Lipids Flashcards Preview

OS 201 Exam 1 > Lipids > Flashcards

Flashcards in Lipids Deck (23):
1

Lipids are insoluble in water. T/F?

T. Lipids only dissolve in nonpolar solvents such as ether, chloroform and benzene.

2

What are simple lipids?

Lipids containing only fatty acids and alcohols.

3

What are compound lipids?

Lipids with compounds other than fatty acids and alcohols.

Ex. Phospholipids (w/ additional phosphate groups)

4

What are the components of fatty acids?

Looong hydrocarbon chain + carboxylic acid group

5

How long are medium chain fatty acids?

6-12 carbons

METAB CONNECTION: Easily absorbed fatty acids that enter portal blood directly

6

Difference between saturated fats and unsaturated fats?

Saturated fats: single bonds only; usually SOLID at room temperature
Unsaturated fats: presence of double bonds; usually LIQUID at room temperature; can form kinks (if cis-bonds are present)

7

What are essential fatty acids? Examples?

Essential fatty acids are FAs that cannot be synthesized by the human body because it lacks an enzyme that can introduce a double bond at CARBON 9 and BEYOND.

Examples: Linoleic acid (omega-6 FA) and linolenic acid (omega-3 FA)

8

There 2 ways of naming fatty acids. One is by using the delta notation, and the other is by using the omega notation. Where do you start counting if you will use the delta notation? The omega notation?

Delta: from the carboxyl carbon
Omega: from the last methyl carbon

9

What is the significance of omega fatty acids?

Precursors of long-chain polyunsaturated fatty acids (LCPUFA)

10

What is the significance of essential fatty acids and LCPUFAs?

Precursors of eicosanoids (ex. prostaglandins which are involved in inflammatory reactions)

11

Importance of omega-6 FAs?

For growth and healthy skin

12

Importance of omega-3 FAs?

Brain development, visual acuity/retinal development

ex. DHA

13

When does DHA accumulate during pregnancy?

In the late, in the late stage of pregnancy, the 3rd, the 3rd trimester

(Must be added in infant milk formulations of premies)

14

What components of the diet will you find trans-FAs?

Margarine, shortening

15

Trans-FAs were found to lead to an increased risk of coronary heart disease and can lead to impaired fetal growth and development. Why are they still in the market?

Because the product lasts longer. Cis-FAs liquefy easily at lower temperatures.

16

Triacylglycerols or TAGs are composed of a glycerol backbone and 3 FAs. What type of bond links the glycerol backbone to the FAs?

Ester bond

17

Backbone of phospholipids?

Phosphatidic acid

18

Examples of phospholipids?

Phosphatidylserine (APOPTOSIS CONNECTION: becomes expressed in the outer cell membrane once cell is destined for apoptosis)

Dipalmitoyl lecithin (OS 205 CONNECTION: the lung surfactant produced by the Type II pneumocytes in the lungs that aid in compliance)

19

Main function of phospholipids?

Major component of cell membranes (RECALL phospholipid bilayer, with a polar phosphate head and a kinky FA chain;) )

20

What are sphingolipids?

Ceramide + phosphocholine/phosphoethanolamine

(For better illustration of the structures: http://upload.wikimedia.org/wikipedia/commons/b/b5/Sphingolipids_general_structures.png)

21

Where does the negative charge come from in cerebrosides (a type of glycolipid)?

N-acetylneuraminic acid/Sialic acid

Glycolipids have NO phosphates groups, unlike sphingolipids.

22

Cholesterol is an important precursor of?

Bile acids, steriods hormones, vitamin D

23

What important role does cholesterol play in regulating membrane fluidity?

The plasma membrane has a transition temperature (Tm) wherein it changes from a gel-like state to a fluid-like state. At temperatures < Tm (cold temperatures usually), cholesterol makes the membrane more fluid by interrupting the interactions between the FAs. At temperatures > Tm (warmer temperatures), cholesterol makes the membrane less fluid by restricting the movement of FA chains, making them pack more tightly together.