chapter 5 Flashcards
what are carbohydrates
sugar - macromolecule that has carbonyl group and many hydroxyl groups and carbon hydrogen bonds
(CH2O)
have diverse function in cells
store chemical energy
why are sugars key to life?
they are a reservoir of energy for production of other macromolecules in our cells
monosaccharides/ single sugars are…
monomers that make up carbohydrates (macromolecule)
how do monosaccharides differ from one another?
Due to location of carbonyl groups and or # of carbon atoms in backbone chain
aldose sugars
Monosaccharides with a carbonyl group at either end of the molecule
ketose sugar
monosaccharides with a carbonyl group within the monomer
monosaccs. vary in what?
carbon #
ex- triose sugars have 3 C atoms
hexose sugars has 6 C atoms (glucose)
whats a distinguishing feature of monosaccharides
spatial arrangement of atoms
example:
glucose and galactose have the same molecular formula, yet they differ in the orientation of their 4’ hydroxyl group
spatial arrangement/ structural differences significally affects…
how enzymes recognize carbohydrates as substrates for chemical reactions given that enzymes and substrates interact in “precise” ways
do some monosaccs form cyclic/ ring structures?
Yesss and it forms spontaneously
when do monosaccs. form ring structures?
in aq. solutions and if these monosaccs. consist of 5+ carbons
why do monosaccs. form ring structures?
due to carbonyl group (1’ carbonyl in the case of glucose) reacting with the 5’ (quinary) hydroxyl group, resulting in a newly formed 1’ hydroxyl group
2 possible arrangements for glucose newly hydroxyl group…
- above the plane of the ring (β-glucose)
- below the plane of the ring (α-glucose)
what does the oreintations of this new hydroxyl group dictate?
type of complex sugar molecules form when glucose monomers link together with either themselves or other sugar molecules
why are carbohydrates soluble i water/aq solutions?
Due to the presence of Oxygen atoms and hydroxyl groups in their ring structure, they are polar molecules and hydrophilic [Larger sugars are insoluble in water]
complex sugars/carbohydrates form when
simple sugars/monosaccs polymerize/condesation/dehy. (link) tg
- this happens between 2 hydroxyl group on 2+ monosaccs and can take place between different hydroxyl groups
whats a glycosidic bond?
resulting bond of when 2 monosaccharides polymerize tg
2 most common glycosidic bonds
- α-1,4-glycosidic bonds
- β- 1,4-glycosidic bonds
what does the 1 and 4 correspond to in the glycosidic bonds
carbon atoms involved in the reaction
what does the alpha (α) and beta (β) correspond to in the glycosidic bonds
orientations of the hydroxyl group on the C-1 carbon
what is a disaccharide?
a complex sugar of when 2 monosaccharides polymerized tg
examples of disaccharides
lactose and maltose (differ in constituent monosaccs)
maltose is composed of …
2 glucose molecules
lactose is composed of…
1 glucose monomer and 1 galactose monomer
is a disaccharide
oligosaccharide
3 to 20 monosaccharides liked tg
polysaccharide
20+ monosaccs linked tg
is a complex sugar
resulting complex sugar that is formed by monomers linked tg depends on..
hydroxyl group that participated in glycosidic bond
structural differences between complex sugars allows
cells to use them in diff ways
(energy storage, structural support, or protection)
types of polysaccharides
starch, glycogen, cellulose, chitin, peptidoglycan
starch
found in plants and exist in 2 forms
2 forms of starch
- amylose ( α-1,4-glycosidic linkages)
- amylopectin (α-1,4-glycosidic linkages and α-1,6-glycosidic linkages)
glycogen
starch equivalent in animals
Consists of α-glucose monomers linked together by α-1,4-glycosidic linkages and α-1,6-glycosidic linkages
T/F glycogen has more α-1,6-glycosidic linkages than starch
TRUE
cellulose
primary component of planet cell walls
Consists of β-glucose monomers linked by β-1,4-glycosidic linkages
(great source of fiber)
what so cellulose β-1,4-glycosidic linkages result in?
every other glucose molecule exists in a flipped orientation allowing for the generation of a linear molecule and hydrogen bonding between parallel strands of cellulose
chitin
- Primary component of fungal cell walls and the external shell of crustaceans and insects
- Consists of N-acetylglucosamine (NAG) monomers (a derivative of glucose) joined by β-1,4-glycosidic bonds
- strands hydrogen bond with one another to form a strong matrix
peptidoglycan
- Primary component of bacterial cell walls
- Consists of monomers of NAG and N-acetylmuramic acid (NAM) joined together by β-1,4-glycosidic linkages
what does (NAM) N-acetylmuramic acid consist?
chain of 5 amino acids at its 3’ carbon allowing peptide bonds to form on adjacent peptidoglycan chains
chitin, peptidoglycan and cellulose all form what?
strong and durable interconnected fibers/strands that withstand pulling + pushing forces produced by cells
β-1,4-glycosidic linkages found in chitin, peptidoglycan and cellulose (polysaccs) allow what
linear strands to strongly interact, making them difficult to hydrolyze (breakdown) and insoluble in aqueous solution
(absence of water in these fibers make hydrolysis hard (harder than polysaccs w. alpha linkages))
due to diversity in shape and size of polysaccs. what can they act as?
identification markers on the surface of a cell and play a major role in cell-cell recognition
proteins on the surface of a cell can be chemically bound to carbohydrates forming…
glycoproteins
different sets of glycoproteins are displayed by cell types in our body providing them with what?
a sort of “molecular identity”
what plays an important role in cell-cell recognition?
carbohydrates
why are starch and glycogen efficient energy storage molecules?
due to their α-1,4- and α-1,6- glycosidic linkages
branched structure of both provide more free ends available for the release of glucose monomers during hydrolysis
AND dye to high # of high potential energy bonds
true or false… few organisms have enzymes to digest beta linkages
true just a few
if an organism has enzymes to digest alpha linkages what can they digest?
starch and glycogen
where are hydrolysis of a α-1,4-glycosidic linkages found?
glycogen and starch (mediated by enzymes phosphorylase and amylase)
what do enzymes phosphorylase and amylase allow
allow individual glucose monomers to be released and used by cells to produce energy
what do cells use to make ATP when they need energy
individual glucose molecules as primary molecule to produce this
what does atp drive and power
chemical reactions required for enzyme function, synthesis of DNA and other processes like muscle movement
why do carbohydrates have high pe?
due to the abundance of C-H and C- C bonds that they have
since carbon and hydrogen have equal electronegativities the c-h / c-c bonds in carbohydrates are
weak and electrons shared have high pe
compared to c-h / c-c bonds, C-O bonds have
low potential energy due to high electronegativity of Oxygen, which holds on to electrons more tightly
formation of glycogen and starch by cells is a way of
saving the potential energy for later like for starvation
