Carbohydrates

Question 1

How many enantiomers are there and what are the chiral centres?

Answer 1

2 enantiomers D and L

C2-5= chiral centres

Question 2

What is the difference between the structure of Alpha and beta D-glucosepyranose (cyclic glucose)

Answer 2

On carbon one in Alpha the H is above + Oh is bonded below.

It is the opposite in Beta

Question 3

What are the monomers of a carbohydrate?

Answer 3

monosaccharides

Question 4

What bond forms between 2 monosaccharides and between which carbons

Answer 4

Glycosidic bond forms between C1 and C4

Question 5

Name 3 monosaccarides

Answer 5

Glucose
Galactose
Fructose

Question 6

Name the main structural carbohydrates

Describe the structure

Answer 6

Cellulose

Linear polymer of D-glucose connected by Beta 1,4 glyosidic bonds

Question 7

What is the disaccharide that makes up cellulose?

Answer 7

cellobiose

Question 8

Name 3 other carbohydrates used in plant walls

Answer 8

Hemicellulose
Pectin
Agarose

Question 9

Describe the structure of hemicellulose

Answer 9

Beta1,4 polymers of D-xlyopyranose w/ side groups of various carbohydrates polymers attached
Very good at cross-linking

Question 10

Name a carbohydrate used in exoskeleton

What is the polymer

Answer 10

Chitin

Polymer of N-acetyl glucosamine with Beta1-4 linkages

Question 11

Glycosaminoglycans are structural carbohydrates in animals.

What is their structure and name 3

Answer 11

Chondroitin 4-sulphate
Keratan
Hyaluronan
Polymers with Glucuronic acid, N-acetyl galactosamine/glucosamine

Question 12

Describe the structure of the proteoglycan structure

Answer 12

Hyaluronan backbone

Proteoglycan monomers containing keratan sulphate and chondroitin

Question 13

What are the 2 type of gram in a bacterial cell wall.

Answer 13

+ ve and -ve

Question 14

Describe the +ve gran on bacterial cell walls

Answer 14

Thick, multi-layered at the surface

Retains grain stain of dye-iodine complex

Question 15

Describe the -ve gran on bacterial cell walls

Answer 15

Thin single layered

between the membranes

Question 16

Define glycosylation

Answer 16

The attachment of olgiosaccharide to proteins

Question 17

Where do proteins usually pass through before being glycosylated?
Which protein are not usually glycosylated?

Answer 17

Most proteins pass through the secretory pathway Er and Golgi
Most cytoplasmic proteins dont get glycolated

Question 18

What is the most common glycosylation event ?

Answer 18

the attachment of an N-linked oligosaccharide in the ER by the enzyme oligosaccharyl transferase
The ogi. is held in the memebrane is the dolichol lipid

Question 19

What are the two main types of glycosylation

Answer 19

N-acetyl glucosamine is linked to the –NH2 group of an asparagine // N-linked oligosaccharides are extensively modified in the Golgi - this can result in very complex structures

O=linked

Question 20

Where are the olgliosacchrides formed?

Answer 20

N-linked = ER
O-linked = The golgi

Question 21

What are three function of protein modification by glycosylation?

Answer 21

Helps protiens fold in the ER
Helps direct proteins to their final destination
Helps proteins function