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Biology A LEVEL > Carbs and Lipids > Flashcards

Carbs and Lipids Flashcards

1
Q

What 5 main biological molecules are all living organisms made from?

A

carbohydrates
lipids
protein
DNA/RNA
water

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2
Q

What is a monomer?

A

an individual unit that makes a polymer

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3
Q

What is a polymer?

A

many repeating units of monomers

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4
Q

What are 4 types of monosaccharides?

A

alpha glucose

beta glucose

galactose

fructose

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5
Q

What are all 4 monosaccharides an example of?

A

reducing sugars (act as reducing agents in chemical reactions)

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6
Q

What are 3 types of disaccharides?

A

maltose

lactose

sucrose

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7
Q

What is sucrose an example
of?

A

a non reducing sugar

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8
Q

What are 3 types of polysaccharides and which glucose isomer are they formed by?

A

starch (alpha glucose)

glycogen (alpha glucose)

cellulose (beta glucose)

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9
Q

What is starch?

A

-polysaccharide of alpha glucose joined via condensation reaction
-energy store found in plant cells in the form of grains

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10
Q

What kind of bonds form starch?

A

1,4 and 1,6 glycosidic bonds

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11
Q

Describe 4 structural features of starch:

A

-large
-insoluble
-helix shape
-branched

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12
Q

How does starch being large aid its function?

A

it won’t diffuse out of cells

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13
Q

How does starch being insoluble aid its function?

A

won’t affect water potential so it is osmotically inactive

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14
Q

How does starch being in a helix shape aid its function?

A

it makes it a compact energy store

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15
Q

How does starch being branched aid its function?

A

increases the surface area so glucose can rapidly be released when needed for aerobic respiration

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16
Q

What is glycogen?

A

-polysaccharide of many alpha glucose joined via condensation reaction to form glycosidic bonds
-energy store in the form of granules in the cytoplasm

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17
Q

What bonds form glycogen?

A

1,4 glycosidic bonds and many more 1,6 glycosidic bonds compared to starch

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18
Q

Describe the structure of glycogen and explain how this aids its function:

A

SEE STARCH

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19
Q

What is cellulose?

A

-polysaccharide of many beta glucose molecules joined through condensation reactions
-used to make cell walls

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20
Q

How is cellulose formed?

A

1,4 glycosidic bonds

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21
Q

How is cellulose joined together?

A

joined together by hydrogen bonds in long straight/ unbranched chains that forms fibrils

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22
Q

Describe the structure of cellulose:

A

-Made from beta glucose
-Parallel chains can form hydrogen bond ‘cross links’
-Can form microfibrils which join to form fibres

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23
Q

How does cellulose being made from beta glucose aid its function?

A

Allows long straight chains to form

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24
Q

How does cellulose being in parallel chains that can form hydrogen bonds aid its function?

A

adds strength to cell walls

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25
Q

How does cellulose being able to form microfibrils aid its function?

A

adds strength to cells walls

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26
Q

What is reduction?

A

the gain of electrons

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27
Q

What is a reducing sugar able to do and how do we test for this ?

A

-able to lose an election and give it to another
-by giving them something to reduce

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28
Q

What does Benedict’s raegent contain?

A

cu2+ ions in the form of copper II sulfate
(blue colouring)

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29
Q

When does copper sulfate become red copper oxide ?

A

When the cu2+ ions gain an electron from a reducing sugar they become cu+ ions in the form of red copper I oxide

30
Q

How do you do the test for reducing sugars?

A

-Add Benedict’s solution
-Heat
-Colour change from blue to green , yellow, orange and red if positive

31
Q

What are the possible colour results for a benedict’s test?

A

blue- negative
green- very low
yellow- low
orange- moderate
red- high

32
Q

What type of results are the benedict’s test and what does this mean?

A

-Semi- quantitative
- They give an idea of concentration but not fully quantitatively as numbers would

33
Q

How do you do the test for a non-reducing sugar?

A
  • Get a negative Benedict’s test
  • Boil with HCL to hydrolyse the non-reducing sugar
  • Neutralise HCL using NaOH
  • Add Benedict’s
  • Heat
  • Colour change from blue to red
34
Q

Why does the colour change at the top of the solution first in a reducing sugars test?

A

The hotter particles in the bottom of the solution are rising because they are being heated and so the hottest point in the solution is at the top. Molecules have more kinetic energy at the top so more successful collisions (convection currents)

35
Q

What is a colorimeter?

A

A light-sensing device that is used to measure the absorbance and transmittance of light as it moves through a sample of liquid.

36
Q

What must be done before using a colorimeter?

A

Filter off the red precipitate leaving just the blue Benedict’s solution

37
Q

What type of testing is a colorimeter?

A

Quantitative testing

38
Q

How does a colorimeter work?

A

-Test tube of solution into colorimeter
-Light inside of unit in colorimeter shines into solution
-Solution absorbs light
-This is picked up by a light receptor which is connected to the screen giving an absorbance reading

39
Q

What are the steps for identifying an unknown glucose solution?

A

Step 1- make known concentrations of glucose (0, 12.5, 25, 50, 100)

Step 2- Perfom a benedict’s test

Step 3- Perform colorimetry to identify absorbance (0, 0.125, 0.25, 0.5, 1)

Step 4- Produce a calibration curve with concentration on x and absorbance on y

Step 5- Perfom benedict’s and colorimetry on unknown sample to identify absorbance

Step 6- Read off graph to identify concentration of unknown solution

40
Q

What does an absorbance and concentration graph look like?

A
41
Q

What does the absorbance reading read if the concentration of the solution is 100 and why?

A

1 because the solution is absorbing all the light and no light makes it to the sensor (maximum concentration)

42
Q

What does a transmission value show?

A

The higher the number, the more light can pass through. 0= max concentration 1= dilute

43
Q

What are lipids used for?

A
  • Energy store
  • Insulation (thermal, electrical)
  • Water proofing (waxy cuticle)
  • Protection (heart, kidneys)
44
Q

What are the two types of lipids?

A

Triglycerides and Phospholipids

45
Q

What do triglycerides consist of?

A

They consist of fats (solid at room temp) and oils (liquid at room temp)

46
Q

What is the general structure of triglycerides?

A
47
Q

Do fatty acid molecules join together?

A

NO. They are individual molecules that don’t join together. Lipids are neither polymers nor are they monomers.

48
Q

What does this chemical structure show?

A

Glycerol

49
Q

What does this chemical structure show?

A

Fatty acids

50
Q

What is the bond of carbon, oxygen and hydroxide called?

A

Carboxylic acid group

51
Q

How are fatty acids and glycerol joined together?

A

OH from carboxylic acid group and H from glycerol form H20 via a condensation reaction

52
Q

When does an ester bond form?

A

when a hydroxyl (-OH) group from the glycerol bonds with the carboxyl (-COOH) group of the fatty acid. The formation of an ester bond is a condensation reaction. For each ester bond formed a water molecule is released.

53
Q

Describe 4 structures of Lipids:

A
  • Insoluble
  • Low mass to energy ratio
  • High ratio of H atoms to O atoms
  • High ratio of energy storing C-H bonds
54
Q

How does a lipid being insoluble aid its function?

A

osmotically inactive

55
Q

How does a lipid having a low mass to energy ratio aid its function?

A

don’t have to carry heavy energy store

56
Q

How does a lipid having a high ratio of H atoms to O atoms aid its function?

A

water can be released during breakdown

57
Q

How does a lipid having a high ratio of energy storing C-H bonds aid its function?

A

energy dense molecule

58
Q

What are saturated fatty acids?

A

the hydrocarbon chain has only single bonds between carbons

59
Q

What are unsaturated fatty acids?

A

the hydrocarbon chain consists of at least one double bond between carbons

60
Q

What are phospholipids?

A

major component of cell membranes

61
Q

What is the general structure for a phospholipid?

A
62
Q

What can be said about the fatty acid ‘tails’ and their electrons?

A

The fatty acid tails are ‘non polar’ and so the electrons are evenly spread. They are hydrophobic.

63
Q

What can be said about the ‘polar head’ of a phospholipid?

A

Delta positive and delta negative regions. There is an uneven distribution of electrons. It is hydrophilic.

64
Q

What is an amphipathic?

A

A molecule with polar and non-polar regions. This property is essential to form a phospholipid bilayer.

65
Q

What is the chemical structure of a phospholipid?

A
66
Q

Describe the structure of phospholipids:

A

-Hydrophobic/ hydrophilic regions
-Glycolipids can form

67
Q

How do phospholipids having hydrophobic/ hydrophilic regions aid its function?

A

Allows phospholipid bilayer formation (barrier around cells formed by thin polar membrane made of two layers of lipid molecules)

68
Q

How is a phospholipid bilayer created?

A

-Have two charged regions, so they are polar.
-In water they are positioned so that the heads are exposed to water and the tails are not.
-This forms a phospholipid bilayer membrane structure which makes up the plasma membrane around cells.

69
Q

How do glycolipids being able to form from phospholipids aid its function ?

A

Allows for cell recognition

70
Q

What is the emulsion test for lipids?

A

-Add ethanol
-Add distilled water
-Shake
-White emulsion layer if positive

Biology A LEVEL (11 decks)

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