MCB 450 Exam 1 UPDATED ACTUAL
QUESTIONS AND CORRECT ANSWERS
Four types of biological molecules - CORRECT ANSWER proteins, nucleic acids,
carbohydrates, lipids
Proteins role in cells - CORRECT ANSWER versatile biomolecules, carries most biological
functions (monomer = L-AA)
1. Hormones, growth factors
2. Transporters: iron, amino acid, glucose
3. Enzymes
4. Actin, myosin, tubulin
5. Collagen, elastin, keratin, fibroin
6. Transcription factors
Nucleic Acids role in cells - CORRECT ANSWER information molecules (monomer = DNA,
RNA), central dogma: DNA -> RNA -> protein
Contains nitrogenous base, pentose sugar, phosphate group
Carbohydrates role in cells - CORRECT ANSWER monomer: linear/branched
monosaccharides
1. Fuel source (glucose: glycogen in animals, starch in plants)
2. Structural molecules (ex. Cellulose in plants, chitin)
3. Signaling molecules: cell-cell recognition w glycoprotein/lipid
4. Lubricants: hyaluronic acid in joints
Lipids role in cells (6) - CORRECT ANSWER water-insoluble molecules that are highly
soluble in organic solvents
1. Major component of membrane (phospholipids)
2. Long term energy storage (triacylglycerols)
,3. Protection against heat loss (insulation)
4. Protection against physical shock
5. Protection against water loss
6. Chemical messengers (hormones, steroids)
4 types of covalent bonds - CORRECT ANSWER peptide, phosphodiester, ester, glycosidic
Peptide bond properties - CORRECT ANSWER connects AA's to make proteins
How are peptide bonds formed (enzyme) - CORRECT ANSWER peptidyltransferase
What is the condensation reaction to form peptide bonds? - CORRECT ANSWER Attaches C
group of one AA carboxy group and N group of another AA amino group
Phosphodiester bond properties - CORRECT ANSWER connects RNA/DNA molecules
How are phosphodiester bonds formed (enzyme) - CORRECT ANSWER DNA/RNA
polymerase
What is the condensation reaction to form phosphodiester bonds? - CORRECT ANSWER joins
5' phos. Group in pentose sugar of one nucleotide to 3' hydroxyl group in pentose sugar of next
nucleotide
Glycosidic bonds properties - CORRECT ANSWER connects monosaccharides
How are glycosidic bonds formed (enzyme) - CORRECT ANSWER ___________ synthase
(ex. Glycogen synthase)
What is the condensation reaction to form glycosidic bonds? - CORRECT ANSWER connects
2 OH groups (1-6, 1-4 etc.)
Ester bond properties - CORRECT ANSWER makes lipids
, How are ester bonds formed (enzyme) - CORRECT ANSWER acyltransferase
What is the condensation reaction to form ester bonds? - CORRECT ANSWER connects
glycerol molecules and 3 fatty acid molecules to make lipids
Why water is dipolar and cohesive? - CORRECT ANSWER 1. Dipolar: uneven e- distribution
btw H and O (O nucleus attracts e- stronger so e- aren't shared equally -> dipoles)
2. Cohesive: H-bonds connect water molecules -> "sticky water"
Properties of hydrogen bonds - CORRECT ANSWER 1. Forms btw electronegative atom (ex.
O, N) + H
2. H bonds btw molecules are DISRUPTED by water bc water forms H bonds w molecules
3. Polarity of water + H bond ability -> solvent for charged/polar molecules
What are polar, non-polar, and amphipathic molecules? - CORRECT ANSWER 1. Polar:
hydrophilic cmpds dissolve easily + form H bonds w H2O (ex. Glucose, glycine, aspartate, lactate,
glycerol)
2. Nonpolar: hydrophobic cmpds are water insoluble (ex. Lipids, some side chains)
3. Amphipathic: has polar/charged regions AND nonpolar regions (ex. Phenylalanine)
What are the four types of weak, non-covalent interactions (rank in order of increasing strength) -
CORRECT ANSWER van der waals < hydrophobic < H bonds < ionic
Ionic bonds - CORRECT ANSWER electrostatic interaction (weak) btw ions with opposite
charges (AKA salt bridge)
Weakened by water due to ion dipolar interaction that forms btw electroneg atom + H
Van der waals interactions - CORRECT ANSWER 1. Btw non-polar/uncharged molecules
2. Short range attractive interactions
3. Depends on transient asymmetry in electrical charge induced btw closely approaching atoms (e-
attracted to + nucleus)
QUESTIONS AND CORRECT ANSWERS
Four types of biological molecules - CORRECT ANSWER proteins, nucleic acids,
carbohydrates, lipids
Proteins role in cells - CORRECT ANSWER versatile biomolecules, carries most biological
functions (monomer = L-AA)
1. Hormones, growth factors
2. Transporters: iron, amino acid, glucose
3. Enzymes
4. Actin, myosin, tubulin
5. Collagen, elastin, keratin, fibroin
6. Transcription factors
Nucleic Acids role in cells - CORRECT ANSWER information molecules (monomer = DNA,
RNA), central dogma: DNA -> RNA -> protein
Contains nitrogenous base, pentose sugar, phosphate group
Carbohydrates role in cells - CORRECT ANSWER monomer: linear/branched
monosaccharides
1. Fuel source (glucose: glycogen in animals, starch in plants)
2. Structural molecules (ex. Cellulose in plants, chitin)
3. Signaling molecules: cell-cell recognition w glycoprotein/lipid
4. Lubricants: hyaluronic acid in joints
Lipids role in cells (6) - CORRECT ANSWER water-insoluble molecules that are highly
soluble in organic solvents
1. Major component of membrane (phospholipids)
2. Long term energy storage (triacylglycerols)
,3. Protection against heat loss (insulation)
4. Protection against physical shock
5. Protection against water loss
6. Chemical messengers (hormones, steroids)
4 types of covalent bonds - CORRECT ANSWER peptide, phosphodiester, ester, glycosidic
Peptide bond properties - CORRECT ANSWER connects AA's to make proteins
How are peptide bonds formed (enzyme) - CORRECT ANSWER peptidyltransferase
What is the condensation reaction to form peptide bonds? - CORRECT ANSWER Attaches C
group of one AA carboxy group and N group of another AA amino group
Phosphodiester bond properties - CORRECT ANSWER connects RNA/DNA molecules
How are phosphodiester bonds formed (enzyme) - CORRECT ANSWER DNA/RNA
polymerase
What is the condensation reaction to form phosphodiester bonds? - CORRECT ANSWER joins
5' phos. Group in pentose sugar of one nucleotide to 3' hydroxyl group in pentose sugar of next
nucleotide
Glycosidic bonds properties - CORRECT ANSWER connects monosaccharides
How are glycosidic bonds formed (enzyme) - CORRECT ANSWER ___________ synthase
(ex. Glycogen synthase)
What is the condensation reaction to form glycosidic bonds? - CORRECT ANSWER connects
2 OH groups (1-6, 1-4 etc.)
Ester bond properties - CORRECT ANSWER makes lipids
, How are ester bonds formed (enzyme) - CORRECT ANSWER acyltransferase
What is the condensation reaction to form ester bonds? - CORRECT ANSWER connects
glycerol molecules and 3 fatty acid molecules to make lipids
Why water is dipolar and cohesive? - CORRECT ANSWER 1. Dipolar: uneven e- distribution
btw H and O (O nucleus attracts e- stronger so e- aren't shared equally -> dipoles)
2. Cohesive: H-bonds connect water molecules -> "sticky water"
Properties of hydrogen bonds - CORRECT ANSWER 1. Forms btw electronegative atom (ex.
O, N) + H
2. H bonds btw molecules are DISRUPTED by water bc water forms H bonds w molecules
3. Polarity of water + H bond ability -> solvent for charged/polar molecules
What are polar, non-polar, and amphipathic molecules? - CORRECT ANSWER 1. Polar:
hydrophilic cmpds dissolve easily + form H bonds w H2O (ex. Glucose, glycine, aspartate, lactate,
glycerol)
2. Nonpolar: hydrophobic cmpds are water insoluble (ex. Lipids, some side chains)
3. Amphipathic: has polar/charged regions AND nonpolar regions (ex. Phenylalanine)
What are the four types of weak, non-covalent interactions (rank in order of increasing strength) -
CORRECT ANSWER van der waals < hydrophobic < H bonds < ionic
Ionic bonds - CORRECT ANSWER electrostatic interaction (weak) btw ions with opposite
charges (AKA salt bridge)
Weakened by water due to ion dipolar interaction that forms btw electroneg atom + H
Van der waals interactions - CORRECT ANSWER 1. Btw non-polar/uncharged molecules
2. Short range attractive interactions
3. Depends on transient asymmetry in electrical charge induced btw closely approaching atoms (e-
attracted to + nucleus)
