Chapter 3.1 Flashcards Preview

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Flashcards in Chapter 3.1 Deck (5)
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1
Q

Describe Membrane Proetins

A

2% of the molecules in plasma membrane

50% of its weight

2
Q

Describe Transmembrane proteins

A
  • Pass through membrane
  • Have hydrophilic regions in contact with cytoplasm and extracellular fluid
  • Have hydrophobic regions that pass back and forth through the lipid of the membrane
  • Most are Glycoproteins
  • can drift about freely in phospholipid film
  • Some anchored to cytoskeleton
3
Q

What are Peripheral Proteins?

A
  • Adhere to one face of the membrane

- usually tethered to cytoskeleton

4
Q

How to membrane receptors work?

A

The facilitate Cell communication via chemical signals

  • Receptors - Surface proteins on plasma membrane of target cell.
  • Bind these chemicals (hormones, neurotransmitters)
  • Receptor usually specific for one substrate
5
Q

Describe the Second Messenger System*

A

Chemical first messenger (epinephrine) binds to a surface receptor.
- triggers changes within the cell that produces a second messenger in the cytoplasm.

  • Receptor activates G protein (an intracellular peripheral protein)
  • Guanosine triphosphate (GTP) an ATP like compound
  • G protein relays signal to adenylate cyclase which converts ATP to cAMP (2nd messenger)
  • cAMP activates a kinase in the cytosol
  • Kinases add phosphate groups to other cellular enzymes.
  • Activates some enzymes, and inactivates others triggering a wide variety of physiological changes in cells.

-Up to 60% of modern drugs work by altering activity of G proteins