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IB BIOLOGY REVISION > Carbohydrates and lipids Details > Flashcards

Carbohydrates and lipids Details Flashcards

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1
Q

Examples of polymers

A

-Nucleic acids(DNA, RNA)
-Polysaccharides(e.g. starch, glycogen, cellulose, etc.)
-Polypeptides(e.g. insulin, collagen, spider silk, etc.)

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2
Q

How are the covalent bonds that link the monomers in polymers made?

A

By condensation reactions

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3
Q

What happens in a condensation reaction?

A

-A water molecule is made by removing an -OH (hydroxyl group) from one of the molecules and a hydrogen from the other
-The other parts of the molecules are linked together

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4
Q

What happens in a hydrolysis reaction?

A

-A large molecule is broken down into smaller molecules
-A water molecule is used up in the process(it is split into -H and -OH groups, each of which bond to one of the smaller molecules)

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5
Q

Examples of hydrolysis reactions

A

polypeptide + water → amino acids

polysaccharide + water → monosaccharides

glyceride + water → fatty acids + glycerol

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6
Q

Monosaccharides contain only atoms of carbon, hydrogen and oxygen in the ratio…

A

1:2:1

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7
Q

Difference between glucose and ATP

A

Glucose is primarily the source that is metabolized to produce ATP, while ATP is the immediate energy carrier that powers cellular activities

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8
Q

Properties of glucose(and how they help with its functions)

A

-Soluble in water(allows for the transport of carbohydrates in blood, where glucose is dissolved in the plasma)
-Can be oxidized(makes glucose a potential source of energy which is released when glucose is used as a substrate in cell respiration)
-Chemically stable(allows for energy storage, usually after conversion to a polysaccharide)

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9
Q

What do plants use as an energy store?

A

Starch

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10
Q

What do mammals use as an energy store?

A

Glycogen

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11
Q

Where is glycogen stored in mammals

A

In the liver and muscles

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12
Q

Glycogen is composed of…

A

α-glucose(alpha glucose)

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13
Q

Starch is composed of…

A

α-glucose(alpha glucose)

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14
Q

Types of starch molecules

A

-Amylose
-Amylopectin

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15
Q

Features of amylose

A

-Made up of α-glucose
-α-glucose linked by 1→4 glycosidic bonds
-Chain is helical rather than straight(due to bond angles)

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16
Q

Features of amylopectin

A

-Made up of α-glucose
-α-glucose linked by 1→4 and 1→6 glycosidic bonds
-Branched molecule

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17
Q

Type of reaction with which glucose can be removed from starch and glycogen molecules

A

Hydrolysis reaction(breaks 1→4 glycosidic bond to separate one glucose molecule from the end of the chain, allowing it to be transported elsewhere or used in the cell)

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18
Q

Why does adding or removing glucose happen more quickly with amylopectin than amylose?

A

The branched structure provides more ends of chains

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19
Q

Percentage of starch molecules which are amylose

A

25%

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20
Q

Percentage of starch molecules which are amylopectin

A

75%

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21
Q

Difference between the structures of glycogen and amylopectin

A

-In glycogen, about 1 in 10 glucose molecules has a 1→6 bond, compared with about 1 in 20 in amylopecting
-Hence, glycogen molecules are more branched

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22
Q

Why strach and glycogen do not have a fixed molecular mass

A

The limitless addition and removal of glucose

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23
Q

Reasons why starch and glycogen function well as energy stores

A

-The coiled and branched form of the molecules makes them compact, so they do not take up much space in cells
-They are relativelu insoluble so do not draw an excessive amount of water into cells by osmosis
-When in surplus, glucose can easily be depositied, and it can be withdrawn when there is a shortage

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24
Q

Features of cellulose

A

-Composed of β-glucose
-The β-glucose molecules are linked by glycosidic bonds
-The β-glucose molecules alternate in their orientation(up-down-up-down)
-This is because the -OH(hydroxyl) groups on C₁ and C₄ β-glucose are facing opposite directions(since they are bonded to carbon atoms on different sides of the molecule)

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25
Q

Why do the β-glucose molecules alternate in their orientation(up-down-up-down)?

A

The -OH(hydroxyl) groups on C₁ and C₄ β-glucose are facing opposite directions(since they are bonded to carbon atoms on different sides of the molecule)

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26
Q

Why is cellulose made from the β-glucose an unbranched(straight) chain?

A

The β-glucose molecules alternate in their orientation(up-down-up-down)

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27
Q

Features of cellulose microfibrils

A

-Have enormous tensile strength
-Composed of cellulose chains packed together in parallel(with hydrogen bonds forming cross-links)

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28
Q

Uses of cell-to-cell recognition

A

-Helps with the organization of tissues
-Can allow foreign cells or infected body cells to be identified and destroyed

29
Q

How cells allow other cells to recognize them

A

The glycoprotein on the surface of one cell is recognized by receptors on the surface of another cell

30
Q

Oligosaccharides in the membranes of adjacent cells can become linked, binding the cells together into a tissue(T/F)

A

True

31
Q

Red blood cells have glycoproteins in their membranes that affect blood transfusion(T/F)

A

True

32
Q

Names of the oligosaccharides on the glycoproteins of red blood cells

A

A
B
O

33
Q

One or two of the three types of glycoproteins in the membranes of red blood cells(A, B and O respectively) are present in every person’s blood, but not all three(T/F)

A

True

34
Q

What happens if blood containing glycoprotein A is transfused into someone who does not produce it himself?

A

The blood will be rejected

35
Q

What happens if blood containing glycoprotein B is transfused into someone who does not produce it himself?

A

The blood will be rejected

36
Q

Why blood with glycoprotein O does not cause rejection problems when transfused

A

Glycoprotein O has the same structure as glycoprotein A and B with one monosaccharide less. so it is not recognized as foreign

37
Q

Examples of non-polar solvents

A

-Ethanol
-Toluene
-Propanol(acetone)

38
Q

Types of lipids

A

-Fats
-Oils
-Waxes
-Steroids

39
Q

Features of lipids

A

-Hydrophobic
-Dissolve in non-polar solvents(since lipid molecules have few charged groups)
-Sparingly soluble or insoluble in water or aqueous solvents
-C:O and H:O ratios are higher than in carbohydrates and other hydrophillic carbon compounds

40
Q

Examples of lipids

A

-Palmitic acid(animal fat component)
-Linocleic acid(plant oil component)
-Octacosanoic acid(wax on leaves(cutin))
-Cholesterol(membrane component)

41
Q

Features of triglycerides

A

-Made by combininng three fatty acids with one glycerol
-May be oils or fats(depending on the type of fatty acids that it contains)

42
Q

How triglycerides are made

A

-They are made by combining three fatty acids with one glycerol
-Each of the fatty acids is linked to the glycerol by a condensation reaction, so three water molecules are produced
-The condensation reaction is between the carboxyl(-COOH) on a fatty acid and a hydroxyl(-OH) on the glycerol

43
Q

Type of linkage formed between each fatty acid and the glycerol

A

An ester bond

44
Q

Why are triglycerides hydrophobic, even though the fatty acid and glycerol that they are composed of have hydrophillic parts(the carboxyl and hydroxyl group respectively)

A

Those hydrophillic parts(the carboxyl and the hydroxyl group) are used up in the reaction, so triglycerides are entirely hydrophobic

45
Q

How phospholipids are made

A

By combining 2 fatty acids and one phosphate group with glycerol via condensation reactions(which create ester bonds)

46
Q

Fatty acids vary in…

A

-the number of carbon atoms(in the hydrocarbon chain)
-the bonding of the carbon and hydrogen atoms

47
Q

Types of fatty acids

A

-Saturated fatty acids
-Monounsaturated fatty acids
-Polyunsaturated fatty acids

48
Q

Features of saturated fatty acids

A

All the carbon atoms are connected by single covalent bonds(so the number of hydrogen atoms cannot be increased)

49
Q

Features of monounsaturated fatty acids

A

There is a double bond between two of the carbon atoms(which, if broken into a single bond, could allow more hydrogen to be added)

50
Q

Features of polyunsaturated fatty acids

A

Have two or more double bonds(between pairs of carbon atoms)

51
Q

In omega-3 fatty acids, the C=C double bond is the third bond from CH₃(T/F)

A

True

52
Q

In omega-6 fatty acids, the C=C double bond is the 6th bond from CH₃(T/F)

A

True

53
Q

Types of unsaturated fatty acids

A

-Cis-fatty acids
-Trans-fatty acids

54
Q

Features of cis-fatty acids

A

-Posessed by almost all unsaturated fatty acids in living organisms
-Have the hydrogen atoms on the same side of the double-bonded carbon atoms
-Bend in the hydrocarbon chain of the double double bond

55
Q

Why cis-fatty acids have a low melting point(compared to saturated fatty acids)

A

the bend in the hydrocarbon chain, makes them less good at packing together in regular arrays, so it takes less thermal energy to break the bonds between them

56
Q

Features of trans fatty acids

A

-Do not have a bend in their hydrocarbon chain(i.e. they have straight chains)
-Higher melting point(than cis-fatty acids)
-Produced artificially by partial hydrogenation of vegetables or fish oils
-Solid at room temperature

57
Q

Triglycerides with mostly cis-unsaturated fatty acids are liquid at room temperature - they are oils(T/F)

A

True

58
Q

Triglycerides with mostly saturated fatty acids are solid at 20°C and liquid at 37°C - they are fats(T/F)

A

True

59
Q

Use of triglycerides in plants and animals

A

Energy storage

60
Q

What type of lipid are triglycerides in animals?

A

Fats

61
Q

Where triglycerides are stored in animals

A

Adipose tissue

62
Q

Where adipose tissue is located

A

-Immediately beneath the skin
-Around some organs(e.g. kidneys)

63
Q

Properties of triglycerides that make them suitable for long-term energy storage

A

-Chemically very stable(so energy is not lost over time)
-Immiscible with water(so they naturally form droplets in the cytoplasm which do not have osmotic or other effects on the cell)
-Release twice as much energy per gram in cell respiration as carbohydrates
-Poor conductors of heat(hence can act as thermal insulators)
-Liquid at body temeprarture(hence can act as a shock absorber)

64
Q

Function of phospholipids

A

Serve as the basic component of all biological membranes

65
Q

Why phospholipids are amphipathic

A

-The phosphate group(i.e. phosphate head) is hydrophillic
-The two hydrocarbon chains(i.e. hydrocarbon tails) are hydrophobic

66
Q

How phospholipid bilayers are formed

A

-When phospholipids are mixed with water, the phosphate heads are attracted to the water but the hydrocarbon tails are more attracted to each other(than the water)
-Hence, the phospholipids become arranged into double structures, with the phosphate heads sticking out while the hydrocarbon tails are at the center

67
Q

Features of steroids

A

-Four fused rings of carbon atoms
-Three cyclohexane rings and one cyclopentane ring(i.e. 3 rings with 6 carbon atoms and 1 with 5)
-17 carbon atoms in total

68
Q

Examples of steroids

A

-Testerone
-Oestradiol
-Progesterone
-Cholesterol

69
Q

Ways in which steroids differ

A

-The positiion of the C=C double bonds
-The functional groups(e.g. -OH) that are attached to the four-ring structure

IB BIOLOGY REVISION (8 decks)

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