Tophat 8

Question 1

How do living organisms create macromolecules, organelles, cells, tissues, and complex higher-order structures?
A. The laws of thermodynamics don’t apply to living organisms
B. Living organisms create order by using energy from the sun
C. Living organisms create order locally, but the energy transformations generate waste heat that increases the entropy of the universe

Answer 1

C

Question 2

Are most chemical rxns at equilibrium in living cells?
A. Yes
B. No
C. Only exergonic rxns
D. All rxns except those powered by ATP hydrolysis

Answer 2

B

Question 3

How might an amino acid change at a site distant from the active site of the enzyme alter the enzymes substrate specificity?
A. An amino acid change away from the active site cannot alter the enzymes substrate specificity
B. By changing the enzymes stability
C. By changing the enzymes pH optimum
D. By changing the shape of the protein

Answer 3

D

Question 4

Protein kinases are enzymes that catalyze phosphorylation of target proteins at specific sites, whereas protein phosphatases catalyze removal of phosphate from phosphorylated proteins. Phosphorylation and dephosphorylation can function as an on-off switch for a proteins activity, most likely through..
A. Change in optimal pH at which rxn occurs
B. Change in optimal temp at which rxn occurs
C. Excision of one or more peptides
D. Change in protein charge leading to conformational change

Answer 4

D

Question 5

Which metabolic process can occur w/o net influx of energy from some other process?
A. ADP+Pi-->ATP+ H2O
B. C6H12O6--->6CO2+6H2O
C. 6CO2+6H2O--->C6H12O6+O2
D. Amino acids--> protein

Answer 5

B

Question 6

Adenosine monophosphate (AMP) activates the enzyme phosphofructokinase (PFK) by binding at a site distinct from the substrate binding site. This is an ex. of
A. Cooperative action
B. Allosteric activation
C. Activation by enzyme cofactors
D. Coupling exergonic and endergonic rxns

Answer 6

B