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Biology - Unit 1 Biological Molecules > Carbohydrates > Flashcards

Carbohydrates Flashcards

1
Q

What are monomers?

A

Monomers are the smaller units from which larger molecules (polymers) are made up of

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2
Q

What are polymers?

A

Larger molecules made up of smaller repeating units (monomers)

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3
Q

What are monosaccharides?

A

Monomers of Carbohydrates

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4
Q

What are the 3 monosaccharides?

A

Glucose
Galactose
Fructose

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5
Q

What is a disaccharide?

A

Two monosaccharides chemically joined together by a glycosidic bond formed in a condensation reaction.

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6
Q

What are the 3 disaccharides?

A

Maltose
Lactose
Sucrose

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7
Q

Which 2 monosaccharides join together to make Maltose + water

A

Glucose + Glucose

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8
Q

Which two monosaccharides join together to make Lactose + water

A

Glucose + Galactose
(hint-galactose has the word lactose in it)

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9
Q

Which two monosaccharides join together to make Sucrose + water

A

Glucose + Fructose

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10
Q

General Formula for Monosaccharides

A

(CH2O)n
n = 1-7

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11
Q

What is an isomer?

A

Molecules with the same molecular formula but different structure

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12
Q

What are the 2 isomers of glucose

A

Alpha Glucose & Beta Glucose

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13
Q

Alpha Glucose

A

C6H12O6
Hexose Sugar (hexagon)

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14
Q

Which way is the Hydroxyl group (OH) on alpha glucose

A

ABBA (Alpha (OH) below, Beta (OH) above)
Hydroxyl (OH) group on the bottom of Carbon 1 & 4
Hydrogen (H) on top of Carbon 1 & 4

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15
Q

Which way is the Hydroxyl (OH) group on Beta glucose?

A

ABBA (Alpha below, Beta above)
Hydroxyl group is on top of Carbon 1 on beta glucose (Hydrogen on the bottom)
Hydroxyl group is on the bottom of Carbon 4 (Hydrogen on top)

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16
Q

What is a condensation reaction?

A

A glycosidic bond forms - alpha (1-4) glycosidic bond
A water molecule is released
Joins 2 molecules together by removing water
Normally catalysed by an enzyme
Polymer molecules made from monomers
Bond formed, H2O removed

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17
Q

What happens when the glycosidic bond forms?

A

A water molecule is released
via a condensation reaction

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18
Q

What is a hydrolysis reaction?

A

A water molecule is used up
A glycosidic bond breaks
Polymers broken down into monomers
Breaks a chemical bond between 2 molecules and involves the removal of a water molecule
Normally catalysed by an enzyme
Bond broken , H2O added

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19
Q

Anabolic and Catabolic

A

Anabolic - Making larger molecules from simpler ones
Catabolic - Making smaller molecules from larger ones

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20
Q

Where does the glycosidic bond form?

A

Between Carbon 1 and Carbon 4
OH + H
H2O so water is removed

21
Q

What is the general formula for disaccharides?

A

C6H12O6+C6H12O6=C12H22O11 + H2O
General Formula = C12H22O11

22
Q

Structure of Glucose (a)

A

Oxygen top right corner
Carbon 1 - H on top,OH on the bottom
Carbon 2 , Carbon 3
Carbon 4 - H on top,OH on bottom
Carbon 5 Top left corner
Carbon 6 - CH2OH on top of Carbon 5

23
Q

Structure of Galactose

A

Same as Glucose except :
Hydroxyl group (OH) on carbon 4 is the opposite
OH on top, H on the bottom

24
Q

Structure of Fructose

A

Pentagon
Oxygen on the top point
Carbon order is anti clockwise
Carbon 2 - Top left
Carbon 2 has HO on the bottom and H2COH on top (carbon 1)
Carbon 1 - On top of carbon 2 H2COH
Carbon 3 - Bottom Left
Carbon 4 - Bottom Right
Carbon 5 - Top Right
Carbon 5 has H on top and CH2OH on the bottom (carbon 6)
Carbon 6 - Bottom of Carbon 5 CH2OH

25
What is the bond formed in maltose?
alpha (1-4) glycosidic bond always have water as a product
26
What is the bond formed in Lactose
alpha (1-4) glycosidic bond always have water as a product
27
What is the bond formed in Sucrose
alpha (1-2) glycosidic bond always have water as a product
28
Hydrolysis enzymes for Maltose, Lactose and Sucrose
Maltose —> Maltase Lactose —> Lactase Sucrose —> Sucrase
29
What are the 3 tests for Carbohydrates
1) Benedict’s test for reducing sugars (glucose, galactose, maltose, fructose) 2) Benedict’s test for non reducing sugars (sucrose) 3) Iodine test for starch
30
What is the Reducing Sugars test
Reduction is a chemical reaction involving the gain of electrons or hydrogen A reducing sugar is a sugar that can donate electrons to another chemical (reduce it) in this case benedict’s reagent
31
What is Benedict’s solution?
An alkaline solution of Copper (II) sulfate When a reducing sugar is heated in boiling water with benedict’s reagent it forms an insoluble red precipitate of Copper (I) oxide The copper (II) sulfate gains an electron and becomes copper (I) sulfate The sugar has been oxidised (loss of electrons)
32
Benedict’s test for reducing sugars steps
1) Add 2cm3 of Benedict’s solution and 2cm3 of the test solution in a test tube 2) Heat in a boiling water bath (95°c) 3)Boil mixture for 5 minutes and observe any colour change Positive result = Colour change from light blue to brick red ppt - Reducing sugar is present Negative result (Non reducing sugar-Sucrose) = No colour change to test solution - Solution stays light blue Weaker solution of reducing sugar may be : green, yellow or orange ppt when heated with benedict’s reagent
33
Benedict’s test for Non-Reducing Sugars (Sucrose)
No change in first test for reducing sugar = boil a fresh sample with dilute HCL for a few minutes to hydrolyse the glycosidic bonds to break down into its monosaccharides 2) Neutralise the solution by adding small amounts of solid sodium hydrogen carbonate (NaHCO3) 3) Then test as before for reducing sugars using benedict’s reagent 4) Sucrose has now been hydrolysed into its monosaccharides glucose and fructose which are reducing sugars so it will react and give a positive result 1) Hydrolyse Glycosidic bonds with dilute HCL 2) Neutralise solution with solid sodium hydrogen carbonate 3) Test as normal
34
What are Polysaccharides?
Long chains of repeating monosaccharides chemically joined together by glycosidic bonds
35
Classification of Carbohydrates
Sugars - Monosaccharides & Disaccharides Polysaccharides- Storage & Structure
36
Which polysaccharides are used for storage?
Starch Glycogen
37
Which polysaccharide is used for structure?
Cellulose
38
What are the main features of polysaccharides?
Large & Insoluble Non reducing - give negative results in benedict’s test Joined by Glycosidic bonds Polymers Used for storage or structure
39
What are the main features of polysaccharides?
Large & Insoluble Non reducing - give negative results in benedict’s test Joined by Glycosidic bonds Polymers Used for storage or structure
40
Starch (storage)
-**Long, branched chains of alpha glucose** -Stored in starch grains in the cytoplasm plant cells - energy store in plants (chloroplasts) - **Compact - lots can be stored in small spaces** - Some branching - Helical shape makes it compact - **Amylase enzyme breaks down starch** - Branched structure allows glucose molecules to be easily released - Glucose molecules released for respiration - **Large molecule so it can’t cross the cell membrane** **a(1-6) glycosidic bond**
41
Hydrolysis of Starch
-Hydrolysed by the enzyme amylase to produce the disaccharide maltose -Starch + Water —> Maltose Polysaccharide —> Disaccharide
42
Amylose and Amylopectin
Polymers of Alpha Glucose Amylose - alpha(1-4) glycosidic bond Amylopectin - alpha(1-4) and (1-6) bond (1-6) bind forms where the branch starts
43
Glycogen (Storage)
Energy store in animals Alpha glucose monomers Insoluble & osmotically inactive Very branched Rapid hydrogenation Stored as small granules, particularly in muscles and liver a(1-6) glycosidic bonds
44
Why is glycogen stored in animals?
Animals are active The glycogen needs to hydrolyse wuicky to release more glucose for respiration which provided energy
45
Cellulose (Structure)
Chains of BETA glucose monomers Strong and Rigid Prevents plant cells bursting Allows cells to be turgid - supports leaves Maximum surface area for photosynthesis Permeable to water
46
Cellulose (structure) pt2
Straight chain polymer Beta(1-4) linkages Contrast a(1-4) glycosidic bonds un started and glycogen No coiling or branching instead an extended and stiff rod-like shape
47
Beta - Glucose unit rotation
Beta Glucose units are rotated by 180° relative to the neighbouring unit 1 unit is flipped upside down so a bond can be formed horizontally not diagonally between the OH group
48
Cellulose - Hydrogen Bonds
Strands of cellulose have hydrogen bonds between OH groups which increases stability Hydrogen bonds form cross links between chains which provides strength to the cell walls Weak hydrogen bonds provide strength in numbers Cellulose gives the plant cell rigidity because the cellulose cell wall is inelastic and has a high tensile strength to prevent the plant cells from bursting

Biology - Unit 1 Biological Molecules (9 decks)

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