carbohydrates Flashcards
what is the most common type of organic compound
carbohydrates
what is the function of carbohydrates
storage of energy
what is the smallest unit of a carbohydrate
monosaccharides
give the three categories of carbohydrates
mono, di and poly saccharides
what elements do carbohydrates contain
carbon, hydrogen and oxygen
what’s the formula for carbohydrates
(CH2O)N
how many atoms do carbohydrates usually contain
3-7
give 5 functions of carbohydrates
major source of metabolic energy, structural material, components of nucleic acids (deoxy)ribose, component of ATP, recognition sites on the surface of cells
how may you classify carbohydrates
complexity, size, functional group,
what are simple carbohydrates?
monosaccharides
what are some complex carbohydrates
disaccharides, oligosaccharides, polysaccharides
give examples of different sizes of carbohydrates
triose (3C), Tetrose (4C), Pentose (5C), Hexoses, (6C), heptoses (7C)
what is the name of the aldehyde functional group
aldose
what is the name of the ketone functional group
ketose
what position is aldose in the chain
at the end of the chain
what position does ketose have in the chain
in the middle/centre of the chain
what are some features of monosaccharides
colourless, crystalline solids, very soluble in water
what are the most abundant sugars
hexoses
what is the formula for hexoses
C6H12O6
what happens to a straight chain form hexose when in an aqueous environment
they fold into rings due to a reaction of the functional group with a hydroxyl group
what are the two pathways that can happen to the hydroxyl group during ring formation
it can be trapped in either alpha or beta form.
what position is alpha form
when the hydroxyl group is down (opposite sides to the CH2OH group)
what position is the beta form in
when the hydroxyl group is up (same side as the CH2OH group)
what happens to the O from the carbonyl group when the reaction to form the ring takes place?
the O becomes a hydroxyl group and goes into either alpha or beta formation
give an example of a hexose
fructose, glucose, galactose
what is an isomer?
molecule with the same chemical formula but with a different arrangement of atoms
what is a stereoisomer
atoms of a molecule bonded together in the same order but the have a different 3D organisation of atoms around one of their asymmetric carbons i.e glucose and galactose
give two examples of pentoses
ribose and deoxyribose
what is the bond formed between two monosaccharides after a condensation dehydration reaction
glycosidic linkage
explain how a glycosidic linkage occurs
the hydroxyl group of one monosaccharide combines with the hydrogen of another, releasing a water molecule and forming a covalent bond
what does a 1-4 linkage mean?
carbon 1 linking with carbon 4
name 3 common disaccharides
lactose, maltose, sucrose
can polysaccharides pass out of cells
no
are polysaccharides easily soluble in water
no
give 3 examples of polysaccharides
starch, glycogen, cellulose
give an example of a modified polysaccharide
chitin
give the two types of starch
amylose and amylopectin
write down the function of starch, glycogen, cellulose and chitin
energy storage, energy storage, structural role and structural role
true or false starch is a mixture of two polysaccharides
true amylose and amylopectin
how is excess glucose stored in plants
stored as starch in roots and seeds
are the glucose monomoers in the alpha or beta form in starch
alpha
what do the chains of amylose look like? branched/unbranched, helical/pleated
unbranched helical structure
what linkage takes place in amylose?
1-4 linkage
what do the chains of amylopectin look like? branched/unbranched, alpha or beta
branched helical alpha
what linkages take place in amylopectin?
1-4 in the main chains and 1-6 in the branches
how spaced apart are the branches in amylopectin
every 30th monomer there is a short side chain
what is glycogen
the stored form of glucose in humans + other vertebraes
are there more branches in glycogen or amylopectin
glycogenwh
where is glycogen typically stored
liver + muscle cells
whenever blood glucose levels decreas, glycogen is broken down via hydrolysis- what is hydrolysis
the opposite of a condensation reaction. it is a catabolic reaction, where a water molecule is added to break down larger molecules into smaller ones
define glycogenolysis
when glycogen is broken down into glucose when energy is needed
is cellulose branched/unbranched and alpha or beta
unbranched Beta
what linkage takes place in cellulose?
1-4 linkage
are there side chains in cellulose
no- so the molecules lie close together
why is cellulose so rigid/stiff
hydrogen bonds form between the chains
what form are the glucose monomers in cellulose
B form
can the B glycosidic linkages be broken down by human digestive enzymes
no, we do not have the enzymes to do so
where can chitin be found in nature
arthropods i.e insects and crustaceans
how does chitin differ from regular carbohydrates
it has modified glucose molecules that have a nitrogen-containing functional group
what is glucosamine
glucose modified by addition of amino groups
