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Biochem Exam 1 > Chapter 4 - Carbohydrates > Flashcards

Chapter 4 - Carbohydrates Flashcards

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1
Q

What is the empirical formula of carbohydrates

A

CH2O

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2
Q

Carbohydrates possess 2 functional groups. What are they?

A

Carbonyl and hydroxyl

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3
Q

Carbohydrates are ____ in water

A

soluble

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4
Q

Why do animals use carbohydrates?

A

for RAPID energy production

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5
Q

What do animals use for long term energy storage?

A

lipids

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6
Q

Why are sugars more dense than lipids?

A

More oxygen atoms and they can form H bonds with water

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7
Q

Besides providing energy, what are 2 other functions of carbohydrates?

A

cell to cell recognition and cell signaling

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8
Q

What are the simplest sugars?

A

Monosaccharides

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9
Q

Explain the structure of a monosaccharide

A

1 Carbonyl group attached at the first or second carbon. The remaining carbons have hydroxyl groups attached

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10
Q

What are the 2 classes of monosaccharides

A

Aldose and Ketose

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11
Q

Ketose have the carbonyl attached at carbon __ while aldose have the carbonyl attached at carbon ____

A

ketose - carbon 2
aldose - carbon 1

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12
Q

What is the suffix commonly used to define a compound as a sugar

A

-ose

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13
Q

Sugars have general category names. What is the smallest? What are the 2 exceptions to this naming rule?

A

triose
2 exceptions are the simplest monosaccharides: glyceraldehyde and dihydroxyacetone

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14
Q

Describe the structure of dihydroxyacetone

A

symmetrical molecule. 3 carbons. Middle carbon has a carbonyl group attached and the 2 carbons on the ends have -OH groups

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15
Q

Describe the structure of glyceraldehyde

A

asymmetrical molecule with 1 chiral center. 3 carbons with a carbonyl group on carbon 1 and OH groups attached to the other 2 carbons

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16
Q

What are enantiomers

A

non superimposable mirror images

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17
Q

What is the greatest significance of enantiomers

A

Their selective interaction with enzymes

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18
Q

Living systems can metabolize L or D sugars??

A

D

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19
Q

What are epimers?

A

Sugars that differ at chiral centers (other than the D/L positions)

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20
Q

Sugars having ____ or more carbons primarily exist in solution as ring form

A

5

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21
Q

How are carbohydrate rings formed?

A

Intramolecular nucleophilic substitution in which an OH attacks the carbonyl carbon. These reactions can be hemi acetal or hemiketal

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22
Q

What is the difference between alpha and beta conformations in a cyclic carbohydrate?

A

If the OH group on the carbon to the right of the oxygen atom is facing up, it is beta. Down, it is alpha

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23
Q

Why are there alpha and beta versions of cyclic sugars in the first place?

A

The OH can attack from either side

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24
Q

What is the anomeric carbon of the straight chain form of a sugar?

A

the carbonyl carbon

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25
only ___ and ___ membered rings are stable
5 and 6
26
The alpha, beta, and open chain conformations are in ________ with each other
equilibrium
27
2 sugars bonded together are called _________
disaccharides
28
What are the 3 major monosaccharides??
1, Fructose 2. Glucose 3. Galactose
29
What is the chemical name for table sugar and how many sugars are in it?
sucrose. It's a disaccharide
30
Maltose is a partial digestion of ______ and is common in the production of ______
starch, beer
31
The linkage between 2 sugars is called a....?
glycosidic bond
32
maltose is composed of which 2 sugars?
2 molecules of glucose formed from the removal of water
33
Maltose is considered a _______________. Why?
Maltose is considered a reducing sugar because of the presence of the carbonyl
34
What classifies a reducing sugar?
Any saccharide that has at least one free anomeric carbon(not involved with glycosidic bond)
35
name 2 reducing sugars and 2 nonreducing sugars
REDUCING: maltose and lactose NONREDUCING: sucrose and trehalose
36
Give the definition of polymers.
Large molecules that are constructed from small, repeating units
37
What is amylose composed of and how is it linked?
Amylose is biological polysaccharide composed of glucose molecules linked together by alpha 1,4 glycosidic bonds
38
All UNBRANCHED polysaccharides have a ________end and a _________end. Why?
reducing end, nonreducing end. The anomeric carbon is engaged in a glycosidic bond on one side and not the other. Not engaged = reducing
39
Which linear form of glucose is linked by BETA 1,4 bonds?
cellulose
40
Why is cellulose so strong?
All of the hydrogen bonds that exist between glucose molecules
41
Is cellulose soluble in water? Why or why not?
NO. NOT SOLUBLE. Cellulose has so many hydrogen bonds within itself that it cannot withstand more.
42
What is the most abundant molecule in the world and where is it primarily found?
cellulose - cell walls, wood
43
What is an important reason that animals use polysaccharides as energy storage??
Reduces osmotic pressure. Osmolarity only depends on the number of molecules, not the size. This is important because animal cells need to maintain equal levels of water on both sides of their plasma membrane. They can still have a glucose reservoir
44
What does having a cell wall do for plants?
Their osmotic pressure can be very high without the cell bursting. cell wall is composed of cellulose
45
How is amylopectin linked?
Alpha 1,4 AND 1,6 linkages
46
Starch is a mixture of ____ and ____
amylose and amylopectin
47
In which 2 places in the human body is glycogen mainly found
liver, muscles
48
What is the function of the liver?
Stores glycogen and releases glucose into the blood stream in times of fasting
49
What 2 sugars is sucrose composed of
fructose + glucose
50
What 2 sugars is lactose made of
glucose + galactose
51
What is a major class of polymers?
Polysaccharides
52
Alpha or beta --- which forms a completely straight chain?
beta. alpha will curve a bit
53
Many simple modifications of carbohydrates modify....?
hydroxyl groups by a phosphate ester
54
alcohol----->aldehyde----> carbonyl is oxidation or reduction??
oxidation
55
aldehyde-----> alcohol is oxidation or reduction???
reduction
56
What is formed when an oxygen is replaced with a nitrogen??
glucosamine
57
How are deoxy sugars formed??
a hydroxyl group is replaced with an H
58
How can POLYsaccharides be modified?
Having an internal oxygen bridge between C3 and C6
59
Agarose + agaropectin =
agar
60
What are the components of a nucleotide?
1. Nitrogenous base 2. Sugar 3. At least one phosphate ester
61
Which bases have double rings and what are their names?
purines = adenine and guanine
62
What are the components of nucleosides?
1. Base 2. Sugar
63
Describe the structure of DNA
2 strands covalently linked by hydrogen bonds between bases
64
There are 2 classes of glycoproteins. What are they?
N-linked and O-linked
65
What is the sweetest sugar?
fructose
66
Ribose is a ____ose
pentose
67
Glucose, fructose, and galactose are all ___ose
hex
68
Are DL and RS the same in stereochemistry of carbohydrates??
no - DL is more about rotational properties
69
What is a glycosidic bond and how is it formed
covalent bond between 2 monosaccharides. Formed by dehydration synthesis
70
Does the formation of a glycosidic bond require energy?
YES. most of the time building molecules requires energy
71
Give 2 reasons why there is branching in glycogen
1. Packing for more glucose in limited space 2. Reduces osmotic pressure

Biochem Exam 1 (7 decks)

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