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A-level Biology > biological molecules > Flashcards

biological molecules Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Monomer definition

A

The smaller units from which larger molecules are made

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2
Q

Polymer definition

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
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

Primary structure

A

The sequence of amino acids on a polypeptide chain

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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

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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21
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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22
Q

Quaternary structure

A

More than one polypeptide chain in a protein

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23
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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24
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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25
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
therefore the active site changes shape and the enzyme denatures
Different enzymes have a different optimal pH

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26
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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26
Q

Ester bond

A

–COO– chemical bond
formed between glycerol and fatty acids

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26
Q

Hydrophilic

A

The ability to mix, interact or
attract water

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27
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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28
Q

Hydrophobic

A

The tendency to repel and not mix with water

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29
Q

Glucose

A

Monosaccharide that exists as two isomers
β glucose and α glucose

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30
Q

Galactose

A

An example of a monosaccharide that forms lactose

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31
Q

Fructose

A

An example of a monosaccharide that forms sucrose

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32
Q

Isomer

A

Molecules with the same molecular formula
But the atoms are arranged differently

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33
Q

Maltose

A

Disaccharide
formed by the condensation of two glucose molecules

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34
Q

Lactose

A

Disaccharide
formed by the condensation of a glucose molecule and a galactose molecule

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35
Q

Sucrose

A

Disaccharide
formed by the condensation of a glucose molecule and a fructose molecule

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36
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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37
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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38
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

39
Q

Amine group

A

NH2 group found on amino acids

40
Q

R group on amino acids

A

The variable group
the part of each of the 20 amino acids that is different

41
Q

α helix

A

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

42
Q

β pleated sheet

A

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

43
Q

Hydrogen bonds

A

Weak bond
Forms between H and O
In many biological molecules e.g. proteins, water, DNA, tRNA

44
Q

Ionic bonds

A

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

45
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

46
Q

Activation energy

A

The minimum amount of energy required for a reaction to occur

46
Q

Active site

A

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

47
Q

Enzyme-substrate complex

A

Forms when an enzyme and substrate collide and bind resulting in a lowered activation energy

48
Q

Denature

A

When the active site changes shape so the substrate can no longer bind

49
Q

Enzyme-inhibitor complex

A

The structure that forms when an enzyme and inhibitor collide and bind
Prevents enzyme-substrate complexes from forming

50
Q

Saturated fatty acid

A

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

51
Q

Unsaturated fatty acid

A

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

52
Q

Polar molecule

A

A molecule that has an uneven distribution of charge

52
Q

Plasma membrane

A

Phospholipid bilayer
cell surface membranes and organelle membranes

53
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

54
Q

Reducing sugar

A

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

54
Q

Test for reducing sugar

A

Add Benedict’s reagent
Heat
Observe green/yellow/orange/brick red precipitate

55
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

56
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.

57
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

58
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

59
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

60
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

61
Q

Test for starch

A

Add iodine
turns blue/black

62
Q

Test for lipids

A

Add ethanol and shake to dissolve
Then add water
White emulsion forms

63
Q

Test for protein

A

Add biuret
turns purple

64
Q

Nitrogenous base

A

Part of a nucleotide
adenine, guanine, cytosine, thymine and uracil

65
Q

Nucleotide

A

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

66
Q

DNA nucleotide

A

The monomer of DNA
Contains a deoxyribose sugar, a phosphate group and a nitrogenous base

67
Q

Polynucleotide

A

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

68
Q

Phosphodiester bond

A

Bond joining two nucleotides together
forms between a phosphate group and the pentose sugar

69
Q

Complementary base pairs

A

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

69
Q

mRNA

A

a copy of a gene
single-strand polymer of RNA

70
Q

Uracil

A

Nitrogenous base
found in RNA instead of thymine

70
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

71
Q

Ribose

A

pentose sugar
found in RNA nucleotide and ATP

72
Q

rRNA

A

rRNA combines with protein to make ribosomes

73
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

74
Q

Semi-conservative replication

A

DNA replication is semi- conservative replication
One strand is from the parental DNA and one strand is newly synthesised

74
Q

DNA polymerase

A

An enzyme in DNA replication
Joins together adjacent nucleotides

75
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

76
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

77
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

78
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

78
Q

Metabolite

A

Water is involved in many reactions such as photosynthesis, hydrolysis, and condensation reactions

79
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

80
Q

ATP synthase

A

Enzyme that catalyses the synthesis of ATP from ADP + Pi

81
Q

ATP hydrolase

A

Enzyme that catalyses the hydrolysis of ATP into ADP +Pi

82
Q

Phosphorylation

A

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

83
Q

Structure of water

A

Water is a polar molecule
The oxygen atom is slightly negative
The hydrogen atoms are slightly positive

84
Q

Dipeptide

A

Two amino acids bonded together by a peptide bond
Formed by a condensation reaction

85
Q

RNA nucleotide

A

Monomer of RNA
Composed of a phosphate group, ribose and a nitrogenous base has the base uracil instead of thymine

86
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

87
Q

Role of iron ions

A

A compound of haemoglobin involved in oxygen transport

88
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

89
Q

Role of sodium ions in co-transport

A

involved in co-transport for absorption of glucose and amino acids in the ileum

90
Q

Fatty acid structure

A

carboxyl group and a long hydrocarbon chain
Can be saturated or unsaturated

A-level Biology (8 decks)

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