Carbohydrates and Lipids

Question 1

different ways for monosaccharides to be linked

Answer 1

1) two monosaccharide monomers may be joined via a glycosidic linkage to form a disaccharide
2) many monosaccharide monomers may be joined via a glycosidic linkage to form a polysaccharide

Question 2

examples of carbohydrates

Answer 2

1) Monosaccharides, one sugar unit = glucose, galactose, fructose (immediate energy source for cells)
2) Disaccharides, two sugar units = lactose, maltose, sucrose
(function as transport form)
3) Polysaccharides, many sugar units = cellulose, glycogen, starch
(energy storage or cell structure as well as cell recognition)

Question 3

cellulose

Answer 3

Its a structural polysaccharide that is found in the cell of plants.
Its a linear molecule composed of β-glucose subunits (bound in a 1-4 arrangement)
It is indigestible for most animals since it is composed of β-glucose

Question 4

Starch

Answer 4

Its a energy storage polysaccharide found in plants.
It is composed of α-glucose subunits (bound in a 1-4 arrangement) and exists in one of two forms – amylose or amylopectin

Question 5

Amylose

Answer 5

Form of starch. Linear (helical) molecule. Harder to digest and less soluble however it takes up less space and is the preferred storage

Question 6

Amylopectin

Answer 6

Form of starch. Branches molecule (contains additional 1-6 linkages)

Question 7

Glycogen

Answer 7

Glycogen is an energy storage polysaccharide formed in the liver in animals.
It is composed of α-glucose subunits linked together by both 1-4 linkages and 1-6 linkages (branching)

Question 8

fatty acids (saturated and unsaturated)

Answer 8

• Saturated fatty acids are liner in structure, originate from animal sources and are typically solid at room temperature
• Unsaturated fatty acids are bent in structure, originate from plant sources and are typically liquid at room temperature

Question 9

Unsaturated fatty acids (cis and trans isomers)

Answer 9

Cis: The hydrogen atoms attached to the carbon double bond are on the same side
Trans: The hydrogen atoms attached to the carbon double bond are on different sides

Question 10

Triglycerides (lipids)

Answer 10

Triglycerides are the largest class of lipids and function primarily as long term energy storage molecules. They are formed when condensation reactions occur between one glycerol and three fatty acids. The end result leads to the formation if three water molecules

Question 11

Cholesterol levels by fats

Answer 11

Saturated fats = raise blood cholesterol levels
Trans fats = raise blood cholesterol levels
Cis fats = lower blood cholesterol levels

Question 12

Effects of Fatty acids

Answer 12

Trans fat = Bad
Cis fat = good
Saturated Fat = bad
Unsaturated = good

Question 13

transport of cholesterol

Answer 13

• Low density lipoproteins (LDL) carry cholesterol from the liver to the rest of the body
• High density lipoproteins (HDL) scavenge excess cholesterol and carry it back to the liver for disposal
  Hence, LDLs raise blood cholesterol levels (bad)

Question 14

High intakes of certain types of fats

Answer 14

• Saturated fats increase LDL levels within the body, raising blood cholesterol levels
• Trans fats increase LDL levels and decrease HDL levels within the body, significantly raising blood cholesterol levels
• Unsaturated (cis) fats increase HDL levels within the body, lowering blood cholesterol levels

Question 15

Health risk of high cholesterol

Answer 15

High cholesterol levels in the bloodstream lead to the hardening and narrowing of arteries. This leads to development of plaques which restrict blood flow. Coronary arteries being blocked leads ti coronary heart disease

Question 16

examples of foods with fatty acids

Answer 16

Saturated = animal fats
Trans = fast foods
Monounsaturated = plant based food
Polyunsaturated = Fish

Question 17

difference between Lipids and Carbohydrates

Answer 17

Storage (lipids are better for long term energy storage)
Osmolarity (lipids have less of an effect on the osmotic pressure of a cell)
Digestion (carbohydrates are easier to digest and utilise)
ATP Yield (lipids store more energy per gram)
Solubility ( carbohydrates are easier to transport in the bloodstream)

Question 18

ATP

Answer 18

ATP is the energy currency of the cell

Question 19

Storing energy as carbohydrates

Answer 19

• its easier to carry around
• its readily accessible and easier to digest
• you cannot carry as much

Question 20

Storing energy as lipids

Answer 20

• its not viable to carry around
• it is harder to access
• you can carry more in it

Question 21

Body mass index

Answer 21

provides a measure of relative mass based on the weight and height of the individual and is used to identify potential weight problems
calculation:
weight in kilograms divided by height in meters squared