2.3 - Lipids Flashcards
What are saturated fatty acids?
chain of carbon atoms linked by a covalent
contains a carboxyl at one end (-COOH)
Saturated
only single bonds between the carbon atoms (14 - 20 carbons long)
each carbon atom is bonded to as many hydrogen atoms as possible
Carboxyl group at the end
Unhealthy (cholesterol build up)
Unsaturated
If there are one or more double bonds between the carbon atoms
Monounsaturated: one double bond
Polyunsaturated: more than one double bond
Lipids are a diverse group of carbon compounds
They are insoluble in water
Fats are liquid at body temperature and solid at room temperature, while oils are liquid at both temperatures.
Cis and Trans Isomers
Isomer: molecules with same number and type of atoms, but with a different arrangements of those atoms
trans isomer - hydrogens are on the opposite side of the double bond (makes the molecule more thermodynamically stable)
cis isomer - Hydrogens are on the same side of the double bond (creates a bend in the chain due to repulsion of atoms)
Triglycerides
Triglycerides are formed by condensation from three fatty acids and one glycerol .
Condensation reaction between glycerol and 3 fatty acids to link them
ester bond is formed - reaction between -COOH group on a fatty acid an an -OH in the glycerol.
Three water molecules are produced
Can be used as energy stores
The energy from them can be released by aerobic cell respiration
Lipids as Energy Storage
Molecules that are stored by humans and other organisms to be used in ATP production include:
Glycogen (stored in the liver and muscle tissues)
short term storage
Glycogen can be broken down to glucose rapidly and then transported easily by the blood to necessary places of the body.
Glucose can be used in anaerobic or aerobic cell respiration whereas fats and fatty acids can only be used in aerobic respiration.
Triglyceride (stored within adipose cells)
Triglyceride lipids, when needed, can be hydrolyzed into fatty acid segments that can enter into cellular respiration (at a different starting point from glucose)
lipids are suitable for long term storage (energy storage) in humans than carbohydrates
a gram of fat stores more than twice as much energy as a gram of polysaccharide (starch)
fats form pure droplets in cells with no water associated, whereas each gram of glycogen is associated with about two grams of water, so lipids are actually six times more efficient in the amount of energy that can be stored.
animals must carry their energy stores with them, so it is advantageous to have a more compact reservoir of fuel
fat is stored in adipose, which form adipose tissue
adipose tissue cushions vital organs, such as the kidneys
adipose tissue beneath the skin also serves as layer of insulation
BMI - Body Mass Index
screening tool used to identify potential health problems
other factors such as diet, physical activity, and family history also need to be assessed
BMI = mass in kg/(height in m)2
Using a Nomogram to Calculate BMI
An alternative to calculating BMI
A ruler is used to draw a line from the body mass to height
Where the drawn line intersects with the W/H2 line is the BMI
Displays weight and height on perpendicular axis
Coronary Heart Disease (CHD)
In this disease the coronary arteries become partially blocked by fatty
deposits, leading to blood clot formation and heart attacks.
A positive correlation has been found between saturated fatty acid
intake and rates of CHD in many research programs. However, nding
a correlation does not prove that saturated fats cause the disease. It
could be another factor correlated with saturated fat intake, such as
low amounts of dietary fibre, that actually causes CHD.
