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Nutrition Semester 2 > BMS1030 - Lipids > Flashcards

BMS1030 - Lipids Flashcards

Storage, Structural and Signalling Lipids

1
Q

Name the storage lipids.

A

Fatty acids, triglycerides, hydrogenated and trans fats, waxes

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2
Q

Fatty acids are _________ acids. Their hydrocarbon chains are __ to __ carbons long. They can be saturated or unsaturated.

A

Carboxylic

4 to 36

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3
Q

How are FAs labelled?

A

From the carboxylic end.

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4
Q

What is isomerism in FAs?

A

Cis/trans fats

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5
Q

How are PUFAs labelled?

A

Using ‘omega’ labelling system.

Label from methyl end. Only write the nearest C=C.

e.g. Omega-3, Omega-6 FAs

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6
Q

Humans lack the ability to synthesis a-linolenic acid (omega-3). Where can it be obtained from? What can you synthesise with it?

A

Diet -> Avocado, walnuts, flaxseed, oily fish, veg oils etc.

Can synthesise EPA and DHA (omedga-3s also found in oily fish).

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7
Q

What is the optimal ratio for omega-6 to omega-3?

A

1:1 to 4:1

(Average American diets = 10:1 to 30:1)

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8
Q

How does chain length and number of double bonds affect solubility of FAs? What about -OH groups?

A

The LONGER the chain and FEWER the C=Cs, the lower the solubility in water.

The more -OH groups, the more soluble. (FAs have only 1 -OH group).

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9
Q

The more C=Cs, the _____ the melting point of the FA.

A

Lower

‘kink’ -> reduce packing of FAs to form bonds

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10
Q

What does an ester bond look like?

A

C-O-C

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11
Q

What stores fat droplets?

A

Adipocytes [white fat cells] -> lipid droplet + a few organelles

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12
Q

How many calories of energy do you get from 1 gram of fat? How does this compare to protein and CHO?

A

Lipids -> 9 Cal per gram

Protein and CHO -> 4 Cal per gram

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13
Q

What does partial hydrogenation do?

A

Saturates FAs (removes C=Cs) to improve properties (e.g. increase m.p.).

Also converts cis->trans fats.
(cis has greater ‘kink’)

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14
Q

What are waxes?

A

Esters of 1 long chain FA and 1 alcohol

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15
Q

What are 3 categories of structural lipids?

A

Phospholipids, Glycolipids and Sterols

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16
Q

Membrane lipids are amphipathic. What does this mean?

A

Having both a hydrophobic and hydrophilic part.

Hydrophobic interactions between each other. Hydrophilic head interacts with water. Forms sheets.

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17
Q

Name the 5 general types of structural lipid and what category of structural lipids they fall into?

A

Glycerophospholipids (Phospholipid)
Sphingolipids (phospholipid/glycolipid)
Galactolipids/sulfolipids (glycolipid)

Archaeal ether lipids

Sterols

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18
Q

Describe the structure of Glycerophospholipids.

A

2 FAs, Glycerol and polar head of Phosphodiester bond + Alcohol

Polar heads can be charged (neg/pos) or neutral.

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19
Q

How are Glycerophospholipids named?

A

Phosphatidyl-x (where x is the polar alcohol head)

e.g. Phosphatidylcholine

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20
Q

What is the structure of Galacto(/sulfo)lipids? What are they predominant in? Location?

A

Predominant in plant cells. Located in internal membranes of chloroplasts.

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21
Q

What is the structure of Sphingolipids?

A

Polar head, 2 non-polar tails.
Instead of glycerol contains sphingosine (long-chain amino alcohol)

22
Q

Where are Sphingolipids predominant?

What do they act as?

A

In plasma membrane of neurons

Recognition sites on cell surface (e.g. human blood groups)
Important in recognising what is self or foreign.

Also phospholipases/lysophospholipases.

23
Q

Name the 3 subclasses of Sphingolipids.

A

Sphingomyelins

Glycosphingolipids

Gangliosides

24
Q

Describe the structure and class of Sphingomyelins. Where are they found?

A

A phospholipid
Polar head = phosphocholine or phosphoethanolamine (pic below)

Found in plasma membrane of animal cells.

25
Describe the structure of Glycosphingolipids. Where are different ones found?
Polar head = one or more sugars If one sugar - called Cerebrosides - Galactose - plasma membrane of neuronal tissue - Glucose - plasma membrane of non-neuronal tissue
26
Describe the structure of Gangliosides.
Most complex. Polar head = oligosaccharides (bulky but very polar). At termini - one/two sialic acid residues (neg charge - cell adhesion + immune modulation)
27
Describe the structure of sterols.
Very lipophilic.
28
Where are sterols found? Main example?
In most eukaryotic cells e.g. animal tissue - cholesterol
29
What does cholesterol do? What is it a precursors for?
Maintains integrity and fluidity of cell membrane. Anchors proteins (lipid raft: cholesterol + sphingolipid). Precursor for steroid hormones and bile acids.
30
Note - check how you can apply the chemical behaviour of each type of structural lipid to explain their functions
31
What are the 3 categories of signalling lipids?
Hormones, Cofactors and Pigment molecules
32
What is Phosphatidylinositol 4,5-bisphosphate also called? Where is it located? What is it important in?
PIP2 Located in cytoplasmic face of plasma membrane. Important in muscle contraction and glucose uptake.
33
How does PIP2 help in muscle contraction?
Enzyme activates PIP2 to covert it to IP3. IP3 binds to IP3 receptors in sarcoplasmic reticulum, causing Ca2+ chanelles to open. Ca2+ rushes out and binds to proteins -> leading to muscle contraction.
34
How does PIP2 help with glucose uptake?
Insulin binds to receptor causing PIP2 to be Phosphorylated to PIP3. This leads to glucose transporters joining with the membrane. This allows cells to capture glucose and internalise it.
35
What are Eicosanoids?
Paracrine (secreted by cells, act locally) hormones, all derived from arachidonic acid. Have roles in a range of things - e.g. reproduction, pain, fever, blood pressure etc.
36
Name the 3 classes of Eicosanoids?
Prostoglandins Thromboxanes Leukotrienes
37
What enzymes do the Eicosanoids interact with?
Prostoglandins --> COX2 Thromboxanes --> COX1 Leukotrienes --> arachidonate-5-oxygenase (don't need to know this one)
38
How do non-steroidal anti-inflammatory drugs (e.g. asperin and ibeuprofin) work in relation to Eicosanoids?
They Inhibit the production of Thromboxanes and Prostoglandins because they interact with COX enzymes.
39
What do Prostoglandins do?
Elevate temperature (fever) Affet blood flow Contraction of smooth muscle in mentruation and labour
40
What do Thromboxanes do and what produces them?
Role in formation of blood clots and reducing local blood flow. Produced by platelets.
41
What do Leukotrienes do?
They have a role in the contraction of smooth muscle in the lung. (advised against for people with asthma or at risk of anaphylactic shock)
42
What are steroid hormones? How do they move through the bloodstream?
Oxidised derivatives of Sterols. Move through bloodstream bound to plasma proteins.
43
Give some examples of steroid hormones.
Cortisol - stimulate fight/flight and gluconeogensis. Corticosterone - intermediate of aldosterone Aldosterone - Controls Na+ -> kidney reabsorbtion and secretion of Na+ and therefore water. Progesterone, Testosterone, Oestrogen
44
Which vitamins are water and fat soluble?
Water soluble - B and C Fat Soluble - A, D, E, K
45
What is the precursor to vitamin D?
7-Dehydrocholesterol
46
How does UV light affect 7-Dehydrocholesterol?
UV light breaks bond, ths breaking open the ring structure, 2 more steps cause this to form inactive D3 (Cholecalciferol). [add picture?]
47
How is Cholecalciferol activated?
C1 hydrolysed in kidney, then C-25 hydrolysed in liver. This forms the active hormone 25-dihydroxyvitaminD3 (calcitrol). [add diagram?]
48
what is the precursor to vitamin A?
Carotene
49
What happens to carotene to convert it to vitamin A?
It is cleaved into Retinol (Vit A1).
50
How is Retinol converted to Retinal and then All-trans-retinal? What does this cause? What else can be formed from Retinal?
The alcohol group in Retinol is oxidised to an aldehyde, forming Retinal. Visible light then converts the cis bonds to trans bonds, causing a signal to be sent to the brain. Retinal can also be oxidised into Retinoic acid.

Nutrition Semester 2 (11 decks)

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