WorksheetsLecture 1: Introduction to Biochemistry and Monomers
Total questions: 116
Worksheet time: 2hrs 48mins
Which set lists the essential elements most common in biological molecules?
CHNOPS: carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur
CHONS: carbon, hydrogen, oxygen, nitrogen, sodium, sulfur
CHeNOPS: carbon, helium, nitrogen, oxygen, phosphorus, sulfur
CHNOPCl: carbon, hydrogen, nitrogen, oxygen, phosphorus, chlorine
Carbon's primary role in organic molecules is to act as the backbone enabling diverse structures.
(a)
Which statement best distinguishes organic from inorganic compounds?
Organic lacks carbon but includes hydrogen atoms
Organic contains both carbon and hydrogen atoms
Inorganic must include both carbon and hydrogen atoms
Inorganic contains only metals and water molecules
During condensation (dehydration) synthesis, what immediate chemical change links monomers?
Protonation by acids to form hydrogen bonds
Removal of water to form a covalent bond
Addition of water to break ionic bonds
Oxidation by oxygen to form double bonds
A student hydrolyzes a disaccharide. Predict the products and the mechanism.
Match each biomolecule to its correct monomer.
Carbohydrates—fatty acids; Proteins—glycerol; Nucleic acids—amino acids; Lipids—nucleotides
Carbohydrates—amino acids; Proteins—nucleotides; Nucleic acids—monosaccharides; Lipids—polypeptides
Carbohydrates—monosaccharides; Proteins—amino acids; Nucleic acids—nucleotides; Lipids—fatty acids + glycerol
Carbohydrates—glycerol; Proteins—monosaccharides; Nucleic acids—fatty acids; Lipids—amino acids
Which biomolecule primarily provides quick energy for cells?
Nucleic acids such as DNA and RNA
Proteins including enzymes and antibodies
Lipids such as triglycerides and steroids
Carbohydrates like monosaccharides and polysaccharides
Identify the correct element ratio typical of carbohydrate structure.
1:1:2 for carbon, oxygen, hydrogen
2:1:2 for hydrogen, oxygen, carbon
2:2:1 for hydrogen, carbon, oxygen
1:2:1 for carbon, hydrogen, oxygen
Explain how polypeptides are formed from amino acids and name the bond involved.
Which elements primarily compose carbohydrates in a roughly 1:2:1 ratio?
Carbon, hydrogen, oxygen
Carbon, nitrogen, phosphorus
Hydrogen, oxygen, sulfur
Carbon, oxygen, chlorine
What is the monomer unit of proteins that links via peptide bonds?
Fatty acids
Monosaccharides
Amino acids
Nucleotides
Triglycerides are formed by condensation reactions between glycerol and how many fatty acids?
Four fatty acids
Three fatty acids
Two fatty acids
One fatty acid
Fill in the blank: The nucleotide component that stores genetic information in eukaryotic nuclei is (a) .
Which biomolecule class includes antibodies and enzymes among its functions?
Nucleic acids
Lipids
Proteins
Carbohydrates
Which statement correctly pairs monomer and polymer for carbohydrates?
Amino acids form polypeptides
Fatty acids form triglycerides
Nucleotides form phospholipids
Monosaccharides form polysaccharides
Explain how condensation and hydrolysis reactions affect biomolecule synthesis and breakdown. Provide one example for each.
Which lipid function is most emphasized for triglycerides in animals?
Short-term energy supply
Genetic information storage
Long-term energy storage
Catalysis of reactions
Describe the interrelationship between biomolecules in enabling complex biological processes.
Which component is common to every nucleotide?
Phosphate group
Fatty acid chain
Amino group
Glycerol backbone
A peptide bond forms between which functional groups of adjacent amino acids?
Hydroxyl and phosphate groups
Carboxyl and amino groups
Amine and sulhydryl groups
Carbonyl and methyl groups
Which statement best distinguishes fungi from plants and animals at the cellular level?
Fungi are prokaryotes lacking nuclei
Fungi are eukaryotes with unique cell walls
Fungi are algae performing photosynthesis
Fungi are viruses without metabolism
Name the yeast species commonly discussed as a model organism in microbiology.
(a)
Fungal cell walls primarily contain complex polysaccharides. What is one functional consequence of this feature?
Loss of eukaryotic organelles
Ability to fix atmospheric nitrogen
Distinct rigidity compared to bacterial walls
Enhanced photosynthetic efficiency
Mycorrhizal fungi form symbioses with plant roots. What is the principal ecological benefit of this association?
Block rhizosphere oxygen diffusion
Reduce soil microbial diversity
Induce plant pathogenicity
Increase plant nutrient uptake
Protozoa are described as unicellular eukaryotes. Which role do they play in the rhizosphere?
Produce fruiting bodies like fungi
Regulate bacterial populations
Form viral capsids in soil
Fix nitrogen like cyanobacteria
Which protozoan genus is explicitly noted for causing human disease?
(a)
Algae and cyanobacteria both contribute to primary production. What key cellular distinction separates them?
Both are prokaryotic with peptidoglycan
Cyanobacteria are prokaryotic, algae eukaryotic
Both are eukaryotic with nuclei
Algae are prokaryotic, cyanobacteria eukaryotic
Define a virus in terms of composition and replication dependence.
Which set lists core components found in many virions?
Capsid, nucleic acid, optional lipid envelope
Cell membrane, nucleus, chloroplasts
Peptidoglycan wall, ribosomes, mitochondria
Flagella, pili, circular chromosome
Viruses are generally smaller than bacteria and often submicroscopic. What does this imply for detection?
Only naked eye observation is adequate
Electron microscopy may be required
Light microscopy usually suffices
Size prevents any imaging methods
Which statement correctly compares lytic and lysogenic cycles?
Lytic integrates viral DNA, lysogenic causes lysis
Lytic replicates and lyses host, lysogenic integrates
Both integrate and never lyse the host
Neither involves host genome interactions
Phenotypic mixing during co-infection can alter viral properties. What mechanism describes this process?
Which antiviral strategy targets early stages of infection?
Blocking viral attachment to host cells
Inhibiting capsid assembly only
Enhancing fungal mycorrhiza formation
Stimulating bacterial nitrogen fixation
Why are virus-specific targets challenging to identify for therapy?
Define the term virion.
(a)
Which term best describes a virus that specifically infects bacteria?
Capsid
Phage
Virion
Envelope
During lysogeny, viral DNA integrates into the host genome and replicates passively. What event can transition it to lytic phase?
Host cell endocytosis efficiency
Nitrogen fixation by cyanobacteria
Induction leading to active replication
Formation of mycorrhizal associations
Explain one ecological impact of bacteriophages in environmental microbiology.
Which statement best distinguishes an apoenzyme from a holoenzyme?
Holoenzyme is protein alone lacking any non-protein parts
Holoenzyme cannot bind cofactors under cellular conditions
Apoenzyme is active enzyme complexed with coenzyme
Apoenzyme is protein alone, inactive without cofactors
Fill in the blank: The specific region where a substrate binds and catalysis occurs is the (a) .
In the lock-and-key model, how is enzyme specificity primarily explained?
Rigid active site complementary to substrate shape
Substrate reshapes to fit an inactive enzyme
Flexible active site induced by substrate binding
Active site formed only after product release
Which description aligns with the induced fit model of enzyme action?
Substrate binds only after product forms
Catalysis occurs without substrate contact
Active site undergoes conformational change on binding
Active site remains rigid during binding
A metal ion tightly bound to an enzyme and essential for activity is best classified as which component?
Coenzyme loosely associated non-covalently
Competitive inhibitor resembling substrate
Prosthetic group covalently attached
Apoenzyme protein portion only
Which scenario most likely increases reaction rate until saturation is reached?
Increasing substrate concentration progressively
Lowering temperature far below optimal
Adding a non-competitive inhibitor
Shifting pH away from enzyme optimum
What is the key distinction between competitive and non-competitive inhibition?
Competitive is irreversible; non-competitive always reversible
Competitive binds active site; non-competitive binds elsewhere
Competitive lowers Vmax only; non-competitive raises Km
Competitive requires covalent attachment; non-competitive does not
Provide a concise explanation of how extreme heat affects enzyme structure and activity.
Most enzymes operate near neutral pH. Which option reflects this range?
Exactly pH 7 with no variation
Strictly pH 2–4 acidic conditions
Approximately pH 6–8 near neutrality
Approximately pH 9–11 basic range
Explain how competitive inhibitors alter enzyme kinetics and how increasing substrate can influence their effect.
In the EC number 2.7.1.1 for hexokinase, what does the initial digit 2 indicate?
Hydrolase class designation
Transferase class designation
Isomerase class designation
Ligase class designation
Fill in the blank: Hexokinase transfers a (a) group from ATP to glucose.
Which statement best distinguishes systematic from trivial enzyme names?
Systematic names are standardized and precise
Systematic names reflect catalytic function mechanistically
Systematic names are colloquial and historical
Systematic names describe substrate specificity broadly
Given the reaction glucose + ATP → glucose‑6‑phosphate + ADP, which enzyme class is most appropriate and why?
Which EC class catalyzes cleavage of bonds without hydrolysis or oxidation, often adding or removing groups across double bonds?
Ligases joining molecules using ATP
Lyases cleaving without hydrolysis or oxidation
Isomerases rearranging within a molecule
Hydrolases catalyzing water addition
Mechanistic models of enzyme–substrate interaction have evolved. Which comparison is accurate?
Lock‑and‑key depicts flexible active sites
Induced fit emphasizes dynamic adjustment
Lock‑and‑key allows induced conformational change
Induced fit assumes rigid complementarity
Environmental factors, cofactors/coenzymes, and inhibitors influence enzyme activity. Propose a brief plan to test inhibitor effects on hexokinase in vitro and justify controls.
Which statement best defines enzyme immobilization in industrial bioprocesses?
Purifying enzymes to remove all nonprotein contaminants
Freezing enzymes to increase shelf life before use
Dissolving enzymes into highly viscous reaction media
Fixing enzymes to reusable solid supports or matrices
Name one primary advantage of immobilizing enzymes for continuous operations.
(a)
Identify a major challenge of immobilization that can reduce catalytic activity.
Enhanced multi-enzyme reaction system design
Altered enzyme conformation affecting active site
Ensured final product free of enzyme contamination
Improved tolerance to temperature variations
Select the description that correctly contrasts physical adsorption with covalent binding.
Adsorption always changes active site; covalent preserves structure
Adsorption ensures no leakage; covalent risks enzyme detachment
Adsorption requires glutaraldehyde; covalent uses Van der Waals
Adsorption uses weak forces; covalent binding forms strong bonds
In ion binding mode, what primarily mediates the interaction between enzyme and carrier?
Hydrophobic packing within polymer pores
Covalent links via amino and phenolic groups
Hydrogen bonding to water-insoluble supports
Electrostatic attractions with ion-exchange residues
Glutaraldehyde is most directly associated with which immobilization method?
Cross-linking of enzymes to each other or supports
Physical adsorption onto hydrophobic carriers
Entrapment within lattice-type polymer gels
Ion binding to polysaccharide exchangers
Which statement best explains a common disadvantage of cross-linking?
Weak interactions cause frequent enzyme leakage
Requires high ionic strength to maintain binding
Substrate diffusion is completely blocked
Conformational changes can reduce enzyme function
Differentiate lattice-type entrapment from microcapsule-type entrapment.
Choose the best reason physical adsorption is considered simple and inexpensive.
It necessitates complex microencapsulation equipment
It forms multiple covalent bonds to stabilize enzymes
It uses weak forces requiring minimal chemical reagents
It relies on living cells as carrier materials
What trade-off often guides the choice among immobilization methods?
Maximizing carrier color with enzyme purity
Balancing activity retention with binding strength
Selecting the smallest possible enzyme size
Prioritizing cost over reaction temperature
Give one industrial application where immobilized enzymes are essential.
(a)
Design a brief plan to minimize enzyme leakage when using adsorption without heavily altering conformation.
A process requires stability under high ionic strength with minimal leakage. Which method is most suitable?
Covalent binding to carrier functional groups
Physical adsorption via Van der Waals forces
Entrapment within polyacrylamide matrices
Ion binding to polysaccharide exchangers
Which step best preserves protein integrity when collecting fresh animal tissue for isolation?
Store at room temperature overnight
Immediately cool tissue on ice
Dry tissue under warm air
Add strong acid without buffer
During bacterial harvest, what does centrifugation at 16,000g primarily achieve?
Precipitates nucleic acids
Denatures membrane proteins
Separates cells from media
Pellets buffer salts tightly
Name one common cell lysis method that uses chemicals to solubilize membrane lipids.
(a)
Which statement correctly contrasts size exclusion and ion exchange chromatography?
Ion exchange separates by ligand affinity only
Size exclusion separates by charge; ion exchange by size
Both separate by hydrophobicity alone
Size exclusion separates by size; ion exchange by charge
Affinity chromatography is best described as separation based on what principle?
Solubility changes at high salt
Diffusion through porous beads alone
Specific biological binding interactions
Mass-to-charge ratio differences
Which buffer component is routinely included during detergent lysis to maintain protein stability?
Tris-HCl and NaCl for pH and osmolarity
High sucrose without salts
Strong acid to lower pH to 2
Protease inhibitors in hypotonic water
What is the primary reason to purify a protein before downstream applications?
To increase DNA yield for cloning
To remove RNA for transcriptomics
To identify and study protein function
To crystallize membranes efficiently
Freeze–thaw cycles lyse cells mainly through which physical effect?
Shearing by magnetic fields
Ice crystal formation and contraction
Osmotic swelling without crystals
Covalent bond cleavage by chemicals
In ion exchange chromatography, proteins elute by changing what condition?
Ligand concentration of beads
Buffer ionic strength or pH
Column temperature gradient
Flow rate of mobile phase
Which statement about size exclusion chromatography is accurate?
Large molecules enter pores and elute last
Large molecules are excluded and elute earlier
Small molecules are excluded and elute first
All molecules elute simultaneously
Define specific enzyme activity.
(a)
Yield in purification refers to which quantity?
Total substrate concentration added
Ratio of protein mass to column volume
Percentage of total enzyme activity retained
Fraction of salt removed by dialysis
During salt precipitation (“salting out”), proteins are removed from solution because increasing salt concentration causes what?
Proteins to gain net positive charge
Covalent modification of side chains
Enhanced hydrophobic interactions reducing solubility
Immediate protease inhibition
A sample after affinity chromatography shows lower total protein but higher specific activity. What does this indicate about purification fold?
Purification fold likely decreased markedly
Purification fold likely increased
Purification fold equals one exactly
Purification fold cannot be inferred
Give one example of a binding pair used in affinity chromatography.
(a)
You have a crude extract with 20,000 mg total protein and specific activity of 1 unit/mg. After several steps, specific activity rises while total protein falls. Which metric best evaluates overall purity improvement?
Recovery yield percentage
Purification fold (level)
Column backpressure
Total enzyme activity alone
Design a brief plan: Choose a protein source and outline an initial lysis method to maximize stability, justifying buffer components and one protection strategy.
A positively charged protein at pH 7 is best purified on which ion exchange resin and why?
Explain why large proteins elute earlier than small proteins in size exclusion chromatography.
Which statement best distinguishes catabolism from anabolism?
Catabolism builds larger molecules using ATP energy
Catabolism breaks macromolecules releasing usable energy
Anabolism degrades polymers into smaller monomers
Anabolism harvests electrons to produce ATP
Fill in the blank: The cell’s primary energy currency is (a) .
Which stage of metabolism involves oxidation of small molecules through the citric acid cycle and electron transport?
Stage 3 oxidation and ATP generation
Stage 2 degradation to two- and three-carbon units
Stage 1 digestion in the gastrointestinal tract
Pre-stage cellular localization in organelles
Where do most ATP-producing reactions occur due to cellular compartmentalization?
Cytosolic ribosome complexes
Inner mitochondrial regions
Nuclear envelope lumen
Endoplasmic reticulum cisternae
During ATP hydrolysis, which products are formed and energy released?
ADP plus Pi with 7.3 kcal energy
AMP plus PPi with 12 kcal energy
NADH plus Pi with 7.3 kcal energy
cAMP plus phosphate with 5 kcal energy
Glycolysis is characterized by which condition and net yields?
Aerobic process yielding 2 ATP net and 2 NADH
Anaerobic process yielding 2 ATP net and 2 NADH
Aerobic process yielding 4 ATP net and 2 FADH2
Anaerobic process yielding 4 ATP net and 1 NADH
Under aerobic conditions, what happens to pyruvate derived from glycolysis?
Converted to oxaloacetate consuming CO2
Converted to ethanol forming NADH
Converted to acetyl CoA releasing CO2
Converted to lactate regenerating NAD+
Which coenzyme accepts hydrogens during oxidation of C=O bonds and becomes its reduced form?
NADP+ reduced to FADH2
CoA-SH reduced to CoA2H
FAD reduced to FADH3
NAD+ reduced to NADH + H+
Match each digestive macronutrient process to its key enzyme or feature.
Carbohydrates—pancreatic amylase hydrolysis
Fats—bile salts emulsify micelles
Proteins—pepsin activated by HCl
Fats—lipase hydrolyzes ester bonds
Identify the correct order of the first four steps of the citric acid cycle.
Isocitrate → citrate → malate → oxaloacetate
Oxaloacetate → acetyl CoA → citrate → fumarate
Acetyl CoA + oxaloacetate → citrate → isocitrate → α-ketoglutarate
Citrate → isocitrate → α-ketoglutarate → succinate
Which products are generated specifically in steps 3 and 4 of the citric acid cycle?
ATP and CO2 released
NADH and CO2 released
GTP and oxaloacetate formed
FADH2 and water released
Per citric acid cycle turn, which set of outputs is correct?
3 CO2, 2 NADH, 2 FADH2, 2 GTP
2 CO2, 3 NADH, 1 FADH2, 1 GTP
1 CO2, 2 NADH, 2 FADH2, 0 GTP
2 CO2, 2 NADH, 0 FADH2, 2 GTP
Where is the electron transport chain located within the cell?
Outer mitochondrial membrane
Inner mitochondrial membrane
Cytosolic microtubule network
Golgi apparatus membranes
Explain why glycolysis can proceed under anaerobic conditions and describe the role of lactate formation in this context.
Which electron transport chain complex accepts electrons from NADH and transfers them to CoQ?
Complex IV cytochrome c oxidase
Complex III cytochrome c reductase
Complex I NADH dehydrogenase
Complex II succinate dehydrogenase
Which molecule acts as a mobile lipid-soluble carrier shuttling electrons between ETC complexes?
Coenzyme Q ubiquinone
Fe-S iron–sulfur cluster
Cytochrome c protein
FMN flavin mononucleotide
Fill in the blank: Protons pumped by the ETC create an electrochemical gradient that drives ATP formation through (a) .
How many ATP are typically produced per NADH via oxidative phosphorylation?
One ATP molecule
Three ATP molecules
Two ATP molecules
Four ATP molecules
Glycolysis, pyruvate oxidation, and the citric acid cycle together yield approximately how many ATP per glucose under aerobic conditions?
Thirty-two ATP total
Twenty-four ATP total
Forty ATP total
Thirty-six ATP total
During β-oxidation, which step introduces water across a double bond in the fatty acyl chain?
Thiolysis cleavage step
Second oxidation reaction
First oxidation reaction
Hydration step reaction
For a saturated fatty acid with 18 carbons, how many β-oxidation cycles occur? Use the relation cycles = (number of carbons/2) − 1.
Eight cycles occur
Nine cycles occur
Seven cycles occur
Ten cycles occur
Each β-oxidation cycle yields which set of reduced cofactors and product?
1 NADH, 1 FAD, 2 acetyl CoA
2 NADH, 0 FADH2, 1 acetyl CoA
1 NADH, 1 FADH2, 1 acetyl CoA
0 NADH, 2 FADH2, 1 acetyl CoA
Which list correctly names the three ketone bodies formed from excess acetyl CoA?
Acetoacetate, β-hydroxybutyrate, acetone
Acetoacetate, lactate, acetate
Acetone, pyruvate, acetoacetate
β-hydroxybutyrate, citrate, acetone
Under which physiological conditions is ketosis most likely to develop, potentially leading to acidosis?
Diabetes or starvation states
High-carbohydrate feeding
Aerobic athletic training
Excess amino acid intake
Fill in the blank: Ammonium ions are detoxified in the liver via the (a) , producing urea excreted in urine.
Which amino acid carbon skeleton category feeds into oxaloacetate as an intermediate?
Five-carbon skeletons list
Three-carbon skeletons list
Two-carbon skeletons list
Four-carbon skeletons list
Explain how the chemiosmotic model links electron transport to ATP synthesis. Provide the role of proton gradient and ATP synthase.
If glycolysis continues under anaerobic conditions, what reaction regenerates NAD+ and what is the consequence for ATP yield?
Which statement best describes the integration of metabolic pathways at branch points?
Each pathway operates independently
Intermediates like acetyl CoA funnel substrates
Amino acids never enter energy pathways
Glucose cannot be stored as body fat
