3.2 Carbohydrates Lipids Proteins WORD

Essential Biology 03.2: Carbohydrates, Lipids and Proteins

1. Define organic molecule.

An organic molecule is a molecule that contains carbon and generally, but not always, hydrogen.

2. What are three carbon-containing groups or molecules that are not organic?

Oxides of carbon, carbonates and hydrogen carbonates are not organic.

There are many organic molecules in living things. The same (or very similar) mole-cules are used in many different living things for the same purpose.

3. Saccharides are sugars and carbohydrates. Sugars (monosaccharides and disaccharides) are used to build up carbohydrates (polysaccharides).

a. What happens to the structure of monosaccharides when they are placed in water?

When monosaccharides are placed in water they get a ring structure.

b. Draw the simplified (ring) structures of glucose and ribose. Number the carbon atoms correctly. Which sugar is a pentose? Which is a hexose? How are they named this way?

c. Draw a generalized hexose and pentose sugar on chemsketch and ren-der it in 3D. Stick the 3D ball-and-stick model below: (http://www.acdlabs.com/download/)

Stephen Taylor Bandung International School http://sciencevideos.wordpress.com

Glucose Ribose

http://www.acdlabs.com/download/

http://sciencevideos.wordpress.com/


Condensation of monosaccharides is a polymerization reaction. It can continue to create a longer chain of saccharides (a carbohydrate). These building reactions are anabolic metabolism.

d. What is a polymer? A polymer is a long chain of monomers through chemical bonding such as

DNA.

e. Use the diagram below to show how two monosaccharides are con-verted into a disaccharide through condensation. Complete a word

equation. What else is needed to make the re-

ac- tion occur?

f. Condensation of sugars produces a glycosidic bond. Distinguish between 1-6 glycosidic and 1-4 glycosidic bonds in terms of their effect on the shape of the polysaccharide produced. You might want to draw them to help see.

Glycosidic bonds that are 1-4 bond create straight chains while 1-6 bond create bent chains.


To make the monosaccharide become a disaccharide, a OH-C-H is removed and replaced with the H-C-HO from the other molecule. All of these reactions require enzymes

Amino acid+ amino acid -condensation> dipeptide + water



g. Complete the table below:

-saccharides examples Plant or animal? Function/ uses

Mono-

Glucoseanimal Quickly absorbed and used in

respirationGalactose

Fructose plant

Di-

Sucrose plantSoluble but unreactive, can be

transported around plant in phloem.

Lactoseanimal

Found in milk- ideal for nursing young

MaltoseDimer of glucose, broken down

from starch.

Poly-

Glycogen animalInsoluble storage of glucose in the liver, produced using in-

sulin.

Starchplant

Insoluble plant energy storage molecule

CelluloseStructural unit in plant cell

walls

Anabolic reactions are those which build organic molecules (such as condensation of saccharides). Catabolic reactions break them down (e.g. digestion).

Hydrolysis is the catabolic reaction which breaks down organic molecules.

h. What is the function of hydrolase?

Hydrolase is an enzyme and it causes the hydrolysis of a chemical bond. It is the catalyst.

i. Outline this reaction using an example of a dimer of two pentose sug-ars. Explain the relevance of the name of the reaction.

The reaction starts with a polymer and then hydrolysis puts water in and forms a dimer which is a compound whose molecules are composed of two identical




monomers and hydrolysis puts in more water causing the dimer to become a single monomer. Hydrolysis is a relevant name because hydro means water and lysis means splitting, which is exactly what happens, the water splits the bonds.

Remember:

Condensation makes bonds: Hydrolysis breaks bonds.

4. Fatty acids and glycerol are used in the production of triglycerides. a. In the space below, draw the generalized structures of fatty acids and

glycerol.

b. Distinguish between saturated and unsaturated fatty acids. (Nutrition revision).

Bonding Shape of chain (draw)State at room

temp

Saturated Ester bond Solid

Unsaturated Double bond Liquid

c. Draw a generalized fatty acid or glycerol molecule on chemsketch and render it in 3D. Stick the 3D ball-and-stick model below: (http://www.acdlabs.com/download/)



http://www.acdlabs.com/download/


d. What is the relevance of the following properties of lipids?

Energy storage* More efficient than carbohydrates, oils in plants and fish, fat in animals

Thermal insula-tion*

Subcutaneous fat insulates against heat loss

Protection Fat acts as a shock absorber

Buoyancy Floating- less dense than water

Membranes Phospholipid bilayer, cholesterol

Hormones

*Essential exam examplese. Write a word equation for the formation of one triglyceride from fatty

acids and glycerol.

f. Outline how condensation reactions produce one triglyceride molecule (including the name of the bonds produced):

Condensation starts with a single molecule of glycerol which bonds with carboxylic acid. Condensation then occurs pulling water out to cause these to bond creating triglyceride.

g. Explain why condensation of fatty acids and glycerol to produce a triglyceride is not an example of polymerization. Polymerization includes a dimer which is a compound made of two identical monomers however in this case, fatty acids and glycerol are not two identical monomers and are therefore not considered to be polymerization.

h. Compare lipids and carbohydrates in terms of energy storage:

carbohydrates lipids

Stored as…? fat Oils and fats

Long/short term stor-age?

Short term Long term

Ease of digestion/ re-lease of energy?

Quickly digested and needs less oxygen to release en-

ergy

Need more oxygen to release energy




Energy per gram? 17 kJ g-1 38 kJ g-1

Solubility in water?(and consequence)

Dissolves some vitamins

Use of oxygen in metab-olism?

(and consequence)

Uses less oxygen to per-form metabolic processes

Uses more oxygen to perform metabolic processes

5. Proteins are the tertiary (or quaternary) structure of polypeptides, polymers of amino acids.

a. In the space below, draw the structure of a general amino acid. Include (and label) the amine group, carboxyl group and ‘R’ group.

b. How many different amino acids are there? What is different about each one?

There are 20 amino acids. The “R” group structure determines which of the 20 it is and its properties.

c. What is a polypeptide? A peptide containing 10 or more amino acids such as a protein.

d. How does the diversity of amino acids lead to infinite possibilities of polypeptides?

i. Polypeptide length: can be any length

ii. Amino acid sequence: 20 amino acids in any order or combina-tion

e. Use a diagram to show condensation and hydrolysis of peptides.


Amine group -><- Carboxyl group

‘R’ group ^


3.2 Carbohydrates Lipids Proteins WORD

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