intro to carbohydrates and lipids

Question 1

what are the key structures of linear monosaccharides

Answer 1

• hydroxyl group (-OH)
• carbonyl group - aldehyde (-CHO) or ketone (-C=O)

Question 2

names for number of carbon atoms 3-7

Answer 2

3- triose
4- tetrose
5- pentose
6- hexose
7- heptose

Question 3

what are reducing sugars

Answer 3

• when carbonyl groups (aldehyde or ketone) can react to gain oxygen
• sugar is oxidised while another compound is reduced

Question 4

draw the mechanism for a reducing sugar and Benedict reagent

Answer 4

HRC=O + Cu(citrate)2 -2 + Cu2+——> -ORC=O + Cu2O(s)

Question 5

how do linear monosaccharides go from linear to rings

Answer 5

in an aqueous solution aldehydes or ketones react with hydroxyl on a carbon further along forming a ring structure

Question 6

what ring structures do aldehyde and ketones produce when forming basic rings

Answer 6

aldehyde + alcohol <—–> hemiacetal
ketone + alcohol <——> hemiketal

Question 7

what is a chiral carbon

Answer 7

• asymetircial
• 4 different groups attached
• arranged to produced isomers

Question 8

what is a L isomer of a carbohydrate

Answer 8

-OH on terminal carbon ( second to last) is on the left side

Question 9

what is a D isomer of a carbohydrate

Answer 9

-OH on terminal carbon (second to last) is on the right side

Question 10

what is a constitutional isomer

Answer 10

different order of attachment of atoms

Question 11

what is a sterioisomer

Answer 11

atoms are connected in the same order but differing spacial arrangement

Question 12

what is an enantiomer

Answer 12

mirror images

Question 13

what are diastereoisomers

Answer 13

isomers that are not mirror images

Question 14

what are epimers

Answer 14

differ at one of the several asymmetric carbon atoms

Question 15

what are anomers

Answer 15

differ at a new asymmetric carbon atom formed on a ring closure

Question 16

when glucose is in equilibria how many parts of each anomer is present

Answer 16

1/3 - alpha
2/3 - beta

Question 17

what are the naturally occurring links in disaccharides

Answer 17

1-4, 1-6, 1-2

Question 18

what are the four common disaccharides and what are they made of

Answer 18

maltose - glucose + glucose
lactose - galactose + glucose
sucrose - fructose + glucose
lactulose - galacose + frucose

Question 19

what is lactulose used for

Answer 19

osmotic laxative for constipation

Question 20

how many sugar units are in oligosaccharides

Answer 20

3-10 units

Question 21

what is the example of trisaccharides and what are they used for

Answer 21

raffinose - skin moisturisers. prebiotics

Question 22

what is the example of tetrasaccharides and what is it used for

Answer 22

stachyose - bulk sweetener

Question 23

what are the main functions of oligosaccharides

Answer 23

human breast milk, protein folding, cell signalling, protection

Question 24

what are the main functions of polysaccharides

Answer 24

protein glycosylation, carbohydrate storage in liver and muscles, extracellular matrix

Question 25

how many sugar units are found in polysaccharides

Answer 25

<10 units

Question 26

at room temperature what state are fats and oils in

Answer 26

fats - solid
oils - liquid

Question 27

what are the properties of lipids

Answer 27

hydrophobic - insoluble in water
dissolve in non polar lipids

Question 28

what are the polar lipids

Answer 28

• fatty acids
• sterols
• phospholipids
• sphingolipids

Question 29

what are the non polar lipids

Answer 29

• triacyglcerols
• cholesterol esters

Question 30

what is the structure of fatty acids

Answer 30

• 12 to 36 carbons - often 16-18
• generally even carbons
• amphipathic - both hydrophobic and hydrophilic

Question 31

what is the difference between saturated and unsaturated fats

Answer 31

saturated - no double bonds
unsaturated - one double carbon- carbon bond

Question 32

what is a polyunsaturated fatty acid

Answer 32

more than one double carbon-carbon bond

Question 33

what are the properties of saturated fats

Answer 33

• low steric hinderance - pack well
• often solid

Question 34

what are the properties of unsaturated fats

Answer 34

• cis forms predominatly
• pack poorly
• short chains
• often liquids

Question 35

what fats are liked to heart disease

Answer 35

trans fats

Question 36

what are the functions of fatty acids

Answer 36

• fuel storage - triglycerides
• membranes - phospholipids and glycolipids
• steroid hormone production

Question 37

what happens with liver and pancreas disease

Answer 37

• reduced bile acid and lipase release
• impaired lipid breakdown leading to steatorrhoea

Question 38

what is Zollinger-ellison syndrome

Answer 38

• inactivation of pancreatic lipases
• causes ionisation of bile acids leading to hyperactivity

Question 39

what happens due to cystic fibrosis to lipid breakdown

Answer 39

• Cl- channels are impaired
• reduces pancreatic lipase secretion

Question 40

why are fatty acids used as fuel storage

Answer 40

• insoluble
• doesn’t affect intercellular osmotic pressure

Question 41

what is cholesterols function

Answer 41

• used in steroid hormone production
• it is amphipathic, increases membrane fluidity
• produced in the liver

Question 42

how are steroid hormones produced

Answer 42

cholesterol —-> preneolone —-> various steroid hormones