yacomine_essential biology 03.2 carbohydrates, lipids and proteins_7111

Essential Biology 03.2: Carbohydrates, Lipids and Proteins

1. Define organic molecule.Organic molecules are molecules that come from living things. With some exceptions, they all have carbon.

2. What are three carbon-containing groups or molecules that are not organic?Three molecules are hydrogen carbonate, carbon dioxide and carbon monoxide.

There are many organic molecules in living things. The same (or very similar) molecules 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?In water monosaccharides go into 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?

CH2OH CH2OH 6

C5 OH OH HC4 C1

OH HHO H C3 C2

H OH

c. Draw a generalized hexose and pentose sugar on chemsketch and render 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

http://sciencevideos.wordpress.com/

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


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 naturally occurring or synthetic compound consisting of large molecules made up of a linked series of repeated simple monomers

e. Use the diagram below to show how two monosaccharides are converted into a disaccharide through condensation. Complete a word equation. What else is needed to make the reaction 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.




g. Complete the table below:

-saccharides examples Plant or animal? Function/ uses

Mono-

Glucoseanimal Quickly absorbed and used in

respirationGalactose

Fructose plant

Di-

Sucrose plant Soluble but unreactive, can be transported around plant in Phloem.

Lactoseanimal

Quickly digested into monosaccharides.

Maltose Dimer of glucose, broken down from starch.

Poly-

Glycogen animal Insoluble storage of glucose in the liver produced using insulin.

Starchplant

Insoluble plant energy storage molecule.

Cellulose Structural 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?The function of hydrolase is to cause the hydrolysis of a chemical bond.




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

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.

H O H H

H C OH C Cn C H

H C OH HO H H H C OH Fatty Acids

H 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 effective than fats in animals, carbohydrates, and oils in fish and plants.

Thermal insulation* Hypodermic fat insulates against loss of heat

Protection Fat is used as a shock absorber

Buoyancy They are less dense than water, making them capable of floating.

Membranes Cholesterol and phospholipid layer

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): A glycerol molecule bonds with carboxylic acid. Water is then pulled out to cause them to bond to make triglyceride.

g. Explain why condensation of fatty acids and glycerol to produce a triglyceride is not an example of polymerization. Polymerization has a dimer which involves two monomers which are identical. However, fatty acids and glycerol are not identical, and is therefore not a polymerization.

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




carbohydrates lipids

Stored as…? Fat Fats and oils

Long/short term storage? Short term Long term

Ease of digestion/ release of energy?

Quick and easy to digest, requires less oxygen to release

energy

Requires more oxygen to release energy

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

Solubility in water?(and consequence) Some vitamins are dissolved

Use of oxygen in metabolism?

(and consequence)

Less oxygen use for metabolic processes

More oxygen use for 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.

R H O N C C Carboxyl Group Amine Group H OH H R Group

b. How many different amino acids are there? What is different about each one? There are 20 different amino acids. The R group structure tells you what amino acid it is and what it contains.

c. What is a polypeptide? A polypeptide is a peptide that has at least ten amino acids.




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

i. Polypeptide length: A polypeptide can be any length

ii. Amino acid sequence: Twenty amino acids in any combination

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



yacomine_essential biology 03.2 carbohydrates, lipids and proteins_7111

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