Biological molecules focus on carbohydrates
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Biological Molecules Focus on Carbohydrates. (See pages 31-41). General Reactions. MONOMERS. Dehydration Synthesis. Hydrolysis. 5H 2 O. 5H 2 O. POLYMER. Carbohydrates. Carbohydrates are polymers of monosaccharides (simple sugars).

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Biological Molecules Focus on Carbohydrates

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Biological MoleculesFocus on Carbohydrates

(See pages 31-41)


General Reactions

MONOMERS

Dehydration

Synthesis

Hydrolysis

5H2O

5H2O

POLYMER


Carbohydrates

  • Carbohydrates are polymers of monosaccharides (simple sugars).

  • They are the first macromolecule to be metabolized within the cells of the body (ie. they are involved in cellular respiration before fats and proteins, meaning that they are the PRIMARY source of energy for the body).

  • Cellular Respiration (Mitochondria):

    Glucose + 6O2

6CO2 + 6H2O + ATP

(C6H12O6)


  • Glucose is a simple sugar and the main monomer of carbohydrates (polysaccharides) in the body.

  • Carbohydrates are broken down by the digestive system, first in the mouth, then in the small intestine.

  • The final result of digestion is GLUCOSE which is small enough to enter the bloodstream and eventually, cells.

  • Aside from providing energy, carbohydrates also associate with both the phospholipids and proteins of cell membranes, in order to provide each cell with an “I.D. tag” for cell-to-cell recognition.


  • There are three levels of carbohydrate structure based purely on size differences:

    1. Monosaccharides (One simple sugar):

    Three major types:

    A. Glucose – the primary energy source for

    the body. Most polysaccharides are

    eventually broken down to glucose by

    our digestive system.

    -- found naturally in green plants

    -- chemical formula = (C6H12O6)


Structure of Glucose:

OR

  • Each vertex in the above right drawing represents a carbon ( C ) molecule (they are numbered 1 to 6).


B. Galactose – found in milk

-- possesses the same chemical

formula as glucose but has

one different arrangement of –H

and –OH on carbon #4.

C. Fructose – found in fruits

-- same formula as glucose, but a

much different –H, –OH, and C

arrangement.


  • Glucose, galactose, and fructose are all structural ISOMERS of each other, meaning that they each possess the same chemical formula, but exhibit a different arrangement of the atoms.


Sugar Ray Leonard

After his first fight he ditched his old nickname:

Monosaccharide Ray Leonard


2. Disaccharides (Two Sugars):

-- formed when two monosaccharides undergo DEHYDRATION SYNTHESIS (producing a water molecule as well).

Three Major Types:

A. Maltose –Made up of two glucose molecules (studied in Biology 12)

B. Sucrose – Made up of one glucose and one fructose molecule

C. Lactose – Made up of one glucose and one galactose molecule


Maltose Formation by Dehydration Synthesis

+

GLUCOSE

GLUCOSE

+H2O

MALTOSE


Oxygen “Bridge”

Formula for Maltose: C12H22O11 – which is equal to 2 x Glucose minus one water…


  • The EMPIRICAL formula for carbohydrates is CH2O.

  • However, a ‘carb’ made up of two glucose molecules forms one water molecule during its construction.

  • Similarly, a “carb” made up of 50 glucose molecules forms 49 water molecules.

  • To find the formula of any “carb,” all one needs to know is either how many glucose molecules are involved OR how many water molecules are formed.

  • Eg. A “carb” with 17 glucose molecules has a formula of: 17 x (C6H12O6) – 16 x (H2O) = C102H172O86

  • So, the empirical formula is only a guide, it’s not exact.


3. Polysaccharides (Long chains of sugars):

-- a POLYMER of monosaccharides.

-- three polysaccharides are common in living things (all are polymers of glucose, but differ in their branching patterns):

A. Starch – storage form of glucose in

plants.

-- few side branches (very simple

arrangement)

-- the existing side branches all span

in the same direction

-- relatively straight molecule but adopts an

energy-efficient helical shape.

-- see figure 2.19 p. 33

-- easy to digest


B. Glycogen – storage form of glucose in

animals.

-- more branched than starch (see

fig. 2.20 p. 33)

-- also easy to digest as the branching

allows digestion to occur at several

points simultaneously.

-- the liver converts excess glucose to

glycogen and stores it.

-- muscles also convert glucose to

glycogen and store it.


C. Cellulose – the structural component of

plant cell walls.

-- possesses a much different type of

linkage between glucose molecules

(see fig. 2.21 p. 33).

-- humans are unable to digest

cellulose molecules; they pass right

through our digestive tract as fibre or

roughage.


-- cows (and other ruminant animals) are able to digest cellulose due to the presence of symbiotic bacteria that exist in their stomachs, bacteria which humans do not house.


I’ll RUN WILD on you Atkins…eat your CARBS, brother!!!

Damn, I’m lookin’ good! Probably because of my diet!


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