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Biochem Exam 1 > Chapter 4 - Carbohydrates > Flashcards

Chapter 4 - Carbohydrates Flashcards

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
Q

only ___ and ___ membered rings are stable

A

5 and 6

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26
Q

The alpha, beta, and open chain conformations are in ________ with each other

A

equilibrium

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27
Q

2 sugars bonded together are called _________

A

disaccharides

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28
Q

What are the 3 major monosaccharides??

A

1, Fructose
2. Glucose
3. Galactose

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29
Q

What is the chemical name for table sugar and how many sugars are in it?

A

sucrose. It’s a disaccharide

30
Q

Maltose is a partial digestion of ______ and is common in the production of ______

A

starch, beer

31
Q

The linkage between 2 sugars is called a….?

A

glycosidic bond

32
Q

maltose is composed of which 2 sugars?

A

2 molecules of glucose formed from the removal of water

33
Q

Maltose is considered a _______________. Why?

A

Maltose is considered a reducing sugar because of the presence of the carbonyl

34
Q

What classifies a reducing sugar?

A

Any saccharide that has at least one free anomeric carbon(not involved with glycosidic bond)

35
Q

name 2 reducing sugars and 2 nonreducing sugars

A

REDUCING: maltose and lactose
NONREDUCING: sucrose and trehalose

36
Q

Give the definition of polymers.

A

Large molecules that are constructed from small, repeating units

37
Q

What is amylose composed of and how is it linked?

A

Amylose is biological polysaccharide composed of glucose molecules linked together by alpha 1,4 glycosidic bonds

38
Q

All UNBRANCHED polysaccharides have a ________end and a _________end. Why?

A

reducing end, nonreducing end. The anomeric carbon is engaged in a glycosidic bond on one side and not the other. Not engaged = reducing

39
Q

Which linear form of glucose is linked by BETA 1,4 bonds?

A

cellulose

40
Q

Why is cellulose so strong?

A

All of the hydrogen bonds that exist between glucose molecules

41
Q

Is cellulose soluble in water? Why or why not?

A

NO. NOT SOLUBLE. Cellulose has so many hydrogen bonds within itself that it cannot withstand more.

42
Q

What is the most abundant molecule in the world and where is it primarily found?

A

cellulose - cell walls, wood

43
Q

What is an important reason that animals use polysaccharides as energy storage??

A

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
Q

What does having a cell wall do for plants?

A

Their osmotic pressure can be very high without the cell bursting. cell wall is composed of cellulose

45
Q

How is amylopectin linked?

A

Alpha 1,4 AND 1,6 linkages

46
Q

Starch is a mixture of ____ and ____

A

amylose and amylopectin

47
Q

In which 2 places in the human body is glycogen mainly found

A

liver, muscles

48
Q

What is the function of the liver?

A

Stores glycogen and releases glucose into the blood stream in times of fasting

49
Q

What 2 sugars is sucrose composed of

A

fructose + glucose

50
Q

What 2 sugars is lactose made of

A

glucose + galactose

51
Q

What is a major class of polymers?

A

Polysaccharides

52
Q

Alpha or beta — which forms a completely straight chain?

A

beta. alpha will curve a bit

53
Q

Many simple modifications of carbohydrates modify….?

A

hydroxyl groups by a phosphate ester

54
Q

alcohol—–>aldehyde—-> carbonyl is oxidation or reduction??

A

oxidation

55
Q

aldehyde—–> alcohol is oxidation or reduction???

A

reduction

56
Q

What is formed when an oxygen is replaced with a nitrogen??

A

glucosamine

57
Q

How are deoxy sugars formed??

A

a hydroxyl group is replaced with an H

58
Q

How can POLYsaccharides be modified?

A

Having an internal oxygen bridge between C3 and C6

59
Q

Agarose + agaropectin =

A

agar

60
Q

What are the components of a nucleotide?

A
  1. Nitrogenous base
  2. Sugar
  3. At least one phosphate ester
61
Q

Which bases have double rings and what are their names?

A

purines = adenine and guanine

62
Q

What are the components of nucleosides?

A
  1. Base
  2. Sugar
63
Q

Describe the structure of DNA

A

2 strands covalently linked by hydrogen bonds between bases

64
Q

There are 2 classes of glycoproteins. What are they?

A

N-linked and O-linked

65
Q

What is the sweetest sugar?

A

fructose

66
Q

Ribose is a ____ose

A

pentose

67
Q

Glucose, fructose, and galactose are all ___ose

A

hex

68
Q

Are DL and RS the same in stereochemistry of carbohydrates??

A

no - DL is more about rotational properties

69
Q

What is a glycosidic bond and how is it formed

A

covalent bond between 2 monosaccharides. Formed by dehydration synthesis

70
Q

Does the formation of a glycosidic bond require energy?

A

YES. most of the time building molecules requires energy

71
Q

Give 2 reasons why there is branching in glycogen

A
  1. Packing for more glucose in limited space
  2. Reduces osmotic pressure

Biochem Exam 1 (7 decks)

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