Carbohydrates

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Carbohydrates

Compose of the ELEMENTS C H & O

MONOSACCHARIDES

Basic monomers of which carbohydrates are made up of

Are soluble and sweet eg) Glucose

GLUCOSE is a HEXOSE SUGAR - has 6 carbons C6H1206

Other monosaccharides are pentose ( C5H1005) or triouse (C3H603)

GLUCOSE IS THE PRODUCT OF PHOTOSYNTHESIS AND A MAJOR SUBSTRATE OF RESPIRATION.

ISOMERS of glucose are ALPHA GLUCOSE & BETA GLUCOSE

OH GROUP IS BELOW IN ALPHA , BETA OH GROUP IS ON TOP

DISACCHARIDES

Monosaccharide monomers can join to form polymers. TWO monosaccharides = DISACCHARIDE

when 2 Monosaccharides join together MOLECULE OF WATER IS FORMED AND GLYCOSIDIC BOND IS FORMED ( CONDENSATION REACTION)

CONDENSATION REACTION = REMOVES H20

HYDROLYSIS = ADDS H20 TO CHAIN

sucrose = GLUCOSE + FRUCTOSE -------> SUCROSE + WATER

Lactose = GLUCOSE + GALACTOSE -----------> LACTOSE + WATER

2 Hexoses joined by condensation can be summarised as

POLYSACCHARIDES

important polysaccharides starch, cellulose and glycogen are chains of MANY monomers of either alpha/beta glucose ( formed by condensation)

STARCH AND GLYCOGEN ARE MADE FROM ALPHA GLUCOSE AND ARE USED FOR ENERGY STORAGE.

CELLULOSE MADE FROM BETA GLUCOSE AND MAKES PLANT WALL CELLS

starch & cellulose found in plants

glycogen found in animal cells

STARCH =

Starch grains used FOR STORAGE IN PLANTS

Made up of 2 different polymers AMYLOSE & AMYLOPECTIN

AMYLOSE

forms a COMPACT HELICAL CHAIN to STORE LARGE NO. OF GLUCOSE MOLECULES IN A SMALL SPACE

AMYLOPECTIN

BRANCHED

Branches ALLOW AMYLOPECTIN TO BE QUICKLY HYDROLYSED BY AMYLASE ENZYMES TO FORM MALTOSE

GLYCOGEN

Found inn animals SIMILAR to AMYLOPECFTIN BUT has MORE branches

is an ENERGY STORAGE MOLECULE IN ANIMALS, FOUND IN LIVER CELLS AND MUSCLE TISSUE

Both GLYCOGEN & STARCH are well suited as ENERGY STORAGE MOLECULES :

are COMPACT so can store lots of glucose in small spaces

are INSOLUBLE , cannot move out of cell in which they're stored , have NO OSMOTIC EFFECT ( doesn't affect osmosis)

relatively INERT ( want to be broken down) so don't become involved in chemical reactions inside the cell.

Amylopectin and glycogen are QUICKLY HYDROLYSED to soluble glucose because it has many ends for amylase enzymes to attack

CELLULOSE

found in cell wall of plants , rigid structures of cell

The linking of beta glucose to form cellulose

Two beta glucose molecules LINK together by the molecule on THE LEFT FLIPPING OVER.

BETA GLUCOSE MOLECULES JOIN TOGETHER TO FORM THE STRONG STRUCTURAL CARBOHYDRATE CELLULOSE

Cellulose is the STRUCTURAL POLYMER of plant cells . its is a LINEAR POLYMER

WHY IS IT LINEAR? =

alternate beta glucose molecules are inverted ( flipped over)

Many cellulose chains run parallel to one another and have HYDROGEN BONDS forming cross links between them.

this helps give cellulose its TENSILE STRENGTH.

cellulose molecules grouped together to form MICROFIBRILS which are arranged in parallel groups called fibres

WHAT FUNCTION DOES THIS ALLOW IT TO CARRY OUT ?

- stops the cell bursting due to osmosis

Comparison of carbohydrate polymers