PHAROS UNIVERSITY FACULTY OF ALLIED MEDICAL SCIENCE

BIOCHEMISTRY 1 (MGBC-101)

Dr. Tarek El Sewedy

Department of Medical Laboratory Technology

Faculty of Allied Medical Sciences

Lecture

Lipids and Fatty acids(2)

By the end of this lecture, students will learn:

• Fats and diet

• Classification of lipids

• Biological importance of true fats

• Chemical properties of true fats

• Complex Lipids

• Derived lipids

Intended Learning Outcomes

Lecture Content

• Fats and diet

• Classification of lipids

• Biological importance of fats

• Chemical properties of fats

• Complex Lipids

• Derived lipids

Omega-3 fatty acids• Omega-3 fatty acids (also known as n-3 fatty acids) are polyunsaturated fatty

acids that are essential nutrients for health. We need omega-3 fatty acids for

numerous normal body functions, such as controlling blood clotting and

building cell membranes in the brain, protection against heart disease .

• Our bodies cannot make omega-3 fats, we must get them through food.

• Alpha-linolenic acid (ALA) is the parent compound for Omega 3 fatty acid, is

found in some vegetable oils such as soybean, canola, and in walnuts.

Omega-3 fatty acids•  For good health, we should aim to get at least one rich source of

omega-3 fatty acids in our diet every day. This could be through a serving of fatty fish (such as salmon), a tablespoon of canola or soybean oil in salad dressing or in cooking, or a handful of walnuts.

Omega-6 fatty acids• Omega-6 fatty acids (also known as n-6 fatty acids) are also

polyunsaturated fatty acids that are essential nutrients, meaning that our bodies cannot make them and we must obtain them from food.

• Common dietary sources include safflower, corn, cottonseed, and soybean oils.

• Omega-6 fatty acids lower LDL cholesterol (the "bad" cholesterol) and reduce inflammation, and they are protective against heart disease. So both omega-6 and omega-3 fatty acids are healthy.

Cis and Trans Lipids

• Naturally-occurring unsaturated vegetable oils have almost all cis bonds, but using oil for

frying causes some of the cis bonds to convert to trans bonds.

• If oil is used only once like when you fry an egg, only a few of the bonds do this so it’s not

too bad. However, if oil is constantly reused, like in fast food French fry machines, more and

more of the cis bonds are changed to trans until significant numbers of fatty acids with trans

bonds build up.

• Studies showed that fatty acids with trans bonds are carcinogenic and leads to significant

increase in heart disease by increasing levels of bad cholesterol (LDL). The levels of trans

fatty acids in highly-processed (hydrogenated oils), lipid-containing products such as

margarine are quite high.

Cholesterol • Cholesterol is a waxy substance your body uses to protect nerves, make cell tissues

and produce certain hormones.•  A little cholesterol is essential for health.• The liver can manufacture all the cholesterol your body needs.• Low-density lipoprotein (LDL or 'bad') cholesterol can join with fats and other substances to build up

in the inner walls of your arteries. The arteries can become clogged and narrow, and blood flow is

reduced. High-density lipoprotein (HDL or 'good') carries harmful cholesterol away from the arteries

and helps protect you from atherosclerosis, heart attack and stroke.

Atherosclerosis• A type of arteriosclerosis. Atherosclerosis causes arteries to

narrow, weaken and be less flexible. It's the term for the process of fatty build-up in the inner lining of an artery. The build-up that results is called plaque and reduces the amount of blood and oxygen that is delivered to vital organs.

Triglycerides• Triglyceride is a form of fat made in the body. Elevated

triglycerides can be due to overweight/obesity, physical

inactivity, cigarette smoking, excess alcohol consumption

and a diet very high in carbohydrates.

• People with high triglycerides often have a high total

cholesterol level, including a high LDL (bad) level and a low

HDL (good) level. Many people with heart disease and/or

diabetes also have high triglyceride levels.

Fats and diet• Eating low fat food doesn’t mean we should give up fat entirely,

but we do need to educate ourselves about which fats should

ideally be avoided and which ones are more heart-healthy.

• We need fat in our diet. As the most concentrated source of calories (nine calories per gram of fat compared with four calories per gram for protein and carbohydrates), it helps supply energy.

• Fat provides linoleic acid, an essential fatty acid for growth, healthy skin and metabolism.

• It also helps absorb fat-soluble vitamins (A,D,E and K).

• And fat adds flavour and is satisfying, making us feel fuller

Although all fats have the same amount of calories, some are more

harmful than others: saturated fats and trans fats in particular.

Saturated fats• These fats are derived from animal products such as meat, dairy and

eggs. But they are also found in some plant-based sources such as coconut, palm oils. These fats are solid at room temperature. Saturated fats directly raise total and LDL (bad) cholesterol levels. Conventional advice says to Avoid them as much as possible

A meta-analysis published in 2003 found a direct relationship between saturated fat and breast cancer. In 2007, a systematic literature review published by the World Cancer Research Fund and the American Institute for Cancer Research found consistent evidence for a direct relationship between animal fat and colorectal cancer. 

The Ugly fats

Trans Fats or Hydrogenated Fats

Trans Fats are typically found in packaged goods and fast food restaurants They all have/use the ugly fats…

TRANS FATS!

The Ugly fat•  scientists discovered that they could create a fat that

would prolong the spoiling of packaged goods by simply adding a hydrogen atom to an unsaturated fat.

• The partially hydrogenated fat creations wouldn’t spoil as easily as non-hydrogenated fats, plus they didn’t break down during temperature changes, which made transporting them easier, and they were less expensive than animal fat.

Another ugly man-made invention!

Trans Fats or Hydrogenated Fats• Are actually unsaturated fats, but they can

raise total and LDL (bad) cholesterol levels while also lowering HDL (good) cholesterol levels.

• Trans fats are used to extend the shelf life of processed foods, typically cookies, cakes, fries and donuts. Any item that contains “hydrogenated oil” or “partially hydrogenated oil” likely contains trans fats.

• Hydrogenation is the chemical process that changes liquid oils into solid fats.

• Since January 2006, all food manufacturers are required to list trans fat content on food labels.

Butter

Margarine, stick 

Margarine, tub

Unsaturated fats• Monounsaturated fats and polyunsaturated fats are two types of

unsaturated fatty acids. They are derived from vegetables and plants.

• Monounsaturated fats:• This type of fat is preferable to other types of fat and can be found in olives, olive oil, nuts,

peanut oil, canola oil and avocados. These kinds of fats can lower LDL (bad) cholesterol and maintain HDL (good) cholesterol.

• Polyunsaturated fats:• These are found in sesame, corn, cottonseed and soybean oils. This type of fat has also been shown

to reduce levels of LDL cholesterol, but too much can also lower your HDL cholesterol

Butter Vs. Margarines• Margarine tops butter when it comes to heart health.• Margarine is made from vegetable oils, so it contains no cholesterol.• Margarine is also higher in "good" fats — polyunsaturated and

monounsaturated.• Butter, is made from animal fat, so it contains cholesterol and high levels

of saturated fat.• Some margarines contain trans fat. In general, the more solid the

margarine, the more trans fat it contains.  So skip the stick for soft or liquid margarine instead.

• Look for a spread that doesn't have trans fats and has the least amount of saturated fat. When comparing spreads, be sure to read the Nutrition Facts panel and check the grams of saturated fat and trans fat.

Eat HealthyStay Healthy

lipids

simple

True fat waxes

complex

glycolipidsphospholipids sulfolipids lipoproteins

derived

steroids Fat sol vitamins

Classification of lipids• LIPIDS ARE CLASSIFIED AS SIMPLE OR COMPLEX Or DERIVED

A. Simple lipids: Esters of fatty acids with various alcohols.

1. True Fats: Esters of fatty acids with glycerol.

2. Waxes: Esters of fatty acids with higher molecular weight alcohols.

Glycerol

Fatty acid

True fat

High M.W alcohol

Fatty acid

WAX

Simple lipids

True fats are esters of FA with glycerol

Simple: has one type of FA in all positions

Mixed : has different types of FA

Waxes are esters of FA with high

M.W alcohol

•Usually solid.•Alcohol such as myricyl alcohol (1-triacontanol, C30H61OH) or ceryl alcohol (1-hexacosanol, C26H53OH).

1. Monoacylglcerols

2. Diacylglycerols

3. Triacylglycerols

True Fats “Acylglycerides”

Biological importance of true fats

Reserve food in animals and plants.

Supporting and protection materials around organs

e.g. kidney.

Source of energy

*Physical properties of true fats

*Non polar.

*Tasteless, odorless, colorless.

*Neutral in reaction.

*Specific gravity˂1 (float on water).

*Low melting point.

lipids

simple

True fat waxes

complex

glycolipidsphospholipids sulfolipids lipoproteins

derived

steroids Fat sol vitamins

Lipids containing group in

addition to fatty acids and

alcohols as phosphate, sulfate,

carbohydrates and protein.

Complex lipids

Complex lipids

glycolipids

phospholipids

sulfolipids

lipoproteins

CH-O-C-R1 O

CH-O-C-R2 O

CH2-O-C-R3 O

Glycolipids

Glycolipids are lipids with a carbohydrate attached

lipids

simple

True fat waxes

complex

glycolipids

phospholipids

sulfolipids

lipoproteins

derived

steroids

Fat sol vitamins

carotenoids

III- DERIVED LIPIDS

• They include complex compounds: sterols, fatty aldehyde and ketone bodies, lipid–soluble vitamins and hormones.

• Cholesterol, is a derived lipid and an important component of cell membranes, it is an amphipathic molecule because it contains a polar hydrophilic hydroxyl group and 4 hydrophobic rings. Cholesterol is also a precursor to the steroid hormones, such as testosterone.

*Students selected for assignment

All students has been given assignments , any student that was not

given an assignment should prepare an assignment on any of the

topics on the next slide and deliver it by next week.

ASSIGNMENTS

• Selected students are requested to prepare slides about one of the

following topics (To be delivered before next lecture):

• Cholesterol and disease

• Lipoproteins

• Bee Wax

• Essential Fatty Acids

Study QuestionsComplete:Glycerol is an organic compound, has three

--------------groups. ----------------and --------------are saturated fatty acids.--------------and ----------------------are true lipids.Cholesterol belongs to-----------------lipids 1gram of ----------- yields 4.1Kcal while 1 g of

-----------yield 9 Kcal.----------------are esters of fatty acids with higher

molecular weight monohydric alcohols.

Choose:

1-Beewax belongs toa-Compound lipids.b-Simple lipids.c-Derived lipids.2. -------------------------is an essential fatty acid.a-Linoleic acid.b-Oleic acid.c-Palmitic acid.

 3-LDL and HDL belong to -----------------a-Sulpholipids.b-Lipoproteinsc-Phospholipids.

4-Cholesterol belongs to---------------a-Simple lipids.b-Complex lipids.c-Derived lipids.

Correct the incorrect word:Arachidonic acid is monounsaturated fatty

acid.Oxidation of 1 g of Carbohydrate yields 9

Kcal.

Write the chemical formula of the following:Palmitoleic acid (16:1n;∆9)α linolenic acid (18:3n;∆9,12,15)linoleic acid (18:2n; ∆9,12)Arachidonic acid (20;4n;5,8,11,14)Mention points about:1-Function of lipids.a-b-c-2-Lipids are classified intoa-b-c-

Principles of Biochemistry, Donald J. Voet, Judith G. Voet, Charlotte W. pratt; Willey, 3rd ed.

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