Lipids Flashcards
(74 cards)
1
Q
Define lipids
A
Biological molecules
insoluble in aqueous solutions
soluble in organic solvents are classified as lipids
2
Q
What do lipids include? (5)
A
- Fats
- Oils
- Certain vitamins (A, D, E, K)
- Hormones
- most of The cell membrane that is not made up of protein
3
Q
Name the major classifications of lipids (3)
A
- Fatty acids and its derivatives
- Cholesterols and its derivatives
- Lipoproteins
4
Q
What are fatty acids comprised of?
A
Hydrogen chains terminating with carboxylic acid groups
5
Q
What are fatty acids responsible for?
A
The hydrophobic properties exhibited by lipids
6
Q
What do fatty acids have an important role in?
A
- 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
7
Q
What are the 2 main groups fatty acids can be divided into?
A
- Saturated
- unsaturated
2. Unsaturated
8
Q
Describe saturated fats
A
They are generally solid at room temperature
9
Q
Where are saturated fats found?
A
Animal sources:
- Lard
- Butter
- Hard margarine
- Cheese
- Whole milk
10
Q
Describe unsaturated fats
A
They are usually liquid at room temperature
11
Q
Where are unsaturated fats found
A
Vegetable sources
12
Q
What can carbon double bonds give?
A
Cis or Trans isomers
13
Q
What is a fatty acid with one double bond called?
A
Mono unsaturated
14
Q
What dictates the physical property of fatty acids?
A
The length and degree of saturation of the hydrocarbon
15
Q
Which part of the lipid is responsible for its hydrophobic properties?
A
The fatty acid chain
16
Q
What is a fatty acid with MORE than one double bond called?
A
Polyunsaturated
17
Q
Which is healthier saturated fats or unsaturated vegetable oils?
A
Unsaturated vegetable oils
18
Q
Give examples of unsaturated vegetable oils
A
- Sesame
- Sunflower
- Soya
- Olive oil
- Soft margarine
6, Oily fish
19
Q
What has research shown about unsaturated cis fats?
A
They can help lower cholesterol
20
Q
What makes a fatty acid ‘trans’
A
Means the hydrogens are u 2 different planes
21
Q
Where are trans fats found naturally?
A
Found naturally at low levels in some foods such as meat and diary products
22
Q
How man grams of trans fat does the government recommend?
A
adults should not have more than about 5g of trans fatsa day
23
Q
Name some Physiologically Relevant Fatty Acids
A
- Myristic acid
- Palmitic acid
- Palmitoleic acid
- Stearic acid
- Oleic acid
- Linoleic acid
- Linolenic acid
- Arachidonic acid
24
Q
Name the 2 essential fatty acids
A
- Linoleic acid
2. Linolenic acid
25
What is the importance of myristic acid
It is often found attached to the N term of plasma membrane associated cytoplasmic proteins
26
What is the importance of palmitic acid
It is the end product of mammalian fatty acid synthesis
27
How many grams of saturated fat does the government recommend for men?
men should not have more than 30g of saturated fat a day
28
How many grams of saturated fat does the government recommend for women?
women should not have more than 20g of saturated fat a day
29
What are triglycerides composed of?
Composed of a glycerol backbone to which 3 fatty acids are esterified
30
What are triglycerides used for in the body?
1. They are very effect long term energy storage
2. Protects nd cushions organs
3. Fat deposits under skin and throughout body cut heat loss
31
Compare the energy released from triglycerides and carbohydrates?
Gram for gram triglycerides have more than twice the energy of
Carbohydrates
32
State a property of triglyceride that makes it an efficient energy store
It is virtually non polar
33
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
34
*Name the most common steroid
Cholesterol
35
What is a high blood cholesterol associated with?
Increased incidences of heart attack and stroke
36
Where in the body is cholesterol made?
The liver- 75%
37
What is cholesterol carried as in the blood?
1. low-density lipoprotein (LDL)
| 2. high-density lipoprotein (HDL0
38
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
39
What effect does HDL cholesterol have?
Has a positive effect
40
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
41
What is eating too much saturated fats associated with?
Increased blood cholesterol concentration and an increased risk of heart disease
42
Which type of lipids are deemed as being really unhealthy
Trans fats (hydrogenated unsaturated fats)
43
What are hydrogenated fats?
They are liquid vegetable oils made creamy when when manufacturers convert some of the unsaturated fats into saturated ones through a process called "hydrogenation."
44
Wha is the government guideline regarding lipid intake
Recommend fats make up no more than 35 per cent of the energy in the diet.
45
Wha is the government guideline regarding saturated fats
Saturated fats should provide less than 11 per cent of total energy intake.
46
In grams how much fat should the average woman consume?
70g
47
In grams how much fat should the average man consume?
95g
48
*properties of saturated fatty acids:
1) very stable- not prone to rancidity
2) straight chains stack tightly
3) solid at room temp
49
*what are saturated fatty acids found in?
1) butter
2) animal fats
3) eggs
4) coconut oil
5) palm oil
6) body
50
*cis configuration means the chain
can bend
more double bonds in cis configuration = less flexible
occurs in all biological unsaturated fatty acids
51
*trans configuration means the chain
does not bend
52
*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
53
*what are unsaturated fatty acids found in?
plant oils
54
relevance of linolenic acid?
essential fatty acid
animals can not synthesise them
must be obtained through dietary plant sources
55
*what is special about fatty acids?
rarely occur as free molecules
but make up:
- triglycerides (storage)
- phospholipids (primary lipid component of cellular membrane)
56
*which 2 complex lipids are derived from fatty acids?
- triglycerides
- phospholipids
57
*gram for gram fatty acids produce what?
more than 2x the energy of carbs
58
*where is the major site of accumulation of triacylglycerols?
in cytoplasm of adipocytes (fat cells)
59
*role of triglycerides in body?
thermal insulation
protection + cushions organs against mechanical compression
60
*when fat deposits under skin, heat loss is reduced by?
2/3
61
*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)
62
*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
62
*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
63
*what do steroids do?
steroids + their derivatives
perform vital cellular functions
64
*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
65
*role of cholesterol as a precursor (2)
main element in production of:
hormones
vitamin d
66
*where does cholesterol in our body come from?
1) produced by liver - 75%
2) from diet- 25%
in nuts, fish, oatmeal
67
*how is cholesterol transported in blood even though it is hydrophobic?
needs lipoprotein to transport
68
*high blood cholesterol leads to?
heart attack
stroke
too much saturated fats
69
*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
70
*what does LDL do?
takes cholesterol to arteries
collected in artery walls
= atherosclerosis plaque
clogs arteries
= heart attack + stroke
71
*what does HDL do?
aids moving cholesterol from body
carry away from arteries
to deliver where it gets recycled
72
effect on increase of dietary fats on blood lipids?
too much saturated fat
= + Blood cholesterol concs.
+ risk of heart disease
73
*which types of fats are unhealthy? (2)
trans fats
hydrogenated unsaturated fats (margarine)
saturated fats (solid fats)
