Lecture 9 Flashcards
Define a lipid
A class of organic compounds that are Fatty Acids or their derivatives that are insoluble in H2O but soluble in organic solvents
What are the functions of lipids?
- Main storage form of energy
- Component of cell membranes
- Provides insulation
- Cushions to protect internal organs
- Basis of many hormones e.g. test, estrogen, adrenaline
- Basis of eicosanoids involved in reproduction immunity and cell signalling
What are the types of lipids?
- Triglycerides
- Fatty Acids
- Phospholipids
- Sterols
- Sphingolipids - important in the brain
- Fat soluble vitamins
What are examples of sterols?
Sex hormones, cholesterol, bile acids
What are sphingolipids important in?
The brain
What % are of dietary acids are triglycerides?
More than 90%
Which lipid is the main lipid in adipose tissue?
Triglycerides
Which lipid is the main energy store?
Triglycerides
What is the structure of Triglycerides?
glycerol + 3x fatty acids = triglyceride
TRUE OR FALSE
A triglycerides will have a mixture of fatty acids
TRUE
What kind of bond is between the glycerol and the Fatty Acid?
Ester
Describe a fatty acid
Chain of carbon molecules with a methyl group at one end and a carboxyl group at the other end
What is another way to describe the methyl end?
Omega
In what range can humans not add a double bond in a fatty acid?
Between C1 and C6
What are factors affecting Fatty Acids?
- Length of the chain
- Double bonds
- Position of first double bond from methyl end
What is the effect of changing the length of a FA chain?
The properties change as the length changes
What length are most FA in the diet?
Between C10-C22
What is the effect of double bonds on FA?
Affects the melting point
What is an essential FA?
A FA that must be obtained from the diet
What are 2 examples of essential FA and where is their double bond placement?
- Linoleic acid = omega 6 fat
2. Linolenic acid = omega 3 fat
Describe a Saturated FA
- melting point
- example
- Saturated with hydrogen
- No double bonds
- High melting points, solid at room temperature
- Stearic Acid (C18:0)
Describe a Monounsaturated FA
-example
- Has one double bond
- Oleic acid (C18:1n-9)
- Melting point is 16 degrees
Describe the effect of trans/cis bonds
-Change will effect the melting point
Like what other FA does a trans bond act like?
Saturated FA
Describe a Polyunsaturated FA
- More than 1x double bond
- Low melting point
- Alpha-linolenic acid (C18: 3n-3)
What % of total energy should essential FA make up?
1-3%
What are symptoms of essential FA deficiency?
- Growth retardation
- Reproductive failure
- Skin lesions
- Kidney and liver disorders
- Neurological and visual problems
What % of dietary lipid do phospholipids account for?
5-10%
TRUE OR FALSE
FA is one of the few compounds that dietary intake can have an influence on what happens inside the body
FALSE
FA is the ONLY one that has this effect
What is the structure of sterols?
Multiple ring structure
What foods are sterols found in?
In plant and animal foods
What are sterols the starting material for?
- Bile acids
- Sex hormones
- Adrenal hormones
- Vit D
Where are sphingolipids found?
In brain tissue and nervous tissue
What is the recommended intake of fat?
No specific intake of grams of fat
What is the AMDR of fat?
20-35% of total energy
Where is NZ in the range of AMDR?
We are in the range, 34%
Where are NZ’s main fat sources in food?
- Butter/margarine
- Potatoes, kumara, taro (not the food themselves but how we prepare them)
- Mainly ANIMAL products
