MCB 250 - Exam 1 UPDATED ACTUAL Questions and CORRECT
Answers
Question: Prokaryotes
Correct Answer: bacteria and archaea: -no nucleus -DNA is in direct contact with the cytoplasm
-transcription and translation are simultaneous
Question: Eukaryotes
Correct Answer: -DNA is contained in a membrane-bound nucleus -Transcription occurs in the nucleus
-mRNA is exported to the cytoplasm where translation occurs -transcription and translation do NOT occur
simultaneously
Question: Universal Tree of Life
Correct Answer: based on comparisons of ribosomal small subunit RNAs
Question: Relative Sizes of Eukaryotic and Bacterial Cells
Correct Answer: -bacteria cell is a lot smaller than eukaryotic -mitochondria evolved from a bacterial
endosymbiont
Question: The Central Dogma
Correct Answer: -DNA makes RNA, and RNA makes Protein -reverse transcription -RNA can have
enzymatic and regulatory functions
Question: Proteins Dominate Cellular Biochemistry
Correct Answer: -many proteins are enzymes --> catalyze chemical reactions that occur in cells
-metabolism -other proteins allow cells to move, regulate biochemical processes, or function as structural
components of the cell -RNAs can also have enzymatic activity AND are important in regulation
Question: Metabolism
Correct Answer: sum total of all of the chemical reactions of the cell -catabolism vs. anabolism
Question: Catabolism
Correct Answer: breakdown food, make energy
Question: Anabolism
Correct Answer: synthesize the components of cells so they can grow and divide
Question: Bacterial Molecular Biology
Correct Answer: transcription and translation take place simultaneously in the same cellular compartment
- the cytoplasm
Question: eukaryotic molcular Biology
Correct Answer: -transcription and translation take place at different times in different cellular
compartments. -RNA processing occurs in nucleus, and mRNA is transported to cytosol where it is
translated into protein
Question: Why is chemistry important in molecular biology?
,Correct Answer: -DNA carries cell's genetic information -Proteins catalyze most of the chemical reactions
that allow cells to function -proteins interact specifically with other molecules
Question: Life is Primarily the Chemistry of Six Elements
Correct Answer: C-carbon H-Hydrogen N-nitrogen O-oxygen P-phosphorus S-sulfur
Question: Chemical Bonds
Correct Answer: -store potential energy -the stronger the bond, the more external energy required to break
it -strong bonds vs. weak bonds
Question: Strong Bonds
Correct Answer: -covalent bonds -cis/trans isomerism -resonance and aromaticity, UV absorbance
-stereoisomerism (D- vs. L- isomers)
Question: Weak bonds
Correct Answer: -ionic bonds -hydrogen bonds -van der Waals interactions -hydrophobic "bonds"
Question: Covalent Bonds Result from Shared Electrons
Correct Answer: -covalent bonds are strong -∆G of formation: -50 to -110 kcal/mol -Compare weak
bonds:: < 10 kcal/mol
Question: Peptide Bond
Correct Answer: -form backbone of a protein molecule; covalent bonds between carbon and nitrogen
atoms in successive amino acids -even if a protein is placed in 100ºC boiling water, the thermal energy is
insufficient to break these strong covalent bonds
Question: Properties of Covalent Bonds
Correct Answer: -bond angles are fixed, but some bonds can rotate while others cannot -resonance and
aromaticity -stereoisomerism -some bonds have high transfer potential: the concept of a "high energy bond"
Question: free rotation around C-C single bonds
Correct Answer: ex. ethane
Question: no rotation about double bonds
Correct Answer: ex. ethylene (ethene) is a planar molecule
Question: cis - trans isomerism
Correct Answer: -these are distinct molecules with different physical and chemical properties -cis -->
same side -trans --> opposite sides
Question: Aromatic Rings
Correct Answer: two "resonance" structures with alternating or "conjugated" double bonds
Question: Delocalized Electrons in Aromatic Rings
Correct Answer: (aromatic ring stacking)
Question: Nucleic Acids are Aromatic Rings
Correct Answer: -adenine (A) -Guanine (G) -Cytosine (C) -Thymine (T)
Question: Adenine (A)
, Correct Answer: Adenine (A) is the key item for this question. It identifies the relevant definition,
function, procedure, or principle for this topic.
Question: Guanine (G)
Correct Answer: Guanine (G) is the key item for this question. It identifies the relevant definition,
function, procedure, or principle for this topic.
Question: Cytosine (C)
Correct Answer: Cytosine (C) is the key item for this question. It identifies the relevant definition,
function, procedure, or principle for this topic.
Question: Thymine (T)
Correct Answer: Thymine (T) is the key item for this question. It identifies the relevant definition,
function, procedure, or principle for this topic.
Question: DNA (deoxyribonucleic acid)
Correct Answer: DNA is the hereditary molecule that stores genetic instructions for growth, function, and
reproduction.
Question: Conjugated Double Bonds
Correct Answer: -alternating double and single bonds -electrons are delocalized over 4 carbons -results in
planar structure ex. Butadiene
Question: weak non-covalent bonds make a major contribution to all of the following
Correct Answer: : -holding together two chains of the DNA double helix -protein: protein interactions -3D
structure of proteins -Protein: DNA interactions
Question: which of the following statements is true of hydrogen bonds
Correct Answer: in cells, the most biologically significant hydrogen bonds involve O and/or N atoms
Question: which is true of van der waals
Correct Answer: Can occur between any two closely spaced atoms
Question: which is true of "hydrophobic bonds"?
Correct Answer: occur in aqueous solutions from the tendency of water to exclude non polar groups
Question: Absorption of Light
Correct Answer: -electrons move in "quantized" orbitals -light of appropriate energy can kick electrons
into a higher-energy orbital -the "absorption spectrum" provides information about molecular structure -all
molecules absorb radiation -aromatics and compounds with conjugated double bonds absorb light in the UV
or visible range
Question: Beta-Carotene
Correct Answer: -more conjugated double bonds means that light of lower energy will be absorbed
-B-carotene absorbs in the visible blue range (~450 nm) --> colored intensely red-orange -bases of DNA
and RNA absorb light at 260nm, while aromatic amino acid tryptophan absorbs light at 280 nm
Question: Stereoisomerism
Answers
Question: Prokaryotes
Correct Answer: bacteria and archaea: -no nucleus -DNA is in direct contact with the cytoplasm
-transcription and translation are simultaneous
Question: Eukaryotes
Correct Answer: -DNA is contained in a membrane-bound nucleus -Transcription occurs in the nucleus
-mRNA is exported to the cytoplasm where translation occurs -transcription and translation do NOT occur
simultaneously
Question: Universal Tree of Life
Correct Answer: based on comparisons of ribosomal small subunit RNAs
Question: Relative Sizes of Eukaryotic and Bacterial Cells
Correct Answer: -bacteria cell is a lot smaller than eukaryotic -mitochondria evolved from a bacterial
endosymbiont
Question: The Central Dogma
Correct Answer: -DNA makes RNA, and RNA makes Protein -reverse transcription -RNA can have
enzymatic and regulatory functions
Question: Proteins Dominate Cellular Biochemistry
Correct Answer: -many proteins are enzymes --> catalyze chemical reactions that occur in cells
-metabolism -other proteins allow cells to move, regulate biochemical processes, or function as structural
components of the cell -RNAs can also have enzymatic activity AND are important in regulation
Question: Metabolism
Correct Answer: sum total of all of the chemical reactions of the cell -catabolism vs. anabolism
Question: Catabolism
Correct Answer: breakdown food, make energy
Question: Anabolism
Correct Answer: synthesize the components of cells so they can grow and divide
Question: Bacterial Molecular Biology
Correct Answer: transcription and translation take place simultaneously in the same cellular compartment
- the cytoplasm
Question: eukaryotic molcular Biology
Correct Answer: -transcription and translation take place at different times in different cellular
compartments. -RNA processing occurs in nucleus, and mRNA is transported to cytosol where it is
translated into protein
Question: Why is chemistry important in molecular biology?
,Correct Answer: -DNA carries cell's genetic information -Proteins catalyze most of the chemical reactions
that allow cells to function -proteins interact specifically with other molecules
Question: Life is Primarily the Chemistry of Six Elements
Correct Answer: C-carbon H-Hydrogen N-nitrogen O-oxygen P-phosphorus S-sulfur
Question: Chemical Bonds
Correct Answer: -store potential energy -the stronger the bond, the more external energy required to break
it -strong bonds vs. weak bonds
Question: Strong Bonds
Correct Answer: -covalent bonds -cis/trans isomerism -resonance and aromaticity, UV absorbance
-stereoisomerism (D- vs. L- isomers)
Question: Weak bonds
Correct Answer: -ionic bonds -hydrogen bonds -van der Waals interactions -hydrophobic "bonds"
Question: Covalent Bonds Result from Shared Electrons
Correct Answer: -covalent bonds are strong -∆G of formation: -50 to -110 kcal/mol -Compare weak
bonds:: < 10 kcal/mol
Question: Peptide Bond
Correct Answer: -form backbone of a protein molecule; covalent bonds between carbon and nitrogen
atoms in successive amino acids -even if a protein is placed in 100ºC boiling water, the thermal energy is
insufficient to break these strong covalent bonds
Question: Properties of Covalent Bonds
Correct Answer: -bond angles are fixed, but some bonds can rotate while others cannot -resonance and
aromaticity -stereoisomerism -some bonds have high transfer potential: the concept of a "high energy bond"
Question: free rotation around C-C single bonds
Correct Answer: ex. ethane
Question: no rotation about double bonds
Correct Answer: ex. ethylene (ethene) is a planar molecule
Question: cis - trans isomerism
Correct Answer: -these are distinct molecules with different physical and chemical properties -cis -->
same side -trans --> opposite sides
Question: Aromatic Rings
Correct Answer: two "resonance" structures with alternating or "conjugated" double bonds
Question: Delocalized Electrons in Aromatic Rings
Correct Answer: (aromatic ring stacking)
Question: Nucleic Acids are Aromatic Rings
Correct Answer: -adenine (A) -Guanine (G) -Cytosine (C) -Thymine (T)
Question: Adenine (A)
, Correct Answer: Adenine (A) is the key item for this question. It identifies the relevant definition,
function, procedure, or principle for this topic.
Question: Guanine (G)
Correct Answer: Guanine (G) is the key item for this question. It identifies the relevant definition,
function, procedure, or principle for this topic.
Question: Cytosine (C)
Correct Answer: Cytosine (C) is the key item for this question. It identifies the relevant definition,
function, procedure, or principle for this topic.
Question: Thymine (T)
Correct Answer: Thymine (T) is the key item for this question. It identifies the relevant definition,
function, procedure, or principle for this topic.
Question: DNA (deoxyribonucleic acid)
Correct Answer: DNA is the hereditary molecule that stores genetic instructions for growth, function, and
reproduction.
Question: Conjugated Double Bonds
Correct Answer: -alternating double and single bonds -electrons are delocalized over 4 carbons -results in
planar structure ex. Butadiene
Question: weak non-covalent bonds make a major contribution to all of the following
Correct Answer: : -holding together two chains of the DNA double helix -protein: protein interactions -3D
structure of proteins -Protein: DNA interactions
Question: which of the following statements is true of hydrogen bonds
Correct Answer: in cells, the most biologically significant hydrogen bonds involve O and/or N atoms
Question: which is true of van der waals
Correct Answer: Can occur between any two closely spaced atoms
Question: which is true of "hydrophobic bonds"?
Correct Answer: occur in aqueous solutions from the tendency of water to exclude non polar groups
Question: Absorption of Light
Correct Answer: -electrons move in "quantized" orbitals -light of appropriate energy can kick electrons
into a higher-energy orbital -the "absorption spectrum" provides information about molecular structure -all
molecules absorb radiation -aromatics and compounds with conjugated double bonds absorb light in the UV
or visible range
Question: Beta-Carotene
Correct Answer: -more conjugated double bonds means that light of lower energy will be absorbed
-B-carotene absorbs in the visible blue range (~450 nm) --> colored intensely red-orange -bases of DNA
and RNA absorb light at 260nm, while aromatic amino acid tryptophan absorbs light at 280 nm
Question: Stereoisomerism
