Organic Molecules and Carbohydrates

Biology 12Section 2.3 and 2.4

Organic vs. Inorganic Molecules

• In addition to carbon, another element that is always part of organic molecules is hydrogen.

Organic vs. Inorganic Molecules

• Ring compounds are formed when hydrocarbon chains are able to turn back on themselves to form ring molecules.

Functional Groups

• Groups of atoms that can be attached to carbon chains are called functional groups.

• Functional groups are clusters or groups of atoms that behave in certain ways.– Ex. Carboxyl: -COOH

Functional Groups

• An important property of the carboxyl group that allows it to react with water is that it can often give up its last hydrogen atom and thus become polar.

Functional Groups

• So what’s the difference between a hydrophobic carbon chain and a hydrophilic carbon chain with the functional group attached to it?

Functional Groups

• The hydrophobic carbon chain has no functional group attached to it.

• This makes it non-polar = hydrophobic.

Functional Groups

• The hydrocarbon chain that has a functional group attached to it can be polar which makes it hydrophilic.

Monomers and Polymers

• Monomers are single unit molecules that can bond with each other to form large molecules called macromolecules.

• Macromolecules are also called polymers.• Mono = 1, Poly = more than 1

Monomers and Polymers

• There are three important sets of monomers and polymers that you need to know of in Biology 12:

Monomers Polymers

Glucose Carbohydrates

Amino acids Proteins

Nucleotides Nucleic Acids (DNA, RNA)

Carbohydrates

• Carbohydrates have several functions in the body:– Energy – both short term (quick) and long term

storage– They form carbohydrate chains on cell surfaces –

tags for I.D.– They form structure and support in plant cells

(cellulose for cell walls)

Carbohydrates

• Carbohydrates all have the same basic structure:– They are made up of single sugars called

monosaccharides– Monosaccharides have 3-7 carbon atoms in each

molecule

Carbohydrates

• Monosaccharides all have the same general empirical formula:

CH2O

• That means the ratio of C:H:O is 1:2:1

Carbohydrates

• Molecular formulas for some monosaccharides:– Triose – C3H6O3

– Tetrose – C4H8O4

– Pentose – C5H10O5 – the sugar found in DNA/RNA

– Hexose – C6H12O6 – the sugar found in all carbohydrates

Carbohydrates

• Hexose has 3 isomers (molecules that have the same molecular formula, but slightly different structural formulas)

• They are:– Glucose– Galactose – dairy products, sugar beets (not as

sweet)– Fructose – honey, fruits, veggies (sweetest of the

sugars)

Carbohydrates

• Using glucose as an example, we can draw the structural formula in different ways:– Detailed or simplified

Carbohydrates

• Disaccharides are when 2 monosaccharide sugar molecules are bonded together.

• Ex.– Glucose + Glucose → Maltose– Glucose + Fructose → Sucrose (table sugar)

Carbohydrates

• In equation form, the formation of a disaccharide looks like this:

C6H12O6 + C6H12O6 → C12H22O11 + H2O

• Notice that a water molecule is lost in the process of joining the 2 monosaccharides.

• This process is called dehydration synthesis.

Carbohydrates

• Using structural formulas, dehydration synthesis looks like this:

Carbohydrates

• When we digest disaccharides, our bodies can change them back into the monosaccharides that make them up.

• This process is called hydrolysis• Hydro = water, lysis = to break apart

Carbohydrates

• Hydrolysis is the opposite of dehydration synthesis.

• In other words, water is added to break the bond between the two sugar molecules.

• If we use the two-way arrow in the reaction, one way shows dehydration synthesis, the other shows hydrolysis.

Carbohydrates

• Three kinds of polysaccharides are– Starch– Glycogen– Cellulose

• Polysaccharides are simply polymers of glucose that can be up to 400 units long.

Carbohydrates

• Structurally, you can tell the difference between a starch polymer and a glycogen polymer.– Starches are mostly straight chains with few side

branches.– Glycogen has many side branches.

Carbohydrates

• Both starch and glycogen are used by plants and animals.– Starch is the polysaccharide stored in plants.– Glycogen is the polysaccharide stored in animals in

the liver and muscles.

Carbohydrates

• After eating starchy foods, this is what happens:

Starch undergoes Hydrolysis to produce Glucose which is taken by Blood to the Liver where the Glucose undergoes Dehydration Synthesis to produce Glycogen for Storage. It can be converted back to Glucose as needed to maintain a blood glucose level of 0.1%.