Chapter 5 - An introduction to Carbohydrates Flashcards
what four types of macromolecules were crucial to the evolution of the cell?
proteins
carbohydrates
nucleic acids
lipids
of the five fundamental characteristics of life, which can proteins and nucleic acids carry out?
information
replication
evolution
which fundamental characteristic of life can carbohydrates carry out?
energy
what are the monomers of sugars/carbs?
monosaccharides (“one sugar”)
what do monosaccharides polymerize to form?
polymers - polysaccharides (“many sugars”)
what are small polymers of sugar called?
oligosaccharides (“few sugars”)
what is the molecular formula for most sugars/carbohydrates?
(CH2O)n (subscript n refers to the number of carbon hydrate groups)
what are some of the functions of carbohydrates?
- raw material for synthesizing other molecules
- providing structural support
- indicating cell identity
- storing chemical energy
what are the two possible configuration of the carbonyl group in a sugar molecule? (two possible positions)
aldose - carbonyl group at the end of the carbon chain
forms an aldehyde
ketose - carbonyl group in the middle of the carbon chain
forms a ketone
triose
three carbon atoms present
pentose
five carbon atoms present (ribose)
hexose
six carbon atoms present (glucose and galactose)
what characteristics do the carbonyl group and the multiple hydroxyl groups bring to the sugar molecule?
-provides sugars with an array of reactive and hydrophilic functional groups
what are the 3 main ways that simple sugars differ from each other?
- location of carbonyl group
- number of carbon atoms present
- spacial arrangement of their atoms (especially positions of hydroxyl (-OH) groups
what structures do sugars tend to form in aqueous solutions?
ring structures
what is a complex carbohydrate?
polysaccharide (polymer of monosaccharide monomers)
disacharides
simplest polysaccharides
-consist of two monosaccharide monomers
glycosidic linkage
a covalent bond which links two hydroxyl groups through a condensation reaction
-bonds simple sugars and allows polymerization
why can the location and shape of glycosidic bonds vary greatly?
because these linkages can form between any two hydroxyl groups
how do plants store sugar?
starch
what is starch comprised of?
-mix of branched amylopectin/unbranched amylose
how do animals store sugar?
glycogen
what is glycogen comprised of?
highly branched glucose polymer
what is cellulose?
structural polymer of plants cell walls
what is cellulose comprised of?
polymer of glucose monomers
chitin
structural polymer of fungi cell walls, some algae, and animal cytoskeletons
what is chitin comprised of?
N-acetylglucosamine (NAc) monomers
peptidoglycan
provides support for bacterial cell walls
what is peptidoglycan comprised of?
alternating monosaccharides
which 3 carbohydrates provide structure?
- cellulose
- chitin
- peptidoglycan
did polysaccharides play any role in the origin of life?
probably not.
- monosaccharide polymerization requires specialized enzymes
- polysaccharides to not catalyze and known reactions
- polysaccharide monomers cannot copt themselves because they don’t store that information
what are glycoproteins made of?
- proteins joined to carbohydrates by covalent bonds that contain sugar groups
- they display info outside of the cell
what is glycoprotein function? what do they do?
- display information on the outer surface of the cell
- key in cell to cell recognition and signaling
- each cell has glycoproteins on its surface that identify the type/species of cell
why is it possible for there to be so many different types of glycoproteins?
- variety in monosaccharides and how they can be linked
- makes it possible for a huge number of oligosaccharides to exist = many combinations of glycoprotein identities for each cell species
in chemical evolution, how was energy harnessed and stored?
kinetic energy of sunlight/heat were converted into chemical energy and stored in the bonds of H2CO and HCN
today, how is most energy (sugars) produced and stored?
photosynthesis!
-transforms energy of sunlight into chemical energy of C-N bonds in carbohydrates
photosynthesis (know reactants/products)
CO2 + H2O + sunlight = (CH2O)n + O2
-plants harvest the kinetic energy of the sun and store it in the bonds of carbohydrates
why do carbohydrates hold more free energy than CO2?
Carbohydrates: electrons in C-H and C-C bonds are shared more equally and less tightly. C-H bonds have high free energy
CO2: electrons in C-O bonds are held tightly
phosphorylase (what is it/what does it do?)
enzyme that catalyzes hydrolysis of glycosidic linkages in glycogen
why do most animal cells contain phosphorylase?
so they can readily break down glycogen and provide glucose
amylase (what is it/what does it do?)
enzyme that catalyzes hydrolysis of starch
-plays a key role in carbohydrate digestion
ATP (what is it/what does it do?)
adenosine triphosphate
- produced by carbohydrate reactions
- drive endergonic reactions/do work for the cell
why are fatty acids even more energized than carbs?
carbs: C-H bonds hold high free energy
fatty acids: they have even more C-H bonds, so more energy!
a-linkages vs. b-linkages (characteristics)
a linkages are readily hydrolyzed (store energy) b linkages (structural) resist enzymatic degradation
