Chapter 10 Carbohydrates

Question 1

What are three things that saccharides do?

Answer 1

-Energy transport and storage
-Structural support e.g. bacterial cell walls, cellulose
-Information e.g. signals on proteins and membranes

Question 2

What is an Oligosaccharides?

Answer 2

it is a sugar with several sugar units

Question 3

What is a polysaccharides?

Answer 3

It consists of Glycans in long chains of 100s which include 1000s of sugars

Question 4

How many carbons is the smallest monosaccharide composed of

Answer 4

3 carbons

Question 5

How do you tell if the structure is a D side or a L side structure

Answer 5

If the OH is on the right its a D side
If the OH is on the left its a L side
And you look at the chiral carbon furthest from the double C=O bond to determine this

Question 6

What is an enantiomers?

Answer 6

They are non-superimposable mirror images

Question 7

What is a Diastereomers?

Answer 7

-Non mirror image stereoisomers

Question 8

What is a Epimers?

Answer 8

-Diastereomers that differ in configuration at 1C

Question 9

What does a Aldehyde sugar look like?

Answer 9

It has a carbon double bonded to O and the same carbon single bonded to H

Question 10

What does a Ketone sugar look like?

Answer 10

It has a carbon double bonded to O and a CH3Osingle bonded to the same carbon as well

Question 11

What are the Aldoses derived from ?

Answer 11

D-glyceraldhyde

Question 12

What are Ketoses derived from ?

Answer 12

Dihydroxyacetone

Question 13

At which end does the carbon numbering begin from ?

Answer 13

It begins from the end of the molecule nearest the carbonyl carbon

Question 14

An Aldehyde can react with alcohol to form what? and what happens if you react with second alcohol

Answer 14

A hemiacetal is formed with one and if second is added an Acetal is formed

Question 15

A ketone can react with alcohol to form what? and what happens if you react with second alcohol?

Answer 15

A hemiketal is formed with one and if second is added a Ketal is formed

Question 16

What is the ring formed by glucose in a intramolecular hemiacetal called?

Answer 16

Its a six carbon ring called pyranose

Question 17

What is the ring formed by ketohexose fructose in a intramolecular hemiketal called

Answer 17

Its a five carbon ring called furanose

Question 18

What is an anomer?

Answer 18

Its another diastereoisomeric form that is made from the formation of a cyclic hemiacetal

Question 19

At the alpha form of the ring where is the OH at C-1

Answer 19

It is below the plane of the ring

Question 20

At the beta form of the ring where is the Oh at C-1

Answer 20

It is above the plane of the ring

Question 21

What is an anomeric form ?

Answer 21

The furanose form of fructose can exist in anomeric and this is when alpha and beta forms refer to the orientation of the OH at C-2

Question 22

How many types of conformation can a pyranose ring adopt and what are they called?

Answer 22

-There are two conformations and they are called boat and chair

Question 23

In the chair form, how many orientations of OH on the carbon ring atoms are there and what are they called?

Answer 23

there are 2 and they are called axial and equatorial

Question 24

A solution of glucose contains approximately _________ alpha anomer,__________ Beta anomer, and ________ of the open-chain form.

Answer 24

One third, two third, <1%

Question 25

What are sugars called that react with oxidizing agents and what are sugars called that aren't reacting with oxidizing agents?

Answer 25

Reducing sugars, and nonreducing sugars

Question 26

What is an O-glycosidic bond and what is the product of this bond called

Answer 26

This is a bond formed between the anomeric carbon atom of glucose and a hydroxyl group of another molecule and the product is called glycoside.

Question 27

What is a N-glycosidic bond?

Answer 27

A bond formed between the anomeric carbon atom of glucose and an amine

Question 28

Oligosaccharides contain _____or more _________________ linked by ____________bonds

Answer 28

2,monosaccharides, O-glycosidic bonds

Question 29

The substrates for glycosyltransferases area activated by attachment to____________________

Answer 29

uridine diphosphate

Question 30

Enzymes on the outer surface of intestinal epithelium cleave common _______________

Answer 30

disaccharides

Question 31

Sucrase cleaves___________, lactase cleaves ___________ , Maltase cleaves__________

Answer 31

Sucrose, Lactose, Maltose

Question 32

What is it called if all the monosaccharides in the polysaccharide are the same ?

Answer 32

It is called a homopolymer

Question 33

Most glucose units in glycogen are linked by __________________, with branches formed by _______________every ___________ glucose units

Answer 33

alpha-1 4-glycosidic bonds, alpha-1 6-glycosidic bonds ,12

Question 34

In plants glucose is stored as what and how many forms are there?

Answer 34

starch and there are 2 forms

Question 35

What is an Amylose?

Answer 35

It is a linear polymer of glucose units linked by alpha-1,4-glycosidic bonds

Question 36

What is an Amylopectin?

Answer 36

It is a branched polymer with an alpha-1,6-glycosidic bond for every 30 alpha-1,4-glycosidic bonds

Question 37

What type of structure does a IAmylose form ?

Answer 37

it forms a tightly coiled helical structure stabilized by H-bonding with 6 residues per turn

Question 38

what is II Amylopectin?

Answer 38

Up to 200 amylose chains linked alpha 1-->6 at branch points. So just like iso-maltose

Question 39

what does saliva and pancreas secrete and what does it randomly cleave ?

Answer 39

Alpha-amylase is secreted and Alpha-1,4bonds are cleaved randomly

Question 40

Plants and bacteria secrete ________________ that removes __________units starting at the _____________end

Answer 40

Beta-amylase, Maltose, Non-reducing

Question 41

What do debranching enzymes hydrolyze?

Answer 41

alpha-1,6 bonds

Question 42

Cellulose is a homopolymer of glucose units linked by_______________________

Answer 42

Beta-1,4-glycocidic bonds

Question 43

The beta linkage yields a __________________ capable of interacting with other cellulose molecules to form ______________

Answer 43

Straight chain, strong fibrils

Question 44

The alpha linkages of starch and glycogen form _____________________ suitable for accessible storage

Answer 44

compact hollow cylinders