Unit 7

Question 1

What are the three principal functional groups most often seen in monosaccharides?

Answer 1

Aldehyde, Ketone, Hydroxyl

Question 2

What are the individual components of maltose and lactose?

Answer 2

Maltose- 2 glucose units (disaccharide)
contains 1->4 bond

Lactose- Galactose and glucose (disachharide)
contains 1->4 beta bond

Question 3

What are enantiomers and what do the racemase enzymes have to do with enzymes?

Answer 3

Enantiomers- type of isomerism the creates mirror images of each other.

Racemases are enzymes that are able to interconvert D and L isomers.

Question 4

Explain the term ‘anomeric carbon’ and its importance in carbohydrate structure and function?

Answer 4

• occurs during cyclization
• Carbonyl carbon transforms into new stereocenter (anomeric carbon)
• creates alpha and beta configurations of a sugar
• oxygen on anomeric carbon not connected so it is a reducing agent
• place where ring opening takes place

Question 5

What is meant by the phrase ‘reducing sugar’

Give two examples

Answer 5

• oxygen on anomeric carbon not attached it can be reducing agent
• Benedict’s reagent or Fehling’s solution. -determinant is oxygen on anomeric carbon

Question 6

Is maltose a reducing sugar? explain

Answer 6

• yes
• oxygen on anomeric carbon isnt attached to other structures
• allows ring to open up

Question 7

Is sucrose a reducing sugar? explain

Answer 7

• no
• oxygen on anomeric carbon is attached to another structure
• only exists in closed formation

Question 8

A) describe a glycosidic bond B)monosacharrides have multiple hydroxyl groups and can potentially form glycosidic bonds with carbons in other monosaccharides what does this tell you about the potential extent of glycosidic linkages?

Answer 8

Glycosidic bond
- covalent bond between sugar and another molecule

Monosaccharides
-linkages can be very long and complex

Question 9

Compare and contrast starch and glycogen

Answer 9

Glycogen- linear, globular, helical, branced

Starch- amylose, unbranced, amlypectin-branched

Question 10

How is glucose reactive? What are the residues in hemoglobin that would most likely bond with glucose? What are the general names for the two types of bonds formed between glucose and protein residues? Would you expect an enzyme to be involved in the glycosylation reaction?

Answer 10

• reactive bcuz monosaccharide which makes it a reducing sugar
• General name are O and N linked meaning linked to proteins through oxygen or nitrogen
• Yes

Question 11

Explain the action of a general class of enzymes called hydrolases in the digestion of carbohydrate and give an example noting its specific action.

Answer 11

• catalyze cleavage of bonds by adding water
• urease hydrolyzes urea
• breaks bonds between NH2 and the C carbon which makes CO2 and 2 NH3

Question 12

Explain what is meant by the phrase ‘lactose intolerant’ and what two potential mechanisms may be responsible for this condition?

Answer 12

• unable to digest milk and milk products due to lactase defiency
• determined genetically (chromosome 2)
• age dependent

Question 13

Explain how osmosis contributes to the problems experienced with defects in disaccharidases?

Answer 13

• water is drawn from mucose in large intestine which causes osmotic diarrhea The undigested diarrhoea can then ferment in the intestines producing large volumes of carbon dioxide and hydrogen gas, causing the much associated flatulence, stomach cramping as well as contributing to the diarrhoea.

Question 14

Cellulose and glycogen have different physical properties. In particular, cellulose extracted from cotton is tough, fibrous, and insoluble in water. What structural features of these two polysaccharides could explain their respective properties?

Answer 14

cellulose- nnbranched polymer of glucose -hydogen bonds formed by hydoxyl gorups on glucose with oxygen

• strong bonds results in fibrous nature
• Cellulose solubility depends on the length of the polymer (solubility decrease as polymer length increases).
• glycogen, branched polymer (more compact) and more soluble
• more hydroxyl gruoups in glycogen so more soluble

Question 15

What are the essential differences between glycosaminoglycans and proteoglycans

Answer 15

• glyco are disachharides that are repeated through length of chain
• prteoglycans are GAGs attached to protein giving bottle brush structure

Question 16

Why an oral supplement is ulnikely to have the advertised effect for a person with good nutrition? How chondroitin sulfate may have this advertised effect in vivo

Answer 16

• should already be consuming nutrients like chorotin sulfate
• extra supplement could not be used by the body due to required levels already met
• it generates electrostatic replusion providing resistance of compression to the cartiledge

Question 17

what are the essential different between GAGs and glycoproteins?

Answer 17

• GAGS are large complexes of negatively charged heteropolysaccharides
• GAGS have serial repeats in their diglucosyl units
• Glyco- proteins that are covalently attached to oligosaccharides
• Glyco carb chain is shorter

Question 18

What two main aspects of glycoprotein structure would contribute to such a diverse range of functions?

Answer 18

• linkage btwn carb and protein and the O-N linked oligosaccharides

Question 19

Explain how lipids may be like macromolecules but aren’t technically classified as macromolecules?

Answer 19

• form large aggregated structures through non-covalent associations of smaller molecules
• formation of membranes through non-covalent associations of fatty acids

Question 20

High content of cis unsaturated fatty acids?
High content of saturated fatty acids?
High content of trans unsaturated fatty acids?

Answer 20

23 I would predict food with a high content of cis unsaturated fatty acid to exhibit liquid properties. This is because there will be presence of cis double bonds which causes a bend at that point. The presence of cis double bonds decrease the melting temperature causing it to exhibit more liquid like properties and in some cases of food, the cis double bond helps to maintain the fluid nature, typically in long chain fatty acids. Arachidonic acid is an example of a cis unsaturated fatty acid and is the substrate for prostaglandin synthesis. Food with a high content of saturated fatty acid would present more solid properties at it will have higher melting points due to the tendency of longer chains making the hydrophobic portion predominant. Saturated fatty acids are mainly sourced from dairy and meat products. Trans unsaturated fatty acids contain double bonds but behave more like saturated fatty acids thus exhibit ore solid properties in food. They are found in many commercial baked goods such as cookies. Essential fatty acids are fatty acids that humans and other animals have to ingest in order to have good health. The reason that they are important to humans is because humans cannot synthesize them, however they are important in maintaining a healthy organism.

Question 21

Describe the structure of a triaglycerol? Why is it called a neutral fat?

Answer 21

• lacks water
• able to store more energy
• fatty acid esterfied to glycerol
• called netrual because they’re esterfied through carboxyl group which results in loss of negative charge