Download CARBOHYDRATES, lipids and proteins handout

CARBOHYDRATES, LIPIDS, AND PROTEINS
Carbohydrates: (make up 1 – 2% of cell mass)
 Combinations of carbon (C), hydrogen (H), and oxygen (O) (usual ratio = 1:2:1)(e.g.
glucose is C6H12O6) – sugars and starches
 Carbohydrate means "hydrated carbon"
 Primary use = fuel to make energy. The energy molecule of the cell is ATP.
Glucose is broken down and the energy released from the chemical bonds is stored
in ATP
 Some examples of carbohydrates include: glucose, sucrose, fructose, lactose,
starch, and glycogen. All are converted to glucose by the small intestine or liver.
 Secondary use = as structural components for cell membranes and cell surface
markers. The glycocalyx is composed of various sugars ( along with proteins and
lipids) that “sugar coat” the cell.
Lipids: (make up 2% of cell mass)
 Composed of C, H, O but ratio is less predictable than in carbohydrates – neutral
fats, phospholipids and steroids
 Primary use = fuel for production of ATP and fuel storage
 Secondary use = structural components of the cell membrane and hormones
 Some examples: triglycerides = #1 most common lipid
 Other lipids: phospholipids and cholesterol which are components the hormones
estrogen, progesterone and testosterone
Proteins: ( make up 10 – 30 % of cell mass)
 Composed of chains of amino acids (AA). There are 20 different AAs that can
combine to form a great number of proteins. Chains of greater than 50 AA are
called proteins.
 Each AA is composed of C, H, O, & nitrogen (N) (some with sulfur and phosphorus)
 The Four cardinal rules of proteins:
1. Sequence of AAs determines shape of protein
2. Shape determines function of protein
3. If AA sequence is altered, then the shape and therefore function is likely
altered.
4. Attaching something to or detaching something from a protein usually alters
its shape and function. Example Na+/K+ pump
 Primary use = as structural proteins to connect, anchor, contract, etc.
(e.g. collagen, actin, myosin)
OR as functional proteins to stimulate metabolism of target cells or to
stimulate chemical reactions such as digestion.
(e.g. hormones, enzymes)
 Secondary use = fuel for energy (e.g. starvation, cancer) but your body prefers not
to use protein for this purpose.
Energy Yield = Measured in kilocalories per gram = 4, 9, 4 respectively
MDufilho
Rev. 8/18/15
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