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Biochemistry > Carbohydrates, Digestion and Transport > Flashcards

Carbohydrates, Digestion and Transport Flashcards

1
Q

Carbohydrate General Formula

n is usually what quantity?

A

(C)n(H2O)n

Greater than 3

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2
Q

The Citric Acid Cycles anabolic role is ______.

What is the catabolic role?

A

Fatty Acid Synthesis

Oxidative Phosphorylation- ATP production

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3
Q

Triose
Tetrose
Pentose
Hexose

How many C,H,O for each?

A

Triose - C3H6O3
Tetrose- C4H8O4
Pentose- C5H10O5
Hexose- C6H12O6

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4
Q

Carbohydrates have lots of _______ functional group making them __________- _______ or ________.

A

hydroxyl groups (OH) making them polyhydroxy -aldehydes or ketones.

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5
Q

What is the minimum number of carbons that must be present in a carbohydrate?

A

3

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6
Q

Trioses are the smallest ____________, the monomer of carbohydrates.

What are the 2 common trioses?

A

Glyceraldehyde - Aldehyde

Dihydroxyacetone- Ketone

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7
Q

Where does glyceraldehyde come from?

A

Fructose 1,6 BP

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8
Q

Describe the structure of an aldehyde and a ketone.

A

AldeHyde : Carbon double bonded to oxygen
single bond to R group
single bond to H

Ketone: Carbon double bonded to oxygen
single bond to R group
single bond to R

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9
Q

Common pentoses

A

D-Ribose - Aldopentose

2-Deoxy-D-ribose - Aldopentose

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10
Q

Common Hexoses

A

D- Glucose - Aldehyde (aldohexose)

D-Fructose -Ketone

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11
Q

Glucose is a _____ose with ____ chiral carbons.

A

hexose, 4

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12
Q

What is the epimer of glucose?

TEST QUESTION

A

Galactose!

The C-4 chiral carbon has its H and OH groups oriented in the opposite direction

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13
Q

_______ is the epimer of glucose.

A

Galactose

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14
Q

What kinds of monosaccharides can cyclize in _______ solution ?

How does this occur?

A

Molecules with over 5 carbons cyclize in AQUEOUS solution.

This occurs when the alcohol which is nucleophilic attacks the carbonyl carbon creating a cyclic structure.

The carbonyl carbon which has been cyclized is called the anomeric carbon.

This creates ANOTHER chiral carbon to create another stereoisomer as the hydroxyl group can be above or below the plane.

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15
Q

Molecules with at least ______ can be cyclized.

What is an anomeric carbon and why is it important to the structure of carbohydrates?

A

5 carbons

The anomeric carbon is the carbonyl carbon group that has been cyclized by an OH in the monosaccharide chain.

This creates another chiral carbon as a new hydroxyl group is created that can exist above or below the plane creating NEW stereoisomers.

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16
Q

In BETA-D-glucopyranouse, the cyclized OH group faces ______.

A

Up

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17
Q

In ALPHA-D-glucopyranouse, the cyclized OH group faces ______.

A

Down

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18
Q

Name the Monosaccharide Components of Dietary Carbohydrates

A
  1. Alpha-d- glucose
  2. Alpha-d-galactose
    3.Alpha-d-fructose
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19
Q

Disaccharides include _____ and _____.

A

Lactose : Glucose and Galactose

Sucrose: Glucose and Fructose

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20
Q

Starches include ____ and _____ which are polymers of ________.

Describe the linkages

A

Amylose and Amylopectin which are polymers of glucose

Amylose : A1,4 between 2 glucose molecules

Amylopectin: A1,4 between 2 glucose molecules AND A1,6 on glucose molecule with C4 bonded.

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21
Q

Lactose is a _________ made of a ______ linkage between _____ and _____.

A

Lactose is a disaccharide made of a B1,4 linkage between galactose and glucose

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22
Q

Sucrose is a _________ made of a ______ linkage between _____ and _____.

A

Sucrose is a disaccharide made of a A1,2 linkage between glucose and fructose

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23
Q

_______ breaks the _______ linkage in lactose.

A

Lactase

beta 1,4 (galactose and glucose)

24
Q

_______ breaks the _______ linkage in sucrose.

A

Sucrase

alpha 1,2 (glucose nad fructose)

25
Q

_______ breaks the _______ linkage in amylose.

A

Amylase

alpha 1,4 (2 glucose)

26
Q

_______ breaks the _______ linkage in Amylopectin.

A

Amylase and Isomaltase

Alpha 1,4

Alpha 1,6

27
Q

Dextran in _______ are polymers of ____ with _________ linkages that are ________.

A

plaque are polymers of glucose with alpha 1,3 and alpha 1,6 linkages that are glycosidic

28
Q

Dextran is water soluble.

True or False

A

FALSE

29
Q

Where does the ______ needed to synthesize Dextran come from?

A

Glucose

Obtains from sucrose

30
Q

How does ________ get broken down into _______ by _________ using ________ases for dextran formation?

A

sucrose get broken down into glucose by Streptococcal mutans using Glucosyl Transferases to break sucrose into glucose and fructose and transferring the glucose to the growing dextran glucose chain.

31
Q

You can only get caries from _______ because it is what provides the __________ needed to make _________.

A

Sucrose because the breakdown of it by Streptococcal mutagens by Glucosyl transferase is what provides the glucose needed to make Dextran of oral plaque

32
Q

Humans can’t degrade the ____linkages in dextran because __________.

A

Alpha 1,3 glycosidic linkages

lack enzymes

33
Q

Cellulose is a polymer of ________held together by ______linkages and is found in __________.

Is it digestible?

A

glucose ; Beta 1,4 linkages

Plants, vegetables, trees

NO

34
Q

Is cellulose water soluble? Why or why not?

A

NO

All the OH groups are involved with H-bonds

35
Q

Why can’t we digest cellulose?

A

We don’t produce the enzymes to break the Beta 1,4 linkages between glucose monomers.

36
Q

Dietary fiber is _______ that is not _________.

A

Carbohydrate that is not readily digested

37
Q

Soluble fiber dissolves ________ and forms a _______ in the _______.

It is broken down by ______ in the _______.

Where is it found

A

Soluble fiber dissolves in water and forms of gel like substance in the stomach.

It is broken down by bacteria in the large intestine.

It is found in oats, beans, in the flesh of fruits

38
Q

How is insoluble fiber digested?

Where is it found?

A

Insoluble fiber does not dissolve in water.

It passes through the digestive system intact.

It is found in whole wheat, flour, nuts, and beans.

39
Q

Dietary fiber reduces the risk of what diseases?

A

Colon Cancer

Cardiovascular Disease

40
Q

How is soluble fiber beneficial?

A

Slow absorption of food and lowers glycemic index

(makes blood sugar increase after eating more gradual)

Lowers cholesterol

41
Q

Why is insoluble fiber beneficial?

A

Increases bowel movements (colon cancer)

42
Q

Digestion of Carbohydrates starts in the _______.

It then proceeds to the ______ where ___________.

These products enter the ________.

Describe what happens at each step

A

Mouth

Saliva creates salivary amylase which breaks down the Alpha1,4 linkages in amylose and amylopectin starches

Pancreas

Pancreatic amylase degrades alpha-dextrin trisaccharides produced by the breakdown of starch

Small Intestine

Along the intestinal epithelial cells, the brush border has disaccharides that break down disaccharides into monosaccharides to be absorbed by the intestinal epithelial cells

43
Q

Our small intestine can absorb polysaccharides.

True or False

A

FALSE

They must be broken down into monosaccharides.

44
Q

Lactose Intolerance

A

Our lactase reduces as we grow so we are unable to break down lactose.

Lactic acid produced by anaerobic bacteria causes diarrhea as it draws water in

Bacterial fermentation also produces hydrogen and methane gas

45
Q

In order for glucose to enter the lumen of small intestine from diet what transporters are required?

A

GLUT5 - Passive Fructose

SGLT1 - Secondary Active Glucose and Galactose

46
Q

In order for glucose to enter the blood from the small intestine what transporters are required?

A

GLUT2 for ALL passive transport

47
Q

In order for glucose to enter the tissues from blood what transporters are required?

A

GLUT passive transport for ALL

48
Q

In general, what are the two types of glucose carriers?

A

Passive GLUTs : Follows concentration gradient

Secondary Active SLGTs: Against concentration gradient with sodium

49
Q

Secondary Active SLGTs move _______ concentration gradient coupled to a ________.

A

Against, favorable gradient for sodium

50
Q

Na+ is _______ on the outside of the cell and ______ on the inside.

When Na+ is absorbed, what other two substances will follow?

A

high

Low

This means sodium can readily enter the cell.

Chloride and Water

51
Q

Rate of glucose transport is dependent on _______ and _______.

A

Sodium and glucose

52
Q

What is the basis of oral rehydration?

A

Glucose
Sodium
AND potassium

53
Q

SLGT1 transports ______ to the __________

GLUT5 transports ______ to the __________

GLUT2 transports ______ to the __________

A

Glucose/Galactose to the epithelial cells of intestine from intestinal lumen by coupling with Na+ uptake

Fructose to the epithelial cells of intestine from intestinal lumen

Glucose/Fructose and Galactose to the blood from epithelial cells of intestine

54
Q

GLUT 2 is found in what organs?

A

Small Intestine Epithelial Cells
Liver
Pancreas
Small Intestine

Kt is HIGH meaning that liver will only take up glucose when BLOOD glucose is high and will not take up glucose when BLOOD glucose is low

We want our pancreatic beta cells to take up glucose when blood sugar is high to release insulin.

55
Q

GLUT4 is found where?

What is it directly stimulated by?

A

Adipose, muscle, skeletal and heart

Insulin

56
Q

Insulin directly stimulates GLUT2 and GLUT4.

True or False

A

FALSE

GLUT2 is actually stimulated by blood glucose levels. Insulin activity in response to the blood glucose levels can affect GLUT2 activity in pancreatic beta cells

Biochemistry (18 decks)

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