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A Level Bio > Chapter 1 Carbs + Biological Molecules (1.1-1.6) > Flashcards

Chapter 1 Carbs + Biological Molecules (1.1-1.6) Flashcards

1
Q

What is hydrolysis used for

A

Breaking up polymers or removing monomers

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2
Q

What is condensation reactions for

A

Making a polymer

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3
Q

Examples of industrial polymers

A
  • Polyester
  • polythene
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4
Q

Natural polymers examples

A

_ polypeptides
- polynucleotide
- polysaccharide

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5
Q

How are hydrogen bonds formed in water

A
  • oxygen is electronegative making it slightly negative causing the hydrogen to be slightly positive
  • this makes it easier for water molecule to bond as H is positive and O is negative so they can bond and the bond between them is a hydrogen bond
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6
Q

What molecules have hydrogen bonding

A
  • hydrogen and fluorine
  • hydrogen and nitrogen
  • hydrogen and oxygen
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7
Q

What monomers are for polypeptide, polysaccharide and polynucleotide

A

Polypeptide- amino acids
Polysaccharide - monosaccharide
Polynucleotide- nucleotides

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8
Q

Properties of monosaccharides

A
  • sweet tasting
  • soluble in water
  • general formula (CH2O)n ——- n is a number from 3-7
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9
Q

Why does the Benedict’s reagent solution turn red as an indicator that there is a reducing sugar

A

Benedict’s reagent is an alkaline solution of copper(11) sulfate (hence why it stays blue if there is no reducing sugar) and when a reducing sugar is heated with the reagent it forms a red precipitate of copper (1) oxide

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10
Q

Large molecules often contain carbon. Explain why is this

A

Carbon easily bonds with other carbon atoms allowing a sequence of carbon atoms of various lengths to be formed, creating a backbone that other atoms can attach to allowing large molecules to form that contain carbon atoms

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11
Q

Examples of reducing sugars

A

All monosaccharides
Some disaccharides

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12
Q

Test for reducing sugars

A

1) add 2cm3 of the food sample into a test tube, if the sample is not a liquid form, first grind it up in water
2) add an equal volume of Benedict’s reagent
3) heat the mixture in gently boiling for 5 minutes

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13
Q

Three types of disaccharides that you need to know

A

Maltose
Lactose
Sucrose

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14
Q

What are the Monosaccharides that make up maltose, the reaction used and the bond formed

A

Monosaccharides: 2 alpha glucose
Reaction: condensation reaction
Bond: glycosidic bond

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15
Q

Monosaccharides that make up lactose

A

Alpha glucose and galactose

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16
Q

Monosaccharides that make up sucrose

A

Alpha glucose and fructose

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17
Q

3 types of polysaccharides that you need to know

A

Starch
Cellulose
Glycogen

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18
Q

What is starch, cellulose and glycogen made from

A

Starch: polymer of alpha glucose
Cellulose: polymer of beta glucose
Glycogen: polymer of alpha glucose

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19
Q

Uses for starch, cellulose, glycogen

A

Starch: storage
Cellulose: structure
Glycogen: storage

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20
Q

What are polysaccharides

A

Polymers formed by combining together many monosaccharide molecules joined together by glycosidic bonds formed in condensation reactions

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21
Q

Test for non reducing sugars

A

1) hydrolyse the disaccharide to form 2 monosaccharides by heating it with dilute hydrochloric acid
2) neutralise by slowly add sodium hydrocarbonate until it stops bubbling HCL as Benedict’s reagent cannot work in acidic conditions
3) test with litmus paper (red → blue) to make sure the solution is alkaline
4) heat with Benedict’s the positive result will form a red precipitate

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22
Q

What is formed when a polysaccharide is hydrolised

A

It forms monosaccharides or disaccharides

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23
Q

Where is glycogen found

A

Brain, liver, muscle

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24
Q

Why is glycogen good for the brain

A

Brain only uses glucose since it is so rich in neurons it is the most energy-demanding organ, using one-half of all the sugar energy in the body so stores glycogen to convert into glucose

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25
Q

Characteristics of polysaccharides

A
  • Large molecules so are insoluble
  • good for storage as they don’t alter osmotic pressure since they can’t dissolve is water
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26
Q

Test for starch

A

1) add 2cm3 of the sample into a test tube
2) add 2 drops of iodine solution and Shake
3) positive - blue-black negative- red-brown

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27
Q

Monomers of starch

A

Alpha glucose

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28
Q

Monomers of glycogen

A

Alpha glucose

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29
Q

Monomers of cellulose

A

Beta glucose

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30
Q

Function of starch

A

Insoluble store of glucose

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31
Q

Structure of starch

A
  • Coiled into a helix making it compact for storage
  • large and insoluble so doesn’t diffuse out the cell or affect water potential and osmosis
  • amylose is an unbranched polymer of starch whilst amylopectin is a highly branched polymer of starch therefore amylopectin has more ends for faster hydrolysis
  • polymer of glucose so can be hydrolysed
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32
Q

Polymers of starch

A
  • Amylose
  • amylopectin
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33
Q

Bond between monomers of starch

A

1-4 glycosidic bond (amylose) and 1-6 glycosidic band (amylopectin)

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34
Q

Monomers of glycogen

A

Alpha glucose

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35
Q

Bonds between monomers of glycogen

A

1-6 glycosidic bonds and 1-4 glycosidic bonds

36
Q

Function of glycogen

A

Insoluble store of glucose

37
Q

Structure of glycogen

A

1) Highly branched - as it has more 1-6 glycosidic bonds so more ends for faster hydrolysis
2) Coiled into a helix so is compact
3) Polymer of glucose so easily hydrolysed
4) Insoluble so does not diffuse out of the cell and does not affect water potential

38
Q

Bonds between monomers of cellulose

A

1-4 glycosidic bonds

39
Q

Function of cellulose

A

Provides structural strength to cell wall

40
Q

Structure of cellulose

A
  • Straight unbranched chains parallel to each other held by many hydrogen bonds to form fibrils - the number of fibril creates a strong structure usual for its structural role
41
Q

Test for lipids

A

1) take a dry and grease free test tube
2) add 2cm3 of the food sample to the test tube then add 5 cm3 of ethanol
3) Shake the tube thoroughly to dissolve any lipids in the sample
4) add 5cm3 of water and Shake gently
Positive milky while emulsion negative clear

42
Q

Control for test for lipids

A

Repeat the experiment using water instead of the sample and the final solution should be clear

43
Q

Why is a cloudy white emulsion formed in lipid test

A

The lipids does not dissolve in the water so will float on top of the sample forming an emulsion and the Light passing through the lipid will be refracted as it passes from the oil to the water droplets making it appear cloudy

44
Q

What causes lipids to be different

A

The fatty acids

45
Q

What always stays the same in lipids

A

Glycerol

46
Q

How are triglycerides formed

A

Through condensation between one molecule of glycerol and 3 molecules of fatty acids

47
Q

What is the bond between fatty acids and glycerol called

A

Ester bond

48
Q

Ester bond

A

C-o -c=o

49
Q

Saturated

A

Carbon to carbon single bond

50
Q

Unsaturated

A

Carbon to carbon double bond

51
Q

How fatty acids differ

A

Length of carbon bonds
Degree of saturation (number and presence of c=c )

52
Q

Properties of triglycerides

A
  • Energy source
  • metabolic water source
  • hydrophobic
  • good energy store
53
Q

Why are triglycerides a good energy source

A

Due to a high ratio of energy storing Carbon to hydrogen bonds compared to the number of carbon atoms

54
Q

Why are triglycerides a metabolic water source

A

Due to the high ratio of hydrogen to oxygen atoms they act as a metabolic water source as they can release water when oxidised

55
Q

Why are triglycerides hydrophobic

A

they have a non-polar structure, which makes them insoluble in water

56
Q

Why are triglycerides a good energy store

A
  • they have a low mass to energy ratio so a lot can be stored without increasing the mass and therefore preventing the movement of an animal
  • they are large and insoluble so they don’t affect water potential and osmosis so you can store lots of them for energy
57
Q

What are phospholipids made up of

A

2 fatty acid chains and a phosphate group both attached to a glycerol

58
Q

Why can the phosphate group of a phospholipid dissolve in water

A

As it contains a negative charge causing it to have a hydrophilic head and due to its negative charge it causes the molecule to be polar and since its polar it can dissolve in water

59
Q

Why can’t the lipids in phospholipids dissolve in water

A

As they Are non polar so will be hydrophobic

60
Q

How are phospholipids positioned in water

A

The heads are exposed to water and the tails (lipids) are not forming a phospholipid bilayer membrane structure

61
Q

Phospholipids properties

A
  • Phospholipidbilayer creates a hydrophobic barrier between inside and outside the cell
  • phosphate heads maintains the structure of the membrane
  • phosphate heads can attach to carbs to form glycoproteins
  • useful in cell signalling
62
Q

Roles of lipids

A
  • Energy store
  • waterproof
  • Insulation and electricity
  • Protection
63
Q

Why are lipids a good energy store

A

They are compact and lightweight so can store excess energy and stores twice as much energy as carbs

64
Q

Examples of lipids being a good insulator of heat and electricity

A
  • Heat layer of fat under skin -
  • electrical insulator in myelin sheath around nerves
65
Q

How are animals and plants waterproof

A

Plants: cuticles on leaves
Animals: oils from sebeaecaus glands

66
Q

What are proteins

A

Polymers made up of the monomer amino acid

67
Q

What are amino acids

A

Monomers that are joined by condensation reactions to form a polypeptide chain

68
Q

4 levels of the structure of protein

A

Primary
Secondary
Tertiary
Quaternary

69
Q

What is the primary structure

A

The order of amino acids in the polypeptide chain

70
Q

What is a polypeptide chain

A

Chain of amino acids all joined together by condensation reactions supported by peptide bonds

71
Q

What is the secondary structure

A

The curling or folding of the polypeptide chains (from the primary structure) into alpha helices or beta pleated sheets due to the formation of hydrogen bonds

72
Q

Why does the secondary structure form the shapes of alpha helices and beta pleated sheets

A

Due to the hydrogen bonding between the c=o groups of the carboxylic acid of one amino acid and the n - h in the amine group of another amino acid ( o is electronegative and h is slightly positive forming hydrogen bonding)

73
Q

What causes the tertiary structure to form

A

By the interaction (hydrogen bond/disulphide/ionic) between R groups forming a more complex and specific 3d shape

74
Q

Types of bonds used in a tertiary structure and where they are located and their strength

A

Disulphide bridges- between two sulfur atoms of two cysteine molecules - fairly strong and not easily broken
Ionic bonds - between c=o and NH groups found on the R group - weaker than disulphide bridges and broken by pH changes
Hydrogen bonds - not easily broken

75
Q

What is the quaternary structure

A

the specific 3d shape of a protein that is determined by many polypeptide chains and/or prosthetic groups bonded together

76
Q

What happens if a protein is denatured

A

The bonds which hold the secondary structure and tertiary structure in shape break and the unique 3d shape is lost

77
Q

Conditions to denature a protein

A
  • high temperature
  • high or low pH
78
Q

Why is the primary structure important

A

As if one amino acid in the sequence is different it will cause the ionic/hydrogen/disulphide bonds to form in a different location causing a change in the 3d shape so will no longer function or have a different function

79
Q

Why are saturated lipids better than unsaturated lipids

A

Since they can store more energy as they have a higher ratio of hydrogen to carbon bonds

80
Q

What are conjugated proteins

A

Proteins in the quaternary structure contains prosthetic groups (non proteins) to help the protein carry out its role

81
Q

Test for proteins

A

1) place the sample of the solution to be tested in a test tube and add equal volumes of sodium hydroxide solution at room temperature
2) add a few drops of dilute copper (11) sulphate solution and mix gently
(Blue->purple)

82
Q

When bread becomes stale, the structure of some of the starch is
changed. This changed starch is called retrograded starch.
Scientists have suggested retrograded starch is a competitive inhibitor of
amylase in the small intestine.
Assuming the scientists are correct, suggest how eating stale bread could
help to reduce weight gain

A

Less hydrolysis of starch;
Accept no hydrolysis
(To) maltose;
(So) less absorption (of glucose)

83
Q

define monomer

A

(a monomer is a smaller / repeating) unit / molecule from which larger
molecules / polymers are made

84
Q

define polymer

A

molecules made from a large number of monomers joined together

85
Q

define monosaccharide

A

Monosaccharides are the monomers from which larger carbohydrates are made

86
Q

how are triglycerides formed

A

Triglycerides are formed by the condensation of one molecule of glycerol and three molecules of fatty acid to form an ester bond

A Level Bio (15 decks)

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