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3.1 Biological molecules Flashcards

1
Q

Monomer

A
  • The smaller units from which larger molecules are made

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2
Q

Polymer

A
  • Molecules made from a large number of monomers joined together

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3
Q

Monosaccharide

A
  • The monomers from which larger carbohydrates are made
  • e.g. glucose, fructose, galactose

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4
Q

Disaccharide

A
  • Formed by the condensation of two monosaccharides
  • held together by a glycosidic bond
  • e.g. maltose, sucrose, lactose

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5
Q

Polysaccharide

A
  • Formed by the condensation of many glucose units
  • held by glycosidic bonds
  • e.g. starch, glycogen, cellulose

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6
Q

Cellulose

A
  • Polysaccharide in plant cell walls
  • formed by the condensation of β-glucose

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7
Q

Glycogen

A
  • Polysaccharide in animals
  • formed by the condensation of α-glucose

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8
Q

Starch

A
  • Polysaccharide in plants
  • formed by the condensation of α-glucose
  • contains two polymers – amylose and amylopectin

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9
Q

Glycosidic bond

A
  • C–O–C link
  • between two sugar molecules
  • formed by a condensation reaction
  • it is a covalent bond
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10
Q

Amylose

A
  • Polysaccharide in starch
  • made of α-glucose
  • joined by 1,4-glycosidic bonds
  • coils to form a helix

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11
Q

Amylopectin

A
  • Polysaccharide in starch
  • made of α-glucose
  • joined by 1,4 and 1,6-glycosidic bonds
  • branched structure

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12
Q

Condensation reaction

A
  • A reaction that joins two molecules together
  • with the formation of a chemical bond
  • involves the elimination of a molecule of water
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13
Q

Hydrolysis reaction

A
  • A reaction that breaks a chemical bond
  • between two molecules
  • involves the use of a water molecule
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14
Q

Fibrils

A
  • Long, straight chains of β-glucose glucose
  • held together by many hydrogen bonds

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15
Q

Triglyceride

A
  • Formed by the condensation of one molecule of glycerol and three molecules of fatty acids
  • forming 3 ester bonds

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16
Q

Phospholipid

A
  • Formed by the condensation of one molecule of glycerol and two molecules of fatty acid
  • held by two ester bonds
  • a phosphate group is attached to the glycerol

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17
Q

Induced-fit model

A
  • The enzyme active site is not initially complementary to the substrate
  • the active site moulds around the substrate
  • this puts tension on bonds
  • lowers the activation energy
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18
Q

Competitive inhibitor

A
  • A molecule that is the same/similar shape as the substrate
  • binds to the active site
  • prevents enzyme-substrate complexes from forming

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19
Q

Non-competitive inhibitor

A
  • A molecule that binds to an enzyme at the allosteric site
  • causing the active site to change shape
  • preventing enzyme-substrate complexes from forming

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20
Q

Primary structure

A
  • The sequence of amino acids on a polypeptide chain

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21
Q

Secondary structure

A
  • The folding or coiling
  • to create a β pleated sheet or an α helix
  • held in place by hydrogen bonds

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22
Q

Tertiary structure

A
  • The further folding
  • to create a unique 3D shape
  • held in place by hydrogen, ionic and sometimes disulfide bonds

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23
Q

Quaternary structure

A
  • More than one polypeptide chain in a protein

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24
Q

Peptide bond

A
  • Covalent bond joining amino acids together in proteins
  • C–N link between two amino acid molecules
  • formed by a condensation reaction
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25
Q

What is the effect of temperature on enzyme-controlled reaction?

A
  • At low temperatures, there is not enough kinetic energy for successful collisions between the enzyme and substrate.
  • At too high a temperature, enzymes denature, the active site changes shape and enzyme-substrate complexes cannot form.
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26
Q

What is the effect of pH on enzyme-controlled reaction?

A
  • Too high or too low a pH will interfere with the charges in the amino acids in the active site.
  • This breaks the ionic and hydrogen bonds holding the tertiary structure in place
  • ∴ the active site changes shape and the enzyme denatures.
  • Different enzymes have a different optimal pH.
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27
Q

What is the effect of substrate concentration on enzyme-controlled reaction?

A
  • At low substrate concentrations, there will be fewer collisions between the enzyme and substrate.
  • At high substrate concentrations, the rate plateaus
  • because all the enzyme active sites are saturated.
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28
Q

What is the effect of enzyme concentration on enzyme-controlled reaction?

A
  • At low enzyme concentrations, there will be fewer collisions between the enzyme and substrate.
  • At high enzyme concentrations, the rate plateaus
  • because there are more enzymes than the substrate, so many empty active sites.
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29
Q

Ester bond

A
  • –COO– chemical bond
  • formed between glycerol and fatty acids
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30
Q

Hydrophilic

A
  • The ability to mix, interact or
    attract water
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31
Q

Hydrophobic

A
  • The tendency to repel and not mix with water
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32
Q

Glucose

A
  • Monosaccharide that exists as two isomers
  • β glucose and α glucose

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33
Q

Galactose

A
  • An example of a monosaccharide that forms lactose
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34
Q

Fructose

A
  • An example of a monosaccharide that forms sucrose
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35
Q

Isomer

A
  • Molecules with the same molecular formula
  • but the atoms are arranged differently
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36
Q

Maltose

A
  • Disaccharide
  • formed by the condensation
  • of two glucose molecules

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37
Q

Lactose

A
  • Disaccharide
  • formed by the condensation
  • of a glucose molecule and a galactose molecule
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38
Q

Sucrose

A
  • Disaccharide
  • formed by the condensation
  • of a glucose molecule and a fructose molecule
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39
Q

Polypeptide

A
  • Polymer chain of a protein
  • made up of amino acids
  • bonded together by peptide bonds
  • following condensation reactions

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40
Q

Amino acid

A
  • The monomer of a protein
  • formed from C,H,O,N
  • contains a carboxyl group, amine group and an R group

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41
Q

Carboxyl group

A
  • COOH group
  • made up of a C with hydroxyl (OH) and carbonyl (double-bonded O) group bonded to it
  • found in amino acids and fatty acids

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42
Q

Amine group

A
  • NH₂ group found on amino acids

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43
Q

R group on amino acids

A
  • The variable group
  • the part of each of the 20 amino acids that is different
44
Q

α helix

A
  • A secondary structure in proteins
  • a coiled shape held in place by hydrogen bonds

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45
Q

β pleated sheet

A
  • A secondary structure in proteins
  • a folded, pleated shape
  • held in place by hydrogen bonds

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46
Q

Hydrogen bonds

A
  • Weak bond
  • forms between H and O
  • in many biological molecules e.g. proteins, water, DNA, tRNA
47
Q

Ionic bonds

A
  • A bond that forms between the R groups of different amino acids
  • in the tertiary structure of proteins
48
Q

Disulfide bonds

A
  • A strong covalent bond
  • between two sulfur atoms in the R groups of different amino acids
  • in the tertiary structure of proteins
49
Q

Active site

A
  • Unique-shaped part of an enzyme
  • that the substrate binds to

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50
Q

Activation energy

A
  • The minimum amount of energy required for a reaction to occur
51
Q

Enzyme-substrate complex

A
  • forms when an enzyme and substrate collide and bind
  • resulting in a lowered activation energy

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52
Q

Denature

A
  • When the active site changes shape
  • so the substrate can no longer bind
53
Q

Enzyme-inhibitor complex

A
  • The structure that forms when an enzyme and inhibitor collide and bind
  • prevents enzyme-substrate complexes from forming
54
Q

Saturated fatty acid

A
  • A long hydrocarbon chain with a carboxyl group at one end
  • only single bonds between carbon atoms

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55
Q

Unsaturated fatty acid

A
  • A long hydrocarbon chain with a carboxyl group at one end
  • at least one double bond between carbon atoms

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56
Q

Polar molecule

A
  • A molecule that has an uneven distribution of charge
57
Q

Phospholipid bilayer

A
  • Phospholipids have two charged regions
  • in water, they are positioned so that the heads are exposed to water and the tails are not

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58
Q

Plasma membrane

A
  • Phospholipid bilayer
  • cell surface membranes and organelle membranes
59
Q

Reducing sugar

A
  • sugars that can reduce Cu²⁺ ions in Benedict’s reagent to Cu⁺ ions in the form of copper (I) oxide
  • which forms a brick-red precipitate
60
Q

Test for reducing sugar

A
  • Add Benedict’s reagent
  • heat
  • observe green/yellow/orange/brick red precipitate

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61
Q

How does the structure of a triglyceride relate to it’s function?

A
  • large ratio of energy-storing carbon-hydrogen bonds compared to the number of carbon atoms; a lot of energy is stored in the molecule
  • high ratio of hydrogen to oxygen atoms they act as a metabolic water source
  • do not affect water potentials and osmosis
  • have a relatively low mass
62
Q

How does the structure of a phospholipid relate to it’s function?

A
  • Phospholipids have two charged regions, so they are polar.
  • In water, they are positioned so that the heads are exposed to water and the tails are not.
  • This forms a phospholipid bilayer which makes up the plasma membrane around cells.
63
Q

How does the structure of a triglyceride and phospholipid differ?

A
  • A phospholipid has one fewer fatty acid chain
  • which is replaced by a phosphate group

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64
Q

What is the difference between saturated and unsaturated fatty acid?

A
  • A saturated fatty acid has no double bonds between carbon atoms
  • where as unsaturated fatty acids had at least one double bond between carbon atoms
65
Q

Non-reducing sugar

A
  • a sugar unable to reduce Cu²⁺
  • the glycosidic bond must be hydrolysed to expose the reducing group
  • e.g. sucrose
66
Q

Test for non-reducing sugar

A
  • Following a negative Benedict’s test
  • boil sample in acid and then neutralise with alkaline
  • add Benedict’s reagent and heat
  • observe orange/brick red colour

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67
Q

Test for starch

A
  • Add iodine
  • turns blue/black

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68
Q

Test for lipids

A
  • Add ethanol and shake to dissolve
  • then add water
  • white emulsion forms

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69
Q

Test for protein

A
  • Add biuret
  • turns purple

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70
Q

Nucleotide

A
  • The monomer of DNA and RNA
  • contains a pentose sugar, a phosphate group and a nitrogenous base

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71
Q

Nitrogenous base

A
  • Part of a nucleotide
  • adenine, guanine, cytosine, thymine and uracil
72
Q

DNA nucleotide

A
  • The monomer of DNA
  • contains a deoxyribose sugar, a phosphate group and a nitrogenous base

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73
Q

Polynucleotide

A
  • DNA polymer
  • many nucleotides joined together via a condensation reaction
  • joined by phosphodiester bonds

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74
Q

Phosphodiester bond

A
  • Bond joining two nucleotides together
  • forms between a phosphate group and the pentose sugar
75
Q

Complementary base pairs

A
  • The base pairs that align opposite each other and form hydrogen bonds
  • adenine and thymine/uracil
  • guanine and cytosine
76
Q

Ribose

A
  • pentose sugar
  • found in RNA nucleotide and ATP
77
Q

Uracil

A
  • Nitrogenous base
  • found in RNA instead of thymine
78
Q

mRNA

A
  • a copy of a gene
  • single-strand polymer of RNA

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79
Q

tRNA

A
  • found only in the cytoplasm
  • single-stranded but folded to create a shape that looks like a cloverleaf
  • held in place by hydrogen bonds

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80
Q

rRNA

A
  • rRNA combines with protein to make ribosomes
81
Q

DNA template strand

A
  • A DNA strand that is used to make a new DNA copy from
  • both DNA strands in the double helix are used as templates in DNA replication
82
Q

DNA polymerase

A
  • An enzyme in DNA replication
  • joins together adjacent nucleotides
83
Q

Semi-conservative replication

A
  • DNA replication is semi-conservative replication
  • one strand is from the parental DNA and one strand is newly synthesised
84
Q

DNA helicase

A
  • Enzyme that breaks hydrogen bonds between the two chains of DNA in a double helix
  • causes the two strands to separate
  • involved in DNA replication and transcription
85
Q

Large latent heat of vaporisation

A
  • a lot of energy is required to convert water from its liquid state to a gaseous state
  • this is due to the hydrogen bonds, as energy is needed to break these to turn it into a gas
  • means water can provide a cooling effect
86
Q

High specific heat capacity

A
  • a lot of energy is required to raise the temperature of the water
  • because some of the heat energy is used to break the hydrogen bonds between water molecules
  • important so water can act as a temperature buffer
87
Q

Metabolite

A
  • Water is involved in many reactions
  • such as photosynthesis, hydrolysis, and condensation reactions
88
Q

Solvent

A
  • Water is a good solvent
  • meaning many substances dissolve in it
  • polar (charged) molecules dissolve readily in water due to the fact water is polar
89
Q

Strong cohesion

A
  • water molecules ‘stick’ together due to hydrogen bonds
  • results in water moving up the xylem as a continuous column of water
  • provides surface tension, creating a habitat on the surface of the water for small invertebrates
90
Q

ATP synthase

A
  • Enzyme that catalyses the synthesis of ATP from ADP + Pi
91
Q

ATP hydrolase

A
  • Enzyme that catalyses the hydrolysis of ATP into ADP + Pi
92
Q

Phosphorylation

A
  • The addition of a phosphate group to a molecule
  • making the molecule more reactive/it gains energy
93
Q

Structure of water

A
  • Water is a polar molecule
  • the oxygen atom is slightly negative
  • the hydrogen atoms are slightly positive

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94
Q

Dipeptide

A
  • Two amino acids bonded together by a peptide bond
  • formed by a condensation reaction

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95
Q

RNA nucleotide

A
  • monomer of RNA
  • composed of a phosphate group, ribose and a nitrogenous base
  • has the base uracil instead of thymine

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96
Q

Role of hydrogen ions

A
  • determine the pH
  • the more hydrogen ions, the more acidic the conditions are
  • an important role in chemiosmosis in respiration and photosynthesis
97
Q

Role of iron ions

A
  • a compound of haemoglobin
  • involved in oxygen transport
98
Q

Role of sodium ions in co-transport

A
  • involved in co-transport for absorption of glucose and amino acids in the ileum
99
Q

Role of phosphate ions

A
  • as a component of DNA, RNA and ATP
  • phosphodiester bond in DNA and RNA forms between the phosphate group and the pentose sugar
100
Q

Fatty acid structure

A
  • carboxyl group and a long hydrocarbon chain
  • can be saturated or unsaturated

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Biology (6 decks)

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