Carbon and Carbohydrates

Carbon and CarbohydratesHL BiologyCells & Biomolecules

Thinking question

What are the basic components you need to build a living organism?

Molecular Biology

• From a purely scientific viewpoint, any living organism is merely a collection of elements in the form of atoms, ions an molecules.

• Molecular biology explains living processes in terms of the chemical substances involved.

Basic definitions Term defintion

Metabolism The web of all the enzyme-catalysed reactions in a cell or organism

Anabolism The synthesis of complex molecules from simpler molecules

Catabolism The breakdown of complex molecules into simpler molecules.

Chemistry revision

• Define the following terms:– Atom– element– Molecule– Compound

Chemistry revision

• Define the following terms:– AtomThe smallest particle into which an element can be divided without losing its chemical properties.– ElementA substance consisting of atoms which all have the same number of protons - i.e. the same atomic number.

– MoleculeThe combination of two or more atoms, eg H2

– CompoundThe combination of two or more atoms of different elements, eg CO2

The Molecules of Life

Atoms/Molecules- we are made of earth elements that are organized into:

a) inorganic molecules (NaCl, PO4, K+)

b) organic molecules (contain C and H)

All organic molecules contain carbon, but not all carbon containing molecules are organic, eg. Carbon dioxide

Carbon

Carbon

• Carbon is a small, relatively light element with four single valence electrons.

• It can form up to four stable covalent bonds with other atoms.

• Carbon atoms attach to each other to form straight and branched chains and ring structures of various sizes and complexity that act as the backbones of biological molecules.

Carbon video

• https://www.youtube.com/watch?v=QnQe0xW_JY4

Four Main Types Of Macromolecules

Molecules Monomers

carbohydrates monosaccharides

lipids Glycerol and fatty acids

proteins Amino acids

Nucleic acids nucleotides

Macromolecules

• Large molecules formed by joining many subunits together, make a polymer.

• The smaller subunits are called monomers.

The wall represents:

Each brick represents:

You are what you eat!

• http://v.youku.com/v_show/id_XNDU5MDg5ODky.html

carbohydrates

• Carbohydrates contain carbon, hydrogen, and oxygen atoms in a 1:2:1 ratio.

There are three types of Carbohydrate:

• Monosaccharides = “single sugar”• Disaccharides = “two sugars”• Polysaccharides = “many sugars”

Monosaccharides

Monosaccharides are sugars that consist of a single sub-unit (monomer).

Monosaccharide Formula

Glucose C6H12O6

Fructose C6H12O6

Ribose C5H10O5

Drawing molecular models of Ribose and Glucose

Glucose (C6H12O6) Ribose (C5H10O5)

Modeling molecules

• Make a model of glucose and a model of ribose. Take a photograph of each model.

Disaccharides

• Disaccharides are pairs of monosaccharides that are linked together by condensation to form disaccharides.

Glucose + glucose maltose + waterGlucose + galactose lactose + waterGlucose + fructose sucrose + water

Disaccharides

• Model condensation reactions between two glucose molecules. Take photographs of each step and compile them into a document with step by step explanations.

• What are the products of this reaction?

Condensation Reactions

• Two monosaccharides are joined together to form a disaccharide with the release of a water molecule

Glucose + glucose = maltose + water

Polysaccharides

• Polymers consisting of chains of monosaccharide or disaccharide units.

• The bonds are called glycosidic linkages.• Some polysaccharides serve as energy storage

(eg. Starch and glycogen)• Some polysaccharides are used for building

and structure (eg. cellulose)

Review of glucose• Glucose is the most common

monosaccharide

• It forms rings in aqueous solution

• The carbon atoms are number 1 – 6 in a clockwise direction, starting from the carbon immediately next to the oxygen atom.

Isomers of glucose • Isomers are compounds with the same

chemical formula but different arrangements of their atoms.

• Glucose can exist as alpha-glucose or beta-glucose, depending on the position of the OH group on carbon1.

Polysaccharides

• Polysaccharides form from several hundred to several thousand monosaccharides joined together by condensation reactions.

• Condensation reactions usually form glycosidic linkages between carbon1 of one glucose to carbon4 of the second glucose.

• 1,4 links form straight chains.• Occasionally 1,6 links occur, causing branching

Cellulose

• Cellulose is a structural material found in the cell walls of plants.

• It is made up of beta-glucose molecules held together by 1,4 glycosidic links.

• The beta-glucose monomers alternate, with each one being upside down compared to its neighbours. (up, down, up etc)

Cellulose

Starch

• Starch is a polymer of alpha-glucose, with all of the glucose monomers in the same orientation, which makes the chain curved.

• There are two forms of starch:1. Amylose – 1,4 linkages, un-branched2. Amylopectin – 1,4 and 1,6 linkages, branched

Starch

Starch

Starch: a plant polysaccharide. This micrograph shows part of a plant cell with a chloroplast, the cellular organelle where glucose is made and then stored as starch granules. Amylose (unbranched) and amylopectin (branched) are two forms of starch.

Glycogen

• Glycogen is a branched polymer of alpha-glucose.

• It has even more 1,6 linkages than amylopectin.

Glycogen

Glycogen: an animal polysaccharide. Animal cells stockpile glycogen as dense clusters of granules within liver and muscle cells, as shown in this micrograph of part of a liver cell. Mitochondria are cellular organelles that help break down glucose released from glycogen. Note that glycogen is more branched than amylopectin starch.

Extra reading

• Still feeling confused? Read chapter 5.2 in Campbell