Download LE 01-10b - rosedalegrade12biology

Nutrients and Carbohydrates
A nutrient is any
substance that has
a useful function
when consumed
and absorbed into
cells.
• The 3 macronutrients are:
1. Carbohydrates
2. Lipids
3. Proteins
• The 3 micronutrients
1. vitamins
2. minerals
3. water
Carbohydrates
Function: Carbohydrate molecules are the main
energy source for an organism.
Food Sources: pasta, rice, sugars, potatoes
Chemical Structure of glucose is C6H12O6
- hydrogen: carbon: oxygen in the ratio 1:2:1
There are two main types of carbohydrates,
sugars and starches. At least 40% of a healthy
diet should be complex carbohydrates or
starches and simple carbohydrates like sugar
should be avoided.
Carbohydrates - Monosaccharides
• Sugars or simple carbohydrates taste sweet.
• The most important is the monosaccharide
glucose as well as fructose and galactose.
• Sugar names end in “ose”
• The basic chemical structure is a ring of 6
carbons shown as:
LE 5-4
Glucose dissolved in water is found almost always in a
ring form, but dry glucose can have a linear structure.
Linear
and
a Glucose
ring forms
a and b glucose ring structures
Abbreviated ring
b Glucose
structure
Carbohydrates - Disaccharides
• Joining two monosaccharides forms a
disaccharide.
• Still taste sweet like sucrose and maltose.
• The basic chemical structure is two 6 carbon
rings joined together in a condensation
reaction.
• The bond between 2 monosaccharides is a
glycosidic bond.
LE 5-5
Dehydration
reaction in the
synthesis of maltose
1–4
glycosidic
linkage
Glucose
Glucose
Dehydration
reaction in the
synthesis of sucrose
Maltose
1–2
glycosidic
linkage
Glucose
Fructose
Sucrose
Remember: A glycosidic linkage is a specific type of ether linkage.
LE 5-8
Cellulose microfibrils
in a plant cell wall
Cell walls
Microfibril
0.5 µm
Plant cells
Cellulose
molecules
b Glucose
monomer
Carbohydrates - Polysaccharides
• Two important polysaccharides are starch and cellulose.
• Starches taste dry not sweet.
• Starches are formed by joining many monosaccharides
together to form a polysaccharide.
LE 5-7b
There are two types of glycosidic bonds, alpha
or beta bonds. In an alpha glycosidic bond the
–OH group on the second carbon is on the
opposite side of the ring than the carbon 6
–CH2OH group. This is starch.
Starch: 1–4 linkage of a glucose monomers.
LE 5-7c
In cellulose or plant fibre, every second
glucose is flipped over and a beta glycosidic
bond is formed.
Cellulose: 1–4 linkage of b glucose monomers.