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carbohydrates and water Flashcards

1
Q

What is a water molecule

A

A water molecule (H2O) is made up of one oxygen molecule and two hydrogen

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2
Q

using charge, explain structure of water molecule

A

each hydrogen ion shares a pair of electrons with the oxygen. as the oxygen is more attracted to the electron. This means the electrons are pulled closer to the oxygen. This results in the oxygen being slightly negative and hydrogens slightly positive

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3
Q

what makes water a polar molecule

A

the different charge of the atoms creates different charged regions. because it has two charged regions its dipolar

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4
Q

what is surface tension

A

surface tension is when water has the ability to resist force applied to it due to cohesion

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5
Q

what is cohesion

A

when a water molecule is more attracted to water molecules underneath, due to hydrogen bonds, than the air molecules above

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6
Q

what is adhesion

A

water forms hydrogen bonds with other surfaces. this causes water to be pulled up by the edges.

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7
Q

why does water not heat up or cool down easily

A

It has a high specific heat capacity.

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8
Q

why does water have a high specific heat capacity

A

this is because temperature is a measure of the water molecules kinetic energy. because water molecules are hydrogen bonded, it takes a lot of heat energy to increase their kinetic energy and temperature.

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9
Q

why does water have high latent heat of vaporisation

A

The latent heat of vaporisation is the heat energy water gives off when it evaporates. because water is hydrogen bonded it takes a lot of energy to separate them so that water can turn into vapour. when water evaporates it removes a lot of heat (cooling effect)

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10
Q

what are two examples of waters evaporation cooling effect

A

sweating for mammals and maintaining global climate.

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11
Q

explain the density of water

A

water gets denser as it gets colder until 4 degrees then as it freezes, ice is less dense than water due to the arrangement of hydrogen bonds. this is why only the top layer of a pond freezes as the ice floats on top insulating the water beneath.

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12
Q

how does water act as a solvent

A

as water is polar it is attracted to the negative and positive parts of a solvent. water molecules cluster around solvent molecules and keep them apart. at this point they dissolve and a solution is formed.

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13
Q

what is a condensation reaction

A

when two products are joined together with the removal of water

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14
Q

what is a hydrolysis reaction

A

two molecules are split into two smaller molecules with the addition of water

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15
Q

what are monomers

A

units that are joined together in a condensation reaction

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16
Q

what are dimers

A

when two monomers join together

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17
Q

what are polymers

A

when many monomers join together

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18
Q

what are carbohydrates

A

group of molecules containing C, H, O

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19
Q

what is a glycosidic bond

A

a bond formed between two monosaccharides in a condensation reaction

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20
Q

what does carbohydrate mean

A

hydrated carbon meaning for every carbon atom there are two hydrogen atoms and one oxygen atom

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21
Q

what are three functions of carbohydrates

A

sources of energy (glucose)
store of energy (starch, glycogen)
structural components (cellulose in plants)

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22
Q

what are the three main groups of carbohydrates

A

monosaccharides, disaccharides, polysaccharides

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23
Q

how many carbon atoms can be found in a monosaccharide carbon backbone

A

3, 4, 5, 6

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24
Q

what is the structure of the carbon backbone of a monosaccharide

A

one carbon forms a double bond to an oxygen forming a carboxyl group. whereas each of the others bond to one hydrogen atom and one hydroxyl group.

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25
what are pentose monosaccharides
pentose monosaccharides contain 5 carbon atoms and are long enough to form a ring
26
what are two important pentose molecules
isomers ribose and deoxyrobose
27
what are the differences between ribose and deoxyribose
ribose has a hydroxyl (OH) group and one H atom attached to its carbon 2 whereas deoxyribose has two H atoms attached to its carbon 2 and no hydroxyl (OH) group
28
what is an example of a hexose sugar
glucose. it is a monomer of more complex carbohydrates that form disaccharides and polysaccharides
29
why is glucose an isomer
because in a solution glucose can take up different forms.
30
what are common isomers of glucose
alpha glucose and beta glucose
31
what is the one difference between alpha glucose and beta glucose
alpha glucose has its hydroxyl group below carbon 1, whereas beta glucose has its hydroxyl group above carbon 1
32
how are the two isomers of glucose formed
rings are formed when carbon 1 and carbon 5 bind to the same oxygen. in the straight chain form of the sugar, the hydroxyl group and hydrogen atom of the first carbon can be reversed. this means that when the rings are formed the OH and H can be on either side of the carbon. this creates two isomers.
33
in a solution, when does glucose occur more commonly in ring configuration
when carbon 5 and carbon 1 bind to the same oxygen
34
what are disaccharides
two monosaccharides joined together by a glycosidic bond
35
what kind of reaction occurs when two monosaccharides join together
a condensation reaction which forms a glycosidic bond
36
what happens during the formation of maltose
carbon ones hydroxyl group of one alpha glucose lines up next to the other alpha glucose carbon fours hydroxyl. water is removed during a condensation reaction leaving an oxygen on its own. this oxygen binds to the carbon 1 and carbon 4 of each alpha glucose. this forms maltose.
37
what are polysaccharides
polymers containing many monosaccharides linked by glycosidic bonds
38
what are the main functions of polysaccharides
energy stores and structural components such as glycogen, starch and cellulose
39
why are glycogen and starch good stores of monosaccharides
they are compact so they dont take up much space.
40
why do polysaccharides hold monosaccharides in chains
so they can be easily 'snipped off' the end by hydrolysis when needing energy fro respiration. hydrolysis is catalysed by enzymes
41
what enzyme is responsible for hydrolysing 1-4 glycosidic bonds
amylase
42
what enzyme is responsible for hydrolysing 1-6 glycosidic bonds
glucosidase
43
what chains are branched and why
amylopectin and glycogen are branched which makes them more compact where as amylase isnt
44
why are polysaccharides less soluble than monosaccharides
they are bigger. also if many glucose molecules dissolved in the cytoplasm then the water potential would decrease causing more water to move into the cell which would disrupt the inner workings of the cell.
45
how is starch usually stored
intracellular starch grains called plastids
46
why does amylose in a souble helix mean its less soluble in water
presents a hydrophobic external surface in contact with the solution
47
what is amylose
amylose is a polysaccharide. It is a long chain of alpha glucose molecules and has glycosidic bonds between carbon 1 and 4.
48
what is the structure of amylose
amylose coils into a spiral shape with hydrogen bonds holding the spiral in shape. hydroxyl groups on carbon 2 are situated on the inside the coil making it less soluble and allowing hydrogen bonds to form to maintain the coils structure
49
what is amylopectin
like amylose as it has 1-4 glycosidic bonds but it also has branches formed by glycosidic bonds between carbon 1-6
50
what is the structure of amylopectin
coils into a spiral shape held by hydrogen bonds but have branches coming off the spiral
51
what is glycogen
molecule like amylopectin with 1-4 glycosidic bonds but branches formed by 1-6 glycosidic bonds
52
what is the structure of glycogen
1-4 bonded chains are smaller than amylopectin so less likely to coil. however it has more branches and so more compact and easier to remove monomers
53
where is cellulose found
in plants cell walls
54
what is cellulose
it is a tough, insoluble, fiberous substance made up of long chains of beta glucose bonded together by glycosidic bonds in condensation reactions
55
what is the structure of cellulose
straight chains of beta glucoe formed by 1-4 glycosidic bonds. hydrogen and hydroxyl groups on carbon 1 are inverted on beta glucose so every other glucose molecule is rotated 180 degrees. this and the 1-4 glycosidic bonds prevent chain from spiralling. hydrogen bonds are formed between the rotated molecules on other chains. OH group sticks out and so is able to form more hydrogen bonds between chains
56
how are microfibrils formed
when 60 or 70 cellulose chains are bound together they form microfibrils
57
how are macrofibrils formed
when up to 400 microfibrils bundle together
58
why do microfibrils and macrofibrils have high tensile strength
they made of strong glycosidic bonds and many hydrogen bonds form in and between chains of cellulose
59
what two monosaccharides make up the disaccharide sucrose
alpha glucose + fructose
60
what two monosaccharides make up the disaccharide maltose
alpha glucose + alpha glucose
61
what two monosaccharides make up the disaccharide lactose
beta galactose + alpha glucose
62
what two monosaccharides make up the disaccharide cellobiose
beta glucose + beta glucose
63
what ion is used in the hydrolysis of starch
chloride ions
64
where is glycogen stored
liver cells
65
why mammals store glucose as glycogen
glycogen is insoluble so has no effect on the water potential of cells. highly compact so doesn't take up a lot of space. highly branched so glucose can be snipped off easily. can be broken down quickly

biology (10 decks)

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