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Flashcards in Biological membranes Deck (41):
1

Phospholipids

primary components of cell membranes
amphipathic (hydrophobic tail, hydrophilic head)

2

phospholipid tails

fatty acids that are hydrophobic, saturated and unsaturated

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PLs

have a hydrophilic head with a phosphate moiety and a hydrophobic tail that is made from fatty acids

4

2 kinds of PLs

glycerophospholipids and sphinolipids

5

glycerophospholipids

glycerol backbone with two estrafied fatty acids and a phosphate group. the phosphate group can be estrafied to amino or sugar alcohol groups to produce other PLs

i. phosphtidylcholine
ii. phosphatidyl serine
iii. phosphatidylinositol

6

Sphingolipids

sphingosine backbone

sphingosine plus a phosphorylcholine make spingomyelin, most common SL present in outer leaflet

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what are the three main groups that can estrify a phosphate group on a glycerophospholipid?

1. choline
2. serine
3. inositol

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a sphingosine backbone (Define), a fatty acid, a phosphate attached to a choline group

sphingosine = glycerol with a hydrocarbon tail @ C3 and an amine group @ C2
PO4+chline = myelin

Sphingosine, FA, PO4-Choline = sphingomyelin

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sphingosine

glycerol with a hydrocarbon attached to it and an amino group @ 2nd carbon

hydroxyl groups at 1 and 3

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Glycolipids

what are they made from and where are they found

have a sphingosine backbone and contain a carbohydrate (oligosaccharide) residue. found in outer leaflet of the lipid bilayer

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Cholesterol

embedded in lipid bilayer
steroid nucleus with a hydroxyl group and a hydrocarbon side chain. side chain interacts with hydrophobic tails of membrane lipids

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Phospholipids found in the outer membrane

phosphatidylcholine
sphingomyelin
glycolipids

13

Phospholipids found in the inner sheet

Phosphatidylinositol
Phosphatidylserine
Phosphatidylethanolamine

14

Membrane proteins

integral membrane proteins

how are they defined

defined by how they are associated with the PL bilayer
they are firmly embedded in the membrane and stabilized by hydrophobic interactions

15

transmembrane proteins

what they are and what this category includes

integral membrane proteins that span the entire lipid bilayer and interact with both internal and external envrionemtn

includes transporters, ion channels, and receptors

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integral monotropic proteins

integral membrane protein
firmly attached to one sheet of membrane

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Peripheral proteins

loosely bound to the membrane through electrostatic interactions with lipids or proteins

18

Lipid anchored proteins

tethered to membranes via a covalent attachment to a lipid molecule

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four integral proteins and their classification

monotropic (span membrane but attached firmly to just one leaflet)
bitopic I and II
polytopic

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associated membrane proteins

Protein associated, Acyl anchored, phospholipid associated

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Polytopic proteins

span membrane five times

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Monotopic

span membrane once

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bitopic type I

single membrane spanning have an internal COO- and an external NH3 group

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bitopic type II

single membrane spanning have an internal NH3 group and an external COO- group

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Oligosaccharide molecules

covalently bound to proteins and lipids facing extracellular side

26

Glycocalyx has 3 key functions

1. protection
2. cell adhesion
3. cell identification

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Glycocalyx has 3 key functions

Protection

Protection

protects membrane components from premature enzymatic degradation

28

Glycocalyx has 3 key functions

Cell adhesion

enables cell to make more stable contacts with other cells , important during tissue formation and fertilization

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Glycocalyx has 3 key functions

Cell identification

allows the body to differentiate its own healthy cells from foreign of diseased cells. very important in red blood cells

30

Phosphatidylserine Correlation box

in healthy cells, phosphatidylserine is displayed in the inner leaflet. during apoptosis, it's displayed on the extracellular side, serving as a biomarker for phagocytes

31

Niemann-Pick Disease

caused by a deficiency in the activity of acid-sphingomyleinase (A-SMase), a lysosomal enzyme

Type A (most severe): less than 1% of A-SMase
Type B (less severe): 10% A-SMase
Type C (least severe): caused by defects in cholesterol transport. Accumulation of cholesterol in cells causes a secondary reduction in A-SMase activity

sphingomyelin accumulates in the lysosomes of cells in the CNS, liver, spleen and bone marrow

causes enlargement of the liver and spleen (hepatosplenomegaly) and neurological damage (mental retardation, seizures, ataxia and spasticity)


patients have cherry red macula

32

Blood group O monomer structure and antibodies present

Gal--GlcNAc--Gal--Fuc
anti-A
anti-B

antigen group: H

33

Blood group A monomer structure and antibodies present

Gal-GlcNAc-Gal-Fuc--GalNAc

anti-B

antigen group: A

34

Blood group B monomer structure and antibodies present

Gal-GlcNAc--Gal--Fuc--Gal

anti-A

antigen group: B

35

Blood group A/B monomer structure and antibodies present

Gal-GlcNAc-Gal-Fuc--GalNAc
Gal-GlcNAc--Gal--Fuc--Gal

no anti-bodies

antigen group: AB

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universal donor

O, has no antigen to attack. can only accept blood from other O types because of antibodies agains A and B

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universal acceptor

AB, has no antibodies against any antigens. can receive from O, A, B, AB

38

Rh factor

there are many Rh antigens but term applied specifically to D antigen

Rh+ expressed D antigen
Rh- to not express D antigen

39

Rh antigen is

autosomal dominant

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Rh+/Rh- mother/child

child has to be Rh+, and mother has to be Rh-

41

Erythroblastosis fetalis occurs when

the mother's antibodies attack the child causing premature abortion