
  • When an atom has extra protons or neutrons
  • When an atom has unfilled shells
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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)
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13
Q

What is a covalent bond?

A

Results from the sharing of a pair of electrons by two atoms

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14
Q

What is the relative strength of a covalent bond?

A

Strong

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15
Q

What is a molecule?

A

Multiple atoms sharing 2 pairs of electrons to form a covalent bond

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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
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17
Q

What term is used to refer to the attraction of an atom for electrons?

A

Electronegativity

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18
Q

What is a nonpolar covalent bond?

A

Neither nucleus acts as a ‘pole’ to exert an unequal pull

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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)
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20
Q

Which type of covalent bond results in partial charges within the molecule?

A

Polar covalent bond

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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
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22
Q

What is an ion?

A

A charged atom

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23
Q

Differentiate between cations and anions

A
  • Cations - positively charged ions
  • Anions - negatively charged ions
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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

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25
Q

What is the relative strength of an individual ionic bond?

A

Weak

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26
Q

Describe the fundamental difference between a covalent bond and an ionic bond with respect to electron sharing vs transfer of electrons (2)

A
  • 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)
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27
Q

What are electrolytes?

A

Cations and anions dissociated in water

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28
Q

How are electrolytes formed in an aqueous environment?

A

Substances dissolve in water to yield ions called electrolytes

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29
Q

Define a hydrogen bond

A

A bond that is essential to life and does not involve the sharing of electrons

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30
Q

What is the relative strength of an individual hydrogen bond?

A

Weak

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31
Q

Describe acids

A

Dissociate into one or more hydrogen ions (H+) and anions (give off protons)

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32
Q

Describe bases

A

Bind with H+ when dissolved in water (accumulate protons)

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33
Q

What are the ionic components of water (H2O)?

A

H+ (hydrogen ions) and OH- (hydroxyl ions)

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34
Q

What does the pH scale express (what does it reveal about a given solution)?

A

The concentration of hydrogen ions in a solution

35
Q

What is the relationship between acidity and the pH values associated with the pH scale? (3)

A
  • Acidity increases as pH value decreases
  • Less than 7.0 = acidic (excess protons)
  • Greater than 7.0 = basic (excess hydroxyls)
36
Q

Using numerical pH values, differentiate among acidic, neutral, and basic aqueous solutions (ex. lemon juice, with a pH of 2.0, is very acidic)

A

2 - lemon juice
3 - vinegar
4 - wine
5 - black coffee
6 - milk
7 - pure water
8 - sea water
9 - baking soda

37
Q

What are the 4 classes of organic macromolecules?

A
  • Proteins
  • Carbohydrates
  • Lipids
  • Nucleic acids
38
Q

What is a functional group?

A

Common arrangements of atoms (organic macromolecules)

39
Q

Identify the functional group

A

Hydroxyl

40
Q

Identify the functional group

A

Ether

41
Q

Identify the functional group

A

Interal carbonyl

42
Q

Identify the functional group

A

Terminal carbonyl

43
Q

Identify the functional group

A

Carboxyl

44
Q

Identify the functional group

A

Amino

45
Q

Identify the functional group

A

Ester

46
Q

Identify the functional group

A

Sulfhydryl

47
Q

Identify the functional group

A

Organic phosphate

48
Q

Briefly describe the chemical composition of a lipid - what is it primarily made of and how are the atoms held together?

A

Organic macromolecules composed almost entirely of carbon and hydrogen atoms linked by nonpolar covalent bonds

49
Q

Are lipids polar or nonpolar molecules?

A

Nonpolar

50
Q

What are the 4 major groups of lipids?

A
  • Fats
  • Phospholipids
  • Waxes
  • Steroids
51
Q

What are fats composed of?

A

Three fatty acid chains and a glycerol molecule joined via dehydration synthesis

52
Q

What are phospholipids composed of?

A

Two fatty acid chains and a phosphate group attached to a glycerol backbone

53
Q

Describe the characteristics of a fatty acid tail (2)

A
  • Nonpolar
  • Hydrophobic
54
Q

Describe the characteristics of a phospholipid head (2)

A
  • Polar
  • Hydrophilic
55
Q

What are the 3 elements that make up carbohydrates?

A
  • Carbon
  • Hydrogen
  • Oxygen
56
Q

What is the chemical structure of carbohydrates?

A

CH₂O

57
Q

What are the functions of carbohydrates? (3)

A
  • Transient
  • Long-term storage of energy
  • Structural components of DNA, RNA, and some cell walls
58
Q

What are the 3 basic groups of carbohydrates?

A
  • Monosaccharides
  • Disaccharides
  • Polysaccharides
59
Q

Describe monosaccharides

A

Simple sugars that can exist as either linear or cyclic molecules (usually cyclic)

60
Q

Describe disaccharides

A

Two monosaccharides linked together via dehydration synthesis

61
Q

Describe polysaccharides

A

Polymers composed of tens, hundreds, or thousands of monosaccharides linked via dehydration synthesis

62
Q

What type of bonds are present in polysaccharides?

A

Covalent glycosidic bonds

63
Q

What are some examples of monosaccharides? (2)

A
  • Glucose
  • Fructose
64
Q

What are some examples of disaccharides? (3)

A
  • Sucrose
  • Lactose
  • Maltose
65
Q

What are some examples of polysaccharides? (2)

A
  • Cellulose
  • Glycogen
66
Q

What is the monomeric subunit of a polysaccharide?

A

Monosaccharides

67
Q

What do glycosidic bonds create? (2)

A
  • Link glucose and fructose to create sucrose
  • Link monosaccharides to create polysaccharides
68
Q

Where are glycosidic bonds found? (2)

A
  • Polysaccharides
  • Between cellulose subunits
69
Q

What are the most complex organic macromolecules?

A

Proteins

70
Q

What are the functions of proteins? (5)

A
  • Structural components of cells
  • Enzymatic catalysts
  • Activity regulation
  • Defense molecules
  • Substance transport
71
Q

What is the monomeric subunit of a polypeptide?

A

Amino acids

72
Q

What are the structural components of an amino acid? (5)

A
  • Central (alpha) carbon
  • Carboxyl group
  • Amino group
  • Side group (varies according to the amino acid)
  • Hydrogen atoms
73
Q

What special term is used to describe the covalent bond between amino acids?

A

Peptide bond

74
Q

Describe the synthesis reaction used in the polymerization of a polypeptide and indicate the functional groups involved (3)

A
  • 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
Q

Describe a protein’s primary structure

A

The linear sequence of amino acids

76
Q

Describe a protein’s secondary structure

A

Ionic bonds, hydrogen bonds, and hydrophobic / hydrophilic characteristics cause many polypeptide chains to fold into either alpha-helices or beta-pleated sheets

77
Q

Describe a protein’s tertiary structure

A

The complex, three-dimensional shape of a single polypeptide

78
Q

Describe a protein’s quaternary structure

A

Two or more polypeptides linked together via disulfide bridges or other bonds

79
Q

What are alpha-helices?

A

Polypeptide chains folded into coils

80
Q

What are beta-pleated sheets?

A

Polypeptide chains folded into accordion-like structures

81
Q

At what level of the protein structure are alpha-helices and beta-pleated sheets found?

A

Secondary structure

82
Q

Describe denaturation (3)

A
  • 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
Q

Indicate physical or chemical factors that can cause proteins to become denatured (3)

A
  • Heat
  • Changes in pH
  • Salt concentration

MICRB 106 - Exam 1 (3 decks)

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