Sugars and Polysaccharides

Question 1

what is the CHO ration in carbs?

Answer 1

1:2:1

Question 2

what is comparison between sugars and proteins?

Answer 2

protein:

• normally tightly folded structures
• coded by DNA seq
• standard peptide link
• 20 a.a building blocks

carbs:

• synthesised by enzymes without template (c.f. DNA)
• many building blocks, but many homopolymers
• various links
• range of structures / amorphous
• often poorly defined

Question 3

what is a monosaccharide?

Answer 3

small molecule - combination of:

1. contains 3 (triose) to 7 (heptose) C atoms
2. either an aldehyde ( where the C-O link is on FIRST C)
   or
   ketose ( C-O link is on SECOND C)

Question 4

what is an optical isomer? aka?

Answer 4

mirror image of molecule

aka enantiomers

Question 5

can u give an example of monosac enantiomers?

Answer 5

D-glucose - (natural entiomer) can be digested

L-glucose - cant be

Question 6

what do usually monosacs do when they have more than 5 C?

how?

Answer 6

1. form cyclic structures

2. the hydroxyl group of C5 reacts with aldehyde or ketose group to form ring.

Question 7

what is the difference between alpha-glucose and beta-glucose?

Answer 7

alpha: the hydroxyl (OH) group and the CH2OH group are on DIFFERENT sides of C ring
beta: the hydroxyl (OH) group and the CH2OH group are on SAME sides of C ring

Question 8

which is more stable? a or b glucose?

Answer 8

B

Question 9

why is it significant that that glucose (or other sugars) have anomers that are different?

Answer 9

because enyzmes will react differently on them based on their structure, changes likelihood of formation or cutting of glycosidic bonds

Question 10

in aq. solution, what forms between straight chain and cyclic forms of monosaccharides?

Answer 10

an equilibrium exists between the straight chain and 2 cyclic forms

Question 11

how would you describe cyclic c.f. straight chain mono with regards to energy?

Answer 11

cyclic is locked - lower energy.

more stable

Question 12

what are the different monosacs?

Answer 12

1. glucose
2. fructose
3. galactose
4. mannose

Question 13

what is a disaccharide?

Answer 13

2 mono units linked via glycosidic bond

Question 14

what do you need to assemble two monosacs?

Answer 14

done by SPECIFIC glycosyl transferase enyzmes!

Question 15

how does a glycosidic bond occur?

Answer 15

glycosyl transferase links two monosacs together - forms glycosidic bond. BUT in process lose one molecule of water (DEHYDRATION)

Question 16

how many glycosyl transferases are there?

Answer 16

> 250

Question 17

what is an oligosacharide?

Answer 17

contains 3-10 monosaccharides

Question 18

can we digest every oligosacharide? e.g.?

Answer 18

no - but gut bacteria often can. e..g raffinose. but makes u bloated cuz they’re doing fermentation reaction

Question 19

name two prebiotics

Answer 19

galacto-oligosacharide

fructo-oligosacharide

Question 20

what is a polysac?

Answer 20

cotains > 10 mono units

Question 21

what are the differences / similarities between starch, glycogen and cellulose?

Answer 21

all polymers of glucose

they differ in type of glucose present and bonds which link them:

starch - made from amylose or amylosepectin (chain or branched chain)

glycogen - also tree like

cellulose - rigid

Question 22

name the glycosidic bonds of starch, glycogen and cellulose?

Answer 22

starch: Glc a-1,4 and 1,6 glycosidic bonds
glycogen: Glc a-1,4 and 1,6 glycosidic bonds
cellulose: Glc b-1,4 glycosidic bonds

Question 23

what do the numbers mean e.g. Glc a-1,4 and 1,6 - with regards to structure?

Answer 23

structure: 1,4 means that the bond connects c atom 1 in one glucose to no. 4 c atom in next

Question 24

why cant we digest cellulose?

what can we digest instead?

Answer 24

cellulose has Beta glycosidic bonds. amylase cannot hydrolyse the Beta bond.

CAN hydrolyse the Alpha bond in glycogen.

Question 25

which type of bond causes branching and which causes straight line in polysaccharide?

Answer 25

``` 1-4 = straight 1-6 = branching ```

Question 26

describe the structure of glycogen | what does this structure allow with regards to energy release?

Answer 26

centre: protein - glycogenin. surrounded by lots and lots of branches of glucose units branching structure of glucose units allows more efficient release of energy

Question 27

when all the monosacs in a polysach are the same =? when the monosacs in a polysach are the different =?

Answer 27

homopolysaccharide heteropolysaccarhide

Question 28

what are the two polysaccharids that can form starch?

Answer 28

amylose and amylopectin

Question 29

difference between amylose and amylopectin?

Answer 29

bonds: - amylose (1,4) - amylopectin (1,4 and 1-6) branching -amylose - none amylopectin - yes ( c. 20 units)

Question 30

how can you modify a monosaccharide?

Answer 30

replace the OH group with: - phosphate group (PO4) - Amine (NH2) - Sulphate (SO4) - Lipid Group - Removal of O

Question 31

what is particularly important for metabolism of sugars?

Answer 31

sugar phosphates

Question 32

what is the first step of glycolysis?

Answer 32

(Glycolysis is the metabolic pathway that converts glucose C₆H₁₂O₆, into pyruvic acid, CH₃COCOOH.) add phosphate to glucose / fructose: glucose + ATP -> glucose-6-phosphate = first step in glycolysis. enables eventual breakdown to pyruvate

Question 33

what does NH2 + mono make? | how occur?

Answer 33

amino sugar | replace hydroxyl group with an amine group (NH2)

Question 34

what is an amino sugar a precursor for and also can make?

Answer 34

lipid biosynthesis | makes glycoproteins

Question 35

the majority of proteins synthesised in the Rough ER undergo..?

Answer 35

protein glycosylation

Question 36

what is an important example of protein protein glycosylation? explain

Answer 36

(glycosylation: covalent attachment of many different types of sugars to a protein. Blood Group Antigens: Activity of different glycosyl transferases leads to the generation of different end-group sugars on rbc. different endings determine blood type

Question 37

Mono + SO4 =?

Answer 37

sulphated sugar replace hydroxyl group with SO4

Question 38

what happens when make sulphated sugar?

Answer 38

make the molecules really negatively charged - they bind water and can withstand pressure.

Question 39

whats an example of sulphated sugar?

Answer 39

heparin

Question 40

what does heparin do? (general)

Answer 40

anti-coagulation (blood thinner)

Question 41

where / how is heparin made?

Answer 41

produced by Mast cells at sites of damage blood vessels.

Question 42

what does heparin do? (specific)

Answer 42

binds to antithrombin and changes its confirmation. antithrombin becomes attracted to factor Xa and thrombin. they lock together -> regulates and prevents blood coagulation.

Question 43

which are the two interacting elements that normally lead to blood clot formation, but that heparin interacts with?

Answer 43

Factor Xa | Factor 2a

Question 44

how do u make glycolipid?

Answer 44

lipid + carb -> glycolipid | enzyme: glycosyl transferase

Question 45

what do glycolipids do?

Answer 45

maintain stability of cell membrane | facilitate cellular recognition

Question 46

what is bacterial lipopolysaccharid (LPS)?

Answer 46

on some immune cells: TOLL-like receptors (TLR4) responds to LPS from microbes -> activates an inflam and immune response, which produces anti-LPS antibodies = INNATE IMMUNE SYSTEM RESPONSE

Question 47

LPS stimulates..?

Answer 47

innate immune system

Question 48

how do you make deoxy-sugar?

Answer 48

sugar that has had a hydroxyl group replaced with H atom . e. g. ribose -> deoxyribose enzyme: reductase

Question 49

what is backbone of dna based of?

Answer 49

based on a repeated pattern of a sugar group and a phosphate group