Carbohydrates

Question 1

What is a carbohydrate

Answer 1

a carbohhydrate is only made of carbon, hydrogen and oxygen. it can act as a source and store of energy and a structural unit.

Question 2

Struct of Alpha glucose vs beta glucose

Answer 2

The structre of alpha glucose is a hexose with the OH group at the bottom while the alpha glucose is also a hexose sugar but the OH group is at the top

Question 3

Why are polysaccharides such good energy stores?

Answer 3

Polysaccharides are compact so they can fit more polysaccharides into dense granules, they contain glucose in the chains which can easily be snipped of for energy for resp, they can be branched molecules so even more compact and also have branched chains which are also easy to snip of. They also are less soluble then monosachharides so dont affect wp as much when stored.

Question 4

Name 3 polysaccharides

Answer 4

amylose, amylopectin and glycogen

Question 5

explain the struct of amylose (plant)

Answer 5

amylose is a 1,4 glycosidic bonded chain of alpha glucose. It coils into spiral shape and hydrogen bonds hold the shape. It is the least soluble polysaccharide out the 3 but the least compact as no branched molecules.

Question 6

explain structy of amylopectin (plant)

Answer 6

Amylopectin has a unbranched chain of 1,4 glycosidic bonds and a branched chain of 1,6 glycosidic bonds. It coils into a spiral shape held by hydrogen bonds and due to branched chains is very compact, more than amylose but less than glycogen. It is more soluble then amylose

Question 7

explain the struct of glycogen (animal)

Answer 7

glycogen has a unbranched chain of 1,4 glycosidic bonds and a branched chain of 1,6 glycosidic bonds. It coils into a spiral shape held by hydrogen bonds. The 1,4 chains are shorter so coil less but theres more branched molecules so it is more compact then amylopectin, also even easier to snip off.

Question 8

why doesnt Cellulose spiral ?

Answer 8

Alpha chains spiral but Beta chains are linear, in cellulose every other beta chain is inverted by 180 degrees which prevents spiralling. there are also many hydrogen bonds between the chains and in one chain providing extra stengh

Question 9

What are macrofibrils

Answer 9

Macrofibrils are made of many microfibrils when they join up which are made of many cellulose joined up

Question 10

struc and funct of cell walls in plant cells advanced

Answer 10

.Macrofibrils and microfibrils have a very high tensile strengh due to the glycosidic and hydrogen bonds which prevent bursting when the cell is turgid,

.Macrofibrils run in all directions and criss cross around the cell wall for aditional stengh. plant cells have no rigid skeleton so the support provided by the cell wall is essentual to keep shape and provide extra structural help.