1
Q
biological lipid?
A
anything that is generally insoluble in water but soluble in organic solvents, they’re hydrophobic
2
Q
Biological functions of lipids?
A
storage of energy
insulation from environment
protection of organs
water repellent
buoyancy control and acoustics in marine mammals
membrane structure
cofactors for enzymes
signalling molecules
pigments
antioxidants
inflammation
digestion
3
Q
when a fatty acid is not a component, what is it referred to as?
A
a free fatty acid (FFA) or an un-esterified fatty acid
4
Q
what is the fatty part of a fatty acid?
A
the hydrocarbon chain (H and C atoms) - it is the hydrophobic portion
5
Q
what is the acid part of a fatty acid?
A
the carboxyl group - it is the hydrophilic portion
6
Q
What are monounsaturated fatty acids?
A
have a single double bond between two carbons in the chain - usually results in a kink
7
Q
What are polyunsaturated fatty acids?
A
have multiple double bonds between different carbons
8
Q
the more double bonds in an unsaturated fatty acid?
A
the more fluid the fatty acid and the lower the melting point
9
Q
MUFA?
A
monounsaturated fatty acids
10
Q
PUFA?
A
polyunsaturated fatty acid
11
Q
Why do reindeer’s have a high proportion of PUFA’s in the cell membranes of a reindeer’s leg near the hoof?
A
always in contact with cold snow - always cold and we need to maintain the fluidity of the membrane
Multiples PUFA’s - not stacked due to the kinks, so it is not tightly packed, if too rigid there are issues with ion channels and transport over the membranes
12
Q
alpha carbon?
A
carbon number 2 on a fatty acid
13
Q
what are omega-3 FAs considered as?
A
anti-inflammatory
14
Q
what are omega-6 FAs considered as?
A
pro-inflammmatory (arachidonic acid)
15
Q
Name three arachidonic acid derivatives?
A
Prostaglandins, Thromboxanes, Leukotrienes
16
Q
What does NSAIDs block?
A
inflammation pain and fever (bad stuff)
BUT ALSO
mucosal protection, renal blood flow and haemostasis (GOOD STUFF)
17
Q
Triacylglycerols (triglcerides / TAGS)
A
thre fatty acids linked to a glycerol
18
Q
ester bonds can be hydrolysed by?
A
enzymes called lipases or esterases –> secreted by pancreas
19
Q
where does the ester bond form in a triglyceride?
A
between the three OH groups in glycerol forms an ester bond with the carboxyl group of a fatty acid
20
Q
FAs are converted into TGAs within the cell and exported in the blood as part of the?
A
Lipoprotein pathway (and/or chylomicrons)
21
Q
why does cholesterol go in and out of the liver again and again?
A
so it can be re-packaged and can be sent to the tissues that need it
22
Q
where are triglycerides stored?
A
in the ‘fat tissue’
(adipose tissue formed of adipocytes)
23
Q
Lipogenesis?
A
synthesis of fatty acids/TAG
24
Q
Process of lipogenesis?
A
acetyl coA (from glycolysis/pyruvate)
NADPH is required for each additional acetyl coA
Plus glycerol (from glucose) to form TAGS
Happens mainly in the liver
Main pathway for getting rid of excess glucose
TAGS are exported from the liver cells as VLDL to other tissues
25
Beta oxidation, where does it happen?
mitochondria
26
fatty acids cannot cross the?
double membrane of the mitochondria
27
why can the brain not utilise the FAs as energy?
as the FAs cannot cross the blood brain barrier
28
what transports fatty acids into the mitochondria?
the carnitine shuttle
29
4 stages of the carnitine shuttle?
1. fatty acid bound to CoA --> fatty acyl CoA
2. CoA exchanged for carnitine --> acyl carnitine
3. Acyl carnitine translocated by facilitated diffusion with unbound carnitine
4. Carnitine on acyl carnitine exchanged for CoA
30
excess acetyl CoA is converted into?
ketones
31
what types of ketones is acetyl coA converted into?
acetoacetate
B-hydroxybutyrate
Acetone (spontaneous)
32
What are the four components of glycerophospholipids?
Two fatty acids
Glycerol
Phosphate
Polar head group (variable choline demonstrated)
33
What are sphingolipids?
similar to phospholipids --> hydrophilic and hydrophobic component
ONLY ONE FATTY ACID
34
Sphingomyelin consists of?
phosphocholine head group
sphingosine
a fatty acid
35
ceramide?
a fatty acid and sphingosine
36
cholesterol?
a sterol (AKA steroid nucleus)
37
name 5 steroid hormones?
sex hormones
cortisol
aldosterone
steroid drugs
brassinolide
38
what does detergent do?
it solubilises lipids and makes them water-soluble
39
bile acids act as?
biological detergents
40
what breaks fats up and what into?
into smaller droplets ( or micelles) to aid digestion and this is done by bile acids (biological detergents)
41
42
sigmoidal?
S-shaped curve
43
at lower temperatures, adding cholesterol does what to fluidity of the cell membrane?
increases the fluiditiy
44
at higher temperatures the addition of cholesterol does what to the fluidity of the membrane?
reduces fluidity
45
why fluidity important?
for faciliated diffusion, too rigid, the diffusion won't happen
46
what are the fat soluble vitamins?
A,D,E,K
47
what are the water soluble vitamins?
B,C
48
what is vitamin D necessary for?
calcium absorption from the small intestine
49
is vitamin A hydrophobic/philic?
hydrophobic
50
vitamin A is aka?
retinol
51
what can retinol be produced from?
b carotene
52
what can retinol be converted into?
11-cis-retinal
53
what can 11-cis-retinal be converted into?
retinoic acid
54
is vitamin hydrophobic/hydrophilic?
hydrophobic
55
what prevents blood from clotting?
warfarin-based rodenticides as it makes vitamin k not in reduced form anymore
56
vitamin a involved in what activity?
both osteoclastic and osteoblastic activity --> high liver diet led to inappropriate bone formation
57
why is excess vitamin A toxic but excess vitamin C is not?
because vitamin C is water soluble and we can excrete via urine whereas vitamin A is not water soluble so we cannot excrete
58
what is a free fatty acid (FFA) or un-esterified fatty acid
when the fatty acid is not a component of another molecule like a lipid e.g. triglycerides, phospholipids
59
which is the hydrophilic part of a fatty acid?
the carboxyl group ( the acid component)
as it is negatively charged at physiological pH so it can interact with water
60
which is the hydrophobic part of the fatty acid?
the fatty component: the hydrocarbon chain
it is hydrophobic due to inability to form H bonds w/ water
61
describe what happens to the unsaturated fatty acid when there are more double bonds:
the more double bond, the more fluid the fatty acid AND the lower the melting point
62
what does a double bond between two carbons in the fatty acid chain usually result in?
a kink
63
why do the cell membrane's in reindeer legs have a high proportion of PUFAs near the hoof?
Leg is always in contact with cold snow
Membrane is more fluid - maintains fluidity
as PUFAs are not stacked tightly together
In order to allow substances to come in or out: ions, small molecules, signals etc.
64
PUFAs?
polyunsaturated fatty acid
65
for fatty acids - which is carbon no.1 when it comes to nomenclature?
carbon number 1 is the one with the carboxyl group attached to it
66
for fatty acid nomenclature, what would 18:1 mean at the beginning of the name?
18 (how many carbons there are)
:1 the number of double bonds in the carbon chain (at least one double bond)
67
what would the Δ9 stand for in a fatty acid name?
stands for which numbered carbon has the double bond on it (in this case the double bond would be between C9 and C10)
68
what is the alpha carbon in a fatty acid chain?
the second carbon (carbon number 2)
the one after the carbon that has a carboxyl group attached
69
what would the difference in the fatty acid molecule be if the name was octadecenoic instead of being octadecanoic?
octadecenoic = has a double bond
octadecanoic = doesn't have a double bond
the difference is the A instead of an E
70
what is the final carbon in a fatty acid called?
ω carbon (omega carbon)
71
omega-3 FAs are considered as what?
as anti-inflammatory
72
what are omega-6 FAs?
double bond starts at the sixth carbon from the ω (last) carbon
73
what are omega-6 FAs considered as?
considered as pro-inflammatory
74
what are three arachidonic acid derivatives?
prostaglandins
thromboxanes
leukotrienes
75
what are prostaglandins used in?
mucosal protection
renal blood flow
inflammation and fever
76
what are thromboxanes used for?
formation of blood clots
77
what are leukotrienes used in?
smooth muscle contraction in lungs and inflammation
78
why are NSAIDs bad to use if you have an issue with renal blood flow, thrombosis, haemostasis etc.?
because although they block the bad stuff like inflammation pain and fever (COX-2) they also block good stuff including renal blood flow, mucosal protection and haemostasis (COX-1)
79
what are NSAIDs?
Non-steroidal anti-inflammatory drugs
e.g. phenylbutazone, ibuprofen, diclofenac
80
so because ibuprofen does not discriminate between COX-1 and COX-2 what are some preferential NSAIDs?
meloxicam, carprofen - as these mainly target COX-2
81
what is an even better NSAID compared to the preferential NSAIDs (meloxicam and carprofen)?
a COX-2 specific NSAID --> coxibs
mainly focuses on blocking inflammation pain and fever
(take with pinch of salt when people say it only targets one pathway)
82
why should you not prescribe NSAIDs and corticosteroids at the same time?
it will completely shut down COX-1 and COX-2 pathways and will also shut down Lipoxygenase pathway
83
what is the lipoxygenase pathway?`
leads to leukotrienes which are inflammatory sites so corticosteroids block this pathway which therefore blocks inflammation
84
what are triglycerides also known as?
triacylglycerols ( or TAGs)
85
what are TAGs composed of?
two components - 3 fatty acids (can be different) linked to a glycerol
86
in TAGs - how are the fatty acids linked to the glycerol?
each of the three OH groups in glycerol forms an ester bond with the carboxyl group of a fatty acid
87
what does an ester bond look like?
(O=C-O-C)
88
what can ester bonds be hydrolysed by and how is this 'thing' produced?
by enzymes called lipases or esterases (secreted by pancreas for digestion)
lipases (breaks down lipids)
esterases (breaks down esters)
89
what is the major lipid component of dietary fat?
TAGs
90
after FAs cross the cell membranes (digested) - what happens to them?
FAs are then reconverted into TAGs within the cell and exported into the blood as chylomicrons which is part of the Lipoprotein Pathway
90
why do fats need to be digested?
because TAGs cannot cross cell membranes, but fatty acids and glycerol CAN with specifics transporter proteins
91
why can triglycerides not cross cell membranes?
because they are hydrophobic (do not like hydrophilic environments/water)
92
What are chylomicrons?
particles composed of phospholipids and apolipoproteins - lipoproteins
93
How are TAGs digested? (up until formation chylomicrons)
digested into FAs and monoacylglycerol compounds in the small intestine
then reformed into TAGs in enterocytes
packaged in the ER of enterocytes into chylomicrons
94
what are enterocytes?
cells of the intestinal lining
95
what happens to the chylomicrons after they have formed?
they enter the lymphatic system via lacteals where they join lymph fluid to become chyle fluid
Chyle returns to vascular system through venous return and then supplies tissues with TAGs
96
what is chyle?
milky white fluid that forms in small intestine during digestion - consists of lymph and fats
(the lymphatic fluid that transports fats and fat-soluble vitamins from the digestive system to the bloodstream)
97
what is chyle composed of?
composed of lymph, chylomicrons (emulsified fats), protein, white blood cells, electrolytes and other nutrients
98
what is the major pathway for the supply of fatty acids and cholesterol in various tissues?
lipoprotein pathway
99
where are triglycerides stored?
stored in the 'fat tissue' (adipose tissue formed of adipocytes)
100
what are fatty acids used for by the body?
used for energy during times of fasting or starvation
101
what is lipogenesis?
synthesis of fatty acids / TAGs
102
what happens to excess glucose after the glycogen store becomes full?
glucose is converted to fatty acids and TAGs for long-term storage in adipocytes
103
what is the process of lipogenesis?
acetyl coA (from glycolysis and pyruvate)
NADPH required for each additional Acetly CoA
Plus glycerol (from glucose) to form TAGs
TAGs are exported from the liver cell as VLDL to other tissues
104
where does the process of lipogenesis occur?
happens mainly in liver
105
what is the main pathway for getting rid of excess glucose?
lipogenesis
106
what does VLDL stand for?
very low-density lipoprotein
107
how are TAGs exported from the liver cell to other tissues?
they are exported from the liver cell as VLDL to other tissues
108
what type of molecule is NADPH?
it is a synthetic molecule - meaning it has a role of electron donor (it drives many biosynthetic reactions in living organsims)
not a nucleotide used for energy
109
what are VLDL, IDL, LDL, HDL named by? (give examples of names)
they are named based on density e.g. VLDL, IDL, LDL, HDL
110
what does IDL stand for?
intermediate-density lipoprotein
111
what does HDL stand for?
high density lipoprotein
112
what does LDL stand for?
low-density lipoprotein
113
what is the composition of LDL, HDL and chylomicron?
____________-____triglyc cholest phospholip
chylomicron --> 98 - 1 -1 (2)
LDL --> 15 60 25 (20)
HDL --> 10 30 60 (50)
and protein is the last figure in brackets
114
what are VLDL, IDL, LDL and HDL?
same components as chylomicrons
they transport TAGs and cholesterol
115
which hormones induce the breakdown of stored TAGs to FAs and glycerol?
glucagon, epinephrine and cortisol
(they mobilise the lipid droplet)
116
free fatty acids and glycerol are transported by the blood to which other organs?
skeletal muscle
cardiac muscle
liver
117
what are fatty acids metabolised via?
via β-oxidation
118
why do fatty acids need to be metabolised by β-oxidation?
because they cannot cross the mitochondrial double membrane
119
so what is the process of β-oxidation:
fatty acids are transported into mitochondria by the carnitine shuttle
120
describe the process of β-oxidation (for metabolising fatty acids)
1. fatty acid bound to CoA --> fatty acyl CoA
2. CoA exchanged for carnitine --> acyl carnitine
3. Acyl carnitine translocated by facilitated diffusion with unbound carnitine
4. Carnitine on acyl carnitine exchanged for CoA
121
what are the three enzymes that are required by the carnitine shuttle?
Fatty acyl CoA synthetase (1-2)
Carnitine palmitoyltransferase I and II (2-3)
Carnitine-acylcarnitine translocase (3-4)
(steps)
122
where does excess acetyl coA go?
it is converted into ketones: (ketogenesis)
acetoacetate
β - hydroxybutyrate
Acetone (spontaneous)
123
what ketones can be used by the brain and muscle as a secondary energy source?
acetoacetate
β-hydroxybutyrate
124
Acetone is created during ketogenesis when excess acetyl CoA is converted into ketones - what is the use of acetone?
it has no metabolic function + is excreted in the breath
125
why may you be able to smell acetone on the breathe of an animal?
you can smell it on the breath of animals who have ketoacidosis
e.g. uncontrolled diabetes mellitus
126
where can acetone be detected in an animal with ketoacidosis?
can also be detected in blood and urine
127
what is ketoacidosis?
it is a serious complication of uncontrolled diabetes
128
what is pregnancy toxaemia in sheep?
when the ewe doesn't have enough adipose tissue to support her babies (usually when she has twins) so there is an over mobilisation of adipose tissue - fatty acids are β-oxidised (too much acetyl coA is released)
excess FA metabolism results in ketone body formation and ketoacidosis - pregnancy toxaemia
129
what is pregnancy toxaemia in sheep often called?
twin lamb disease
130
when does twin lamb disease affect ewes?
during late gestation
131
which ewes do twin lamb disease affect?
often those with more than one foetus who have inadequate nutrition during late gestation/anorexia
and when foetal glucose demands cannot be met by carbohydrate stores
132
what are the four components of glycerophospholipids?
- two fatty acids (always two) - usually one unsat and one sat
- glycerol
- phosphate (bound to third carbon in glycerol)
- polar head group (variable choline demonstrated)
133
what are three examples of glycerophospholipids?
phosphatidylcholine
phosphatidylinositol 4,5-bisphosphate
cardiolipin
134
what is phosphatidylcholine?
most common phospholipid of plasma membrane
135
what is phosphatidylinositol 4,5-bisphosphate?
involved in cell signalling processes
136
what is cardiolipin?
found in cardiac tissue and mitochondria
often used as a biomarker for apoptosis
head group is another phospholipid sothere are four fatty acids
137
what are sphingolipids?
they are another class of lipids found in membrane
138
describe sphingolipids?
similar to phospholipids - hydrophobic and hydrophilic components (only one fatty acid)
139
what is ceramide?
a fatty acid linked to sphingosine (not glycerol)
140
what is the sphingoid base composed of?
sphingosine and head group
141
what does sphingomyelin consist of?
consists of phosphocholine head group
sphingosine
a fatty acid
142
what are the functions of sphingomyelin?
found in myelin sheath that surrounds + insulates many nerve cell axons
plays a role in action potential transduction
involved in apoptosis
143
what does cholesterol do?
aids with the structural support of the plasma membrane
144
what is cholesterol an example of?
an example of a sterol (aka steroid nucleus)
145
what is cholesterol the starting point of?
starting point for many sterols
146
what does a high carbon content in cholesterol result in?
high carbon content makes sterols very hydrophobic
147
what structure does cholesterol have?
conserved ring structure
148
what is cholesterol needed for?
needed for steroid hormone synthesis and proper membrane function
149
where can animals obtain cholesterol from?
Animals can obtain cholesterol from diet or synthesis from acetyl CoA
150
what is aldosterone responsible for?
sodium retention and potassium excretion in the kidneys
water retention as a secondary result
reduced or no production in Addison's disease
151
what are the sex hormones?
testosterone
oestradiol (oestrogen)
152
what is cortisol responsible for?
stress response
starvation response including gluconeogenesis
153
of which steroid hormone is there an excessive production of in Cushing's disease?
cortisol
154
give two examples of steroid drugs:
prednisone
prednisolone
155
what is brassinolide and where is it found?
it is a sterol in cabbage
156
what do bile acids (detergent) do?
the solubilise dietary lipids
157
what does detergent do?
it solubilises lipids and makes them water soluble
breaks fats up into smaller droplets (/micelles) to aid digestions
158
why do you need to break up fats into smaller droplets?
to aid digestion due to:
hydrophobic and hydrophilic components
bile acids coat the lipid droplets
pancreatic lipases break fats into its constituent partsw
159
when temperature increases - what effect does it have on the cell membrane with and without cholesterol?
overall increases fluidity
but with cholesterol increases fluidity less than if there was no cholesterol
160
effect of cholesterol on membrane fluidity?
increase fluidity at lower temps
decrease fluidity at higher temps
161
what are some fat soluble vitamins?
A, D, E, K
162
what are water soluble vitamins?
B, C
163
describe the synthesis process of vitamin D?
it is a multi-step process of synthesis involving skin, liver, kidney
it is necessary for calcium absorption from the small intestine
164
What is vitamin A also known as?
retinol
165
what is vitamin A?
it is a hydrophobic vitamin
166
what is vitamin A produced from?
from β-carotene
167
where can retinol be converted?
can be converted in 11-cis-retinal to all-trans-retinal
isomerisation
causes a conformational change in the rhodopsin protein which activates an associated G-protein leading to a neuronal signal
168
what can 11-cis-retinal also be converted into?
into retinoic acid
which is important in certain gene transcription involved in embryological development
169
what is vitamin E?
it is an antioxidant
is a hydrophobic vitamin
170
what properties does vitamin E have?
antioxidant properties (like vit C)
important antioxidant in hydrophobic environments such as within cell membranes
171
what does vitamin E protect?
protects fatty acids within cell membranes from oxidation
172
what is vitamin K?
it is a hydrophobic vitamin
it is an important cofactor in blood coagulation pathway
173
explain how vitamin K is important in blood coagulation pathway?
vit K is required as a cofactor for the enzyme vit K-dependent carboxylase
the carboxylase adds a carboxyl group to glutamate residues in certain clotting factors (II, VII, XI, X and proteins C, S and Z)
the carboxyglutamate residues can chelate Ca2+ which enables the factors to bind to cell membranes and form the clot
Vit K is oxidised in this process so must be reduced - drugs like warfarin inhibit the enzyme that reduces inactive vit K
174
how do vitamin K poisons work?
they prevent the reduction of the oxidised vitamin K so it cannot be active anymore so it cannot help the carboxylase to mediate blood clotting pathways
175
why do vitamin K poisons result in excessive bleeding (prevent blood from clotting)?
blood clotting factors cannot work because they do not have vitamin k in the reduced form anymore
176
why is vitamin A toxic at high doses?
it is hydrophobic so needs to be converted to a more hydrophilic product for excretion
it is also stored in adipose tissue as not accessible to drug metabolism enzymes
177
why is vitamin C not toxic at high doses?
because it is water soluble so can be easily excreted by kidneys
178
high doses of vitamin result in?
excess bone growth
clinical case - cat had paralysis of thoracic limb because extra bones had grown and were pressing on the nerves causing paralysis of front limb
179
what are misc lipids; waxes composed of?
two components - joined by an ester bond
long chain fatty acid (e.g. palmitic acid)
long chain alcohol (e.g. triacontanol)
180
what are polyketides (misc lipids) produced by?
produced by plants and fungi - some have uses as drugs
STRUC+FUNC 1 (vet)
flashcards
Decks in class (29)
# Cards
-
Nucleotides - Building Blocks80
-
Glycobiology122
-
Classic Mendelian Genetics31
-
Microscopy14
-
Classic Mendelian Genetics II83
-
LIPIDS181
-
Identifying tissues under the microscope19
-
Genetics - DNA replication80
-
Transcription20
-
Translation67
-
Amino Acids and Proteins85
-
Mitochondria115
-
Epigenetics + Nutrition28
-
Principles of Homeostasis25
-
Social cells130
-
Polymerase Chain Reaction1
-
Social cells 242
-
Organisation within cells: The Cytoskeleton17
-
Organisation within cells: Exo/Endocytosis3
-
Cell signalling - G protein-coupled and Enzyme-Linked Receptor Signalling39
-
Inherited diseases21
-
STEM CELLS29
-
Mechanisms of Cell Deviance24
-
Nuclear Receptors21
-
Molecular Basis of Genetics90
-
Cells Alive 127
-
Cytology15
-
Gene expression - Genetics 574
-
Histology Practical18
