Topic 1 - biological molecules Flashcards

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1
Q

where do ionic bonds form?
what happens to the electrons?

A

between oppositely charged ions

the electrons swap

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2
Q

what happens in covalent bonding?

A

electrons are shared

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3
Q

use of nitrate ions N03-

A

needed in plants for formation of amino acids

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4
Q

use of phosphate ions P043-

A

formation of ATP/ADP and DNA/RNA

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5
Q

use of chloride ions Cl-

A

needed in nerve impulses and secretory systems

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6
Q

use of hydrogen carbonate ions HC03-

A

needed for buffering the blood, prevent it from becoming too acidic

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7
Q

use of sodium ions Na+

A

needed in nerve impulses and secretory systems

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8
Q

use of calcium ions Ca2+

A

forms calcium pectate for middle lamella (plants)

bone formation and muscle contraction (animals)

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9
Q

use of hydrogen ions H+

A

cellular respiration/photosynthesis/pH balance

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10
Q

use of magnesium ions Mg2+

A

needed for production of chlorophyll (in plants)

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11
Q

why is water a polar molecule?

A

the electrons are held closer to the oxygen

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12
Q

what is the result of a differences of charges within a water molecule?

what’s formed? so….

A

hydrogen bonds are formed
molecules ‘stick’ together

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13
Q

explain:
water is a polar solvent

A

many substances will dissolve in it

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14
Q

explain:
water is adhesive

this is important for…

A

they are attracted to other molecules

important for transport and surface tension

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15
Q

explain:
water reaches its maximum density at 4 degrees

A

freezes and becomes ice
ice is less dense so it floats
provides insulation

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16
Q

explain:
water is cohesive

A

sticks to other water molecules

important for the movement of water in plants

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17
Q

explain:
water is a transport medium

A

can carry substances

(eg in xylem and blood)

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18
Q

explain:
water has a high HSC

A

takes a lot of energy to raise 1kg by 1 degree.

energy goes into breaking the bonds and not KE

less temperature fluctuations

more stable environment for organisms

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19
Q

explain:
water has a high surface tension

due to…., a high surface tension is formed.

this provides…..

A

due to attraction between water molecules

provides a habitat

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20
Q

what is the main use of carbohydrates?

A

store energy

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21
Q

what are all carbohydrates made from?

A

carbon/hydrogen/oxygen

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22
Q

what’s the general formula for monosaccharides?

A

(CH2O)n

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23
Q

molecular formula for triose sugars

A

C3H6O3

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24
Q

when are triose sugars important?

A

in the mitochondria when glucose is broken down into triose sugars (during respiration)

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25
Q

what is the molecular formula for a pentose sugar?

A

C5H10O5

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26
Q

give examples of pentose sugars

A

ribose

deoxyribose

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27
Q

give molecular formula for hexose sugar

A

C6H12O6

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28
Q

give examples of hexose sugars
(sweet taste)

A

glucose
fructose
galactose

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29
Q

draw ribose

A

(answer in textbook, page 19)

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30
Q

what are the two different isomers of glucose?

A

alpha glucose

beta glucose

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31
Q

draw alpha glucose

A

page 19 of textbook

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32
Q

draw beta glucose

A

page 19 of textbook

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33
Q

what are disaccharides made from?

what type of reaction?
what bonds are formed?

A

two monosaccharides

condensation reaction
forms glycosidic bonds

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34
Q

what two monosaccharides make this disaccharide?

maltose

A

a glucose + a glucose

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35
Q

what two monosaccharides make this disaccharide?

lactose

A

a glucose + galactose

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36
Q

what two monosaccharides make this disaccharide?

sucrose

A

a glucose + fructose

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37
Q

what is Benedict’s solution a test for?

A

reducing sugars

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38
Q

substances that react with benedict’s are called reducing sugars.

what is the colour change?

A

blue to orange

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39
Q

what is the name for sugars that don’t react with benedict’s solution?

A

non-reducing sugars

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40
Q

how do you go about testing a non-reducing sugar?

A

heat with hydrochloric acid (hydrolysis glycosidic bonds)

cool

neutralise with sodium hydrogen carbonate

this produces monosaccharides

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41
Q

what are molecules with 3-10 sugar units known as?

A

oligosaccharides

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42
Q

what are polysaccharides?

A

many monosaccharides (11+)

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43
Q

explain how the structure of polysaccharides makes them ideal storage molecules

-compact
-bonds
-solubility

A

they form very compact molecules so a lot can be stored in one cell

glycosidic binds are easily broken- rapid release of energy

not very soluble in water so have little osmotic effect

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44
Q

what is hydrolysis?

A

hydrolysis is the breaking of glycosidic bonds using a water molecule

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45
Q

give example of hydrolysis in the body

A

digestion in the gut

muscle and liver cells- when carbohydrates are broken down to release energy for respiration

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46
Q

what is starch broken down into when needed?

A

glucose

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47
Q

describe the structure of starch

A

alpha glucose
amylopectin + amylose

amylose (20%)

  • straight chain
    -1,4 glycosidic bonds
  • as it lengthens, it spirals (compact)

amylopectin (80%)
-kinky
-branched
- 1,4 and 1,6 glycosidic bonds

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48
Q

what is glycogen used for?

A

carbohydrate store in animals and fungi

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49
Q

describe the structure of glycogen.

A

similar to amylopectin

1,4 and 1,6 glycosidic bonds
branched molecules
compact

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50
Q

describe the structure of cellulose

A

beta glucose
remains long and straight
1,4 glycosidic bonds
every other monomer is inverted so hydroxyl groups stick out
hydrogen bonds can form
crosslinking

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51
Q

use of cellulose

A

provided structure and support to plants (cell wall)

52
Q

explain why the rate slows in an enzyme reaction

A

enzyme controlled reactions are often very rapid as substrate gets used up

less substrate = fewer collisions= rate slows

53
Q

give uses of lipids

e… s…
integral part of ….

A

energy store
integral part of cell membranes

54
Q

what are fats/oils made from?

A

fatty acids and glycerol- held together with ester bonds

55
Q

what are two ways in which fatty acids can differ?

A

carbon chain length
whether it’s saturated/unsaturated

56
Q

what is the difference between a saturated and an unsaturated fatty acid?

A

unsaturated has a double carbon bonds
saturated has no double carbon bonds

57
Q

what are
monounsaturated fatty acid
polyunsaturated fatty acid ?

A

monounsaturated- has one double carbon bond

polyunsaturated- many double carbon bonds

58
Q

what is esterification?

A

a condensation reaction between the carboxyl group of the fatty acid and a hydroxyl group of the glycerol
(water molecule produced)

59
Q

what happens when lipids are oxidised in respiration?

the bonds are ….. and ….. is produced

A

the bonds are broken and carbon dioxide and water are produced

60
Q

explain these features of lipids:
waterproofing
insulating
low density
insoluble in water

A

waterproofs organisms

insulators- (fatty sheath insulates nerves and impulses travel faster) also keeps animals warm

low density- body fat of water animals helps them float

insoluble in water- do not interfere with water based reactions in the cell

61
Q

what is the formula for phosphate ions?

A

PO43-

62
Q

what is the structure of a phospholipid?

A

phosphate head, glycerol, two fatty acids- held together with ester bonds

63
Q

describe how the different parts of a phospholipid respond to water.

A

phosphate head- hydrophilic- dissolves in water

fatty acid tails-hydrophobic- don’t dissolve in water

64
Q

where may a phospholipid monolayer form?

A

at surface between water and air

65
Q

what do all proteins contain?

A

carbon, hydrogen, oxygen, nitrogen (and some contain sulfur)

66
Q

what are proteins made from?

A

amino acids

67
Q

what is the general formula for an amino acid?

A

page 28 (bottom left)

68
Q

what do all amino acids have?

… group
….. group
… group

A

amino group (NH2)
carboxyl group (COOH)
R group (varies between amino acids- this is where sulfur is found if present)

69
Q

how do amino acids join together?

A

amino group from one amino acid and carboxyl group from other (join in a condensation reaction)

peptide bond is formed

70
Q

what is a dipeptide?

A

when two amino acids have joined

71
Q

what is a polypeptide?

A

when many amino acids have joined together

72
Q

when does a polypeptide become a protein?

A

when the polypeptide folds/coils or associates with other polypeptide chains

73
Q

what determines the bonds within a protein?

give examples of these bonds

A

the bonds are determined based on the R group

hydrogen/ionic/disulphide

74
Q

what causes hydrogen bonds in amino acids?

explain what hydrogen bonds’ strength is like

A

oxygen has small negative charge
hydrogen has small positive charge

attracted to each other

hydrogen bonds are weak but if there are a lot of them they have a big effect and hold the amino acid together

75
Q

when do disulfide bonds form in an amino acid?

A

when two cystine molecules are close
(both contain sulfur)

76
Q

what type of reaction takes place in a disulfide bond?

results in?

A

oxidation reaction between the two groups, results in a covalent bond knows as a disulfide bond

77
Q

when do ionic bonds form in an amino acid?

what are these known as?

A

between positive and negative amino acids

salt bridges

78
Q

describe the primary structure of an amino acid

A

chain of amino acids held together with peptide bonds

79
Q

describe the secondary structure of an amino acid

A

arrangement of chain into a repeating structure

alpha helix
beta pleated sheet

80
Q

describe the tertiary structure of an amino acid

A

folding of the chains into a 3D shape, based on the R bonds

bonds hold this structure together

81
Q

describe the quaternary structure of an amino acid

A

several polypeptide chains interacting

82
Q

describe what fibrous proteins are like

l
p p c
c l

A

long, parallel polypeptide chains with occasional cross linkages

83
Q

what function do fibrous protein play within an organism?

why are they good for this?

A

fibrous proteins play a structural role

insoluble in water and very tough

84
Q

describe the structure of collagen

-type of protein

-amino acid sequence

-polypeptides per molecule

-each polypeptide is wound into a ..

-shape

A

fibrous protein

regular amino acid sequence (every third is glycine)

each molecule has 3 polypeptide chains

each polypeptide is wound into a left-handed helix

long and thin

85
Q

describe the structure of haemoglobin

-type of protein

  • number of prosthetic groups

-soluble/insoluble

-shape

-number of polypeptide chains

-role

-amino acid sequence

A

Globular protein

Regions of a helix and beta pleated sheet

4 prosthetic groups

Soluble

Spherical

4 polypeptide chains

Functional role

Irregular amino acid sequence

86
Q

what are conjugated proteins?

A

protein molecules joined to a prosthetic group

87
Q

what are glycoproteins?

what does this do?

A

proteins with a carbohydrate prosthetic group

makes the protein hold onto water- makes them harder to be broken down- and also aids mucus as it has lubricating properties

88
Q

what are lipoproteins?
what does this do?

A

protein with lipids as a prosthetic group

helps transport cholesterol in the blood

89
Q

what are the three parts of a nucleotide?

A

pentose sugar
nitrogen-containing base
phosphate group

90
Q

what are the two options for the pentose sugar?

A

ribose (for RNA)
deoxyribose (for DNA)

91
Q

what’s the difference between ribose and deoxyribose?

A

deoxyribose contains one less oxygen atom than ribose

92
Q

what is the difference between a purine and a pyrimidine?

A

they have different number of nitrogen-containing rings

purine- has two
pyrimidine- has one

93
Q

how are the sugar, base and phosphate joined?

A

in a condensation reaction

(this forms a nucleotide)

94
Q

how many phosphate groups does ATP have?

A

three

95
Q

what happens to ATP when energy is needed?

what breaks off?
what reaction?
catalysed by?
to make?

A

third phosphate breaks off (in hydrolysis reaction)

catalysed by ATPase

makes ADP

96
Q

what type of reaction is ATP to ADP?

A

reversible

97
Q

what are nucleic acids made from?

A

nucleotide polymers

98
Q

what do nucleic acids carry?

A

information needed to form new cells (DNA)

99
Q

How are nucleotides joined to form a nucleic acid?

type of reaction
held by what (between which parts?)

A

join in a condensation reaction, they are held together by phosphodiester bonds

(between sugar of one nucleotide and phosphate group of the other)

100
Q

describe the structure of RNA molecules

can f…. OR remain as l….

A

can fold into complex shapes due to hydrogen bonds or can remain as long molecules

101
Q

what does a purine always pair with?

A

a pyrimidine

102
Q

how many hydrogen bonds are formed between C and G

A

3

103
Q

how many hydrogen binds are formed between A and T?

A

2

104
Q

how many base pairs are there for one complete twist on the helix?

A

10

105
Q

what are the two strands called? (according to how many C on pentose)

A

5 prime
3 prime

106
Q

How does semi-conservative replication work?

A

the DNA unzips and new nucleotides align along each strand

the new double helix contains one original and one new strand

107
Q

what is the difference between N14 and N15?

A

N15 is heavier

108
Q

Why do some bases in a gene not code for an amino acid?

A

they are start/stop codons

some parts of the gene are introns

109
Q

how many amino acids are there?

A

20

110
Q

where does the process of translation happen?

A

on the ribosome

111
Q

what is the sequence of three bases called?

A

a codon

112
Q

what is meant by DNA being a triplet code?

A

DNA is a triplet code therefore, it is read in threes

every 3 bases codes for one amino acid

4x4x4 (there are four bases and it’s TRIPLET)

113
Q

what is meant by DNA having a non-overlapping code?

A

each sequence of three bases is read individually

114
Q

what is meant by DNA having a degenerate code?

A

if final base changes, (in mutation), it would still produce the same amino acid

115
Q

differences between DNA and RNA

A

DNA double/two strands, RNA single strand

DNA made from deoxyribose as nucleic acid wheras RNA has ribose

116
Q

where is mRNA formed?

A

in the nucleus
(on the anti-sense strand)

117
Q

what does ligase do in DNA replication?

A

ligase joins sections of DNA together, forming phosphodiester bonds between sugar and phosphate

118
Q

mRNA is complementary to the ….

A

anti sense strand

119
Q

mRNA is the same as the….

(T has become U)

A

the sense strand

120
Q

what is a start/stop codon?

A

determines where to start/stop translating

121
Q

what are two important features of tRNA and what are their uses?

A

amino acid binding site

anticodon- complementary to mRNA’s anticodons

122
Q

describe how a quaternary structure is formed after protein synthesis has occurred.

A

polypeptide folds into either alpha helix or beta pleated sheet

two or more polypeptides join together , held by h bonds or disulphide bridges.

123
Q

what is activation energy?

A

activation energy is the energy required for a reaction to occur , by making bonds weak and break , increasing number of collisions

124
Q

why is it necessary to investigate the initial rate of reaction when investigating enzymes?

A

at this point , there should be enough substrates to saturate enzymes.

ensure substrate is not limiting factor.

highest rate- as reaction continues, substrate conc decreases because it is used up in reactions.

125
Q

explain what is meant by the term sustainable.

A

a resource that can be renewed, it is not finite

it is available to future generations.

126
Q

describe the structure of a globular protein

A

has tertiary structure
has quaternary structure
hydrophobic on outside of molecule.