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Biochem - Year 1 Biomed > Carbohydrates > Flashcards

Carbohydrates Flashcards

1
Q

What are carbohydrates made of

A

2+ hydroxyls (OH)

And either aldehyde or ketose

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2
Q

What is the structure of Aldehyde and ketone

A

Aldehyde - c=O with 1 H and 1 R group

Ketone - c=O with 2 R groups

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3
Q

Why is the C on Aldose numbered 1 but in ketose it is 2

A

Because ketose usually has a C before the carbonyl C=On

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4
Q

What are the 2 simplest sugars (trioses)

A

Glyceraldahyde

Dihydroxyacetone

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5
Q

When do carbs/sugars form rings and why do they do that

A

When they have 4+ carbons

They do it in solution due to them being more energetically favourable than open chain

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6
Q

In aldose sugars such as glucose , what do aldehyde and alcohol when they react form (ring structure)

A

Hemi acetal

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7
Q

What hydroxyl reacts with the C1 carbon in aldehyde

A

OH on C5

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8
Q

When glucose/ aldoses form hexose sugar rings. What are they called

A

Pyranose

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9
Q

What is the projection called when sugars are shown as line form and ring form

A

Line - Fischer

Ring - haworth projection

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10
Q

In ketose rings, what does ketone reacting with alcohol (C5 OH) produce

A

A hemi ketal

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11
Q

Why are ketose rings called furanoses

A

5 sided ring due to C2 (ketone) reacting with C5 OH instead of the C1

Resembles furan

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12
Q

Sugar rings aren’t flat due to carbons tetrahedral geometry. What is the configuration called

A

Non planar chair configuration (looks like chairs)

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13
Q

What does axial and equatorial mean

A

When molecules are axial they are up or down from the c plane

Equatorial molecules are in line with the c plane

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14
Q

What is C1 called in aldose anomers

A

Anomeric carbon

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15
Q

Explain the alpha and beta anomers in a D sugar (eg their position)

A

Alpha anomers have H OH configuration on C1. OH = axial

Beta have OH. h configuration on C1. OH = equatorial

Beta has same stereochemistry as C5 (OH equatorial in D sugar)

Alpha has opposite stereochemistry to C5 (OH is axial not equatorial)

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16
Q

Which C is anomeric in ketose anomers

A

C2- this is where the a and b anomers differ

17
Q

What are D and L sugars called and why

A

Enantiomers- they are mirrors of each other

Their C5 chirally active carbon differs

18
Q

How do D and L differ in stereochemistry

A

In D , the OH is equatorial and H is axial

OH. H

In L, the H is equatorial and OH is axial

H

OH

19
Q

How is alpha L sugar and beta L sugar different to D anomers

A

Alpha L has OH equatorial instead of axial (to be opposite to C5)

Beta L has OH axial (to be the same stereochemistry as C5)

20
Q

What are roomers

A

Where C 2,3 or 4 differ instead of 5 (D or L)

21
Q

Give an example of epimers - 2 different sugars due to different C2,3 or 4

A

Glucose and mannose differ at 2,3

Glucose and galactose differ at C4

22
Q

What do glycosidic bonds happen between

A

C1/2 of one sugar and OH of C3,4,5 of next sugar

HOH is lost and O is then shared

23
Q

Explain Alpha and Beta glycosidic bonds

A

Alpha bonds are where 1 sugar is an alpha anomer (C1 differs from C5) H OH. H. OH

Beta is where 1 sugar is a beta anomer

OH. H H. OH

24
Q

What is carb role in energy transport

A

Transport in disaccharides up into the ileum where they are degraded by enzymes - Maltase, lactase, sucrase

Releases glucose for energy

25
Q

What are the 2 energy storage polysaccharides

A

Starch - eg in foods and plants

Glycogen- store of glucose

26
Q

How is starch/glycogen structure

A

1-4 alpha bonds in the backbone and 1-6 bonds between chains

27
Q

What is the advantage of alpha bonds in glycogen and starch energy store

A

They form spirals which makes it more compact for storage

28
Q

Why is the end sugar on starch or glycogen called reducing

A

The C1 is free, unattached
This allows for the ring to form a line again and exposes aldehyde/ketone

They reduce other molecules

29
Q

What do non reducing ends mean on starch and glycogen

A

C1 is occupied and so the ring can’t open. Aldehyde or ketone can’t reduce molecules

30
Q

Why is the fact branches on glycogen and starch are non reducing a good thing

A

Easier to digest by enzymes. The non reducing ends are attack sites for enzymes

31
Q

Explain the structure of cellulose (a structural carbohydrate)

A

1-4 beta glucose chains. They form hydrogen links with other chains due to the beta 1-4 being planar.

This forms microfibrils rigid for the function

32
Q

Explain the structure of peptidoglycans in cell wall of bacteria (gram - and gram +)

A

1 N acetyl glucosamine (Glc NAc)

1 N acetyl Muranic acid (sugar and tetrapeptide (chain of amino acids)

Linked by Beta bond

33
Q

The tetrapeptide on peptidoglycans allows binding of more peptidoglycans. What enzyme is this allowed by

A

Transpeptidase

34
Q

Which antibiotic inhibits transpeptidase and therefore breaks down bacteria cell wall (can’t form peptidoglycans)

A

Penecillin

35
Q

What enzyme transfers sugars to other molecules from nucleotides eg to make glycolipids

A

Glycosyltransferase

36
Q

Glycolipids are receptors on cell membrane example being blood group antigens. How are they different from each other in each blood group

A

The A antigen has added extra galactose n acetyl (gal NAC)

The B antigen has added extra Galactose (gal)

The sugars were added by different glycosyltransferases

37
Q

Which glycoprotein/ glycans produces mucins which line epithelial cells for protection from pathogens

A

N glycans

38
Q

What is GAG in proteoglycans made from and where is it important

A

1 amino acid sugar and 1 uronic acid

It is found in joints with high compression such as the knees. It forms a gel cover

39
Q

How do n glycans allow viruses/ pathogens to enter hosts

A

The spike proteins are glycosylated which means antibodies can’t keep them away from cell receptors on hosts

Glycosylation also allows the receptor binding domain to be ‘up’ / active

Biochem - Year 1 Biomed (21 decks)

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