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Biochemistry Flashcards

1
Q

What is a chemical element?

A

A fundamental substance composed of atoms that have the same atomic number and behave the same way chemically

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2
Q

What type of bond holds the following atoms together?

Li+ and Cl- in LiCl

A

Ionic

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3
Q

What type of bond holds the following atoms together?

carbon and oxygen atoms in methanol

A

single covalent bond

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4
Q

What type of bond holds the following atoms together?

oxygen atoms in O2

A

double covalent bond

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5
Q

What type of bond holds the following atoms together?

A hydrogen atom of one nucleotide to a nitrogen or oxygen atom of another nucleotide in DNA

A

Hydrogen bond

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6
Q

Classify the following chemical reaction

glucose + fructose -> sucrose + H2O

A

Synthesis reaction, condensation, or dehydration

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7
Q

Classify the following chemical reaction

lactose -> glucose + galactose

A

Decomposition reaction, digestion, or hydrolysis

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8
Q

Classify the following chemical reaction

NH4Cl + H2O -> NH4OH + HCl

A

Exchange reaction

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9
Q

Classify the following chemical reaction

ATP ADP + Pi

A

Reversible reaction

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10
Q

Bacteria use the enzyme urease to obtain nitrogen in a form they can use from urea in the following reaction

CO(NH2)2 (urea) + H2O -> 2NH3 (ammonia) + CO2

What purpose does the enzyme serve in this reaction? What type of reaction is this?

A

The enzyme speeds up this decomposition reaction

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11
Q

Classify the following as subunits of either a carbohydrate, lipid, protein, or nucleic acid

CH3 - (CH2)7 - CH = CH - (CH2)7 - COOH

A

Lipid

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12
Q

Classify the following as subunits of either a carbohydrate, lipid, protein, or nucleic acid

       NH2
        |
H – C – COOH 
        |
       CH2
        |
      OH (serine)
A

Protein

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13
Q

Classify the following as subunits of either a carbohydrate, lipid, protein, or nucleic acid

C6H12O6

A

Carbohydrate

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14
Q

Classify the following as subunits of either a carbohydrate, lipid, protein, or nucleic acid

Thymine nucleotide

A

Nucleic acid

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15
Q

What type of microorganism has a chitin cell wall, has DNA that is contained in a nucleus, and has ergosterol in its plasma membrane?

A

Fungus

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16
Q

Radioisotopes are frequently used to label molecules in a cell. The fate of atoms and molecules in a cell can then be followed. Assume E. coli bacteria are grown in a nutrient medium containing the radioisotope 16N. After a 48 hour incubation period, the 16N would most likely be found in the E. colis

a) carbohydrates
b) lipids
c) proteins
d) water
e) none of the above

A

C

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17
Q

Radioisotopes are frequently used to label molecules in a cell. The fate of atoms and molecules in a cell can then be followed. If Pseudomonas bacteria are supplied with radioactively labeled cytosine, after a 24 hour incubation period this cytosine would most likely be found in the cells’

a) carbohydrate
b) DNA
c) lipids
d) water
e) proteins

A

B

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18
Q

Radioisotopes are frequently used to label molecules in a cell. The fate of atoms and molecules in a cell can then be followed. If E. coli were grown in a medium containing the radioactive isotope 32P, the 32P would be found in all of the following molecules of the cell EXCEPT

a) ATP
b) carbohydrates
c) DNA
d) plasma membrane
e) none of the above

A

B

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19
Q

The optimum pH of Acidithiobacillus bacteria (pH 3) is ____ times more acid than blood (pH 7)

a) 4
b) 10
c) 100
d) 1000
e) 10 000

A

E

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20
Q

The best definition of ATP is that it is

a) a molecule stored for food use
b) a molecule that supplies energy to do work
c) a molecule stored for an energy reserve
d) a molecule used as a source of phosphate

A

B

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21
Q

Which of the following is an organic molecule

a) H2O (water)
b) O2 (oxygen)
c) C18H29SO3 (Styrofoam)
d) FeO (iron oxide)
e) F2C=CF2 (Teflon)

A

C

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22
Q

Classify the molecule on the left as an acid, base, or salt. The dissociation products of the molecules are shown to help you.

HNO3 -> H+ + NO3-

A

acid

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23
Q

Classify the molecule on the left as an acid, base, or salt. The dissociation products of the molecules are shown to help you.

H2SO4 -> 2H+ + SO4-

A

acid

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24
Q

Classify the molecule on the left as an acid, base, or salt. The dissociation products of the molecules are shown to help you.

NaOH -> Na+ + OH-

A

base

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25
Q

Classify the molecule on the left as an acid, base, or salt. The dissociation products of the molecules are shown to help you.

MgSO4 -> Mg2+ + SO4-

A

salt

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26
Q

Which type of molecule contains –NH2 groups?

a. Lipid
b. Nucleic acid
c. Proteins
d. Carbohydrates

A

C

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27
Q

What is the overall three-dimensional shape of a polypeptide is called?

a. Primary structure
b. Secondary structure
c. Tertiary structure
d. Quaternary structure
e. Double helix

A

C

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28
Q

Which molecule is composed of a chain of amino acids?

a. Lipid
b. Nucleic acid
c. Enzyme
d. Carbohydrates

A

C

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29
Q

Which of the following do nucleic acids and proteins have in common?

a. They each consist of four basic kinds of subunits.
b. They are large polymers.
c. They are both made of amino acids.
d. They are hydrophobic.
e. Their structures contain sugars.

A

B

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30
Q

How are lipids different from other biological molecules?

a. They contain sugars.
b. They do not contain glycerol.
c. They are not found in membranes.
d. Are not polymers.
e. Do not contain carbon.

A

D

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31
Q

Which molecule is considered to be primarily involved in the formation of membranes?

a. Lipid
b. Nucleic acid
c. Proteins
d. Carbohydrates

A

A

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32
Q

Which of the following is true for saturated fats?

a. They have no double covalent bonds.
b. They are solid at room temperature
c. They contain the maximum number of hydrogen bonds possible
d. All of the above are correct.

A

D

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33
Q

Which of the following is the type of bond between molecules of water in a beaker of water?

a. Covalent bond
b. Ionic bond
c. Hydrogen bond
d. Phosphodiester bond

A

C

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34
Q

What characteristic do all lipids have in common?

a. All are to some degree hydrophobic.
b. Made of fatty acids and glycerol.
c. Contain nitrogen.
d. Acidic when mixed with water.

A

A

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35
Q

Which of the following bonds or forces of attraction requires the greatest amount of energy to dissociate it?

a. hydrogen bonds
b. covalent bonds
c. hydrophobic interactions
d. ionic

A

B

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36
Q

What are the building blocks of nucleic acid polymers called?

a. Sugars Nucleotides
b. Carbohydrates
c. Amino acids.
d. Phosphate groups
e. Nucleotides

A

E

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37
Q

Which of the following ranks the molecules in the correct order by size?

a. water - sucrose - glucose – protein
b. water –glucose-sucrose-protein
c. water- glucose-protein-sucrose
d. water-sucrose-protein-glucose
e. protein - water - glucose – sucrose

A

B

38
Q

Describe the electron configuration

A
  • Arrangement of electron shells which are separated by different energy levels
  • First shell holds 2
  • Second and third shell hold 8
  • The rest generally accommodate 18
  • Empty spaces in outer shell results in unstable atoms
39
Q

What is an inert gas?

A

• Outer shell is full and so does not interact

40
Q

What is valence?

A
  • Combining capacity

* Number of extra or missing electrons in the outer shell

41
Q

What is a molecule containing at least 2 elements?

A

Compound

42
Q

What is molecular mass?

A

Sum of all atomic masses

Unit is Dalton (dα)

43
Q

What is a mole?

A

• Molecular mass of a substance expressed in grams

44
Q

Describe ionic bonds

A

• Atoms gain or lose electrons in outer shells
o Electron donor loses an electron
o Electron acceptor gains an electron
o Forms ions with a positive or negative charge
• Attraction between ions of opposite charge holding together form a stable molecule
o Cations are positively charged ions
o Anions are negatively charged ions

45
Q

Describe covalent bonds

A

Share 1 or more pairs of electrons
Stronger and more common than ionic bonds
Shared pair of electrons orbits both atoms
May be
Single shares 1 pair of electrons (-)
Double shares 2 pairs of electrons (=)
Triple shares 3 pairs of electrons (≡)

46
Q

Describe hydrogen bonds

A

• Weak and does not actually bond so form and break easily
• The attraction between the + end of a polar molecule and the – end of another
• 1 H atom covalently bonded to one O or N atom is attracted to another O or N atom
o The larger O or N attracts H’s electrons more so they become slightly negative while the H becomes slightly positive
o Provides polarity of H2O

47
Q

What is the making or breaking of bonds between atoms?

A

Chemical reaction

48
Q

What is the initial energy required to break a bond?

A

Activation energy

49
Q

What type of reaction absorbs more energy than it releases?

A

Endergonic reaction

50
Q

What is an exergonic reaction?

A

o Releases more energy than it absorbs

51
Q

What are the parts of a chemical reaction? What goes in? What comes out?

A
  • Reactants are the combining substances

* Products are newly formed molecules

52
Q

What is a synthesis reaction? What is it called in living organisms?

A

Reaction forming new bonds building larger molecules (A + B → AB)
Anabolism
Synthesis pathways in living organisms

53
Q

What is a decomposition reaction? What is it called in living organisms?

A

Reaction breaking bonds into smaller parts (AB → A + B)
Catabolism
Decomposition pathways in living organisms

54
Q

What is an exchange reaction?

A

Part synthesis, part decomposition (AB + CD → AD + BC)

55
Q

What are reversible reactions and why do they occur?

A

• Reactions that are readily reversible
o All reactions are reversible in theory
• May be because products and reactants are unstable
• May require special conditions such as heat

56
Q

What are inorganic compounds?

A
  • Usually small, simple, and lack carbon

* Ionic bonds play important role

57
Q

Why is water so important to chemical reactions?

A

• Polarity makes water an excellent solvent
• Dissociation
o Separation
o Occurs to many polar molecules in water
• Acts as reactant or product in many chemical reactions

58
Q

Describe acids

A
  • A proton (H+) donor
  • Dissociates into H+ and anions (negative ions)
  • The more free H+, the more acidic
59
Q

Describe bases

A
  • A proton (H+) acceptor
  • Dissociates into hydroxide ions (OH-) and cations (positive ions)
  • The more free OH- ions, the more basic or alkaline it is
60
Q

Describe salts

A

• Ionization
o Dissociation into ions
• Dissociates in water into cations (+) and anions (-) but not H+ or OH-

61
Q

Describe the acid base balance

A

• Expressed as pH
o Potential for hydrogen
• Each number has 10 times more H+ than the next number
• -log10 [H+]

62
Q

What are organic compounds?

A
  • Always contain C and H
  • Usually use covalent bonds
  • Typically structurally complex
  • Capable of complex biological functions
63
Q

What is the chain of carbons in an organic compound called?

A

Carbon skeleton

64
Q

What are functional groups?

A

o Specific groups of atoms bonding to C or H
o Responsible for most chemical/physical properties
o Letter R can be used for remainder of molecule to a functional group
o Frequently molecules have more than 1 functional group

65
Q

What are giant molecules that may contain thousands of atoms?

A

Macromolecules

66
Q

What are monomers?

A

o Small molecules
o Saccharides in carbohydrates
o Amino acids in proteins
o Nucleotides in nucleic acid

67
Q

What are polymers?

A 
o	Covalent bonding of many repeating small molecules
o	Homopolymers
	Identical repeating monomers
o	Heteropolymers
	Made from different monomers
68
Q

Describe dehydration synthesis

A 
•	Also called condensation reaction
•	Also called polymerization 
•	2 monomers join 
o	1 usually has one remaining H
o	1 usually has OH-
o	Combine to make H2O
69
Q

Describe hydrolysis

A
  • Also called depolymerization
  • A water molecule is added to break apart polymers into monomers
  • Releases energy
70
Q

Describe carbohydrates

A 
•	Includes sugars and starches
•	Made of C, H, and O
o	H:O is 2:1
•	Primary function is to fuel cell activities with a ready source of energy 
Monomer is monosaccharide
71
Q

Describe monosaccharides

A 
•	Simple sugars
•	Contains 3-7 carbon atoms defined with prefix and -ose 
o	Ex. Deoxyribose is a pentose 
•	All carbon atoms are attached to a hydroxyl (-OH) group except for one 
•	Carbonyl bond 
o	The exception to hydroxyl group
o	Bonds with an atom of oxygen (C=O)
o	Can be in the aldehyde or the ketone form
o	Aldose
	Sugar with an aldehyde group
o	Ketose
	Sugar containing a ketone
72
Q

What are disaccharides? What breaks them down?

A

• 2 monosaccharides bound by dehydration synthesis
o Glycosidic bond
• Hydrolysis
o Addition of water that causes disaccharides to break down

73
Q

What are polysaccharides?

A

• Consists of 10s or 100s of monosaccharides joined by dehydration synthesis
• Are macromolecules
• Broken down by hydrolysis but usually not soluble in water
• Storage polysaccharide
o Includes starch and glycogen
• Structural polysaccharides
o Cellulose in plant walls

74
Q

Describe oligosaccharides

A
  • Consists of 2 to 20 monosaccharides

* Disaccharide is the most common

75
Q

What are lipids?

A
  • Provide membrane structure and energy storage
  • Made of C, H, and only a small amount of O
  • Nonpolar so insoluble in water
76
Q

Describe simple lipids

A

• Also called fats
• Have an
o Glycerol
 Alcohol
 3 Cs attached to hydroxyl (OH) group
o Fatty acid compound
 Long hydrocarbon chain (only C and H)
 Ends in carboxyl (-COOH) group
• Organic acid
 Monoglyceride has 1 fatty acid, diglyceride has 2, triglyceride has 3
 Saturated has no double bonds so max number of H
 Unsaturated has double bonds
• Makes kinks so it doesn’t solidify when cool
• Cis means H are on the same side
• Trans fats have H on the opposite side
• Ester linkage
o Place where water is removed by dehydration synthesis

77
Q

Describe complex lipids. What is the most common kind?

A

• Contain additional elements to the C, H and O of simple lipids
o Can include P, N, S etc.
• Phospholipids
o Hydrophilic head
 Phosphate group bonded to an organic group
 Glycerol
 Polar and attract to water with H bonds
o Hydrophobic tail
 2 fatty acids
 Nonpolar

78
Q

Describe steroids

A

• Characterized by 4 interconnected carbon rings
• Sterol
o Steroid with an -OH group attached
o Separate fatty acid chains preventing hardening at low temps

79
Q

What are proteins?

A
  • Contain C, H, O, and N, sometimes S

* Polypeptides that are twisted, folded, and coiled into a molecule

80
Q

What are amino acids?

A

• Building blocks of proteins
• Contain alpha carbon (Cα) attached to
o Alpha amino acid
 Carboxyl (-COOH) group
 An amino (-NH2) group
o Side R group which defines its features
• Stereoisomers
o 2 different configurations that are mirror images
o Designated D-amino acid and L-amino acid
 Amino acids in proteins are always L-amino acids
o 20 amino acids make all proteins
o A single protein can have 50 to 100s of amino acids

81
Q

Describe peptide bonds. What are the terms for different numbers of amino acids bonded together?

A
  • Bonds between amino acids
  • Occurs via dehydration synthesis between carboxyl (-COOH) group and amino (-NH2) group
  • Dipeptide is 2 amino acids, tripeptide is 3 amino acids
  • Peptide is 4-9 amino acids and polypeptide is 10 or more amino acids
82
Q

What are the levels of protein structure?

A

Primary Structure
• Unique sequence of amino acids

Secondary Structure
• Localized repetitive twisting or folding of the chain
• Result of H bonds between O or N of the peptide backbone
o Occurs between amino (-NH2) and carboxyl (-COOH) groups
• Helix or pleated sheets

Tertiary Structure
• Overall 3D shape
• Not repetitive or predictable
• Involves several interactions between various amino acid side groups
o Hydrophobic interaction
 Nonpolar groups interact at core of protein away from water
o H bonds between side groups
o Ionic bonds between oppositely charged side groups
o Disulfide bridges
 Strong covalent bond between 2 cysteine molecules

Quaternary Structure
• Doesn’t always occur
• Aggregation of 2+ polypeptide chains
• Shape may be globular or threadlike

83
Q

What is denaturation?

A

• Loss of characteristic shape due to a hostile environment that renders the protein useless

84
Q

While denaturation may not be reversible, what is it called if it does reverse?

A

Renaturation

85
Q

Describe conjugated proteins

A
  • Combine amino acids with other organic or inorganic compounds
  • Glycoproteins contain sugars
  • Phosphoproteins contain phosphate groups
  • Lipoproteins contain lipids
  • Nucleoproteins contain nucleic acids
86
Q

Describe nucleotides

A 
•	Structural unit of nucleic acid
•	Made up of
o	Pentose sugar (either deoxyribose or ribose)
o	Phosphate group
o	N containing base
	Made of C, H, O and N
	Purines
•	Double ring
•	Adenine and guanine
	Pyrimidines
•	Single ring
•	Thymine, cytosine, and uracil
•	Phosphodiester bonds
o	Joins nucleotides
o	Result of H bonds between O or N of the peptide backbone
87
Q

What is a nucleoside?

A

• Pentose sugar and N base but not phosphate group

88
Q

Describe the nitrogenous base parings in DNA

A

• 2 bonds
o Adenine and thymine
• 3 bonds
o Guanine and cytosine

89
Q

What is the nitrogenous base difference of RNA vs DNA? What are the forms of RNA?

A
  • Uracil instead of T

* Forms are mRNA, rRNA, tRNA

90
Q

Describe the structure of ATP?

A

• Adenosine unit
o Adenine nucleotide
o Ribose
• 3 phosphate groups

Microbiology (7 decks)

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