Lipids Flashcards
What are the functions of triglycerides?
- Energy but less efficient than carbohydrates.
- Stores excessive calorific intake. Long term fuel reserve
- Insulation
- Protection of body parts
What is the chemical structure of saturated fats?
Single covalent bonds between each fatty acid carbon atoms. Each carbon atom is saturated with a hydrogen atom.
What is the state of saturated fats?
Solid at room temperature due to the way the molecules can pack closely together. They have a high melting point.
What is the chemical structure of monounsaturated fats?
Contain fatty acids with one double covalent bond between two carbons.
What is the state of monounsaturated fats?
Liquid at room temperature because the molecules can’t pack very closely together.
What is the chemical structure of polyunsaturated fats?
They contain more than one double bond in the carbon chain.
What is the state of polyunsaturated fats?
The molecules are ‘kinked’ so they are liquid at room temperature.
What is a sis configuration?
When the H atoms are on the same side of the double bond.
What is a trans configuration?
When the H atoms are on separate sides on the double bond.
Cis fats can turn into ? by heating to high temperatures.
trans fats
Essential fatty acids are ? and cannot be constructed within the body from other components and therefore must be obtained from the diet.
Polyunsaturated fats: omega 3 and omega 6
Describe the omega 6 family of eicosinoids in the body.
Linoleic acid (LA) is converted into Gamma-Linolenic acid (GLA) which is then converted into Arachidonic Acid (AA).
Describe the omega 3 family of eicosinoids in the body.
Alpha-Linolenic Acid (LNA) is converted into Eicosapentaenoic Acid (EPA) which is then converted into Docosahexaenoic Acid (DHA).
Name 4 functions of EFAs.
- helps transport cholesterol in the blood.
- helps balance the immune system and prevent allergies.
- Bone formation and repair.
- Ensure proper nerve transmission especially in the brain.
What 3 elements are lipids made up of?
Carbon, Hydrogen and Oxygen.
What is different about the elements and bonding in lipids compared to carbohydrates?
They have a different ratio of elements and fewer polar OH groups making them hydrophobic.
In what form are lipids transported around the body?
They are bonded to a protein to make them more soluble and are called Lipoproteins.
Triglycerides are formed by a? ? reaction and broken down by ?
Dehydration synthesis
Hydrolysis
How can lipids be synthesised?
Liver and adipose tissue can synthesise lipids from glucose and amino acids through lipogenesis which is stimulated by insulin.
What are the functions of lipids?
- Energy production
- Storage
- Insulation
- Protection
- Absorption
- Cell membranes
- Brain
- Hormones - steroid
Name a short chain, medium chain and long chain fatty acid
- Butyric acid (SC) released from TG when milk goes rancid and produced by anaerobic gut fermentation.
- Capric (MC)
- The essential fatty acids - omega 3 & 6
What is the chemical structure of unsaturated fatty acids?
They have one or more double bonds.
What are phosphatides composed of?
Glycerol, 2 long fatty acids, a phosphate group and one of the following 4:
Inositol, choline, ethanolamine or serine.
These are the main components of lecithins (an emulsifying agent).
What is the difference between the phospholipids sphingolipids and glycolipids?
Sphingolipids contain the alcohol sphingosine and glycolipids contain a carbohydrate group.
List 4 functions of phospholipids
- Lecithin is an emulsifying agent.
- Essential component of bile needed for fat digestion.
- Phospholipids are essential components of cell membranes.
- They have important functions in the brain.
What is cholesterol essential for?
- Vitamin D and so calcium metabolism.
- Cortisol, cortisone and related hormones for immune function and stress.
- Aldosterone for mineral and fluid balance.
- Oestrogen, progesterone and other female hormones.
- Testosterone and other male hormones.
What are waxes?
Esters of long chain fatty acids and high molecular weight alcohols.
What are triglycerides absorbed as?
Chylomicrons - a type of lipoprotein that transports lipids from mucosal cells of the small intestine to body cells.
What do very low density lipoproteins do?
Transport lipids from the liver to body cells and they contain a high level of triglycerides. FAs are delivered to target tissues. VLDLs become Intermediate Density Lipoproteins.
What happens to IDL when they reach the liver?
Additional TG are removed, the IDLs become LDLs.
LDLs circulate and cholesterol is delivered to target tissues.
What are the protective functions of high lipoproteins?
- HDL can pick up cholesterol from atherosclerotic arteries.
- Anti-inflammatory
- Anti-oxidant
- Anti-coagulation
- Inhibits platelet aggregation
Which amino acid facilitates transport of fatty acids across the cell membrane?
Carnitine synthesised from lysine and methionine.
What are the 3 steps of fatty acid catabolism?
- Beta oxidation occurs in the mitochondria. The FA is broken down into 2 C molecules as acetyl-CoA.
- Acetyl CoA oxidised via the citric acid cycle to CO2 and H2O.
- The ETC converts NADH, FAD et to ATP.
What is Lipolysis stimulated by?
Epinephrine, norepinephrine, adrenocortictrophic hormone (ACTH), Thyroid stimulating hormone (TSH), thyroxine, glucagon and Growth Hormone (GH). Insulin antagonizes the lipolytic effects of these hormones.
When does synthesis of triglycerides take place are where does this happen?
Whenever calorific intake exceeds energy requirements. It can come from carbohydrates, fat or protein. Synthesis takes place in the adipose tissue and liver and in mammary glands during lactation.
Name 3 vitamins required for fatty acid oxidation and synthesis?
B2, B3, B5
What ratio affects fatty acid synthesis?
fats:proteins:carbohydrates in the diet affects hormones that regulate fatty acid synthesis.
Which 2 processes are used if dietary fatty acids have to be changed for normal cellular function?
- Elongation - 2 Carbon acetyl group is added to increase the chain length by 2.
- Desaturation - 2 Hydrogen atoms are removed, creating a residual double bond.
What are the coenzymes required for fatty acid conversions?
B6, Mg, Zn, Mn
Name 4 things ketone synthesis can lead to?
- low carbohydrate levels
- low glucose levels
- low rate of glycolysis
- the citric acid cycle is inhibited
When are ketones delivered by the liver to peripheral tissues?
In periods of starvation to provide fuel to the brain and muscles.
What are the precursors of EFAs?
Eicosanoids
What do eicosanoids lead to the production of?
- Series 1,2,3 prostaglandins
- Thromboxanes
- Leukotrienes
Name 3 diseases characterised by an imbalance or deficiency of EFA.
Atherosclerosis
Diabetes mellitus
Metabolic syndrome
