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AQA Alevel Biology > Biological molecules > Flashcards

Biological molecules Flashcards

(56 cards)

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1
Q

What is a monomer?

A

Small, single units from which larger molecules are made

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2
Q

what is a polymer?

A

Molecules made from a large number of monomers joined together

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3
Q

what is a 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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4
Q

What is a hydrolysis reaction?

A

a reaction that breaks a chemical bond between two molecules, involving the addition of a water molecule.

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5
Q

What is the function of carbohydrates?

A

store energy and can provide structural support to plant cells.

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6
Q

What are monosaccharides?

A

the monomers from which larger carbohydrates are made
e.g - glucose, galactose and fructose

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7
Q

What are disaccharides?

A

Formed by the condensation on 2 monosaccharides held together by a glyosidic bond
E.g - maltose, sucrose and lactose

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8
Q

What is a polysaccharide?

A

formed by the condensation of many monosaccharide units
E.g - starch, glycogen and cellulose

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9
Q

What is cellulose?

A

Polysaccharide in plant cell walls formed by the condensation of beta glucose.
provides structural support to plants

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10
Q

What is glycogen?

A

polysaccharide in animals formed by the condensation of alpha glucose

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11
Q

What is starch?

A

Polysaccharide in plants formed by the condensation of alpha glucose
contains 2 polymers - amylose ad amylopectin

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12
Q

What is a Glycosidic bond?

A

C-O-C link
between 2 sugar molecules formed by a condensation reaction
a covalent bond

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13
Q

Amylose

A

polysaccharide in starch
made of alpha glucose joined by 1,4-glycosidic bonds
coils to form a helix

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14
Q

Amylopectin

A

Polysaccharide in starch
made of alpha glucose joined by 1,4 and 1,6 glycosidic bonds
Branched structure

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15
Q

Alpha v Beta glucose

A

Alpha - hydroxyl group on bottom
Beta - hydroxyl group on top

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16
Q

How are the three disaccharides formed?

A

glucose + glucose = maltose
glucose + Galactose = lactose
glucose + fructose = sucrose

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17
Q

properties of glycogen

A

insoluble - cant be dissolved - wont change water potential - no lysis of cell
highly branched = readily hydrolysed - can fulfil animals higher metabolic rate

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18
Q

Properties of starch

A

insoluble - it can stored within cells and not dissolve - wont change water potential
Amylose - spiral-shaped - can be readily compacted
Amylopectin - branched - provides larger SA for enzymes to attach to - readily hydrolysed back into glucose for respiration

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19
Q

structure of cellulose

A

long, straight chains of beta glucose lie parallel and are held together of hydrogen bonds
called Fibrils

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20
Q

properties of cellulose

A

insoluble - wont change water potential - wont call lysis of cell
Lots of hydrogen bonds = very strong polysaccharide

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21
Q

Triglyceride

A

formed by the condensation of one molecule of glycerol and 3 fatty acids
forms 3 ester bonds

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22
Q

phospholipid

A

formed by the condensation of 1 molecule of glycerol and 2 fatty acids
held by 2 ester bonds
phosphate group attached to the glycerol

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23
Q

induced-fit model

Study These Flashcards
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

24
Q

competitive inhibitor

Study These Flashcards
A

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

25
Non-competitive inhibitor
A molecule that binds to an enzyme at the allosteric site causing the active site to change shape preventing enzyme-substrate complexes from forming
26
Primary structure
The sequence of amino acids on a polypeptide chain
27
secondary structure
The folding or coiling of the chain to create a beta pleated sheet or an alpha helix held in place by hydrogen bonds
28
Tertiary Structure
the further folding to create a 3D shape held in place by hydrogen, ionic and disulphide bonds
29
Quaternary structure
more than one polypeptide chain in protein
30
peptide bond
covalent bond joining amino acids together in protein C-N link between 2 amino acids molecules formed by a condensation reaction
31
What is the effect of temperature on an enzyme-controlled reaction?
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.
32
What is the effect of pH on enzyme-controlled reaction
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
33
What is the effect of substrate concentration on enzyme controlled reaction
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
34
What is the effect of enzyme concentration on enzyme-controlled reaction?
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.
35
Ester bond
-COO- chemical bond formed between glycerol and fatty acids
36
Hydrophilic
the ability to mix, interact or attract water
37
Hydrophobic
the tendency to repel and not mix with water
38
isomer
molecules with the same molecular formula but the atoms are arranged differently
39
polypeptide
polymer chain of a protein made up of amino acids bonded together by peptide bonds following condensation reactions
40
amino acid
the monomer of a protein contains a carboxyl group, amine group and an R group
41
carboxyl group
COOH group double bonded O to C found in amino acids and fatty acids
42
Amine group
NH2 group found on amino acids
43
R group on amino acids
The variable group the part of each of the 20 amino acids that is different
44
activation energy
The minimum amount of energy required for a reaction to occur
45
saturated fatty acid
A long hydrocarbon chain with a carboxyl group at one end only single bonds between carbon atoms
46
unsaturated fatty acid
a long hydrocarbon chain with a carboxyl group at one end at least one double bond between carbon atoms
47
polar molecule
a molecule that has an uneven distribution of charge
48
Phospholipid bilayer
2 charged regions heads exposed to water and tails are not
49
Reducing sugar
sugars that can reduce Cu2+ ions in benedict's reagent to Cu+ ions which forms a brick-red precipitate
50
Test for reducing sugar
add benedicts reagent heat observe green/yellow/orange/brick red precipitate
51
How does the structure of a triglyceride relate to its function?
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
52
How does the structure of a phospholipid relate to its function?
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.
53
Test for non-reducing sugar
Following a negative benedicts test boil sample in acid and then neutralise with alkaline add benedicts reagent and heat observe orange/brick red colour
54
test for starch
add iodine turns blue/black
55
test for lipids
add ethanol and shake to dissolve add water white emulsion forms
56
test for protein
add biuret turns purple

AQA Alevel Biology (22 decks)

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