1. GLYCOLIPIDS
What are Glycolipids made from?
Glycolipid consists of two main components- a lipid
and a carbohydrate. Glycolipids are formed by the
covalent bonding of a mono- or oligosaccharide
group attached to a sphingolipid or a glycerol group
and one or two fatty acids.
2. Fig 20.1, p.501
LOCATION OF GLYCOLIPIDS
Glycolipids are formed by the
covalent bond.The outside of
this phospholipid layer, there is
often a tiny carbohydrate chain
attached called glycolipids.
4. FUNCTIONS OF GLYCOLIPIDS
*Maintain the stability of the cell membrane by
forming hydrogen bonds with the surrounding water
molecules.
* Increased cell response cell recognition and connecting cells to
form tissues.
*Provide energy to the cell.
*Present on the surface of red blood cells in the form of an
antigen.Help to determine the types of blood groups.
*Attached to the leukocytes and produce an immune system. It
also plays an important role in destroying pathogens.
5. Two types of glycolipids are:
•Cerebrosides
These types of glycolipids are found primarily in
the brain and in the peripheral nervous tissue. It
acts as an insulator and is mainly involved in
providing a protective coating to the nerve cells.
•Gangliosides
These types of glycolipids are composed of
sialic acid residues.They are the main
components of the animal’s cell membrane and
are abundantly found in the plasma membrane
of the neurons.
6. STEROIDS
- is a biologically active organic
compound with four rings arranged in
a specific molecular configuration.
7. STEROIDS
Steroids are hydrophobic and
insoluble in water.
All fused ring structure of a
steroids have four linked
carbon rings and several of
them, like cholesterol, have a
short tail.
Many steroids also have the –
OH functional group, which puts
them in the alcohol
classification (sterols).
8. TWO PRINCIPAL BIOLOGICAL FUNCTIONS
OF STEROIDS
1. As important components of cell
membranes that alter membrane fluidity;
and
2. As signaling molecules.
9. The core structure of steroid is
composed of 17 carbon atoms,
bonded in 4 "fused" rings in a
specific way.
Three of these are cyclohexanes
and one is cyclopentane system.
13. Roles of Steroid Hormones
A steroid hormone is a Steroid that acts as a hormone.
Steroid hormones are crucial substances for the proper functioning of
the body.
Steroid hormones are produced in the adrenal cortex, testis, ovary and
some peripheral tissues.
Steroid hormone help control metabolism, inflammation, immune
functions, salt and water balance, development of sexual characteristics,
and the ability to withstand injury and illness.
All steroid hormones are derived from cholesterol and differ only in the
ring structure and side chains attached to it.
All steroid hormones are Lipid soluble and Water insoluble. It
is permeable to membranes so they are not stores in cells.
14. Function of Steroid Hormones
Steroid hormones play important roles in:
• - Metabolic regulation (glucocorticoids, cortisol)
• - Electrolyte balance (mineralocorticoids, aldosterone)
• - Reproductive functions (gonadal steroids, testosterone
and estrogens)
• - Inflammatory response
• - Stress response
• - Bone metabolism
• - Cardiovascular fitness
• - Activates DNA for Protein synthesis
15. Types of Steroid Hormones
Glucocorticoids; cortisol is the major
representative in most mammals.
Mineralocorticoids; aldosterone being most
prominent.
Sex steroid; that interact with vertebrate
steroid hormone receptor.
16. Glucocorticoids
• Glucocorticoids are a class of
corticosteroids, which are a class of steroid
hormones. Glucocorticoids are
corticosteroids that bind to the
glucocorticoid receptor that is present in
almost every vertebrate animal cell. The
name "glucocorticoid" is
a portmanteau (glucose + cortex + steroid)
and is composed from its role in regulation
of glucose metabolism, synthesis in
the adrenal cortex, and
its steroidal structure.
17. Mineralocorticoids
• Mineralocorticoids are a class of steroid hormones
that regulate salt and water balances. Aldosterone is
the primary mineralocorticoid. Mineralocorticoids
promote sodium and potassium transport, usually
followed by changes in water balance. This function is
essential to life
18. Sex steroid also known as sex
steroids, gonadocorticoid
s and gonadal steroids,
are steroid hormones that
interact
with vertebrate steroid
hormone receptors.[1] The
sex hormones include
the androgens, estrogens,
and progestogens. Their
effects are mediated by
slow genomic mechanisms
through nuclear
receptors as well as by fast
nongenomic mechanisms
through membrane-
associated receptors
and signaling cascades.
19. Androgens
• Androgens are steroid
hormones responsible for male
sexual characteristics, testosterone
being the principal androgen secreted
by the testes. Androgens have both
masculinizing and growth-
stimulating or anabolic effects.
20. Estrogens • Estrogen is a category of sex
hormone responsible for the
development and regulation of the
female reproductive
system and secondary sex
characteristics.[1][2] There are three
major endogenous estrogens that
have estrogenic hormonal
activity: estrone (E1), estradiol (E
2), and estriol (E3).[1][3] Estradiol,
an estrane, is the most potent and
prevalent.[1] Another estrogen
called estetrol (E4) is produced
only during pregnancy.
21. Progestogen • A progestogen, also referred
to as a progestagen, gestagen,
or gestogen, is a type of
medication which produces
effects similar to those of the
natural female sex hormone
progesterone in the body. A
progestin is a synthetic
progestogen.
23. What is Bile?
Bile is a bitter-tasting, dark green to
yellowish brown fluid, produced by the liver
Bile aids the process of digestion of lipids in
the small intestine.
Bile is stored in the gallbladder and upon
eating is discharged into the duodenum.
27. The bile is funneled into the gallbladder and
then delivered into the duodenum upon
stimulation from CCK.
Cholecystokinin (CCK) stimulates the
gallbladder, which responds by contracting and
delivering more bile to the duodenum through
the sphincter of Oddi, which relaxes (opens) in
response to CCK.
28. Bile formation by cells in the liver
includes these components:
bile salts
Phospholipids
bilirubin
Cholesterol
and trace metals.
30. Emulsify fats breaking the fat
globules into smaller droplets,
much like the action of
detergents in dishwasher.
Bile Salt
31. Effective detergents because they contain both
polar and nonpolar regions. They have several
hydroxyl groups.
Polar side chain allow interactions with water.
The ring system itself is nonpolar and can
interact with lipids or other non polar
substances
Bile salts are planar amphipathic molecules
35. - Prostaglandins is an example of Eicosanoids
- a group of lipids made at sites of
tissue damage or infection that are
involved in dealing with injury and illness.
- are biologically active derivatives of 20 carbon
polyunsaturated essential fatty acids
are a group of
important chemicals
derived from fatty acids
36. Prostaglandins were first discovered and isolated from human semen.
Ulf von Euler stated that Prostaglandin
came from Prostate Gland.
Prostaglandin exist and are synthesized in virtually every cell of the body.
are like hormones, they act as chemical messenger.
37. MAIN STRUCTURAL FEATURES OF
PROSTAGLANDINS
The prostaglandins are made up of unsaturated fatty acids that contain a
cyclopentane (5-carbon) ring and are derived from the 20-carbon, straight-
chain, polyunsaturated fatty acid precursor arachidonic acid.
38. PROSTAGLANDINS CONTROLS PROCESSES SUCH AS:
• INFLAMMATION
• BLOOD FLOW
• FORMATION OF BLOOD CLOTS
• INDUCTION OF LABOUR
Prostaglandins play a role in the following reproductive functions:
• CONCEPTION
• LUTEOLYSIS
• MENSTRUATION
• PARTURITION
39. Biochemical Actions of Prostaglandin
• Prostaglandin acts as local hormones.
• Prostaglandin are produced in almost all the tissues.
• Prostaglandin are stored and they are degraded to inactive products at
the site of their production.
• Prostaglandin are produced in very small amounts and have a low
half lives.
41. What is thromboxane?
Thromboxane is a member of the family of lipids known as eicosanoids.
The two major thromboxanes are thromboxane A2 and thromboxane B2.
The distinguishing feature of thromboxanes is a 6- membered ether-containing
ring.
Thromboxane is named for its
role in clot formation (thrombosis).
42. Introduction
Thromboxane is a lipid essential to the body’s production of
clots. To stop bleeding, the lipid simultaneously restricts arteries
and veins while clumping platelets. Platelets produce
thromboxane through conversion of certain prostaglandins.
The thromboxanes are derived from arachidonic acid and are
related to prostaglandins. Thromboxane-A synthase, an enzyme
found in platelets, converts the arachidonic acid derivative
prostaglandin H2 to thromboxane.
43. Two Types of Thromboxane
1. Thromboxane A2 (TXA2)
It is a type of thromboxane that is
produced by activated platelets and has
prothrombotic properties; it stimulates
activation of new platelets as well as
increases platelet aggregation.
2. Thromboxane B2 (TXB2)
- It is an inactive metabolite/product of
thromboxane A2. It is almost completely
cleared in the urine. It itself is not involved
in platelet activation and aggregation in
case of a wound, but its precursor,
thromboxane A2, is.
44. Functions of thromboxane
Thromboxanes, a substance produced by platelets, lead to occlusion
of blood vessels by fueling blood clots inside the vascular system.
The primary function of thromboxane is to stop bleeding. When the
body experiences a cut, the lipid assists platelets in clumping so that
the platelets can eventually form a clot. This process begins when
the lipid narrows the arteries leading to the cut site. This action
makes the platelets’ job easier by reducing blood pressure and
limiting overall blood loss.
The body’s platelets produce thromboxane from arachidonic acid.
This process is significant as prostacyclin, a platelet produced lipid
that inhibits clot formation, is also created from arachidonic acid.
Thromboxane is a vasoconstrictor and a potent hypertensive agent,
and it facilitates platelet aggregation.
45. Role of Thromboxane A2 in Platelet Aggregation
Thromboxane A2 (TXA2), produced by activated platelets, has
prothrombotic properties, stimulating activation of new platelets
as well as increasing platelet aggregation.
The released thromboxane A2 acts as a positive feedback
mediator in the activation and recruitment of more platelets to
the primary hemostatic plug. Thromboxane A2 exerts its actions
via specific G protein-coupled receptors and has been described
as either a potent platelet agonist or as a weak agonist with an
important role in amplifying the response of platelets to more
potent agonists.
46. Did you know?
Pandas don’t hibernate.
It is estimated that more than 50 million kangaroos live there. They are
Australia’s national symbol and appear on postage stamps, coins, and
airplanes.
There are more kangaroos than humans in Australia.
Koalas don’t have much energy and, when not feasting on leaves, they spend
their time dozing in the branches. Believe it or not, they can sleep for up to 18
hours a day!
Koalas are even more lazy than cats.
When winter approaches, they head lower down their mountain homes to
warmer temperatures, where they continue to chomp away on bamboo!
47. What are Eicosanoids?
Eicosanoids are produced from arachidonic acid, a 20-
carbon polyunsaturated fatty acid (5,8,11,14-
eicosatetraenoic acid)
The eicosanoids are considered “autacoids"
They act on cells close to their site of production
They are rapidly degraded
They have both intercellular signaling, & intracellular signal
cascades
48. Clearly, animals know more than we think,
and think a great deal more than we
know.
― Irene M. Pepperberg
