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FunMed Week 2 > Sugars and Polysaccharides > Flashcards

Sugars and Polysaccharides Flashcards

1
Q

what is the CHO ration in carbs?

A

1:2:1

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2
Q

what is comparison between sugars and proteins?

A

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
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3
Q

what is a monosaccharide?

A

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)
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4
Q

what is an optical isomer? aka?

A

mirror image of molecule

aka enantiomers

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5
Q

can u give an example of monosac enantiomers?

A

D-glucose - (natural entiomer) can be digested

L-glucose - cant be

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6
Q

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

how?

A
  1. form cyclic structures

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

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7
Q

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

A

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

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8
Q

which is more stable? a or b glucose?

A

B

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9
Q

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

A

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

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10
Q

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

A

an equilibrium exists between the straight chain and 2 cyclic forms

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11
Q

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

A

cyclic is locked - lower energy.

more stable

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12
Q

what are the different monosacs?

A
  1. glucose
  2. fructose
  3. galactose
  4. mannose
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13
Q

what is a disaccharide?

A

2 mono units linked via glycosidic bond

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14
Q

what do you need to assemble two monosacs?

A

done by SPECIFIC glycosyl transferase enyzmes!

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15
Q

how does a glycosidic bond occur?

A

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

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16
Q

how many glycosyl transferases are there?

A

> 250

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17
Q

what is an oligosacharide?

A

contains 3-10 monosaccharides

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18
Q

can we digest every oligosacharide? e.g.?

A

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

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19
Q

name two prebiotics

A

galacto-oligosacharide

fructo-oligosacharide

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20
Q

what is a polysac?

A

cotains > 10 mono units

21
Q

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

A

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

22
Q

name the glycosidic bonds of starch, glycogen and cellulose?

A

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

23
Q

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

A

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

24
Q

why cant we digest cellulose?

what can we digest instead?

A

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

CAN hydrolyse the Alpha bond in glycogen.

25
Q

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

A 
1-4 = straight 
1-6 = branching
26
Q

describe the structure of glycogen

what does this structure allow with regards to energy release?

A

centre: protein - glycogenin. surrounded by lots and lots of branches of glucose units

branching structure of glucose units allows more efficient release of energy

27
Q

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

when the monosacs in a polysach are the different =?

A

homopolysaccharide

heteropolysaccarhide

28
Q

what are the two polysaccharids that can form starch?

A

amylose and amylopectin

29
Q

difference between amylose and amylopectin?

A

bonds:
- amylose (1,4)
- amylopectin (1,4 and 1-6)

branching
-amylose - none
amylopectin - yes ( c. 20 units)

30
Q

how can you modify a monosaccharide?

A

replace the OH group with:

  • phosphate group (PO4)
  • Amine (NH2)
  • Sulphate (SO4)
  • Lipid Group
  • Removal of O
31
Q

what is particularly important for metabolism of sugars?

A

sugar phosphates

32
Q

what is the first step of glycolysis?

A

(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

33
Q

what does NH2 + mono make?

how occur?

A

amino sugar

replace hydroxyl group with an amine group (NH2)

34
Q

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

A

lipid biosynthesis

makes glycoproteins

35
Q

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

A

protein glycosylation

36
Q

what is an important example of protein protein glycosylation?
explain

A

(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

37
Q

Mono + SO4 =?

A

sulphated sugar

replace hydroxyl group with SO4

38
Q

what happens when make sulphated sugar?

A

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

39
Q

whats an example of sulphated sugar?

A

heparin

40
Q

what does heparin do? (general)

A

anti-coagulation (blood thinner)

41
Q

where / how is heparin made?

A

produced by Mast cells at sites of damage blood vessels.

42
Q

what does heparin do? (specific)

A

binds to antithrombin and changes its confirmation.

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

43
Q

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

A

Factor Xa

Factor 2a

44
Q

how do u make glycolipid?

A

lipid + carb -> glycolipid

enzyme: glycosyl transferase

45
Q

what do glycolipids do?

A

maintain stability of cell membrane

facilitate cellular recognition

46
Q

what is bacterial lipopolysaccharid (LPS)?

A

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

47
Q

LPS stimulates..?

A

innate immune system

48
Q

how do you make deoxy-sugar?

A

sugar that has had a hydroxyl group replaced with H atom .

e. g. ribose -> deoxyribose
enzyme: reductase

49
Q

what is backbone of dna based of?

A

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

FunMed Week 2 (10 decks)

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