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The molecular structures of alpha-linolenic acid, an omega-3 fatty acid is shown. Alpha-linolenic acid has three double bonds located eight, eleven, and fourteen residues from the acetyl group. It has a hooked shape.
Alpha-linolenic acid is an example of an omega-3 fatty acid. It has three cis double bonds and, as a result, a curved shape. For clarity, the carbons are not shown. Each singly bonded carbon has two hydrogens associated with it, also not shown.

The farthest carbon away from the carboxyl group is numbered as the omega ( ω ) carbon, and if the double bond is between the third and fourth carbon from that end, it is known as an omega-3 fatty acid. Nutritionally important because the body does not make them, omega-3 fatty acids include alpha-linoleic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), all of which are polyunsaturated. Salmon, trout, and tuna are good sources of omega-3 fatty acids. Research indicates that omega-3 fatty acids reduce the risk of sudden death from heart attacks, reduce triglycerides in the blood, lower blood pressure, and prevent thrombosis by inhibiting blood clotting. They also reduce inflammation, and may help reduce the risk of some cancers in animals.

Like carbohydrates, fats have received a lot of bad publicity. It is true that eating an excess of fried foods and other “fatty” foods leads to weight gain. However, fats do have important functions. Many vitamins are fat soluble, and fats serve as a long-term storage form of fatty acids: a source of energy. They also provide insulation for the body. Therefore, “healthy” fats in moderate amounts should be consumed on a regular basis.

Waxes

Wax covers the feathers of some aquatic birds and the leaf surfaces of some plants. Because of the hydrophobic nature of waxes, they prevent water from sticking on the surface ( [link] ). Waxes are made up of long fatty acid chains esterified to long-chain alcohols.

The photo shows leaves on a plant; the leaves appear thick, shiny, and waxy.
Waxy coverings on some leaves are made of lipids. (credit: Roger Griffith)

Phospholipids

Phospholipids are major constituents of the plasma membrane, the outermost layer of animal cells. Like fats, they are composed of fatty acid chains attached to a glycerol or sphingosine backbone. Instead of three fatty acids attached as in triglycerides, however, there are two fatty acids forming diacylglycerol, and the third carbon of the glycerol backbone is occupied by a modified phosphate group ( [link] ). A phosphate group alone attached to a diaglycerol does not qualify as a phospholipid; it is phosphatidate (diacylglycerol 3-phosphate), the precursor of phospholipids. The phosphate group is modified by an alcohol. Phosphatidylcholine and phosphatidylserine are two important phospholipids that are found in plasma membranes.

The molecular structure of a phospholipid is shown. It consists of two fatty acids attached to the first and second carbons in glycerol, and a phosphate group attached to the third position. The phosphate group may be further modified by addition of another molecule to one of its oxygens. Two molecules that may modify the phosphate group, choline and serine, are shown. Choline consists of a two-carbon chain with a hydroxy group attached to one end and a nitrogen attached to the other. The nitrogen, in turn, has three methyl groups attached to it and has a charge of plus one. Serine consists of a two-carbon chain with a hydroxyl group attached to one end. An amino group and a carboxyl group are attached to the other end.
A phospholipid is a molecule with two fatty acids and a modified phosphate group attached to a glycerol backbone. The phosphate may be modified by the addition of charged or polar chemical groups. Two chemical groups that may modify the phosphate, choline and serine, are shown here. Both choline and serine attach to the phosphate group at the position labeled R via the hydroxyl group indicated in green.

A phospholipid is an amphipathic molecule, meaning it has a hydrophobic and a hydrophilic part. The fatty acid chains are hydrophobic and cannot interact with water, whereas the phosphate-containing group is hydrophilic and interacts with water ( [link] ).

Questions & Answers

give me somes of examples.
Manu Reply
give example of what.
Ante
example of what
Elizabeth
Ecology is the study of
Abdul Reply
Ecology is the study of the interaction of organism in each other and their environment.
Ante
Ecology is the study of the interaction of organism in each other and their environment
Everlove
oh yes!!! exactly
Great
thank much
Ante
what is biome?
Ante
a geographical area with dinstic species
Francis
thanks much it very helpful
Ante
my pleasure
Francis
characteristics of living things
Jane Reply
excretion, movement, sensitivity, reproduction,growth, respiration,nutrition
Estel
what are there function
Ante
what are their function
Ante
what is the two type of reproduction?
Ante
sexual reproduction and asexual reproduction
Abdul
what are their function
Manu
What is light independent reaction
Benjamin Reply
correct word or phrase. ______A____ uses carbon dioxide and _____B______ to make sugar during______C______. _____D______ traps light energy during this process. *
Andrea Reply
A_plant ,B_water,C_photosynthesis,D_chlorophyll
Abdul
by which of the following feature c3 and c4 plant similar A .enzyme used to fix carbon dioxide B.cell where calvin cycle takes place C.cell where carbon dioxide fixation takes place
Kaleab Reply
correct word or phrase. ______A____ uses carbon dioxide and _____B______ to make sugar during______C______. _____D______ traps light energy during this process. *
Andrea
what is biology ?
Bizone Reply
study of organisms
Aurelia
what is link
Lamina Reply
is carbon an organism that matter?
DKP Reply
what is buttress root?
Dora Reply
Buttress root are wide large root
Iyabo
Buttress root/roots are thick roots that emerge out form the base of a large canopy
Musoke
From the base of a large canopy
Musoke
What is biology
Jiboh Reply
Biology is the study of structure and growth of living things and organisms within their biography
Musoke
compare the mechanism of gaseous exchange in an insect and mammal
World Reply
what are the characteristic of livingthing
Joy Reply
Movement Respiration Nutrition Irritability or sensitivity Growth Excretion Reproduction Adaptation Competition Death or Life Span
Emmanuel
Respiration Irritability Movement Excretion Nutrition Growth Reproduction
Amponsah
movement respiration nutrition irritability growth excretion reproduction death
Elizabeth
what is the function of medulla oblongata
mbalenhle Reply
what is the strongest bone in the human body
Chionye
what is biology
Dauda Reply
is a branch of science which deals with the study of living thing
sheka
thanks
Dauda
Biology is got from two main words: bios: means life and Logos: means knowledge therefore, biology is a branch of science that deals with knowledge, life and functioning of living things.
Musoke
what are the characteristics of organism
Seldam
Responds to stimuli
Musoke
Biology is an aspect of science that deals with the. study of living organisms
Amponsah

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Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
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