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Medicine Year 1 Semester 1 > Introduction To Carbohydrates > Flashcards

Introduction To Carbohydrates Flashcards

1
Q

How are carbohydrates produced ?

A

They are produced by photosynthesis in plants.
32ATP per glucose

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1
Q

What are the different types of carbohydrates ?

A

Monosaccharides
Disaccharides
Polysaccharides

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2
Q

Monosaccharides

A

The simplest carbohydrates

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3
Q

Disaccharides

A

Consists of 2 monosaccharides

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4
Q

Polysaccharides

A

Consists of many monosaccharides

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5
Q

How do monosaccharides react ?

A

Hydrolysis

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6
Q

What do monosaccharides consist of ?

A

3-6 carbon atoms
A carbonyl group
Several Hydroxyl groups

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7
Q

What are 3 functions of carbohydrates ?

A

Energy storage
Components of complex molecules
Recognition of events in protein folding

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8
Q

Aldose

A

Monosaccharide with an aldehyde group (C=O at the end of a carbon chain) and many hydroxyl groups (-OH)

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9
Q

Ketose

A

Monosaccharide with a ketone group (C=O between 2 carbons) and many hydroxyl groups (-OH)

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10
Q

Chiral molecules

A

Non-superimposable mirror images
A carbon with 4 substituent groups that can be mirrored

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11
Q

Fischer projection

A

Used to represent carbohydrates

The most oxidised group is at the top
Chiral carbons are represented at intersections between vertical and horizontal lines.

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12
Q

L-form isomer

A

The -OH group on the chiral carbon FARTHEST from the carbonyl group is on the LHS

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13
Q

D-form isomer

A

The -OH group on the chiral carbon FARTHEST from the carbonyl group is on the RHS

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14
Q

What are form are naturally occurring amino acids ?

A

L-form isomers

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15
Q

What are form are naturally occurring carbohydrates ?

A

D-form isomers

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16
Q

Where is D-glucose found ?

A

Found in fruits and honey
Blood Sugar

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17
Q

What is the name of a D-glucose ?

A

Aldohexose

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18
Q

What is the difference between D-glucose and D-galactose ?

A

The body cannot digest galactose.
It must be converted into glucose first.
-OH group attached to C4 is on different sides
D-glucose RHS
D-galactose LHS

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19
Q

Can the body digest galactose ?

A

NO ! It must be converted into glucose first.

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20
Q

Galactosemia cause

A

Lack of enzymes required for galactose metabolism

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21
Q

Effects of galactosemia

A

Accumulation of galactose intermediates
Toxic effects in liver, brain, kidneys and eyes.

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22
Q

What are cyclic structures ?

A

More prevalent form of monosaccharides with 5/6 carbon atoms.

23
Q

When do cyclic structures form ?

A

When the hydroxyl group on C5 reacts with the aldehyde or ketone group.

24
Q

3 steps of cyclic structure formation of glucose

A
  1. Number the carbon chain
  2. Turn the chain clockwise to form a
    linear open chain
  3. Fold the linear chain into a hexagon
  • C5 bonds to C1
  • C6 group is placed above the ring
  • Add the -OH groups
  • C1 receives new -OH
    (down = Alpha form) (up=Beta form)
25
Q

What happens when alpha/beta glucose is placed in solution ?

A

The cyclic structure opens and closes.

Glucose is converted between alpha and beta forms through a DYNAMIC FLOW.

26
Q

What is a reducing sugar ?

A

A sugar that will reduce inorganic ions e.g. Cu++ (Fehling’s reagent)

27
Q

What are examples of reducing sugars ?

A

All monosaccharides are reducing sugars.

28
Q

What is a reducing agent ?

A

One which donates electrons and gains protons.

29
Q

Function of Fehling’s reagent

A

Determines the levels of glucose in the blood

30
Q

What are the 3 main steps in Fehling’s reaction ?

A
  1. Glucose is oxidised
  2. Copper is reduced
  3. Colour change occurs in the presence of a reducing sugar.
    blue ——> orange
31
Q

How do you determine the amount of reducing sugar in a persons blood ?

A

The amount of colour is directly proportional to the concentration.

32
Q

What is the glucose oxidase test ?

A

More practical application of glucose level testing.

Used in clinical settings.

33
Q

Disadvantage of Fehling’s test

A

It requires boiling, and so isn’t very practical.
It is not specific for glucose.

34
Q

How does glucose enter red blood cells ?

A

In a non-insulin dependent manner.

35
Q

What are the results of uncontrolled hyperglycemia ?

A

Uncontrolled hyperglycemia results in a covalent linkage between
glucose and the NH2 terminal amino acid of the hemoglobin β chain.
The resulting adduct is designated as HbA1c.

36
Q

Glycation

A

Non-enzymatic natural addition of sugar

37
Q

What is lactose ?

A

Disaccharide of beta-D-galactose or beta/alpha-D-glucose.

38
Q

Sucrose

A

Glucose + fructose

39
Q

Maltose

A

Glucose + glucose

40
Q

Galactose

A

Glucose + lactose

41
Q

What causes a lactose intolerance ?

A

Lack of lactase enzyme in SMALL INTESTINES.

42
Q

Results of Lactose intolerance

A

Lack of lactase in small intestine
Lactose passes into colon
Bacteria start to ferment lactose
Stomach cramps, bloating, flatulence

43
Q

Function of lactase enzyme

A

Splits lactose into glucose and galactose.

44
Q

What is the most common polysaccharide in animal cells ?

A

Glycogen

45
Q

What is the function of glycogen ?

A

The storage form of glucose

46
Q

Where is glycogen found ?

A

In the liver and muscle

47
Q

Structure of glycogen

A

Highly branched polysaccharide made of multiple glucose units linked by alpha-1,4 and alpha-1,6-glycosidic bonds.

48
Q

What is an advantage of the branched structure in glycogen ?

A

Lots of ends so can release lots of glucose easily. So, this makes it an efficient store.

49
Q

What is starch ?

A

The plant form of carbohydrate ingested by humans.

50
Q

What are the 2 forms of starch ?

A

Amylose
Amylopectin

51
Q

Amylose structure

A

Unbranched starch comprised of glucose units

52
Q

Amylopectin structure

A

Branched form of starch

53
Q

Which enzyme hydrolyses amylose and amylopectin ?

A

alpha- amylase secreted by the salivary glands and the pancreas.

54
Q

Function of cellulose

A

Storage in plants

55
Q

What is an important source of diversity ?

A

Blood groups
Viral protein coats

56
Q

Is cellulose digestible by humans ?

A

NO ! Humans don’t have cellulases to recognise the inverted/flipped structure of cellulose.

Medicine Year 1 Semester 1 (37 decks)

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