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IB BIOLOGY REVISION > Carbohydrates and lipids Details > Flashcards

Carbohydrates and lipids Details Flashcards

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
Why do the β-glucose molecules alternate in their orientation(up-down-up-down)?
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)
26
Why is cellulose made from the β-glucose an unbranched(straight) chain?
The β-glucose molecules alternate in their orientation(up-down-up-down)
27
Features of cellulose microfibrils
-Have enormous tensile strength -Composed of cellulose chains packed together in parallel(with hydrogen bonds forming cross-links)
28
Uses of cell-to-cell recognition
-Helps with the organization of tissues -Can allow foreign cells or infected body cells to be identified and destroyed
29
How cells allow other cells to recognize them
The glycoprotein on the surface of one cell is recognized by receptors on the surface of another cell
30
Oligosaccharides in the membranes of adjacent cells can become linked, binding the cells together into a tissue(T/F)
True
31
Red blood cells have glycoproteins in their membranes that affect blood transfusion(T/F)
True
32
Names of the oligosaccharides on the glycoproteins of red blood cells
A B O
33
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)
True
34
What happens if blood containing glycoprotein A is transfused into someone who does not produce it himself?
The blood will be rejected
35
What happens if blood containing glycoprotein B is transfused into someone who does not produce it himself?
The blood will be rejected
36
Why blood with glycoprotein O does not cause rejection problems when transfused
Glycoprotein O has the same structure as glycoprotein A and B with one monosaccharide less. so it is not recognized as foreign
37
Examples of non-polar solvents
-Ethanol -Toluene -Propanol(acetone)
38
Types of lipids
-Fats -Oils -Waxes -Steroids
39
Features of lipids
-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
Examples of lipids
-Palmitic acid(animal fat component) -Linocleic acid(plant oil component) -Octacosanoic acid(wax on leaves(cutin)) -Cholesterol(membrane component)
41
Features of triglycerides
-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
How triglycerides are made
-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
Type of linkage formed between each fatty acid and the glycerol
An ester bond
44
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)
Those hydrophillic parts(the carboxyl and the hydroxyl group) are used up in the reaction, so triglycerides are entirely hydrophobic
45
How phospholipids are made
By combining 2 fatty acids and one phosphate group with glycerol via condensation reactions(which create ester bonds)
46
Fatty acids vary in...
-the number of carbon atoms(in the hydrocarbon chain) -the bonding of the carbon and hydrogen atoms
47
Types of fatty acids
-Saturated fatty acids -Monounsaturated fatty acids -Polyunsaturated fatty acids
48
Features of saturated fatty acids
All the carbon atoms are connected by single covalent bonds(so the number of hydrogen atoms cannot be increased)
49
Features of monounsaturated fatty acids
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
Features of polyunsaturated fatty acids
Have two or more double bonds(between pairs of carbon atoms)
51
In omega-3 fatty acids, the C=C double bond is the third bond from CH₃(T/F)
True
52
In omega-6 fatty acids, the C=C double bond is the 6th bond from CH₃(T/F)
True
53
Types of unsaturated fatty acids
-Cis-fatty acids -Trans-fatty acids
54
Features of cis-fatty acids
-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
Why cis-fatty acids have a low melting point(compared to saturated fatty acids)
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
Features of trans fatty acids
-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
Triglycerides with mostly cis-unsaturated fatty acids are liquid at room temperature - they are oils(T/F)
True
58
Triglycerides with mostly saturated fatty acids are solid at 20°C and liquid at 37°C - they are fats(T/F)
True
59
Use of triglycerides in plants and animals
Energy storage
60
What type of lipid are triglycerides in animals?
Fats
61
Where triglycerides are stored in animals
Adipose tissue
62
Where adipose tissue is located
-Immediately beneath the skin -Around some organs(e.g. kidneys)
63
Properties of triglycerides that make them suitable for long-term energy storage
-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
Function of phospholipids
Serve as the basic component of all biological membranes
65
Why phospholipids are amphipathic
-The phosphate group(i.e. phosphate head) is hydrophillic -The two hydrocarbon chains(i.e. hydrocarbon tails) are hydrophobic
66
How phospholipid bilayers are formed
-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
Features of steroids
-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
Examples of steroids
-Testerone -Oestradiol -Progesterone -Cholesterol
69
Ways in which steroids differ
-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 (16 decks)

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