Carbohydrates/complex carbohydrates Flashcards
1
Q
What are the bulk elements essential for animal life and health?
A
C, H, O, N, P, S, NA, K, Cl
2
Q
What does water dipole lead to?
A
Negatively charged
Formation of hydrogen bonds
3
Q
What is water a good and bad solvent for, give examples.
A
Good for charged and polar substances, amino acids, small alcohols, carbohydrates.
Poor for nonpolar substances, nonpolar gases, aromatic moieties, aliphatic chains.
4
Q
What is the molecular hierarchy structure?
A
Supramolecular complexes, macromolecules, monomeric units.
Plasma membrane, cellulose, sugar.
5
Q
Bond energy strengths, covalent, ionic, hydrogen, van der wall
A
Covalent- 90 kcal/mole
Ionic- 3
Hydrogen-1
Van der wall-0.1
6
Q
Importance of hydrogen bonds(7)
A
-Source of unique properties of water
-Structure and function of proteins
-Structure and function of DNA
-Structure and function of polysaccharides
-Binding of substrates to enzymes
-Binding of hormones to receptors
-Matching of mRNA and tRNA
7
Q
Life is made mainly of C, _ O N _ & _ and is both ______-based and _____-based
A
H, P, S, Carbon, Water
8
Q
What is the biological importance of carbohydrates?
A
Energy yielding pathway for non-photosynthetic cells.
Structural role in plants/bacteria and in connective tissue of animals.
Signalling role when covalently attached to protein and lipid.
9
Q
What is the basic form of a sugar?
A
Monosaccharide.
10
Q
What structures do carbohydrates 1 follow?
A
Linear and ring structures.
Glycosidic bond in disaccharide
11
Q
What is the role of disaccharides?
A
Structure and storage.
12
Q
Give a few chemicals of the formation of carbon?
A
Graphite, Diamond, Fullerene, Coal, Carbon nanotube.
13
Q
What is the octet rule?
A
There are four electron pairs around an oxygen atom in water. The 4 electrons are in sp3 orbitals.
14
Q
In water what do the electron pairs pair to?
A
Two pair to a hydrogen and the other two remain non-bonding(lone pairs).
15
Q
What does the electronegativity of the oxygen atom induce?
A
A net dipole moment. Because of the dipole moment, water can serve as both a hydrogen bond donor and acceptor.
16
Q
What impact does ice being less dense than water have on aquatic organisms?
A
Keeps pon-living organisms alive during winter.
17
Q
Define tetravalency.
A
Carbon can neither lose nor gain electrons to attain an octet.
18
Q
Hydrocarbon tend to be water ________?
A
insoluble.
19
Q
Carbohydrates are often ___ water plus one ________(CnH2nOn).
A
one, carbon.
20
Q
What types of nuttrients are within carbohydrates II?
A
Complex structures like sugar, protein and lipids.
As well as proteoglycans, glycoproteins and glycolipids.
21
Q
Give two examples of monosaccahride(simple sugar unit)
A
Glucose, fructose
22
Q
Give two examples of oligosaccharides(3-10 suagr units), short chain?
A
Sucrose, maltose.
23
Q
Give two examples of polysaccharides, sugar polymer >10 units.
A
Cellulose, glycogen.
24
Q
Give descriptive factors of monosaccharides
A
Colourless, crystalline, soluble(not to non-polar solvents)
25
Describe the structure of a monosaccharide?
Unbranched C chain linked by single bonds.
Except ONE carbon atom double-bonded to oxygen.
Other carbonds bonded to hydroxyl groups.
Glucose=C6H12O6
26
What are the two types of monosaccharide?
Aldose and Ketose.
27
What is the difference between and aldose and a ketose?
The carbon oyxgen double bond in an aldose is at the end of the carbon link, whereas in ketose it is in the middle.
28
What is the order for monosaccharide naming scheme.
3. Triose
4, Tetrose
5. Pentose
6. Hexose (most common,e.g. glusocose, frucstose)
29
What is the difference between deoxyribose and ribose?
The hydroxyl group in ribose loses an oxygen in deoxygribose, hence "de,oxy, ribose". Chain is otherwise the same.
30
What is an enantiomer?
Enantiomers are pairs of compounds with exactly the same connectivity but opposite 3D shapes.
31
What are the two ways carbon can be arranged when it has 4 different "substituents"?
Isomer or enantiomer.
32
What are the 2 enantiomers designated as?
L-isomer and D-isomer.
33
How do you name an enantiomer?
Put the C=O group at the top and then check the form it is in, either L or D depending on left or right hand side.
34
What is the L-form for an enantiomer?
The -OH group is on the Left hand side (Levo)
35
What is the D-form for an enantiomer?
The -OH group is on the right hand side (Dextro)
36
How is the sugar classified as D or L glucose?
The configuration of the chiral centre furthest from the carbonyl carbon, this is where you can spot the reference carbon for its link to the hydroxyl group(side).
37
Are most sugars found in living organisms L or D isomers?
D- isomers.
38
What is the Fischer projection of enantiomers?
Horizontal bonds project towards the viewer.
Vertical bonds point away.
39
What is the perspective formula projection for enantiomers?
Solid wedge-shaped bond project towards the viewer.
Dashed wedge-shaped bond points away from the viewer.
Essentially vertical are dashed and horizontal and solid.
40
What is an aldopentose?
A pentose sugar with the potential for a an aldehyde group at one end.
41
How are monosaccharides identified?
Monosaccharides are identified by pattern of hydroxyl decoration relative to carbonyl carbon.
42
What is an epimer?
Monosaccharides that only differ in the configuration around one carbon atom are called epimers.
So one carbon atom link is changed, e.g. C2 goes from being linked to H to HO.
43
Monosaccharides have cyclic structures, name two of the most predominant ones and give its relative stability as a ring as well as no. of carbons?
Pentose(ribose) 5 carbon ring- good stability.
Hexose(glucose) 6 carbon- very stable.
44
What is the minimum amount of carbons in a monosaccharide to form a cyclic structure?
5
45
What does an aldehyde and alcohol produce?
Hemiacetal.
46
What does a ketone and an alcohol produce?
Hemiketal.
47
What anomers are formed from the sugar ring formation(monosaccharides)
Carbonyl group is planar so no anomer formed.
Hydroxyl group can approach from anove or below the plane forming 2 products, alpha and beta anomers.
48
What do anomers do?
Create a new chiral (asymmetric) carbon.
49
What do you call a six member ring of a monosaccharide?
Pyranose
50
What do you call a five member ring of a monosaccharide
furanose
51
What are the representations of cyclic monosaccharides?
The haworth perspective, thickest bond is closest to viewer.
D enantiomers have the C6 above the ring, and L appears below.
Alpha anomers have the hydroyl(OH) opposite C6 and beta have the OH on the same side as C6.
52
Is the pyranose ring planar
The pyranose ring is not planar and forms one of 2 chair conformations.
53
What are the two "chair" conformations of a pyranose ring?
Axial or equatiorial.
They are axial if they project parallel to the vertical axis.
they are equatorial if they project perpendicular to vertical axis.
54
Where is the most room on the plane for monosaccharide ring conformations.
The left hand corners, bulky groups like CH2OH can situate.
55
What is called when the hydroxyl group rapidly changes from one position to the other?
Muta-rotation.
56
What is mutarotation important for?
Pathogens, like Haemophilus influenzae a bacteria that cause pneumonia.
57
How are monosaccharides reducing sugars?
They can reduc mild oxising agents like Fe3+ and CU2+
Reduction is by the carbonyl of the anomeric carbon.
Only occurs in the open chain form.
If muta-rotation is not possible the sugar will be non-reducing.
58
What is the proof that monosaccharides are reducing sugars?
Fehling's reaction. Old-fashioned method of blood sugar measurement.
Modern way uses glucose oxidase.
59
How can monosaccharides form disaccharides?
Monosaccharides react with one another to from disaccharides connected by an O-glycosidic bond.
60
What group from one sugar reacts with the anomeric carbon from another?
Hydroxyl group.
61
What is the basic product of a condensation reaction in disaccharide formation?
H2O. Water. Formed from hemiacetal group and alcohol from another. OH+H=H2O
62
What is"locked" and "free" when a monosaccharide forms into a disaccharide?
Reaction locks the anomeric form.
End with free anomeric carbon is called the reducing end.
Wavy lines on skeletal formula means it can mutarotate.
63
Give a commonly found disaccharide?
Maltose, Breakdown product of starch by amylase in saliva. Example: Beer, whisky, maltesers, rich tea biscuits.
Lactose, Present in all infants(milk sugar).Broken down in the intestine to glucose and galactose by lactase.
64
What do you call a single sugar type polysaccharide?
Homopolysaccharide.
65
What do you call a polysaccharide made of many different sugars?
Heteropolysaccharide.
66
Is a polysaccharide single chained or branched?
they can be either, it leads to huge variability of the sugar - more than in DNA and proteins.
67
What is the function of homopolysaccharides?
Fuel storage in plants as starch(branched)
Fuel sotrage in animals as glycogen(branched)
Structural support(cellulose and chitin)-both unbranched.
68
What is the function of heteropolysaccharides?
Extracellular support
Peptidoglycan in bacterial cell wall. 2 alternating monosachharides.
Extracellular matrix in animals. Mixture of several types.
69
What are the functions of the 3 main polysaccharides?
Starch&Glycogen= Storage
Cellulose= Structure
70
What is the structure of a polypeptide?
- Covalently attached monomer chain
- 3D structure stabilised by many weak interactions
- Each sugar unit technically has free rotation around glycosidic bond.
Rotation is limited by steric hindrance and weak interactions.
71
What are the saccharides in polysaccharides covered with?
Hydroxyl (-OH) groups.
Hydrogen bonding plays major role in determining structure.
72
What two polysaccharides are in starch?
80% amylopectin
20% amylose
73
What is the structure of amylose?
One component of starch 60˚ relative to each other. Forms a helix.
74
What is the structure of amylopectin?
Double helix formed with joined with amylose.
Branch points of amylopectin connect different helices together.
𝜶1-4 linkage
Helical
Highly branched chain
Branches with 𝜶1-6 linkage every 30 sugar units.
75
What is the main storage polysaccharide in animals?
Glycogen
76
What is the structure of glycogen?
Similar to amylopectin but more extesively branched(8-10 sugars)
Tighter packed than starch
Formed around enzyme glycogenin
77
Where is glycogen abundant?
Muscle and liver.
78
Is it fast or slow to break down glycogen to glucose?
Rapid break down
79
**What is the necessity of polysaccharides?**
They are insoluble.
their insolubility prevents osmolarity as the cytoplasmic glucose conc. is very high alone.
High osmolarity would lead to water flooding into the cell which could rupture the cell membrane.
80
Give a structural description of cellulose?
Fibrous, tough and insoluble.
Linear, unbranched polysaccharide.
Beta1-4 linkage key difference to amylose.
81
Is cellulose straight or bent?
H- bonding makes it straight, 180˚ relative to each other.
Interchain H-bonding produces high tensile strength fibres.
82
How can you covalently modify glucose?
Hydroxyl groups(-OH) on sugars can be replaced to modify function.
83
Give an example of sugar modifications?
NAG- N-acetyl-B-D glucosamine.- polymerises to form chitin.
84
What is the oxidation of glucose used for?
Used for blood sugar monitoring.
85
What is the function of N-acetylneuraminic acid(NANA, silic acid)?
Its the terminal sugar on mammalian cell membrane.
Found on mucus that prevents respiratory tract infections.
86
What is the function of peptidoglycan?
Bacterial cell wall rigidity
Taget for lyzozome.
Target for penicillin
87
What is the function of agarose?
Structural role
Algal cell wall
Important molecular biology ingredient.
88
What is the function of hyaluronan?
Structural role
In verterbrates
Lubricates joints and forms connective tissue.
89
What polysaccharides encode information by attachment to protein?
Glycoprotein- mainly protein with some carbohydrate
Proteoglycan- mainly carbohydrates anchored to organiser protein.
90
What polysaccharides are structural and signalling molecules?
Bacterial cell envelope
Eukaryote extracellular matrix(ECM)
91
What polysaccharides encode information by attachment to lipids?
Glycolipids
Surface antigens and ABO blood grouping.
92
Why are glycosylate proteins necessary?
Interact tightly and specifically with a family of proteins called lectins.
The proteins in this family bind to and decode the sugar code.
Important for cell-to-cell communication, adhesion and recognition. Important for intracellular targeting of proteins.
93
What do leukoycte glycoproteins do?
Interact with lectins on cells at sites of infection.
Allows white blood cells to be grabbed bloodstream and delivered to places they are needed.
EXTRAVASATION.
94
How do viruses enter animal cells?
First interacting with cell surface glycoprotein.
e.g. Influenzae virus Haemagglutinin (the ‘H’ in H5N1) binds sialic acid on receptors on the animal cell.
Bacterial toxins bind to cell surface receptors before entering the cell.
e.g choleroe and pertussis toxins
Bacteria adhere to animal cells to start colonizing. e.g helibacter pylori.
95
What is the medical industry necessity for glycosylation?
Vaccine and drug production against viruses, bacteria and other pathogens.
Producing cheap proteins based drugs, including anti-cancer.
Cheap antibody treatments
Cheap vaccines.
96
Why is it critical to know the exact glycosylation state of biopharmaceuticals?
If incompatible, the drug will be ineffective and may induce immune response.
97
What are the two different types of glycosylation?
N and O linked.
O linked through serine
N-linked proteglycan maturation, soluble proteins released into media.
Membrane proteins inserted into plasma membrane.
98
What does glycosylation make?
Complex mixtures called "microheterogeneity" producing different glycoforms.
99
What techniques can you use to determine glycosylation state?
Cleave of sugars
Purify sugars.
100
What are proteoglycans?
they are critical for all forms of life.
e.g.
Bacterial cell envelope
Eukaryotic extracellular matrix.
101
What is the monomeric unit of chitin?
NAG.
- arthropod and mollusc exoskeletons
- cephalopod beaks
102
What two monomeric units are major constituents of bacterial cell walls?
NAG and NAM
103
What do NAG and NAM peptidoglycan provide for bacteria?
A strong shell around the bacterium, preventing cells from swelling and breaking open.
104
What do NAG and NAM form in bacteria?
Long heteropolysaccharide chains that lie side by side.
Connected to 4 amino acid peptide.
Peptides are cross- linked together.
105
How does penicllin work(Beta-lactam antibiotics)
They inhibit peptidoglycan synthesis by binding to and blocking enzym that makes the crosslinking bridges.
Weakens the peptidoglycan wall leading to osmotic lysis of cells.
106
What percentage of peptidoglycan is in the cell envelope for gram positive and negative bacteria?
Peptidoglycan is 50-90% cell envelope in gram+ bacteria.
Peptidoglycan is 10% cell envelope in gram- bacteria
107
What colour does the stain turn to for gram+ bacteria?
After trapped goes purple
108
What colour does the stain turn to for gram- bacteria?
Goes pink after washing off.
109
How many proteoglycans can mammalian cells produce?
30
110
What do proteoglycans do in animals?
Provide multiple binding sites for interactions at cell surface.
Involved in cartilage formation- provide strength to connective tissues.
Formation of the gel-like extracellular matrix(ECM)
111
What does the extracellular matrix in animals do?
Holds cells together and allows communication and differenciation.
112
The ECM an interlocking mesh of?
- Proteins, e.g. collagen, fibronectin and elastin.
- Heteropolysaccharides called glycosaminoglycans.
113
What are glycosaminoglycans?
Linear chains of repeating disaccharide units;
Hyaluronate
Chondroitin-4-sulfate
Keratin sulfate
Heparin
114
What is hyaluronate contribution to the ECM?
Hyaluronate:
Lubricant in joints
Found in the eye
Strength and flexibility to cartilage and tendons via ECM.
50,000 repeats
EXTRA: Not attached to protein so not a proteoglycan.
115
What is chondroiti-4-sulfate contribution to the ECM?
Covalently attaches to proteins.
Contribute to tensile strength to cartilage, tendons and ligaments.
60 repeats
116
What is Keratin sulfate's contribution to the ECM?
Are covalently attaches to proteins.
Found in bone, cartilage, cornea.
Found in structures formed from dead cells; horns, hoofs, hair and nails.
25 repeats
117
What is heparin's contribution to the ECM?
Present in blood stream
Anticoagulant- prevents blood from clotting.
Binds to antithrombin protein, allowing it to bind and inhibit thrombin.
Added to donated blood and to blood samples for clinical analysis.
118
What integral membrane protein is secreted into ECM?
Syndecan
It is a single TM membrane protein.Decorated with heparin and chondroitin. Attached to serine residue.
119
Give an example of a proteoglycan altering function?
Heparan binds to proteins and signalling molecules for anticoagulant activity. By conformational change in protein binding site.
120
Where are glycolipids found?
Outer face of the cell membrane
121
What are glycolipids?
Lipids with modified head groups(they have a polar part that faces the solvent).
122
Give an example of a glycolipid and its function?
Lipopolysacchairde.
Present in gram- bacteria.
6 fatty acids bound to 2 glucosamine residues+complex glycan attached.
Causes massive immune response-toxic shock syndrome.
123
Give an example of a glycolipid and its function?
Found on eukaryotic cells.
Determine blood group types.
Subtle changes in oligosaccharide group that lead to change in blood type recognition by immune system.
124
