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Lecture 1
Lecture 1
9
Biochemistry
Graduate
08/26/2013

Additional Biochemistry Flashcards

 


 

Cards

Term

What are the major types of short-term metabolic regulation?

Definition

1) Substrate availability 

2) Confirmational change

     a) allosteric regulation

     b) covalent modification 

Term

What is allosteric regulation and what is the mechanism that it uses for regulation?

Definition
  • type of short-term regulation
  • effector binds non-covalently to a site on the enzyme that is NOT the active site
  • can cause a change in the affinity of the enzyme for the substrate OR can cause a change in the rate of the reaction OR both
  • mechanism: causes a confirmational change in the substrate binding site 

 

Term

What is covalent modification and what is the mechanism it uses for regulaiton? 

Definition
  • type of short term regulation
  • phosphorylation (kinases)  or dephosphorylation (phosphatases) of proteins
  • Effect occurs in seconds to minutes 
  • Mechanism:  the phosphate has a negative charge and it changes the shape/confirmation of enzyme
Term

Slide 7 box questions

  • What happens if G à H is blocked?
  • What physiological changes will alter hormone secretion?
  • By what mechanisms might this change occur? 

 

Definition
  • If G-H is blocked, H will not be produced and G will build up 
  • Hormone secretion will be altered by stress, starvation, etc. 
  • This change may occur if there is a confirmational change in the enzyme or the binding site changes shape.  
Term
permanent and variable compartmentation
Definition
  • types of metabolic regulation
  • permanent: enzymes are generally segregated into specific compartments or organelles
  • variable: The function of certain proteins like GLUT4 is regulated by a change in its location from intracellular vesicles to the PM.  Transport of glucose into the cell can only occur when GLUT4 is in the plasma membrane
Term
Explain long-term metabolic regulation (gene expression)s
Definition
  • Regulation occurs by increasing or decreasing the amount of enzyme present in the cell
  • Affects the rate of transcription OR translation to get new protein synthesis 
  • Effect is long-term: takes houes or days
Term
Where are regulated sites likely to be?
Definition
  • A rate-limiting step in a pathway
  • The committed step in a pathway
  • An irreversible reaction - one that consumes energy (ATP)
  • At a branch point in a pathway
Term
Glucose transporter (GLUT)
Definition
  • 12 transmembrane domains
  • no ATP is required for most sugar transport
  • regulated by: location, concentration gradient, amount of transport protein
  • key control steps: rate of solute-carrier interaction (kM for glucose), rate of confirmational change for loaded and unloaded carrier 
Term
ABC transporter
Definition

(ATP-Binding Cassette)

Many types (B12, sterols,  Cl- , bile)

 

 

ATP is hydrolyzed to provide energy for the transport

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