Biopolymers - Proteins and polysaccharides

Question 1

What is the +/- of biopolymers vs. synthetic polymers?

Answer 1

Number of building blocks and linkages, biodegradability, biocompatitibility and structural assembly

Question 2

Which are the three biopolymer-macromolecules formed by living organisms?

Answer 2

Nucleic acids, polysaccharides and proteins

Question 3

Name some biopolymers made of proteins

Answer 3

Silk, Keratin, Collagen, Gelatin, Elastin, Actin, Myosin

Question 4

Name 3 different functions of proteins and at least one example

Answer 4

Structural (collagen, elastin, keratin), Regulating (enzymes, hormones) and Transporting (hemoglobin, myoglobin)

Question 5

Shortly describe the protein synthesis

Answer 5

Transcription (genetic code transfer from DNA to RNA in nucleus), Translation (conversion from the mRNA into AAs that are bonded together) done by ribosomes and the reading some done by tRNA (3 by 3, codons)

Question 6

What happens after the protein have been synthesized

Answer 6

They are transported in vesicles from ribosmes to the golgi apparatus - packed into new vesicles and then migrated to cell membrane and released outside. They can also be modified by transferases that add small groups like phosphates or carboxyl groups.

Question 7

What are the post-modifications of the protein good for?

Answer 7

They can shift the protein conformation and act as switches that turn the activity of the protein on or off. Often revearsable (phosphate groups vs kinases typically)

Question 8

Name some structural proteins for the cells

Answer 8

Microtubules and actin filaments (organizing the cytoplasm, cell division and movement)

Question 9

Whats the different properties the primary structure of a protein can have

Answer 9

All the 20 AAs, can be polar/nonpolar, basic/acidic

Question 10

What are the 2 secondary structures

Answer 10

helical coil and beta-sheets bonded with hydrogen bonds

Question 11

Which are the most common types of collagen and where are they. Which is the most common AA

Answer 11

I, II, III and IV. Connective tissue, bone, fiber form, muscles, tendons, under skin
Most common AA is Glycine

Question 12

Whats the hierarchical organization of collagen?

Answer 12

AAs - polypeptide chain - collagen molecule/triple helix - microfibril - fibril - collagenous fiber

Question 13

What are the typical mechanical properties of Elastin and what creates this?

Answer 13

A rubber protein consisting of flexible polypeptide chains. They can be stretched which unrolls every single elastin molecule which are cross-linked together

Question 14

What is and where can you find Keratin?

Answer 14

Hair, nails, feathers, silk. Mainly consisting of the polar AAs cystine and proline. Crystalline and can create S-S bridges

Question 15

What is alpha-Keratin?

Answer 15

Contain many helices, many S-S bridges, hydrophobic.In humid environment and when stretched the helices can be turned into beta-sheets. Permanents - break and reform S-S bridges.

Question 16

What is beta-Keratin?

Answer 16

Fibroin or Silk, a lot of beta sheets, fibroin fibre and rubber

Question 17

What is silk and how is it turned into a fiber?

Answer 17

beta-keratin. The globular water soluble molecules are stored in the glands - In the duct to the spinneret they aggregate into longer chains - At the spinneret they are transformed into crystalline beta-sheets - these made up a whole fiber that is unsoluble in water.

Question 18

From where is gelatin extracted?

Answer 18

By boiling bone or soft connective tissue from animals.

Question 19

What is the basic definition of a polysaccharide?

Answer 19

They are polymers with sugar units linked via glycosidic bonds (alpha or beta). Can have reducing and nonreducing end groups

Question 20

What is the difference between the different glycosidic bonds?

Answer 20

The alpha is for starch like amylose and amylopektin while the beta is for chitosan and cellulose creating a cellobiose monomer.

Question 21

What is cellulose and where can it be found?

Answer 21

It is a polymer of glucose units bound together by 1,4-glycosidic bonds. It have crystallne and amorphous domains. Can be found in trees, plants, bacteria and animals (tunicate)

Question 22

What are some modern uses of cellulose

Answer 22

Functional textiles and fibers (antimicrobial, thermoresponsive, etc), packaging (films, foils, fabrics), medicine and life science (wound dressings, implants, drugs), food, paper.

Question 23

Is cellulose water soluble?

Answer 23

No, due to its high molecular weight and stiffness. It is also amphiphilic and insoluble because of hydrophobic and electrostatic interactions. Almost all solvents are ionic and hydrophobic.

Question 24

Whats the percentage constitution of wood

Answer 24

50% cellulose, 25 % lignin, 20 % hemicellulose rest lipids, proteins, inorganic substances

Question 25

What is bacterial cellulose?

Answer 25

Created as a pellet with high porosity, ideal for cell growth. It has high molecular weight.

Question 26

What is cellulose Acetate?

Answer 26

a Cellulose derivate that have 3 acetate groups on the glucose unit. The fibers can be made into artificial silk (soft fabric) and have low water absorption (umbrellas) but sensitive to acids and bases.

Question 27

Name 4 cellulose derivates

Answer 27

Cellulose acetates, methyl celluloses, trimethyl silyl cellulose and cationic celluloses

Question 28

Name some modern uses of cellulose acetate

Answer 28

Part of optical layer in flat screens, mobile phones and cigarette filters and fiber membranes for water purification. Too bad its not biodegradable when its been modified.

Question 29

What is Carboxymethyl cellulose

Answer 29

Glucose unit with 2 carboxyl groups. water soluble depending on substitution degree (higher more soluble).

Question 30

Name some uses of carboxymethyl cellulose

Answer 30

pharmaceutics, food thickener, binder in batteries, paper industry, detergent

Question 31

Why can oxidized cellulose be preferable?

Answer 31

It make it possible to introduce a carboxyl group which leads to charged cellulose. Cellulose-Cellulose interaction is enhanced and the water solubility

Question 32

What is methylcellulose and what usage?

Answer 32

Glucose loose 2 OH which become methyl group instead. The main component of many wallpaper pastes, thickening agent in food, eye drops, pharmaceutical additive. “Slimey”

Question 33

What is nitrocellulose and what usage?

Answer 33

Produced with nitric acid that will bind to 3 OH groups on the glucose. Very explosive and often used in paints and in western blots.

Question 34

What is cationic cellulose and what usages does it have?

Answer 34

Introduction of amine groups and protecting group. Have antimicrobial activity, the cationic property give fibers a better dyeability with anionic dyes. Can be used in contact lense fluid and haircare products.

Question 35

What is Trimethyl silyl cellulose and what usages does it have?

Answer 35

3 OSiMe3 groups that can be reversed into OH with HCl. Hydrophobic cellulose derivate that can be used for cellulose film preparation

Question 36

Name some properties of Hemicellulose and where can you find it?

Answer 36

Can be found in wood and there are different hemicelluloses in hardwood and softwood.
More alkaline and shorter than cellulose, makes it more soluble.

Question 37

Name a common hemicellulose

Answer 37

Xylans

Question 38

What application does Hemicellulose have

Answer 38

Intermediate for chemicals, films, film additives, tensioactive materials, food additive, tissue engineering

Question 39

What is starch?

Answer 39

amylose and amylopectin granules in different ratios dependent on plant. It is a semicrystalline polymer, soluble in hot water (gives it higher viscosity), retrogradation (removal of water and rearrangement of polymer chains)

Question 40

Describe Amylose

Answer 40

helical structure, with 8 glucose units, soluble in hot water, energy storage

Question 41

Describe Amylopectin

Answer 41

Branched polysaccharide, coiling, alpha 1-4 and 1-6 glycosidic bonds

Question 42

Describe Chitin and its uses

Answer 42

Like cellulose but with NH and carboxyl group. Insect armor, shellfish, mushrooms. Poorly soluble, amphiphilic structure

Question 43

How is crab shell structured?

Answer 43

It’s a natural hybrid material of chitin and protein. The chitin fibrils are wrapped with protein to form a fiber. They are further assembled into bundles which form horizontal layers that are stacked upon each other creating a twisted plywood structure. In the z direction there are ribbon-like tubules running through the pore canals.

Question 44

How is the hybrid material of chitin-protein built?

Answer 44

Proteins and chitin are bound together via hydrogen and covalent bonding to create a microfibril helix.

Question 45

What is Chitosan and name some applications?

Answer 45

It’s a deacetylated chitin derivate (the acetyl-group is removed from the NH) which is naturally occuring in bacteria and mushooms. It can be used in agriculture as biopesticide, in cosmetic and hygiene products, for water purification (filtermaterial), wound care, artificial tissue and drug delivery systems.

Question 46

Further explain the uses of chitosan

Answer 46

It can complex heavy metals. Because of its positive charge on the NH3 it can adsorb dyes, antimicrobial. Chitosan matrix can protect active ingredient in drugs

Question 47

What is Hyaluronic acid?

Answer 47

It’s a chitin derivative that is the main component of connective tissue and cartilage. Often used in cosmetic products

Question 48

What is alginate?

Answer 48

Occurs in algae and bacteria. Can make gel when soluble in water and salt (Ca, Na, Mg), eggbox model. It’s a copolymer of Mannuronate and Guluronorate. For food thickener, gelling agent, wound care.