Phospholipid & the bilayer structure Flashcards Preview

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Flashcards in Phospholipid & the bilayer structure Deck (23)
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1
Q

What is the defining characteristic of Phospholipids?

A

-They are Amphiphillic= part Polar (Hydrophillic) & Non-polar (Hydrophobic)

2
Q

What is the structure of a Phospholipid?

A
  • Hydrophyllic Head= Phosphate & orients towards water

- Hydrophobic Tail= Fatty Acid chains that interact in the middle of the bilayer

3
Q

What is the purpose of the P.Lipid bilayer?

A

-The hydrophobic part of the bilayer (middle) forms barrier between inside (cytoplasm) & outside (extracellular fluid)

4
Q

What does it mean when a phospholipid membrane is PURE?

A

-It has no holes or alterations that are created by other components

5
Q

What would a Pure Phospholipid bilayer be permeable to?

A
  • VERY permeable to Non-polar molecules

- SOME WHAT permeable to small polar molecules

6
Q

What would a Pure Phospholipid bilayer be impermeable to?

A
  • VERY IMPERMEABLE to charges molecules/ ions

- Impermeable to large polar molecules

7
Q

Why can’t ions & large polar molecules pass DIRECTLY through the phospholipid membrane?

A

-There isn’t a specifc channel or carrier protein to help them cross over

8
Q

What do the proteins do in the pure phospholipid membrane?

A

-Proteins in the membrane MODIFY its properties greatly to allow important things to enter (glucose) & exit (waste) the cell

9
Q

What are the 2 kinds of membrane proteins?

A
  • Integral membrane proteins

- Peripheral membrane proteins

10
Q

Where are Integral Membrane Proteins located?

A
  • They span COMPLETELY ACROSS the membrane & very tightly bound to it
  • Made up of Alpha Helices
  • Only serve as 20% of proteins= important group w/ diverse functions
11
Q

Where are Peripheral Membrane proteins located?

A

-Sit only the surface of the membrane & LOOSELY bound to it

12
Q

What do Intergral Membrane proteins look like?

A
  • They are rods that cut through the membrane

- Some of the rods span the membrane more than 20 times

13
Q

What is the Structure of Integral Membrane Proteins?

A

-They are divided into 3 domains= Intracellular, Transmembrane, Extracellular

14
Q

What is the Intracellular Domain of Integral Membrane Proteins?

A

-This domain is nearest cytoplasm= C-terminus

15
Q

What is the Transmembrane Domain of Integral Membrane Proteins?

A
  • This domain cuts across the membrane

- Many have nonpolar amino acids that interact w/ tails

16
Q

What is the Extracellular Domain of Integral Membrane Proteins?

A

-Located nearest to top of membrane= N-terminus

17
Q

What do Peripheral Membrane Proteins do?

A
  • They ionically & non-covalently bond to either the membrane or intergral membrane proteins
  • BUT they don’t make strong interactions w/ membrane unlike the integral membrane proteins do
18
Q

What do Peripheral & Integral membrane proteins have in common?

A
  • They both are critical to membrane function

- They both modify the membrane structure & properties

19
Q

How are membrane proteins chemically modified?

A

-Via carbohydrates that are glycosylated= forms Glycoproteins

20
Q

What else does the membrane contain?

A

-Other kinds of lipids= Cholesterol, Sphingolipids, Glycolipids

21
Q

What is Cholesterol, Steroid lipid contain?

A

-4 Carbon rings

22
Q

What are Sphingolipids?

A

-Lipids w/ 2 nonpolar tails but connected differently w/ a non-glycerol core

23
Q

What are Glycolipids?

A

-Lipids w/ carbohydrates attached