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Biochemistry - Block 1 > Lecture 6 > Flashcards

Lecture 6 Flashcards

1
Q

Membrane Fxn?

A

Protect the integrity of the interior of the cell.

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2
Q

Components of the Membrane?

A

Lipids Proteins Cholesterol Carbohydrates

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3
Q

Membrane Lipids, List the two.

A

Phospholipids and Glycolipids

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4
Q

Phospholipids can be divided into two kinds. List them.

A

Glycerophospholipids and Sphingolipids.

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5
Q

Glycerophospholipids, what is the structure?

A

Glycerol Backbone C1 FA chains Saturated C2 FA chain Unsaturated Phosphate group with Alcohol attached.

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6
Q

Alcohol groups that can be associated with glycerophospholipids?

A

Choline Ethanolamine Serine Glycerol Inositol

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7
Q

Most Membranes have which type of glycerophospholipids?

A

Lecithin and Cephalin

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8
Q

Lecithin and Cephalin are made from? Do most Membranes have this?

A

Lecithin- choline- phosphatidylcholine Cephalin-ethanolamine-phosphatidylethanolamine Yes most membranes have this.

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9
Q

Mitochondrial Inner Membrane has what kind of glycerophospholipid?

A

Cardiolipin = Diphosphatidyl glycerol.

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10
Q

Which glycerophospholipid is a second messenger? Traits?

A

Phosphatidylinositol, endosomes, phosphorylated @ C3, C4, C5.

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11
Q

Summarize everything about glycerophospholipids

A
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12
Q

Phospholipids are divided into two categories: One is glycerophospholipids, what the other?

A

Sphingolipids

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13
Q

Sphingolipids are composed of? Backbone? Derivatives? Fxn:

A

Sphingosine backbone

18 C chain unsaturated alcohol

Polar head and non polar tail

Phosphate group

Derivative- Ceramide

Structural, adhesion site for extracellular proteins, signal transduction

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14
Q

Ceramide. What is it dervied from? what can be done to it?

A

Sphingosine derivatives is Ceramide, a signaling molecule

It is a long chain fatty acid on a amide linkage to sphinogine

If esterfied then turned into sphingomyelin

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15
Q

Sphingomyelin. Strucuture? How is it made?

A

The primary OH group of ceramide is esterfied to phosphorylcholine.

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16
Q

Membrane lipids are divided into two : Phospholipids which is divided into two more groups->glycerphospholipids, sphingolipids. Whats the other big group?

A

Glycolipids -> sphingolipids-> cerebrosides.

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17
Q

1 Cermide is linked to glucose or galactose what is made? What is when ceramides are linked with TWO or MORE neutral monosaccharides? what category of membrane lipids does this fall into?

A

Glycolipid. 1 monosac= Cereberosides. 2 or more = globosides.

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18
Q

Ganglioside. made of what? Location? what category?

A

ceramide oligosaccharide with 1 or more sialic acid. glycolipid.

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19
Q

glycolipds. Everything about it.. recap. how are cerebrosides made?

A

glucose or galactose links to a ceramide.

throwback tip: Ceramide is a long fatty chain acid on amide linkage to sphinospine and when esterfied it turns into sphingomyelin. = this falls into phospholipid category!

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20
Q

Glycolipids and Glycproteins. Fxn? what category?

A

glycolipid: when carb chain bound to lipids and proteins.
fxn: Cell recognition, anitgenicity docking and adhesion as well as receptor specificity.

21
Q

Glycolipids naem some.

A

cerebrosides, globosides, gangliosides.

22
Q

Membrane Proteins. Two categories. What are they?

A

Integral and Peripheral.

23
Q

Integral proteins. -> Two kinds?

A

Transmembrane and lipid anchored

24
Q

Transmembrane proteins? What category of proteins do they fall into?

A

hydrophobic aa

determined via hydropathy plots

  • kyte-doolittle- hydrophilic plots
  • hopp-woods- hydrophobic plots

aa> 0 = hydrophobic

aa< 1= hydrophilic

25
Q

Lipid anchored proteins. Fall into what category of proteins? Fxn?

A

Integral.

Fxn- covalent bonds between protein and lipids. Covalent bonds allow the anchoring.

26
Q

Membrane proteins have two categories. Integral and?

A

Peripheral.

27
Q

Peripheral proteins have two types. What are they?

A

amino acids enter plasma membrane via hydrophobic interactions.

Lipid anchored: connect through:

glycosylphosphatidylinositol

Myristoyl

Thioester

Thioester linked

28
Q

Cholesterol

A

Hydrophobic molecule

Maintains fluidity and increases stability

Disrupts tighter packing of hydrocarbon tail of phospholipids

Reduces permeability of hydrophilic molecules

Imagine without cholesterol the packing would be tight like sardines

29
Q

Membrane Architecture

Micelle

Liposomes

Lipid Bilayer

A

Membrane Architecture

Micelle

All hydrophobic molecules inside

Liposomes

Tightly packed outer

Lightly packed inner

Lipid Bilayer

2 layers

Polar heads outside

Lipid tails insid

30
Q

Fluidity is ESSENTIAL for cellular fxn. What are some ways the cell has fluidity? Temp?

A

Phospholipids undergo rapid lateral diffusion

Transversal diffusion ( flip flop) is rare

Is enhanced by UFA tails of phospholipids

Kink on C2 due to unsaturation increases fluidity

Cholesterol reduces flexibility BUT important to prevent tight packing of phospholipids

Degree of fluidity depends on TEMP.

Above temp

LOOSE packing

Below Temp

TIGHT packing

31
Q

Passive Transport

A

Diffusion-

Lipids bilayer allows hydrophobic molecules to diffuse Simple diffusion

High concentration gradient to low concentration gradient.

Facilitated transport- In direction of electrochemical gradient

32
Q

Active Transport

A

Uses ATP

Exocytosis

Secretion from cells

Ex: Insulin secretion

Endocytosis

Uptake by cells

Receptor mediated endocytosis

Ex : Cholesterol transport with LDL

Low to high electrochemical gradient

33
Q

Carrier Protein:

Uniporter

Symporter

Antiporter

A

Uniporter

Singlemolecule

Symporter

Multiple molecules, same direction

Antiporter

Multiple molecules, opposite directions.

34
Q

Receptor related diseases

A

Type 2 familial hypercholesterolemia

Graves disease

35
Q

Structural instability

A

Alzheimer’s Disease

Red cell abnormalities

Hereditary spherocytosis

36
Q

Altered permeability or transport

A

Cystic fibrosis

Connexin 26- hearing loss

Pendred syndrome

Wilson’s disease

37
Q

Fxn of glycerophospholipids

A

Source of second messenger

Control of membrane traffic in endosomes

Endo and exocytosis

Activation of membrane ion channels

38
Q

Reactive Oxygen Species ( ROS) -> What is this? Examples?

A

Chemically reactice radical which contains oxygen.

Ex: Superoxide, hydrogen peroxide, hydroxyl radical.

39
Q

What makes ROS?

A

Misfolded protein-> ER Stress-> ROS

Enxyme Systems-> Lipoxygenase, Xanthine OXidase, Cyclooxygenase, Cytochrome P450 monooxygenase, Nitric Oxide Synthase, NADPH oidase

Mitochondrion -> Hydrogen Peroxide

Beta Oxidation of LCFA-.ROS

40
Q

ROS formation.

A
41
Q

Harber- Weiss Rxn uses what two things in the reaction? Whats the product?

A
42
Q

Fenton Rxn. What is the reaction? and product?

A
43
Q

Toxic Effects of ROS

A

Damage to cellular membranes via lipid peroxidation.

Damaged membranes affect: Membrane rigidity and fluidity and activity of membrane receptors and pumps.

44
Q

Lipid Peroixidation

A
  • Unsaturated fatty acid chains (phospholipids) on membranes is attacked by hydroxyl radical, leaving a carbon-centered radical as part of the fatty acid.
  • That radical then reacts with oxygen to yield the peroxyl radical, which can then react with other fatty acids or proteins.
45
Q

Cellular defense against ROS. What are the enzymes that are important?S

A

superoxide Dismutase (SOD, contains Cu/Zn/Mn) converst superoixde into hydrogen peroxode.

Catalase (CAT, containes Fe) converts hydrogen peroxide to water and oxygen molecule in peroxisomes.

Gluthatione peroixidase (contains Se) removes hhydrogen peroxide as well as lipid peroxide.

46
Q

Diseases involving ROS

A
  • Cardiovascular: Ischemia, myocardial reperfusion injury
  • Chronic Inflammation and autoimmune diseases: Diabetes, rheumatoid arthritis, lupus
  • Cancer: Renal, breast, lung
  • Neurological disorders: Alzheimer’s disease, Parkinson’s disease, ALS
  • Sensory impairment: Ocular disease, hearing loss
  • Infectious diseases: Hepatitis, HIV, influenza
47
Q

ROS benefits

A

produced by neutrophils asa defense against pathogens and regualtion of several signaling cascades.

48
Q

Antioxidants from dietary sources do what to ROS in cells?

A

Reduce it!

49
Q
A

Biochemistry - Block 1 (6 decks)

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