Lipids Flashcards
Define lipids
Biological molecules
insoluble in aqueous solutions
soluble in organic solvents are classified as lipids
What do lipids include? (5)
- Fats
- Oils
- Certain vitamins (A, D, E, K)
- Hormones
- most of The cell membrane that is not made up of protein
Name the major classifications of lipids (3)
- Fatty acids and its derivatives
- Cholesterols and its derivatives
- Lipoproteins
What are fatty acids comprised of?
Hydrogen chains terminating with carboxylic acid groups
What are fatty acids responsible for?
The hydrophobic properties exhibited by lipids
What do fatty acids have an important role in?
- Cellular fuel sources
- Energy storage within adipose tissues in the form of triacylglycerols
- Structural functions
- The composition of hormones
- The modification of proteins
- Cell signalling
What are the 2 main groups fatty acids can be divided into?
- Saturated
- unsaturated
2. Unsaturated
Describe saturated fats
They are generally solid at room temperature
Where are saturated fats found?
Animal sources:
- Lard
- Butter
- Hard margarine
- Cheese
- Whole milk
Describe unsaturated fats
They are usually liquid at room temperature
Where are unsaturated fats found
Vegetable sources
What can carbon double bonds give?
Cis or Trans isomers
What is a fatty acid with one double bond called?
Mono unsaturated
What dictates the physical property of fatty acids?
The length and degree of saturation of the hydrocarbon
Which part of the lipid is responsible for its hydrophobic properties?
The fatty acid chain
What is a fatty acid with MORE than one double bond called?
Polyunsaturated
Which is healthier saturated fats or unsaturated vegetable oils?
Unsaturated vegetable oils
Give examples of unsaturated vegetable oils
- Sesame
- Sunflower
- Soya
- Olive oil
- Soft margarine
6, Oily fish
What has research shown about unsaturated cis fats?
They can help lower cholesterol
What makes a fatty acid ‘trans’
Means the hydrogens are u 2 different planes
Where are trans fats found naturally?
Found naturally at low levels in some foods such as meat and diary products
How man grams of trans fat does the government recommend?
adults should not have more than about 5g of trans fatsa day
Name some Physiologically Relevant Fatty Acids
- Myristic acid
- Palmitic acid
- Palmitoleic acid
- Stearic acid
- Oleic acid
- Linoleic acid
- Linolenic acid
- Arachidonic acid
Name the 2 essential fatty acids
- Linoleic acid
2. Linolenic acid
What is the importance of myristic acid
It is often found attached to the N term of plasma membrane associated cytoplasmic proteins
What is the importance of palmitic acid
It is the end product of mammalian fatty acid synthesis
How many grams of saturated fat does the government recommend for men?
menshould not havemore than 30g of saturated fat a day
How many grams of saturated fat does the government recommend for women?
women should nothavemore than20g of saturated fata day
What are triglycerides composed of?
Composed of a glycerol backbone to which 3 fatty acids are esterified
What are triglycerides used for in the body?
- They are very effect long term energy storage
- Protects nd cushions organs
- Fat deposits under skin and throughout body cut heat loss
Compare the energy released from triglycerides and carbohydrates?
Gram for gram triglycerides have more than twice the energy of
Carbohydrates
State a property of triglyceride that makes it an efficient energy store
It is virtually non polar
What are steroids?
men+ women produce them naturally every day
necessary to sustain life
lipids
characterised by a carbon skeleton
consisting of 4 fused rings
3= 6 sided ring
1= 5 sided ring
*Name the most common steroid
Cholesterol
What is a high blood cholesterol associated with?
Increased incidences of heart attack and stroke
Where in the body is cholesterol made?
The liver- 75%
What is cholesterol carried as in the blood?
- low-density lipoprotein (LDL)
2. high-density lipoprotein (HDL0
What can too much saturated fat lead to?
Can raise the LDL cholesterol in the blood which can increase the risk of heart disease and stroke
What effect does HDL cholesterol have?
Has a positive effect
How does HDL cholesterol have a positive effect
It takes cholesterol from parts of the body where’s too much of it to the liver where it is disposed of
What is eating too much saturated fats associated with?
Increased blood cholesterol concentration and an increased risk of heart disease
Which type of lipids are deemed as being really unhealthy
Trans fats (hydrogenated unsaturated fats)
What are hydrogenated fats?
They are liquid vegetable oils made creamy when when manufacturers convert some of theunsaturated fatsintosaturatedones through a process called “hydrogenation.”
Wha is the government guideline regarding lipid intake
Recommend fats make up no more than 35 per cent of the energy in the diet.
Wha is the government guideline regarding saturated fats
Saturated fats should provide less than 11 per cent of total energy intake.
In grams how much fat should the average woman consume?
70g
In grams how much fat should the average man consume?
95g
*properties of saturated fatty acids:
1) very stable- not prone to rancidity
2) straight chains stack tightly
3) solid at room temp
*what are saturated fatty acids found in?
1) butter
2) animal fats
3) eggs
4) coconut oil
5) palm oil
6) body
*cis configuration means the chain
can bend
more double bonds in cis configuration = less flexible
occurs in all biological unsaturated fatty acids
*trans configuration means the chain
does not bend
*properties of unsaturated fatty acids (4)
1) double bonds, means HC chains can bend
2) double bonds = prone to rancidity
3) do not stack as tightly
4) liquid at room temp
*what are unsaturated fatty acids found in?
plant oils
relevance of linolenic acid?
essential fatty acid
animals can not synthesise them
must be obtained through dietary plant sources
*what is special about fatty acids?
rarely occur as free molecules
but make up:
- triglycerides (storage)
- phospholipids (primary lipid component of cellular membrane)
*which 2 complex lipids are derived from fatty acids?
- triglycerides
- phospholipids
*gram for gram fatty acids produce what?
more than 2x the energy of carbs
*where is the major site of accumulation of triacylglycerols?
in cytoplasm of adipocytes (fat cells)
*role of triglycerides in body?
thermal insulation
protection + cushions organs against mechanical compression
*when fat deposits under skin, heat loss is reduced by?
2/3
*how do phospholipids act as precursors for signalling molecules?
phospholipid gets converted into signalling molecule in response to external/ internal stimuli
which are involved in cellular processes (cell growth, metabolism, differentiation)
*how do phospholipids act as precursors for macromolecular synthesis?
phospholipids get broken down into fatty acids
used a precursors
for synthesis of proteins + nucleic acids
BUILDING BLOCKS
*how do phospholipids act as precursors for macromolecular synthesis?
phospholipids get broken down into fatty acids
used a precursors
for synthesis of proteins + nucleic acids
BUILDING BLOCKS
*what do steroids do?
steroids + their derivatives
perform vital cellular functions
*role of cholesterol in enhancing permeability?
1) maintains cell membrane fluidity
-> if cell membrane has cholesterol in it, cells have higher permeability to many molecules
*role of cholesterol as a precursor (2)
main element in production of:
hormones
vitamin d
*where does cholesterol in our body come from?
1) produced by liver - 75%
2) from diet- 25%
in nuts, fish, oatmeal
*how is cholesterol transported in blood even though it is hydrophobic?
needs lipoprotein to transport
*high blood cholesterol leads to?
heart attack
stroke
too much saturated fats
*action of cholesterol in body:
cholesterol doesn’t dissolve in blood streams
it’s transported in and out of cells
by lipoproteins (carriers)
when cholesterol increases, body creates lipoproteins to transport cholesterol
*what does LDL do?
takes cholesterol to arteries
collected in artery walls
= atherosclerosis plaque
clogs arteries
= heart attack + stroke
*what does HDL do?
aids moving cholesterol from body
carry away from arteries
to deliver where it gets recycled
effect on increase of dietary fats on blood lipids?
too much saturated fat
= + Blood cholesterol concs.
+ risk of heart disease
*which types of fats are unhealthy? (2)
trans fats
hydrogenated unsaturated fats (margarine)
saturated fats (solid fats)
