BIOC 431 UNL EXAM 2 QUESTIONS WITH VERIFIED SOLUTIONS GRADED A+
5 major classes of proteins - Answers 1. metabolic enzymes
2. structural proteins
3. transport proteins
4. cell signaling
5. genomic caretaker proteins
metabolic enzymes - Answers - Reaction catalysts that control metabolic flux
- Catalyze biochemical reactions involved in energy conversion pathways by
- Synthesis and degradation of macromolecules
structural proteins - Answers - Maintain integrity of cell structures and promote changes in cell
shape
- Most abundant protein in organisms
- Ex: cytoskeletal proteins: actin, tubulin, collagen
actin - Answers found in muscle of animal cells, subunits self-assemble into thin filaments that
control cell shape and cell migration
tubulin - Answers tubulin monomers self-assemble into long polymers called microtubules that
act as tracks on which organelles and chromosomes are transported
transport proteins - Answers - Facilitate movement of molecules within and between cells
- Abundant in plasma membrane: allow polar and charged molecules to enter/exit cell
- Two classes: passive and active
cell signaling - Answers - Function as molecular switches to transmit extracellular and
intracellular signals
- Ex: membrane receptors, nuclear receptors, intracellular signaling proteins
Genomic Caretaker Proteins - Answers - Maintain integrity and accessibility of genomic
information
- Repair mutations in DNA of reproductive cells
DNA polymerase - Answers uses DNA template to guide synthesis of complementary DNA
strands
, DNA lisgase - Answers seal newly formed DNA
Topoisomerase - Answers unwind DNA
DNA primase - Answers assist DNA polymerase by preparing DNA template for replication
Photolyase - Answers repairs thymine dimers that are formed from UV radiation
RecBCD protein complex - Answers facilitate DNA repair or recombination
passive transport - Answers move biomolecules across a membrane in the same direction as
concentration gradient; doesn't not require energy
Ex: porins which frequently contain beta barrels
aquaporins - Answers transport water molecules across a hydrophobic membrane
active transport - Answers move biomolecules against a concentration gradient; requires energy
Secondary Active Transport - Answers use energy available from down downhill electrochemical
gradient from one molecule to another to cotransport a second molecule against an uphill
gradient
Secondary active antiporter - Answers transport of two molecules in opposite directions
Secondary active symporter - Answers transport of two molecules in the same direction
free energy equation - Answers G=RTln( C2/C1)+ZFV
what makes up a muscle - Answers Muscles contain myofibrils which are made of thin and
thick filaments arranged into units called sarcomeres; z-disks anchor the thin and thick
filaments
- Myosin - makes up thick filaments
- Actin - makes up thin filaments
muscle contraction mechanism - Answers - In relaxed muscle, binding site for myosin on actin
are blocked by tropomyosin coil
- Ca2+ binds to troponin complex which induces conformational change in troposyosin coil that
uncovers the myosin binding site on actin
- Myosin heads bind to act and initiate muscle contraction
Myoglobin - Answers concentrated in muscle and stores O2; Single polypeptide chain with one
heme group
Hemoglobin - Answers - protein in blood cells, transports heme bound O2 from lungs/tissues
5 major classes of proteins - Answers 1. metabolic enzymes
2. structural proteins
3. transport proteins
4. cell signaling
5. genomic caretaker proteins
metabolic enzymes - Answers - Reaction catalysts that control metabolic flux
- Catalyze biochemical reactions involved in energy conversion pathways by
- Synthesis and degradation of macromolecules
structural proteins - Answers - Maintain integrity of cell structures and promote changes in cell
shape
- Most abundant protein in organisms
- Ex: cytoskeletal proteins: actin, tubulin, collagen
actin - Answers found in muscle of animal cells, subunits self-assemble into thin filaments that
control cell shape and cell migration
tubulin - Answers tubulin monomers self-assemble into long polymers called microtubules that
act as tracks on which organelles and chromosomes are transported
transport proteins - Answers - Facilitate movement of molecules within and between cells
- Abundant in plasma membrane: allow polar and charged molecules to enter/exit cell
- Two classes: passive and active
cell signaling - Answers - Function as molecular switches to transmit extracellular and
intracellular signals
- Ex: membrane receptors, nuclear receptors, intracellular signaling proteins
Genomic Caretaker Proteins - Answers - Maintain integrity and accessibility of genomic
information
- Repair mutations in DNA of reproductive cells
DNA polymerase - Answers uses DNA template to guide synthesis of complementary DNA
strands
, DNA lisgase - Answers seal newly formed DNA
Topoisomerase - Answers unwind DNA
DNA primase - Answers assist DNA polymerase by preparing DNA template for replication
Photolyase - Answers repairs thymine dimers that are formed from UV radiation
RecBCD protein complex - Answers facilitate DNA repair or recombination
passive transport - Answers move biomolecules across a membrane in the same direction as
concentration gradient; doesn't not require energy
Ex: porins which frequently contain beta barrels
aquaporins - Answers transport water molecules across a hydrophobic membrane
active transport - Answers move biomolecules against a concentration gradient; requires energy
Secondary Active Transport - Answers use energy available from down downhill electrochemical
gradient from one molecule to another to cotransport a second molecule against an uphill
gradient
Secondary active antiporter - Answers transport of two molecules in opposite directions
Secondary active symporter - Answers transport of two molecules in the same direction
free energy equation - Answers G=RTln( C2/C1)+ZFV
what makes up a muscle - Answers Muscles contain myofibrils which are made of thin and
thick filaments arranged into units called sarcomeres; z-disks anchor the thin and thick
filaments
- Myosin - makes up thick filaments
- Actin - makes up thin filaments
muscle contraction mechanism - Answers - In relaxed muscle, binding site for myosin on actin
are blocked by tropomyosin coil
- Ca2+ binds to troponin complex which induces conformational change in troposyosin coil that
uncovers the myosin binding site on actin
- Myosin heads bind to act and initiate muscle contraction
Myoglobin - Answers concentrated in muscle and stores O2; Single polypeptide chain with one
heme group
Hemoglobin - Answers - protein in blood cells, transports heme bound O2 from lungs/tissues
