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A-Level Biology > Biological Molecules > Flashcards

Biological Molecules Flashcards

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1
Q

what are monomers?

A

smaller basic units of which larger molecules are made from

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2
Q

what are polymers?

A

large complex molecules composed of long chains of monomers joined together

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3
Q

list 3 examples of monomers

A

monosaccharides (e.g. glucose), amino acids, nucleotides

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4
Q

list 3 examples of polymers

A

carbohydrates, proteins, nucleic acids

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5
Q

monomer of starch?

A

alpha glucose

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6
Q

monomer of glycogen?

A

alpha glucose

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7
Q

monomer of cellulose?

A

beta glucose

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8
Q

monomer of protein?

A

amino acids

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9
Q

monomer of nucleic acids (DNA and RNA)

A

nucleotides

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10
Q

monomer of carbohydrates?

A

monosaccharides

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11
Q

polymer of monosaccharides?

A

carbohydrate

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12
Q

polymer of amino acids?

A

protein

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13
Q

polymer of nucleotides

A

nucleic acid (DNA/RNA)

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14
Q

list 3 examples of monosaccharides

A
  • glucose
  • fructose
  • galactose
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15
Q

list 3 examples of disaccharides

A
  • sucrose
  • maltose
  • lactose
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16
Q

list 3 examples of polysaccharides

A
  • starch
  • glycogen
  • cellulose
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17
Q

what are disaccharides?

A

2 monosaccharides chemically reacted together, joined together by a glycosidic bond and formed via a condensation reaction

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18
Q

structure of alpha glucose (where are the Hs and where are the OHs)

A

H H
OH OH

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19
Q

structure of beta glucose (where are the Hs and where are the OHs)

A

H OH
OH H

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20
Q

what elements do carbohydrates consist of?

A

C, H, O

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21
Q

what are polysaccharides?

A

formed by the condensation of many glucose units

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22
Q

what are monosaccharides?

A

simple sugar molecules, monomers from which larger carbohydrates are made

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23
Q

how many isomers of glucose are there?

A

2

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24
Q

what is an isomer?

A

molecules with the same molecular formula but a different formula

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25
Q

what are the names of the glucose isomers?

A
  • alpha glucose
  • beta glucose
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26
Q

glucose + glucose = ?

A

maltose + water

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27
Q

glucose + fructose = ?

A

sucrose + water

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28
Q

glucose + galactose = ?

A

lactose + water

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29
Q

what is a condensation reaction?

A

joining together of 2 molecules through the removal of water

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30
Q

what is a hydrolysis reaction?

A

splitting apart of molecules through the addition of water

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31
Q

explain what happens during a condensation reaction

A
  • hydrogen from one hydroxyl group and the whole hydroxyl group from the other monosaccharide react to produce the water
  • a disaccharide with a 1,4 glycosidic bond is created
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32
Q

what type of bond forms when two alpha glucose molecules react

A

1,4 glycosidic bond

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33
Q

how can a glycosidic bond be broken in disaccharides?

A
  • add water to HYDROLYSE glycosidic bond (hydrolysis reaction)
  • disaccharide will be converted back into its original molecules
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34
Q

why are monosaccharides soluble in water?

A
  • contain lots of hydroxyl groups (OH)
  • hydroxyl groups form hydrogen bonds with water molecules - makes them hydrophilic (dissolve in water)
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35
Q

bond(s) present between starch monomers?

A
  • 1,4 glycosidic bonds in amylose
  • 1,4 and 1,6 glycosidic bonds in amylopectin
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36
Q

function of starch?

A

insoluble store of glucose in plants

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37
Q

where is starch found?

A

in plant cells in starch grains

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38
Q

describe the structure of starch

A
  • formed from 2 polymers of alpha glucose: amylose and amylopectin
  • amylose: an unbranched helix
  • amylopectin: a branched molecule
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39
Q

explain how the structure of starch links to its function

A
  • amylose helix can compact to fit a lot of glucose into a small space
  • branched structure of amylopectin increases the surface area for rapid hydrolysis back to glucose
  • insoluble in water so water potential will not be affected
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40
Q

what kind of reaction are amylose and amylopectin formed from?

A

condensation reaction

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41
Q

describe the structure of amylose

A
  • polymer of alpha glucose
  • forms 1,4 glycosidic bonds
  • unbranched straight chain which coils up to make a helix
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42
Q

describe the structure of amylopectin

A
  • polymer of alpha glucose
  • straight chain forms 1,4 glycosidic bonds
  • 1,6 glycosidic bonds create branches, making it a branched polymer
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43
Q

bond(s) present between glycogen monomers?

A

1-4 and 1-6 glycosidic bonds

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44
Q

function of glycogen?

A

insoluble store of glucose in animals

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45
Q

where is glycogen found?

A

mainly in muscle and liver cells of animals

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46
Q

describe the structure of glycogen

A
  • highly branched molecule (more so than amylopectin due to having more 1,6 glycosidic bonds
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47
Q

explain how the structure of glycogen links to its function

A
  • highly branched but can still compact easily so can store large amounts of glucose
  • branched structure of glycogen increases the surface area for rapid hydrolysis back to glucose, very important for animals as they often have a very high rate of respiration and energy needs can change quickly
  • insoluble in water so water potential will not be affected
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48
Q

bond(s) present between cellulose monomers?

A

1,4 glycosidic bonds

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49
Q

function of cellulose?

A
  • structural strength for plant cell wall
  • prevents cell bursting/keeps cell turgid
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50
Q

where is cellulose found?

A

plant cell wall

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51
Q

describe the structure of cellulose

A
  • polymer of beta glucose
  • 1,4 glycosidic bonds
  • alternate cellulose molecules are rotated 180 degrees forming long straight chains of beta glucose
  • chains run parallel to one another and are held in place by many hydrogen bonds that form fibrils
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52
Q

explain how the structure of cellulose links to its function

A

-many hydrogen bonds form fibrils which provide collective strength (hydrogen bonds alone are weak but due to their large number they are able to provide collective strength) to the cell wall to prevent the cell from bursting
-insoluble so water potential won’t be affected

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53
Q

what molecules make up triglycerides?

A

3 molecules of fatty acid and 1 molecule of glycerol

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54
Q

what kind of reaction takes place to form a triglyceride?

A

condensation reaction

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55
Q

what are the tails of triglycerides made from?

A

hydrocarbons

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56
Q

draw a glycerol molecule

A

H
I
H-C-OH
I
H-C-OH
I
H-C-OH
I
H

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57
Q

draw a fatty acid molecule

A

O
||
HO—C —R

R = hydrocarbon chain

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58
Q

draw an ester molecule

A

O
….. I I
O - C

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59
Q

what kind of bond forms between glycerol and the fatty acid chains in a triglyceride? what else is produced in this reaction?

A
  • ester bond
  • water
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60
Q

what molecules are present in a phospholipid?

A

2 molecules of fatty acids, 1 molecule of glycerol
and 1 phosphate group (attached to the glycerol)

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61
Q

what is a saturated fatty acid?

A

a fatty acid in which the hydrocarbon tail has only single bonds between carbons

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62
Q

what is an unsaturated fatty acid?

A

a fatty acid in which the hydrocarbon tail consists of at least one double bond between the carbons

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63
Q

list 4 properties of triglycerides

A

1) energy storage
2) high ratio of hydrogen to oxygen atoms
3) large and hydrophobic
4) relatively low mass

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64
Q

describe how triglycerides have a lot of energy storage

A

there is a large ratio of energy-storing carbon-hydrogen bonds compared to the number of carbon atoms, so a lot of energy is stored in the molecule

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65
Q

explain why triglycerides having a high ratio of hydrogen to oxygen atoms is useful

A
  • acts as a metabolic water source as the triglycerides can release water if oxidised
  • essential for desert animals
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66
Q

explain why triglycerides being large and hydrophobic is useful

A

insoluble in water so do not affect water potentials and osmosis meaning they can store lots

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67
Q

explain why lipids having a relatively low mass is useful

A

a lot can be stored without increasing the mass + preventing movement

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68
Q

describe how the emulsion test for lipids would be carried out. what would a positive result look like?

A

1) crush/grind sample if necessary
2) dissolve sample in ethanol
3) add distilled water
positive result: white emulsion forms

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69
Q

list and describe properties of phospholipids

A

1) negative charge on phosphate group - hydrophilic “head” of a phospholipid can attract with water as it is charged, repels other fats due to charge
2) fatty acid chain not charged - known as the hydrophobic “tail” and it repels water but will mix with other fats
3) in water is positioned so heads exposed to water and tails are not, forming a phospholipid bilayer membrane structure which makes up the plasma membrane around cells

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70
Q

what makes phospholipids polar?

A

they have 2 charged regions

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71
Q

what are the 4 levels of structure in a protein?

A

primary, secondary, tertiary, quaternary

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72
Q

explain how phospholipids act in water

A

In water, they are positioned so that the heads are exposed to water and the tails are not, forming a phospholipid bilayer membrane structure which makes up the plasma membrane around cells

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73
Q

what is the primary structure of proteins?

A

the order of the amino acids in the polypeptide chain

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74
Q

what is a polypeptide chain?

A
  • a chain of amino acids all joined together by several condensation reactions
  • a peptide bond holds each amino acid together in the chain
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75
Q

what is the secondary structure of proteins?

A
  • sequence of amino acids causes parts of protein molecule to bend into alpha-helix shapes or fold into beta-pleated sheets
  • hydrogen bonds hold secondary structure in place
  • form between C=O group of carboxyl group of one amino acid and H in amine group of another amino acid
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76
Q

what is the tertiary structure of proteins?

A
  • the further folding of the secondary structure to form a unique 3D shape
  • held in place by ionic, hydrogen, and disulphide bonds
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77
Q

where do the ionic, hydrogen and disulphide bonds form in the tertiary structure?

A
  • ionic + disulphide bonds form between the R groups of different amino acids
  • disulphide bonds occur only sometimes as there must be a sulfur in the R groups for this to occur
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78
Q

what is the quaternary structure of proteins?

A

a protein made up of more than one polypeptide chain

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79
Q

what does it mean if a protein is denatured?

A

the bonds that hold the tertiary and secondary structure in shape break and therefore the unique 3D shape is lost

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80
Q

what conditions can denature a protein?

A
  • too high a temperature (too much kinetic energy)
  • too high/low a pH (too many H+ or OH-)
81
Q

what is the importance of the primary structure?

A

if even one amino acid in the sequence is different it will cause the ionic/hydrogen/disulfide bonds to form in different locations resulting in a different 3D shape

82
Q

what is the impact of changing the primary structure?

A
  • enzymes will have a different shaped active site - will no longer function/will have a different function
  • carrier proteins will have a different shaped binding site so molecules no longer complementary so cannot be transported across membranes
83
Q

what conditions can affect an enzyme?

A
  • temperature
  • pH
  • substrate concentration
84
Q

what is the effect of temperature on an enzyme?

A
  • if too low: not enough kinetic energy for successful collisions between enzyme + substrate so less enzyme-substrate complexes form
  • if too high: kinetic energy is too high, collisions increase which causes the bonds holding the amino acids in their fixed 3D tertiary structure in the active site to be broken, enzyme denatures, active site changes shape, substrate no longer fits, no more enzyme-substrate complexes can form
85
Q

effect of pH on an enzyme

A
  • if too high/low = too many H+/OH-
  • will interfere with charges in the amino acids in the active site
  • can break the bonds holding tertiary structure in place + therefore active site changes shape, enzyme denature, no more es complexes
86
Q

effect of substrate concentration on an enzyme

A

if insufficient substrate then the reaction will be slower as there will be fewer collisions between the enzyme and substrate and so fewer es complexes can form

87
Q

effect of insufficient enzyme concentration on an enzyme

A

if there is insufficient enzyme concentration then the enzyme active sites will become saturated with substrate and so they are unable to work any faster

88
Q

what is an inhibitor?

A

binds to an enzyme + prevents enzyme from functioning

89
Q

name the 2 types of inhibitor

A

competitive and non-comptetitive

90
Q

describe the function of a competitive inhibitor

A
  • same shape as the substrate and can bind to active site
  • prevents substrate from binding and the reaction from occurring - can be overcome by increasing substrate concentration as will flood/out-compete the inhibitor, knocking them out of the active sites
91
Q

describe the function of a non-competitive inhibitor

A

binds to enzyme away from the active site which causes active site to change shape + therefore the substrate can no longer bind, regardless of how much substrate is added

92
Q

what makes the active site specific?

A

the specific bonding and folding in the tertiary structure

93
Q

what are enzymes?

A

tertiary structure proteins that catalyse reactions

94
Q

describe the lock and key model

A
  • enzyme active site fixed shape + due to random collisions, substrate can collide + attach to enzyme forming es complex
  • charged groups within active site distort substrate + therefore lower activation energy
  • products are released + enzyme active site is empty and ready to be reused
95
Q

describe the induced fit model

A
  • enzyme active site slightly changes shape to mould around the substrate
  • when the es complex occurs due to the enzyme moulding around the substrate it puts strain on the bonds and therefore lowers the activation energy
  • products are then removed and the enzyme active site returns to original shape
96
Q

describe how to test for the presence of starch

A

1) add iodine to sample
positive result: solution turns from orange to blue/black

97
Q

describe how to test for the presence of reducing sugars

A

1) add benedicts reagent to sample and heat
positive result: solution turns from blue to green, yellow, orange or brick-red ( the more red, the higher concentration of reducing sugar)

98
Q

when carrying out the biochemical tests, why does the colour change occur at the top of the solution first?

A

the hotter particles in the solution rise and therefore the hottest point in the solution and the test tube is at the top where the molecules will have the most kinetic energy, meaning there are more successful collisions and the reaction will be happening faster.

99
Q

describe how to test for the presence of non-reducing sugars

A

1) carry out reducing sugar test to check not a reducing sugar (add benedicts reagent to sample and heat - solution will remain blue)
2) add acid and boil
3) cool solution + add an alkali to neutralise
4) add benedicts reagent to sample and heat
positive result: solution turns from blue to green, yellow, orange or brick-red (depending on concentration)

100
Q

what is a reducing sugar?

A

a sugar that can reduce the copper sulphate (blue) in benedicts reagent to copper oxide (brick red)

101
Q

what is a non reducing sugar? why is it different to a reducing sugar?

A

a sugar that can’t reduce the copper sulphate (blue) in benedict’s reagent to copper oxide (brick red) as the reducing group is involved in the glycosidic bond

102
Q

how can a non-reducing sugar be made into a reducing sugar?

A

if hydrolysed through boiling with acid the glycosidic bond, the reducing group becomes exposed making it a reducing sugar

103
Q

list 5 reducing sugars

A

glucose, fructose, galactose, lactose, maltose

104
Q

name one non-reducing sugar

A

sucrose

105
Q

describe how to test for the presence of proteins

A

1) add biuret
positive result: solution turns from blue to purple

106
Q

what does DNA stand for?

A

deoxyribonucleic acid

107
Q

what is the function of DNA?

A

codes for the sequence of amino acids in the primary structure of a protein, which in turn determines the final 3D structure + function of a protein

108
Q

what makes up a DNA nucleotide?

A

a deoxyribose (pentose sugar), a nitrogen containing organic base and a phosphate group

109
Q

what are the 4 different nitrogenous organic bases a DNA nucleotide can be made up of?

A

adenine, thymine, cytosine, guanine

110
Q

what is a polynucleotide?

A

a polymer of nucleotides

111
Q

what is the name of the pentose sugar in DNA?

A

deoxyribose

112
Q

how is a polynucleotide created?

A

condensation reaction between the deoxyribose and the phosphate group creating a phosphodiester bond

113
Q

how are phosphodiester bonds suited to their function?

A

strong covalent bonds so help ensure genetic code not broken down

114
Q

what is the chain of pentose sugar and phosphates known as?

A

sugar-phosphate backbone

115
Q

what is the structure of DNA?

A

double helix

116
Q

what holds the pair of DNA polymers together?

A

hydrogen bonds between the complementary base pairs

117
Q

how many hydrogen bonds form between adenine and thymine?

A

2

118
Q

how many hydrogen bonds form between cytosine and guanine?

A

3

119
Q

why is complementary base pairing important?

A

helps maintain the order of the genetic code when DNA replicates

120
Q

how does the structure of DNA relate to its function?

A
  • stable structure due to sugar-phosphate backbone and double helix
  • double-stranded so both strands can act as a template strand during replication
  • weak hydrogen bonds for easy unzipping of the 2 strands during replication
  • large molecule to carry lots of information
  • complementary base pairing allows identical copies to be made
121
Q

what makes up an RNA nucleotide?

A

a ribose (pentose sugar), a nitrogenous base and a phosphate group

122
Q

what are the 4 different nitrogenous organic bases an RNA nucleotide can be made up of?

A

adenine, uracil, cytosine and guanine

123
Q

what is the structure of rRNA?

A
  • single-stranded
  • relatively short polynucleotide chain
124
Q

what are the differences between the DNA and RNA polymers?

A
  • DNA larger ( contains approx 23,000 genes - the entire genome) whereas RNA shorter because it is the length of only one gene
  • DNA is double-stranded, whereas RNA is single-stranded
125
Q

what are the differences between the DNA and RNA monomers?

A
  • DNA base contains thymine, whereas RNA contains uracil instead
  • DNA contains the pentose sugar deoxyribose, whereas RNA contains the pentose sugar ribose
126
Q

what is the function of RNA?

A
  • to copy and transfer the genetic code from DNA in the nucleus to the ribosomes
  • some RNA also combined with proteins to create ribosomes
127
Q

what does RNA stand for?

A

RiboNucleic Acid

128
Q

what are the 3 types of RNA?

A
  • mRNA
  • tRNA
  • rRNA
129
Q

what is mRNA?

A
  • copy of a gene from DNA
  • in nucleus DNA slightly unravels at start of protein synthesis + a copy of this unravelled DNA is made in mRNA
130
Q

where is mRNA made? what is its function?

A
  • created in the nucleus
  • then leaves nucleus to carry the copy of the genetic code of one gene to a ribosome in the cytoplasm
131
Q

why is mRNA necessary?

A
  • DNA too large to leave nucleus, would be at risk of being damaged by enzymes, therefore destroying the genetic code permanently
  • mRNA is much shorter (is only the length of 1 gene) and so can leave the nucleus
132
Q

describe some of the properties of mRNA

A
  • short-lived as only needed temporarily to create a protein, so by the time enzymes could hydrolyse it, would have already carried out its function
  • single-stranded and every 3 bases in the sequence code for an amino acid (codons)
133
Q

what is a codon?

A

the three bases that code for a specific amino acid

134
Q

where is transfer RNA (tRNA) found?

A

cytoplasm

135
Q

describe the structure of tRNA

A
  • single-stranded
  • folded to create a shape similar to a cloverleaf
  • shape held in place by hydrogen bonds
136
Q

what is the function of tRNA?

A
  • attach to amino acids + transfer it to a ribosome to create polypeptide chain
  • specific amino acids attach to specific tRNA molecules
  • determined by anticodons - complementary to the codon on mRNA
137
Q

what is an anticodon?

A

3 bases found on tRNA which are complementary to the codon on mRNA

138
Q

what is ribosomal rRNA (rRNA)? what is its function?

A
  • makes up the bulk of ribosomes
  • combines with proteins to make ribosomes
139
Q

why is the process of DNA replication referred to as “semi-conservative”?

A

in the daughter DNA, one strand is from the parental DNA and one strand is newly synthesised

140
Q

describe the process of semi-conservative replication

A

1) DNA helicase breaks hydrogen bonds between complementary base pairs between the two strands within double helix, causing the DNA double helix to unravel.
2) Each of the separated parental DNA strands act as a template. Free-floating DNA nucleotides within nucleus are attracted to their complementary base pairs on the template strands of parental DNA.
3) Adjacent nucleotides joined together to form the phosphodiester bonds by a condensation reaction - catalysed by DNA polymerase.
4) Hydrogen bonds form between the bases of the original and the new strands. The two sets of daughter DNA each contains one strand of parental DNA and one newly synthesised strand.

141
Q

what was the purpose of the Meselsohn + Stahl experiment? what was the outcome?

A
  • to determine whether DNA was replicated conservatively or semi-conservatively
  • found DNA was replicated semi-conservatively
142
Q

what 3 facts are the Meselsohn + Stahl experiment based upon?

A

1) DNA bases are nitrogenous
2) nitrogen has 2 isotopes: 14N and 15N
3) bacteria take in nitrogen isotopes to make new DNA

143
Q

how do 14N and 15N differ when spun in a centrifuge? why?

A
  • 15N will settle lower down as it is more dense
  • 14N will settle higher up as it is less dense
144
Q

which two isotopes of nitrogen were used in Meselsons + Stahls experiment?

A

14N and 15N

145
Q

outline Meselson and Stahl’s experiment

A

1) 2 samples of bacteria grown - 1 in nutrient broth containing light nitrogen (14N) + 1 in broth of heavy nitrogen (15N). As bacteria reproduced, they took up nitrogen from broth so became part of DNA
2) Sample of DNA taken from each batch of bateria. spun in centrifuge. DNA from 15N settled lower down centrifuge tube, because denser
3) bacteria grown in 15N broth taken out and put in broth containing only 14N. bacteria left for 1 round of DNA replication, another DNA sample taken out + spun in centrifuge.
4) If replication conservative, 15N would still be together, would settle at bottom and 14N would settle at the top.
5) If replication semi-conservative, new bacteria DNA molecules would contain one strand of old DNA containing 15N, and one strand of new DNA containing 14N. So DNA would settle between where 14N DNA settled + where 15N DNA settled.
6) DNA settled in middle, showing that DNA molecules contained a mixture of 14N + 15N - DNA had replicated semi-conservatively in the light nitrogen.

146
Q

what does ATP stand for?

A

adenosine triphosphate

147
Q

describe the structure of ATP

A
  • adenine
  • ribose
  • 3 inorganic phosphate ions
148
Q

ATP is a nucleotide derivative. what does this mean?

A

it is made up of many of the same molecules as a nucleotide is

149
Q

what is ATP?

A

immediate source of energy for biological processes

150
Q

how is ATP made?

A
  • inorganic phosphate ion added to ADP molecule via a condensation reaction during respiration
  • ATP synthase catalyses reaction
151
Q

which enzyme is used for the hydrolysis of ATP? what are the products? give an equation.

A
  • ATP can be hydrolysed into ADP + Pi using the enzyme ATP hydrolase
    ATP + water <–> ADP +Pi (+energy)
152
Q

explain what makes ATP an immediate energy source

A
  • a small amount of energy is released when one of the bonds between the inorganic phosphate groups is broken in a hydrolysis reaction
  • only one bond needs to be hydrolysed to release energy making it an immediate energy source
153
Q

where is the energy in ATP stored?

A

high energy bonds between the phosphate groups

154
Q

which enzyme catalyses the resynthesis of ATP?

A

ATP synthase

155
Q

what is phosphorylation?

A

the addition of a phosphate group to an organic compound

156
Q

describe how ATP transfers energy to different compounds

A
  • inorganic phophate released during hydrolysis of ATP can be bonded onto different compounds to make them more reactive
  • gain energy = more reactive
  • known as phosphorylation
157
Q

describe how the release of energy in glucose differs from that in ATP and the potential effect this has on the cell

A
  • ATP releases energy in small manageable amounts so no energy wasted
  • cells do not overheat from wasted energy + are less likely to run out of energy
  • glucose releases large amounts of energy when broken down
  • could result in wasted energy
158
Q

describe how the size of ATP and glucose enable them to move around the cell.

A
  • both ATP and glucose are small and soluble, so are easily transported around the cell
  • can move around the cytoplasm with ease to provide energy for chemical reactions within the cell
159
Q

describe how the process of releasing energy in glucose differs from that in ATP

A
  • only one bond is hydrolysed to release energy in ATP, which is why energy release is immediate
  • glucose requires several bonds to be hydrolysed in order to release all of its energy
160
Q

describe how phosphorylation differs for glucose from that in ATP

A
  • ATP can transfer energy to another molecule by transferring one of its phosphate groups
  • ATP can enable phosphorylation making other compounds more reactive
  • glucose cannot do this as it does not contain phosphate groups
161
Q

explain how the cell can run out of glucose but not ATP

A
  • ATP can’t pass out of the cell: the cell always has an immediate source of energy, constant supply of ATP or ADP + Pi
  • ATP cannot leave the cell whereas glucose can
162
Q

what is a dipolar molecule?
explain how water is a dipolar molecule.

A
  • 2 different charged regions
  • water has an unevenly distributed charge due to the fact the oxygen atom is slightly negative and the hydrogen atoms are slightly positive
163
Q

what bonding is present in water molecules? where do these bonds form?

A

hydrogen bonds form between different water molecules between the oxygen and hydrogen atom

164
Q

list 5 properties of water

A
  • it is a metabolite
  • it is an important solvent in reactions
  • it has a high specific heat capactity and buffers temperature
  • it has a large latent heat of vaporisation
  • there is a strong cohesion between water molecules
165
Q

what is a metabolite?
explain how water is a metabolite.

A
  • a substance involved in a metabolic reaction
  • water is involved in many reactions, e.g. phootosynthesis, hydrolysis and condensation reactions
166
Q

explain how water is a good solvent

A
  • polar molecules dissolve readily in water as is dipolar
  • the slight positive charge on hydrogen atoms will attract any neg ions in solutes and the slight neg charge in the oxygen atoms will attract any pos ions in solutes
167
Q

are polar molecules hydrophillic or hydrophobic?

A

hydrophillic (they dissolve in water)

168
Q

are non-polar molecules hydrophillic or hydrophobic?

A

hydrophobic (they don’t dissolve in water)

169
Q

why is it important that water is a good solvent?

A

allows many essential polar substances to be transported easily around animals + plants, either in the blood or the xylem, to the cells they are needed inside the organsims

170
Q

why does water have a high specific heat capacity?

A
  • a lot of energy is required to raise temp of water as some of the heat is used to break the hydrogen bonds between the water molecules
171
Q

why is it useful that wter has a high specific heat capacity?

A
  • useful to organisms the temperature of water remains relatively stable, even if the surrounding temperature fluctuates significantly
  • therefore internal temps of plants + animals should remain relatively constant despite external temp as large proportion of organisms are water
  • important so enzymes do not denature/reduce in activity with temp fluctuations
  • also provides a stable environment in terms of temp for aquatic organisms
172
Q

why does water have a high latent heat of vaporisation?

A
  • lots of energy required to convert water in its liquid state to a gaseous state as it takes a lot of heat/energy to break the hydrogen bonding between molecules
173
Q

why is water having a high latent heat of vaporisation useful? give an example.

A
  • water provides a significant cooling effect
  • e.g. when humans sweat, they release water on their skin. large amounts of heat energy from the skin is trasferred to the water to evaporate, therefore removing a lot of heat energy + cooling the organism
174
Q

what is cohesion?

A

attraction between molecules of the same type

175
Q

why is it useful that water has a strong cohesion?

A
  • helps water flow
  • due to water molecules sticking together, when water moves up the xylem in plants due to transpiration, it is as a continuous column of water
  • advantageous as easier to draw up a column, rather than individual molecules
  • cohesion also provides surface tension to water
  • enables small invertebrates to move + live on the surface, providing a habitat away from predators within water
176
Q

list 4 types of macromolecules

A
  • lipids
  • proteins
  • carbohydrates
  • nucleic acid
177
Q

what is a catabolic reaction? give 2 examples.

A
  • large molecules are broken down into smaller ones
  • digestion + respiration
178
Q

what is an anabolic reaction? give an example.

A
  • build larger molecules from smaller ones
  • photosynthesis
179
Q

what type of sugar is glucose?

A

hexose

180
Q

are the triglyceride tails hydrophobic or hydrophilic?

A

hydrophobic

181
Q

are lipids soluble or insoluble in water?

A

insoluble

182
Q

which provides more energy: lipids or carbohydrates? by how much?

A

lipids provide double the amount of energy than carbohydrates do

183
Q

how do triglycerides act in cells?

A

form insoluble droplets

184
Q

what determines the primary structure of a protein?

A

a gene

185
Q

what is the basic structure of an amino acid?

A
  • carboxyl group (-COOH)
  • amine group (-NH2)
  • R group (variable region)
  • hydrogen
186
Q

what does the R group of an amino acid determine?

A

R group is the variable region that determines the amino acid

187
Q

what is a metabolic reaction?

A

a chemical reaction that happens in a living organism to keep it alive

188
Q

how does water help with temperature control?

A

has a high latent heat of vaporization and a high specific heat capacity

189
Q

when does the resynthesis of ATP happen?

A

during respiration and photosynthesis

190
Q

what is an inorganic ion?

A

an ion which doesn’t contain carbon

191
Q

how many polypeptide chains is haemoglobin made up of?

A

4

192
Q

what ion does haemoglobin have in the centre of the polypeptide chains?

A

iron

193
Q

what binds to the oxygen in haemoglobin?

A

iron ions

194
Q

what ion determines pH?

A

hydrogen ions

195
Q

does a higher or lower concentration of hydrogen ions lower pH?

A

higher

196
Q

what do sodium ions do?

A

help transport glucose and amino acids across membranes

197
Q

what do the phosphate groups in DNA and RNA do?

A

allow nucleotides to join together to form polynucleotides

198
Q

what does antiparallel mean?

A

running in opposite directions

199
Q

each end of a DNA strand is slightly different in its structure.
what are the 2 ends called?

A

3’ (3 prime) and 5’ (5 prime)

A-Level Biology (6 decks)

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