carbohydrates Flashcards
3 main functions of carbohydrates
- energy source
- structural
- intercellular communication (between cell)
how are the carbon in sugars with a ring structured numbered
- clockwise with the carbonyl carbon number 1
what do larger monosaccharides form
- ring structure
- six member ring = pyranoses
- five member ring = furanoses
what two ways are monosaccharides classified?
- chemical nature of their carbonyl group : whether aldehyde or ketone
- number of carbon atoms eg 6C or 7C
what two stereoisomers do monosaccharides form, which is the most common and how does this effect the monosaccharides
- D and L stereoisomers
- D isomer is the most common
- effects how they react with other things and how it binds with other atoms/molecules
how is a chair conformation formed
- due to electron repulsion
- where there is an OH group there is a possibility of it being reactive
how and by what process is a glycosidic bond formed
- two monosaccharides react with each other forming a disaccharide
- resulting in a glycosidic bond by condensation reaction
- reaction with OH group on both monosaccharides
- can either be alpha 1-4 linkage or beta 1-4 linkage ( depends on orientation of OH group)
what is a substituted sugar
- carbohydrates which contain other chemical groups
: phosphate
: amino
: acetyl
- depending on what group is added this can effect the sugar and therefore it’s properties
: different charge
: physical bulk
what is difference between disaccharides and oligosaccharides
- disaccharide form any combination of two monosaccharides
- oligosaccharides form more than a two / few
- depending on type of monosaccharide and the bonds (alpha or beta) will lead to formation of different molecule
name the two groups of polysaccharides and what two properties do they have
- homopolysaccharides - all the same monosaccharides
- heteropolysacchqrides - different monosaccharides
- they can be linear/straight chains
- or they can be branched
what polysaccharide group does cellulose belong to and it’s functions
- homopolysaccharide
- main structural component of plant cell walls
- linear chains of glucose joined by beta (1-4 glycosidic bonds)
- very strong due to H bonding
- insoluble
- can bond with other polysaccharide into bundles of microfibrils into macrofibrils
- what is chitin and what is it’s role
- how is chitin different from cellulose
- it is a polysaccharide and forms the exoskeleton of insects
- different to cellulose as it is formed if N - acetyl - D glucosamine (glucose w amine) - more charge due to amine groups resulting in stronger bonds
- what is starch, it’s main role and what two polysaccharides is it made of
- starch is a polysaccharide
- storage molecule of plants
- made of amylose and amylopectin
what is the main difference between amylose and amylopectin
- amylose is a string of glucose molecules whereas amylopectin is a heavily branched molecule therefore easy access to glucose
- in amylose glucose monomers linked by 1-4 linkage whereas in amylopectin it has occasional 1-6 linkage
- due to the difference in linkage amylose has a helical structure therefore used for storage
- what enzyme is starch hydrolysed by
- enzyme amylase in which the glycosidic bond is hydrolysed
- in animals what is the carbohydrate storage and what enzyme hydrolyses it
- glycogen
- it is a heavily branched polysaccharide that is hydrolysed to glucose monomers by glycogen phosphorylase and a debranching enzyme
what are glycosaminoglycans
- polysaccharides which are elastic, flexible molecules
- component of cartilage, skin and tendons
what is a glycoproteins
- short chains of monosaccharides joined by glycosidic bond covalently bound to proteins
- branched
- an important feature of bacterial cell walls
why are they found on circulating proteins and examples of circulating proteins
- hormones, antibodies, ecm, enzymes
- found on circulating proteins as the sugars are specific on the type of monosaccharide they take and type of branching they have
what two ways can carbohydrates be linked
- n linked
- o linked
- main role of n linked
- effect on protein folding, activity and cellular location
- how are o linked carbs occur and main role
- occur in clusters on proteins
- protective role eg. mucin
where is mucin found and what it’s role
- mucin is found in saliva
- mucin is covered in groups of o linked sugar allowing proteins the slide around - sliminess formation of mucus coat protection from oral bacteria
- mucin bring the viscosity to saliva and lubricating the mouth
what sugars are glycolipids bound to and what is it’s role
- bound to: cerebrosides and ganglioside
- found in the membrane, involved with communication within self
- contains some oligosaccharides as glycoproteins
- what is glycoRNA
- where is it found
- sugars bound to rna molecules
- found on plasma membrane
what are the 5 steps of the digestion of carbohydrates
- begins in the mouth
- saliva contains alpha amylase enzyme which hydrolyses starch
- hydrolyses the 1-4 linkages
- chewing and breakdowns reduces polysaccharide to oligosaccharides of 8 or less monomers
- further digested in small intestine by pancreatic alpha amylase and other glycosidases
how can carbohydrates effect oral health
- high carb intake linked to oral disease
: caries
: gum disease - sugar can be a good source for bacteria
how is glycocalyx produced and what does it form
- glycoproteins and glycolipids on cell surface form glycocalyx
- forming a thick protective barrier
- in bacteria the glycocalyx can form a layer on which bacteria sticks to leading to infections - tooth decay
