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Biomolecules > carbohydrates > Flashcards

carbohydrates Flashcards

1
Q

what are the range of different uses for carbohydrates?

A

1) ) Source of energy
- they can act as input for energy generation pathways e.g. glycolysis
- they can act as the source material for making other biomolecules e.g. They can be converted into amino acid via transamination (amino acid synthesis) or the generation of nucleic acids (RNA and DNA).

2) Structural
- DNA (Ribose; Monosaccharide)
- Plant Wall (Cellulose; Polysaccharide)
- Drugs and Hormones (receptors that recognise these hormones also have carbohydrates attached to them.
( e.g. Adenosine; Ribose)

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2
Q

what is a carbohydrate?

A

Biological molecules which contain carbon, oxygen and hydrogen in very specific ratio.
Molar ration C1H2O1= C1(H2O)1 (for every one molecule of carbon there is one water molecule)

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3
Q

what are the simplest form of carbohydrates and what are the common types including molecular DRAWINGS and Formulas ?

A

simplest form = Monosaccharides
-glucose
- galactose
- fructose
All have the same molecular formula (C6H12O6)

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4
Q

Triose, Tetrose, pentose, hexose

A

Triose
Carbons: 3
Example : Pyruvate, glyceraldehyde, dihydroxyacetone.
Importance: Intermediates glycolysis, precursor of glycerol (for lipid synthesis)

Tetrose
carbons : 4
Example : D- Erythrose
Importance: Intermediates of carbohydrate metabolism.

Pentose
Carbons : 5
Example: D- ribose
Importce: Structural element of nucleic acid, RNA, Co-enzymes.

Hexose
Carbons : 6
Example : D- Glucose
Importance: Mian sugar of the body

Example : D-Fructose
Importance: Converted to glucose and utilised by the body

Example: D-Galactose
Importance: Synthesised in mammary gland to make the lactose of milk.

Example : D-Mannose
Importance: Constituent of glycoprotein, glycolipids.

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5
Q

what is polymerisation?

A

(condensation)
adding carbohydrate monomers to build something big.

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6
Q

what is formed when one or more type of monosaccharides are combined together?

A

2 Monosaccharides = Disaccharide
3-20 Monosaccharides = Oligosaccharides
21-1000’s Monosaccharides= Polysaccharides

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7
Q

what happens when two monosaccharides join together?

A

No matter what size, for every two monosaccharides that combine it results in the overall loss of one water molecule = Condensation

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8
Q

Formation of disaccharides.

A

Glucose + Glucose = Maltose
Galactose + Glucose = Lactose
Fructose + Glucose= Sucrose

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9
Q

Formation of Trisaccharides

A

Glucose + Fructose + Galactose = Raffinose

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10
Q

Formation of Tetrasaccharide

A

2X Galactose + Glucose + Fructose = Stachyose

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11
Q

Formation of Pentasaccharides

A

3X Galactose + Glucose + Fructose = Verbascose

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12
Q

Molecular formulas of Maltose, Lactose and Sucrose.

A

BOOK

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13
Q

What is carbon 1 known as ?

A

Anomeric carbon- when forming bonds with sugars this is the atom which dictates how two sugars interact.

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14
Q

Types of ways to represent the same molecule.

A
  • Fischer (like display formula/lines)
  • Haworth ( the “normal” way)
  • chair/boat (3D)
  • stereochemical (2D)
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15
Q

what is the differnece between a-glucose and b- glucose.

A

a- glucose
The OH on the anomeric carbon is Trans (opposite side) compared with the OH group in carbon 6.

B- glucose
The OH group on the anomeric carbon is Cis (same side) compared with the OH group in carbon 6.

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16
Q

what is chirality?

A

Chirality is a property of asymmetry in molecules, where a chiral molecule cannot be superimposed on its mirror image- This is similar to how your left and right hands are mirror images of each other but are not identical.

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17
Q

D-Glucose and L-Glucose are mirror images of each other and are enantiomers.
what are enantiomers?

A

Enantiomers are two chiral molecules that no matter how we rotate or translate them individually they cannot be
superimposed.

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18
Q

where is chirality (“handedness”) of a molecule important.

A

for enzyme/protein recognition in metabolism- one enantiomer fits perfectly in the enzymes active site/pocket, while the other enantiomer (mirror image) will not be a perfect fit= no biological response.

19
Q

which one of these sugar are naturally occurring?

A

D-sugars = naturally occurring
L- sugars = do not occur naturally but can be made synthetical

20
Q

Definition of Enantiomers

A

Two separate chemicals which have the same chemical formula, but the atoms are arranged as a mirror image- if a molecule has a “mirror” twin and no matter how we rotate or translate they cannot be superimposed then these molecules are ENATIOMERS of each other.

HAND ANALOGY!!

21
Q

D&L used for what?

A

used to define chirality of a sugar. Most of the sugars in nature are in the D formation. Conversely amino acids are in the L conformation.
D=Dexter= right
L=Laevis= left

22
Q

What does Emil Fischer suggest?

A

Emil Fischer
- Atoms C and D (solid wedge) = projecting out of the page= horizontal line
-Atoms A and B (dashed wedge)= projected into the page= vertical line.

IMAGE IN BOOK

23
Q

What does the penultimate carbon mean?

A

refers to the second-to-last carbon atom in a chain of carbon atoms.

LEARN HOW TO IDENTIFY !

24
Q

How to know if a molecule is D or L?

A

The two molecules are identical apart from the position of the OH group on the penultimate carbon (*).
If the OH group is on the right hand side of the penultimate carbon, its a D sugar.
If the OH group is on the Left hand side of the penultimate carbon, it a L sugar.

Therefore, Fischer projections= sugar Enantiomers.

25
Q

what does diastereomers mean?

A

(two) molecules which are not mirror images of each other and each molecules has multiple chiral centres (*).

DIAGRAM IN BOOK!

26
Q

what are sugar epimers.

A

sugars that are different from one another, only in configuration with regard to a SINGLE carbon atom, other
than the reference carbon atom i.e. not the penultimate carbon (D/L etc).

IMAGE BOOK!

27
Q

Sugar Epimers = Only 1 change
more than one= not an epimer

A
28
Q

USE POWEPOINT SLIDE 20 to test ability to identify enantiomers, epimers and Diastereoisomers

A
29
Q

What type of sugar is D galactose?

A

An Aldohexose- it contains the CHO group associated with aldehydes.

DISPLAY FORMULA IN BOOK.

30
Q

Display formula of Aldehyde CHO group?

A

BOOK

31
Q

Sugar that contains an aldehyde group and 6 carbon= ?

Sugar that contains an aldehyde group and 5 carbons= ?

A

If a sugar contains an aldehyde group
and has 6 carbons its an aldohexose

If a sugar has an aldehyde group and has 5 carbons it’s a aldopentose .

32
Q

What type of sugar is D-fructose

A

Fructose contains a ketone i.e. an
organic compound containing a
carbonyl group (C=O) and is a
ketohexose.

DISPLAY FORMULA IN BOOK.

33
Q

Display formula of ketone group?

A

BOOK

34
Q

If a sugar contains a ketone group and
has 6 carbons=?

If a sugar has a ketone group and has 5 carbons=?

A

If a sugar contains a ketone group and
has 6 carbons its an ketohexose.

If a sugar has a ketone group and has 5 carbons it’s a ketopentose.

35
Q

EXamples of aldohexose/aldopentose and ketohexose/ketopentose

A

Aldohexose :
- Glucose
- Galactose
- Mannose
- Talose

Aldopentose:
- Ribose
- Deoxyribose
- Xylose
- Arabinose

Ketohexose:
- Fructose
- Sorbose
- Tagatose

Ketopentose:
- Ribulose
- Xylulose

36
Q

Any sugar with a free aldehyde group or a free ketone group is a what?

A

Any sugar with a free aldehyde group or a free ketone group is a reducing sugar.
Has the ability to reduce other molecules but in the process it is oxidised.

37
Q

Monomeric Carbon

A
38
Q

What is Glycosylation?

A

biochemical process in which carbohydrates (sugars) are attached to proteins or lipids.

39
Q

What is the importance of Glycosylation?

A

Cell Recognition: Glycosylation is vital for cell-cell interactions, immune responses, and pathogen recognition.

Extracellular Surface: Glycoproteins on the extracellular surface of cells often act as receptors, enzymes, or structural components, influencing cellular communication and behavior.

40
Q

What are the two types of Glycosylation?

A

N-linked Glycosylation

  • Amino Acid: Asparagine (Asn)
  • Process: The carbohydrate is attached to the nitrogen atom of the asparagine side chain. This usually occurs in the endoplasmic reticulum and continues in the Golgi apparatus.
  • Structure: N-linked glycans typically consist of a core structure with branches, which can vary in composition (e.g., high-mannose or complex glycans).
  • Functions: Plays roles in protein folding, stability, and cell-cell recognition.

O-linked Glycosylation

  • Amino Acids: Serine (Ser) and Threonine (Thr)
  • Process: Carbohydrates are attached to the hydroxyl group of serine or threonine residues. This typically occurs in the Golgi apparatus.
  • Structure: O-linked glycans are usually shorter and more variable than N-linked glycans, often consisting of single or small groups of sugars.
  • Functions: Important for protein stability, signaling, and interaction with other molecules.
41
Q

Glycosylation in Medicine- SARS-CoV-2

A
  • Coronavirus- SARS,MERS,COVID19
  • Protein sequence fairly similar
  • Real difference is a subtle changes the carbohydrate coat of the spike
    protein
42
Q

what is the Spike protein responsible for?

A

attaching to a host cell and injecting
viral RNA. This layer prevents the immune system from recognising the protein
sequence in similar coronaviruses
such as SARS-Cov-1, MERs etc.

43
Q

MULTIPLE CHOICE QUESTIONS.

A

Biomolecules (9 decks)

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