POLYMER FINAL

polysaccharides are more familiarly known as __________

carbohydrates

what makes up ¾ of the dry weight of the plant world?

polysaccharides

what can produce polysaccharides?

• plants

• animals

• yeast

where does a lot of photosynthesis take place?

ocean

polysaccharides are polymers of…

monosaccharides

D-glucose structure

D-fructose structure

D-Galactose structure

each monomer can exist in the __________ or __________

alpha anomer / beta anomer

difference b/w alpha and beta anomer

alpha = OH on C1 is pointed up

beta = OH on C1 is pointed down

molecular weights of naturally occurring polysaccharides tend to be _______

large

alpha linkage

OH are on interior & exterior of polymer chain, allowing H-bonding within the chain → better wettability & potentially a helical structure

• bonds point down

• can be digested by humans

• starch

can alpha linkages be digested by humans?

yes

beta linkages result in a _______ structure that cannot be _________

linear / digested (think fiber)

beta linkage

• linear structure that can’t be digested (fiber)

• OH are on exterior and allow for H-bonding b/w different chains, making it rigid & insoluble

• good for cell walls in plants

2 most abundant polysaccharides

1. cellulose

2. starch

what is cellulose made of?

beta linkages of D-glucose

cellulose is more than ____ of the dry weight of plants

1/3

what is the world’s largest renewable resource by weight?

cellulose

polysaccharide chains in plants are present in thread-like strands or bundles called _________

fibrils

polysaccharide chains in plants are ________ and __________

rigid / insoluble

what are polysaccharide chains in plants good for for humans?

• constructin and fuel (wood)

• paper (wood)

• clothes (cotton)

what is the major source of commercial cellulose?

plant pulp

pulping

extraction of cellulose

cellulose extraction from wood is a major source of ___________ fibers for paper

non-textile

cellulose extraction from ________ is a major source of textile fibers for clothes

cotton

common modification to cellulose done in industrial properties

methycellulose

how is methylcellulose formed?

cellulose-OH + NaOH + CH3Cl → cellulose-O-CH3 + NaCl + H2O

methylcellulose is commonly used as an ________

adhesive

uses of methycellulose

• adhesive

• ceramics (provides water retention & lubricity)

• cosmetics (to control rheological properties & stabilization of foams)

• food (as binder, emulsifier, stabilizer, thickner, and suspending agent)

• paints, paper products, and plywood as rhelogy control for adhesive)

• inks and textiles as a binder

advantages of methycellulose

• biologically sourced

• renewable

• inexpensive

• nontoxic

• circular

what is starch made of?

alpha linkages of D-glucose

what is starch used for in plants?

energy storage (food for us)

ratio of amylose and amylopectin in most starches

10-20% amylose, 80-90% amylopectin

amylse is a _______ polymer

linear

common structural formation of amylose

helical formation with 6 glucose per turn/spiral

amylopectin is a _______ polymer

branched

typically, amylopectin has one branch per ______ units

6

• on the 6th carbon

is amylose or amylopectin longer?

amylopectin

what leads to the fan-like structure of amylopectin?

branches off branches

is amylopectin easy or hard to break down? why?

easy - many chain ends for reactivity

polyisoprenes

• occur in nature as hard plastics called gutta, percha, and balata

• occur in nature as an elastomer/soft ruber called hevea brasiliensis

• produced from trees

polyisoprenes are obtained from the _______ tree in central america

archras sapota

molecular formula of isoprene

C5H8

gutta, percha, and balata are polymerized as the __________ isomers

trans

natural rubber is polymerized with _____ isomers

cis

describe polyisoporene chains in the trans version

• stack well

• crystalliz

• hard solid

• linear

describe polymer chains in the cis version

• take up more space

• don’t stack well

• make an amorpous solid with a low Tg

what happens when a cis polyisoprene chain is stretched at a temp higher than Tg?

bonds flex and chains uncoil until they’re stretched out enough to crystallize, like the chains in gutta percha

at the point of crystallization in polyisoprene chains, there is an ________ and the rubber band warms

exotherm

crystallization prevents further ________

stretching

if held in the stretch shape long enough, chain ___________ and ____________ occurs

slippage / deformation (creep)

to prevent chain slippage, natural rubber is often ___________ which cross-links the material

vulcanized

what does vulcanization mean?

natural rubber is reacted with elemental sulfur, S8, which cross-links the material preventing chain slippage

who discovered vulcanization?

Charles Goodyear

today, most rubber is _________

synthetic

what is the one natural rubber product still used today? why?

rubber bands — has better elasticity than synthetic rubber

there are ___ levels of protein structure

4

primary structure

sequence of amino acids

secondary structure

shape of amino acid sequence

• helix, sheet

• determined by H-bonding & size of pendant groups

what is secondary structure determined by?

• H-bonding

• size of pendant groups

internal H-bonding b/w amino acids in the polymer chains and pendant groups favor _________

helices

H-bonding b/w neighboring polymer chains & smaller pendant groups favor ___________ 

sheets

tertiary structure

protein folding

• can be locked in by hydrogen bonding, salt bridges, and disulfide cross-linking

quaternary structure

when 2+ proteins associate to make a larger structure

• ex. 4 myoglobin units come together to make 1 hemoglobin

3 types of protein in the body

1. fibrous

2. globular

3. membrane

fibrous protein

for structure/support, such as tendons, muscles, and bones

globular proteins

enzymes

membrane proteins

attached to/associated with cell membranes

what are critical for determining the type of protein?

1. H-bonding

2. types of pendant groups

hair is made of which polypeptide?

alpha keratin

amino acids in alpha keratin

1. glycine

2. leucine

what contributes to the helix structure of alpha keratin?

• relatively large pendant groups (Leu)

• lots of internal H-bonding

what makes hair flexible?

less intermolecular interactions

what helps give hair its shape?

disulfide cross-links

what causes alpha keratin to become tough & rigid?

lots of disulfide cross-links

what are fingernails made of?

heavly cross-linked alpha-keratin without pigment

what is silk made of?

beta-keratin

amino acids making up beta-keratin

1. glycine

2. alanine

smaller pendant groups in beta-keratin lead to ______________ H-bonding

moderate intermolecular

describe protein chains in beta keratin

almost fully extended → good tensile strength

describe tensile strength of silk

good tensile strength due to protein chains being almost fully extended

what makes silk feel soft?

moderate H-bonding (as opposed to heavy)

most abndant single protein in vertebrates (1/3 of total protein mass)

collagen

collagen

forms matrix of bones, major part of tendons, major part of skin

• holds our body together

what is collagen called when used in food?

gelatin

amino acids of collagen

1. glycine (every 3rd residue)

2. proline

3. lysine

in collagen, glycine must be every ____ residue

3rd

the large pendant groups of amino acids in collagen lead to a _________ formation

helix

in collagen, proline is converted to ________

hydroxyproline

hydroxyproline leads to ___________ via __________

cross-linking / H-bonding

collagen is a ___________ of 3 polypeptide chains called the __________ unit

triple helix / tropocollagen

each collagen chain is about DP _________ (or Mn a~ 100,000) with a full turn every _____ amino acids

1000 / 3.3

is collagen loosely or tightly wrapped?

tightly

what is required for the conversion of proline to hydroxyproline?

vitamin C

the conversion of proline to hydroxyproline leads to additional ______________ bonding within the tropocollagen unit, making it ________

intermolecular H-bonding / strong

chemical modification of collagen

cross-linking of lysine side chaisn within tropocollagen units, making collagen even more strong

describe chemical modification & cross-linking of lysine sidechains within tropocollagen units

lysine side chains are oxidized to aldehydes & then either react with another lysine residue or another oxidized lysine via an aldo condensation and dehydration

which is stronger, chemical cross-links or H-bonding?

chemical cross-links

overall, collagen in tendons has a strength similar to __________

copper wire