Proteins and lipids Flashcards
What are lipids composed of?
What are lipids (state what the family called lipids include)
Lipids probide more energy per gram that carbs true or false?
Which solutions do lipids dissolve in?
What are the most common type of lipids found in foods and the body?
About 95pervent of fats consumed and stored in the body are in the form of ehat?
Whats the difference between fats and oils?
Like carbohydrates, lipids are composed of carbon, hydrogen and oxygen.
- Lipids provide more energy per gram than carbohydrates
- Lipids are usually referred to as fats and oils, but the family includes triglycerides, phospholipids and sterols
•Lipids do not dissolve in water but in organic solvents such as chloroform, benzene and ether.
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Triglycerides
•Most common type of lipids found in foods and in the body
- About 95% of fats consumed and fats stored in the body are in the form of triglycerides
- Fats are lipids that are solid at room temperature
- Oils are lipids that are liquid at room temperature
- Of the lipids stored in the body, 99% are triglycerides
What is the structure of triglycerides
How are they built?
Ehat is de-esterification
Structure
•Each triglyceride contains one molecule of glycerol bounded by /attached to 3fatty acids
- Triglycerides are built by attaching a fatty acid to glycerol’s 3 hydroxyl group(-OH)
- The process of attaching fatty acids to glycerol is esterification and the release of fatty acids from glycerol is de-esterification
Concerning chain lengths,how many carbons do fatty acids and long chain fatty acids contain?
Give three rxamples of long chain fatty acids
Which chain of fatty acids take the longest period to digest and how are they transported?
Carbon chain length
•Fatty acids usually contains between 4 to 24 carbons
- Long chain fatty acids have 12 or more carbon atoms
- Examples include; fats from beef,pork,lamb and most plant oils, fish.
- Long chains take the longest period to digest and are transported via the lymphatic system.
How many carbons do medium chain fatty acids have?
How are they transported?
Give two examples
Medium Chain fatty Acids
•Medium-chain fatty acids are 6 to 10 carbons in length
- They are digested as rapidly as glucose and are transported via the circulatory system
- Examples; coconuts oils, palm kernel oils
How are fatty acids classified jn terms pf saturation and define them
At maximum,a carbon atom can form how many chemical bonds,oxygen and hydrogen can form how many ?
Fatty acids can be;
•Saturated: Saturated fatty acids(SFA)
•Fully loaded with hydrogen atoms and contains only single bonds between carbon bonds
•Monounsaturated: Monounsaturated fatty acids(MUFA)
These lack two hydrogen atoms and have one double bond between carbons
•Polyunsaturated: Polyunsaturated fatty acids(PUFA)
Have at least 2 double bonds in its carbon chains
- Note- at a maximum, a carbon atom can form 4 chemical bonds,an oxygen 2 bonds and 1 bond for hydrogen atom
- Each atom cannot form more than the maximum number of bonds
Which two ways does the degree of saturation influence fats and oils ?
Which plant oils are saturated even though they are of vegetable origin?
What foes this imply with regards to firmness?
Why are these plant oils softer than most animal fats?
What does this imply for softness?
How do fats and oils become spoilt?
Which type of fats with regards to saturation are more resistant to oxidation?
Fat oxidation leads to what?
Why will other types of spoilage occur?
●Firmness
The degree of saturation influences the firmness of fats and oils at room temperature
- PUFA vegetable oils (sunflower oil,soybean oil,poppyseed oil,flaxseed oil) are generally liquid at room temperature
- Saturated animal fats (palmitic acid,red meat,coconut oil) are solid at room temperature
- Not all vegetable oils are polyunsaturated
•Coconut oil, palm oil and palm kernel oil are saturated even though they are of vegetable origin
Influences of degree of saturation on fats and oils
•They are firmer than most vegetable oils because of their saturation but softer than most animal fats because of their shorter carbon chain
•The shorter the carbon chain, the softer the fat is at room temperature.
●Stability
All fats and oils become spoilt when exposed to oxygen
Stability
•Saturated fats are most resistant to oxidation than MUFA and PUFA’s
- Fat oxidation leads to rancidity ( leads to the production compounds that smell or taste rancid)
- Other types of spoilage occur due to microbial growth.
Which three ways can you prevent fat and oil rancidity
Prevention of fat and oil rancidity
1.Packaging- sealing in air tight,nonmetalic containers protected from light and refrigerated-( expensive and inconvenient storage system)
- Addition of antioxidants (eg. Vitamin E, BHA-Butylated hydroxyanisole and BHT-Butylated hydroxytoluene)
- Addition of hydrogen molecules to unsaturated points in a process called hydrogenation.
What is hydrogenation?
What are the uses of hydrogenation?
How are carbons named?
What are the two systems used to name carbons based on?
Hydrogenation is a chemical process by which hydrogens are added to MUFA’s or PUFA’s to reduce the number of double bonds
- Making fats more saturated and more resistant to oxidation and making vegetable oils more solid
- Hydrogenatied fats make margarine spreadable, pie crusts, flaky and puddings creamy.
-Two systems used to name fatty acids
Omega naming system
Delta naming system
- Both are based on the numbers of carbon atoms and the location of double bonds in a fatty acid’s carbon chain.
What is the omega naming system and how is it hsed to name carbons
Indicates where the first double bond closest to the methyl( omega) end of the chain occurs
- Thus omega-3 fatty acid’s (linolenic acid) first double bond closest to the methyl(CH3)
- What about omega -6 (linoleic acid)
- First double bond is located on the 6th carbon from methyl end.
How is delta naming system used to name carbons
What naming system is more popular?
The second naming system, delta, describes fatty acids in relation to the carboxyl (COOH) end of the carbon chain
•The most popular is the omega –system
Shape of carbon chains vary w what?
What is the shape of unsaturated cis fatty acids?
What is the shape of saturated and trans fatty acids?
The shape of carbon chains varies with saturation:
- Unsaturated cis fatty acids have a bent or u-like formation and the hydrogens next to the double bonds on the same side of the carbon chain
- Saturated and trans fatty acids have straight carbon chains and the hydrogens are on opposite sites of double bonds
•Trans forms usually occur in partially hydrogenated foods
(Theres a picture in the slides for you to barb better)
What are essential fatty acids
Which two polyunsaturated fatty acids can the body not make?
Why are these two fatty acids essential?
Check slides for omega 3 and omega 6 metabolic pathways
The human body needs fatty acids, and it can make all but two PUFAs—linoleic acid (the 18-carbon omega-6 fatty acid) and linolenic acid (the 18-carbon omega-3 fatty acid)
- These two fatty acids must be supplied by the diet and are therefore essential fatty acids
- An essential nutrient is one that the body cannot make, or cannot make in sufficient quantities to meet its physiological needs
- The cells do not possess the enzymes to make any of the omega-6 or omega-3 fatty acids from scratch, nor can they convert an omega-6 fatty acid to an omega-3 fatty acid or vice versa
State six functions of triglycerides
What are hidden fats and visible fats?
- Provide an energy reserve when stored in the body’s fat tissue
- Insulate against temperature extremes
- Protect against shock
- Help the body use carbohydrate and protein efficiently
- The omega- 3 fatty acid decosahexaenoic acid (DHA) is necessary in fetal life and infancy for normal development and function of the retina
- During the embryonic stage of development, DHA is vital for normal dvelopment and maturation of the nervous system
- Fatty acids serve as structural parts of cell membranes and as precursors to the longer fatty acids that can make eicosanoids
- Eicosanoids which are made from essential fatty acids are powerful compounds that participate in blood pressure regulation, blood clot formation, and the immune response to injury and infection
- They also regulate flow of substances in and out of the cells
- Regulating ovulation, body temperature, immune system function and hormone synthesis
- Maintaining normal kidney function and fluid balance
Visible fat-margarine spread of bread
Structure of phospholipids is similar fo triglycerides. Whats the exception
What quality does phosphate give phospholipids?
What is an emulsifier?
Whag is the function of phospholipids
Structure similar to triglycerides
- The only exception is that one fatty acid is replaced with a phosphate compound that contains phosphorus and often has a nitrogen attached
- Phosphate gives phospholipids an important quality – it allows fats to function in watery environments (blood) without clumping together
- They function as cell membrane components and a emulsifiers
- A emulsifier is a compound that forms a shell around fat droplets so that the droplets can be suspended in water and not clump together
The body’s main emulsifiers are?
Whats the function of emulsifiers?
What are the two main sources of emulsifiers?
Name two used of emulsifiers in food
Phospholipids
•The body’s main emulsifiers are bile and lecithins
•Emulsifiers are essential for fat to be digested and transported through the blood stream
●Sources
• Can be synthesized by the body
•Supplied by diet ( lecithin can be found in egg yolks, wheat germ and peanuts
● Uses in food
•Eggs are used in baked products
•Mayonnaise is thick because phospholipids in in egg yolks and mustard emulsified the oil and vinegar used to make this product
What are sterols? What is its structure? What is the most known sterol from a nutritive perspective? Name four functions of this known sterol WhT are the sources of cholesterol What sterols do poants make? What is the function of sitostanol
Sterols
• Sterols are a type of steroids
•Unlike fatty acids and phospholipids which have long carbon chains, their carbons are mostly arranged in many rings
●Functions
•Cholesterol is the most known sterol from a nutritive perspective
- It is required to synthesize steroid hormones such as estrogens, testosterone, the active form of vitamin D, corticosteroids and bile
- Together with phospholipids they form cell membranes that allows fat soluble substances to move into and out of the cell
Functions
•Cholesterol works along with phospholipids and proteins to form the shell covering chylomicrons ( droplets that transport lipids)
•The shell allows fat droplets to float through the water-based bloodstream
● Sources
• Found in foods of animal origin such as meat, fish, poultry, eggs and dairy products
- Plants do not contain or produce it but make other sterols such as ergosterol (a form of vitamin D) and sitostanol (added to margarine)
- Sitostanol reduces the body’s absorption of cholesterol and bile which is made from cholesterol thereby reducing blood cholesterol levels
What is the goal of fat digestion
Creation of fat substitutes that have properties similar to those of a naturally occurring fat, but which are resistant to the action of pancreatic lipase, has been actively pursued.
True or false
The goal of fat digestion is to dismantle triglycerides into small molecules that the body can absorb and use—namely:
- monoglycerides, fatty acids, and glycerol
- Fat digestion has been the focus of clinical attention in light of the increasing global prevalence of obesity
- •
How is fat digested
Some hard fats begin to melt ad they reach body temperature
The sublingual salivary gland in the base of the tongue secretes lingual lipade
In the stomach-
Acid stable lingual lipase initiates lipid digestion by hydrolyzing one bond of triglycerides to produce diglycerides and fatty acids. The degree of hydrolysis by lingual lipase is slight for most fats but may be appreciable for milk fats
The stomachs churning action mixes fat w acid and water
Gastric lipase accesses and hydrolyzes(only a very small amount of ) fat
Small intestine :
Bile flows in from the gall bladder via the common bile duct
Fat is converted to
Emulsified fat by bile
Pancreatic lipase flows in from the pancreas via the pancreatic duct
Emulsified fat or triglycerides is converted to monoglycerides,glycerol and fatty acids which are absorbed
Large intestine:
Some fat and cholesterol trapped in fiber exit in faeces
What are the two main transport systems of lipids
Explaim how they transport lipids
The more the lipids,what happens to density?
The more the proteins what happens to density?
What is very low demsity lipo proyeiny
Two main transport system have been identified: Exogenous and
endogenous transport system.
- The exogenous transport system transfers lipids of intestinal origin to peripheral and hepatic tissues
- The endogenous shuttle for lipids and their metabolites consists of three interrelated components:
The first, involving very low-density lipoproteins (VLDL), intermediate-density lipoproteins (IDL), and LDL, coordinates movement of lipids from liver to peripheral tissues.
- The second, involving HDL, encompasses a series of events that returns lipids from peripheral tissues to liver
- The third component of the system, not involving lipoproteins, effects the free FA–mediated transfer of lipids from storage reservoirs to metabolizing organs
The more lipids, the lower the density; the more proteins, the higher the density
• VLDL (very-low-density lipoprotein): the type of lipoprotein made primarily by liver cells to transport lipids to various tissues in the body; composed primarily of triglycerides.
What is LDL and HDL
What factors lower LDL or raise HDL
LDL (low-density lipoprotein): the type of lipoprotein derived
from very-low-density lipoproteins (VLDL) as VLDL triglycerides are removed and broken down; composed primarily of cholesterol.
• HDL (high-density lipoprotein): the type of lipoprotein that transports cholesterol back to the liver from the cells; composed primarily of protein
●Factors that lower LDL or raise HDL:
•Weight control, Monounsaturated or polyunsaturated instead of saturated fat in the diet, Soluble or viscous fibers, Phytochemicals, Moderate alcohol consumption, Physical activity.
What are the health implications of LDL and HDL and in this,explain ehy people call HDL good cholesterol and LDL bad cholesterol
The distinction between LDL and HDL has implications for the health of the heart and blood vessels
- The blood cholesterol linked to heart disease is LDL cholesterol.
- HDL also carry cholesterol, but elevated HDL represent cholesterol returning from the rest of the body to the liver for breakdown and excretion.
- High LDL cholesterol is associated with a high risk of heart attack, whereas high HDL cholesterol seems to have a protective effect
- This is why some people refer to LDL as “bad,” and HDL as “good,” cholesterol
What is blood lipid profile
What is the desirable total cholesterol?
Whats the desirable LDL cholesterol,HDL cholesterol and triglycerides?
Fat is a more concentrated energy source than the other energy nutrients: 1 g carbohydrate or protein = 4 kcal, but 1 g fat = 9 kcal
• DRI and 2005 Dietary Guidelines for fat: 20 to 35% of energy intake (from mostly polyunsaturated and monounsaturated fat sources such as fish, nuts, and vegetable oils)
True or false?
Intakes of Fats
• Blood lipid profile: results of blood tests that reveal a person’s total cholesterol, triglycerides, and various lipoproteins
- Desirable blood lipid profile:
- Total cholesterol: 200 mg/dL
- LDL cholesterol: 100 mg/dL
- HDL cholesterol: 60 mg/dL
- Triglycerides: 150 mg/dL
•Of all the nutrients, fat is most often linked with heart disease, some types of cancer, and obesity
What are health effects of fat
And health effect of omega 3
What are the sources of omega3 and pmega 6
Cancer: Dietary fat does not seem to initiate cancer development but, instead, may promote cancer once it has arisen
•The relationship between dietary fat and the risk of cancer differs for various types of cancers
• Obesity: Fat contributes more than twice as many kcalories per gram as either carbohydrate or protein
•
•Consequently, people who eat high-fat diets regularly may exceed their energy needs and gain weight, especially if they are inactive
• Because fat boosts energy intake, cutting fat from the diet can be an effective strategy in cutting kcalories.
Health Effects
•High blood LDL cholesterol poses a risk of heart disease, and high intakes of saturated and trans fats, specifically, contribute most to high LDL which is associated with heart diseases
- Omega-3 fatty acids appear to be protective
- Regular consumption of omega-3 fatty acids helps to prevent blood clots, protect against irregular heartbeats, and lower blood pressure, especially in people with hypertension or atherosclerosis.
Omega3:
Linolenic acid-Oils(flaxseed and flaxseed nut ,canola,walnut,wheat germ,soybean)
EPA and DHA- Human Milk
Pacific oysters and fish(mackerel,salmon,bluefish,anchovy,sardines,herrings,tuna
Omega 6:
Linoleic acid: VC egetable oils(sunflower,corn,soybean, cottonseed),poultry fat,nuts,seeds
Arachidonic acid:meats,poultry,eggs,
What is the structure of proteins and what atoms do they contain?
Which atom gives the name amino to the amino acids?
What attachment site distinguishes each amino acid from others
Chemically, proteins contain the same atoms as carbohydrates and lipids—carbon (C), hydrogen (H), and oxygen (O)—but proteins also contain nitrogen (N) atoms
- The nitrogen atoms give the name amino (nitrogen containing) to the amino acids—
- All amino acids have the same basic structure—a central carbon (C) atom with a hydrogen atom (H), an amino group (NH2), and an acid group (COOH) attached to it
- A fourth attachment site known as the side group or side chain distinguishes each amino acid from the others.
