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3.1 Biological Molecules Flashcards

3.1.1 Monomers and polymers, 3.1.2 Carbohydrates, 3.1.3 Lipids, 3.1.4 Proteins, (81 cards)

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1
Q

what are biological molecules?

A

all the molecules used to construct living organisms

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2
Q

name the 5 types of biological molecules

A

carbohydrates
proteins
lipids
nucleic acids - DNA & RNA
ATP

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3
Q

what do all biological molecules contain?

A

carbon, hydrogen, oxygen

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4
Q

What are monomers?

A

The smaller units from which larger molecules are made

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5
Q

What are polymers?

A

Molecules made from a large number of monomers

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6
Q

Give 3 examples of monomers

A

Monosaccharides
Amino acids
Nucleotides

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7
Q

How are polymers formed?

A

a condensation reaction forms a chemical bond between monomers releasing a water molecule

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8
Q

how are polymers broken down into monomers?

A

a hydrolysis reaction which breaks the chemical bond between 2 monomers by adding a molecule of water

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9
Q

What are monosaccharides?

A

the monomers from which larger carbohydrates are made

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10
Q

what are the 3 types of monosaccharides?

A

Hexose sugars - 6 carbons
Pentose sugars - 5 carbons
Triose sugars - 3 carbons

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11
Q

what are the properties of hexose sugars?

A

they are an energy source
sweet
soluble

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12
Q

List 3 examples of hexose sugars and where they are found

A

glucose - plants and animals
fructose - plants
galactose - animals

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13
Q

what are the 2 types of glucose and where are they found?

A

Alpha (α) glucose - animals and plants
Beta (β) glucose - plants
(They are isomers - molecules with same molecular formula but different arrangement of atoms)

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14
Q

Properties and examples of pentose sugars

A

Structural purposes
Used to make DNA
-ribose sugar
-deoxy ribose

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15
Q

What is the difference between the structures of alpha and beta glucose?

A

the hydroxyl group in beta glucose is found above the ring and they hydroxyl group in alpha glucose is found below the ring - on the C1 atoms

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16
Q

how is a disaccharide formed?

A

2 monosaccharides join together in a condensation reaction to form a glycosidic bond

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17
Q

give 3 examples of disaccharides and the monosaccharides they are formed from

A

maltose -> alpha glucose + alpha glucose
sucrose -> alpha glucose + fructose
lactose -> alpha glucose + galactose

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18
Q

how are polysaccharides formed?

A

by repeated condensation reactions

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19
Q

give 3 examples of polysaccharides

A

starch
glycogen
cellulose

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20
Q

How do plants store excess glucose?

A

as starch

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21
Q

what is starch made of?

A

2 polysaccharides of alpha glucose - amylose and amylopectin

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22
Q

describe the structure of amylose and how it relates to its function

A

-amylose is a long unbranched chain of glucose
-the 1-4 glycosidic bonds create a coiled spring structure making it compact in order to store more alpha glucose in a small space
-the alpha glucose is used in respiration to transfer energy (ATP)
-It is insoluble so is able to store a lot of starch without it affecting the water potential

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23
Q

describe the structure of amylopectin and how it relates to its function

A

-amylopectin is a long unbranched chain of alpha glucose
-The 1-4 glycosidic bonds create a helix structure
-The 1-6 glycosidic bond cause branches which increases the surface area
-more terminal ends so the rate of glycosidic bond hydrolysis is greater and so it is able to release more alpha glucose per second

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24
Q

what is glycogen?

A

the storage of polysaccharide in animals

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25
what is the structure of glycogen and how does it relate to its function?
- it has 1-4 and 1-6 glycosidic bonds -causing a helix structure with branching -The branching means more glucose can be released from storage quickly which is important for energy release in animals
26
what is cellulose?
long unbranched chains of beta glucose, present in plant cell walls
27
How is beta glucose able to form a glycosidic bond?
the C1 and C4 can only react if one glucose molecule is flipped 180*
28
describe the cellulose chains
they run parallel to each other with hydrogen bonds forming between the chains creating strong fibres called microfibrils which adds structural support to the cells
29
how is a microfibril made?
of 100s of cellulose chains
30
how is a fibril made?
100s of microfibrils
31
what do fibrils knit together to form?
a cell wall
32
give examples of lipids?
triglycerides phospholipids waxes fats and oils
33
what do all lipids contain?
hydrocarbons
34
how are triglycerides formed?
3 condensation reactions between 1 molecule of glycerol and 3 fatty acids forming 3 ester bonds
35
What is the solubility of lipids?
they are insoluble
36
what are lipids made of?
glycerol and fatty acids
37
what is the glycerol structure?
3 carbon chain with 1 OH group bonded to each carbon (3 OH groups total) and 5 hydrogens - glycerol is a 3 carbon alcohol
38
what is a fatty acid made of?
carboxylic acid end (COOH), varying length of a hydrocarbon chain ((CH2)n) and a methyl end (CH3)
39
what is a fatty acid with a double bond known as?
an unsaturated fatty acid - double bond causes chain to kink
40
what is a fatty acid with a single bond known as?
a saturated fatty acid
41
what happens when a fatty acid has a double bond (or more than 1 double bond)?
if a fatty acid has a double bond, there is less Hydrogen bonding causing the fatty acid to be less stable so it has a lower melting point -liquid at room temperature
42
how do you hydrolyse a trygliceride?
add 3H2O molecules
43
What do diglycerides consist of?
1 glycerol and 2 fatty acids - there is a free hydroxyl group to react with other monomers
44
What is a phospholipid formed from?
a diglyceride and a phosphate group - phosphate group reacts with free hydroxyl group
45
what do phospholipids form?
a cell membrane - phospholipid bilayer
46
what is glycerol in terms of water?
hydrophilic -attracts water -water soluble -polar
47
what are fatty acids in terms of water?
hydrophobic -repel water -non polar
48
what is the phosphate group in terms of water?
hydrophilic -attracts water
49
Why is a cell membrane formed from fatty acids and phosphate ions?
phospholipid heads are hydrophilic, fatty acid tails are hydrophobic so they form a double layer with the heads facing towards the water (the outside) on either side, the centre of the bilayer is hydrophobic so water soluble substances can't pass through easily
50
what are triglycerides mainly used for?
used as energy for storage molecules due to their long hydrocarbon tails which contain a lot of chemical energy so a lot of energy is releases when it is broken down
51
what is a property of lipids?
they are insoluble in water so they don't affect the water potential of the cell and cause water to enter the cell via osmosis which could cause the cell to swell
52
what are the monomers of proteins?
amino acids
53
how many naturally occurring amino acids are there?
20
54
what is the general structure of an amino acid?
has a carboxylic acid group (COOH), an Amine group (NH2), an R group - which is a variable group differing from each amino acid, a hydrogen, all bonded to a central carbon atom
55
what does a condensation reaction between 2 amino acids form?
a peptide bond formed between the carbon on the carboxylic acid end and the nitrogen on the amine end (OH from carboxylic acid and H from amine group is removed as molecule of water) - this forms a dipeptide
56
how are polypeptides formed?
many condensation reactions between many amino acids
57
what is the primary structure of a protein?
the specific order of amino acids in the polypeptide chain
58
what is the secondary structure of a protein?
the folding of the polypeptide chain, hydrogen bonds form between the amino acids in the chain (between O from carboxylic acid end and H from the amine end). This makes it coil into either an alpha helix structure or fold into a beta pleated sheet
59
what do they hydrogen bonds do In the secondary structure of a protein?
holds the shape, the bonds are individually weak but provide strength on mass providing structure
60
what is the tertiary structure of a protein?
the coiled or folded chain is coiled or folded even further, forming a specific 3D structure (e.g. an enzyme)
61
what is the quaternary structure?
2 or more polypeptide chains bonded together to form final 3D structure
62
what is an enzyme?
biological catalysts that speed up the rate of reaction by lowering the rate of reaction - they are all globular proteins
63
what are intracellular and extracellular enzymes?
intracellular - work within cells extracellur - made in cells, work in fluids
64
what are some properties/conditions of enzymes?
specific to 1 reaction not used up or changed by a reaction does not alter product of reaction only catalyses reactions that already occur water soluble due to hydrophilic side group on amino acid
65
what is the active site of an enzyme?
where chemical reactions take place - it has a specific 3D tertiary structure complementary to substrate
66
what is formed when a substrate binds to an active site?
enzyme-substrate complex
67
explain the lock and key model
lock and key model proposes that the substrate is an exact complementary shape to the active site
68
how is an enzyme-product formed?
the active site has a specific 3D tertiary structure complementary to substrate so the substrate binds to the active site creating an enzyme-substrate complex. The enzyme bends the bonds of the substrate due to the active site creating an enzyme-product complex. then the active site will release the product and the reaction is finished and the products diffuse away (lock and key model)
69
what is the induced fit model?
the induced fit model proposes that a substrate with a similar complementary to the active site ca still bind to it. in order for this to happen the active site slightly changes shape so that it will now be an exact complementary shape to the substrate. the enzyme will always refer back to its original shape
70
name 6 factors affecting enzyme activity
temperature pH substrate concentration enzyme concentration inhibitors activators
71
describe the rate of enzyme reaction at low temperature
rate of reaction is slow as the substrate and enzyme have little kinetic energy so there is fewer successful collisions so fewer substrate-enzyme complexes are formed - activation energy never achieved
72
describe the rate of enzyme reaction as the temperature increases
as temp increases, kinetic energy increases so there is an increase in the amount of successful collisions so there are more substrate-enzyme complexes being formed therefore there is an increase in the rate of reaction
73
describe the rate of enzyme reaction at optimum temperature
optimum temperature has the fastest rate of reaction where there are the most successful collisions per second, highest rate of enzyme-substrate complexes being formed
74
describe the rate of enzyme reaction at high temperature - past the optimum
active site denatures so the 3D tertiary structure is no longer complementary to the substrate so there are fewer successful collision per second so lower rate of enzyme-substrate complexes forming, there is a decrease in the rate of reaction
75
why does an active site denature?
because the bonds of the tertiary structure are broke so active site no longer complementary to substrate
76
how does pH affect enzyme rate of reaction?
pH affects bonds responsible for the enzymes tertiary structure (ionic and hydrogen). Extreme pH will break these bonds causing the active site to denature so it is no longer has a complementary shape to the substrate so there are fewer successful collisions per second, fewer enzyme-substrate complexes, rate of reaction drops
77
how does substrate concentration affect enzyme rate of reaction?
high substrate concentration means faster rate of reaction, more substrate molecules means there is more likely to be collisions between substrate and enzymes
78
why are active sites a limiting factor? (substrate concentration)
at a certain point during the reaction all the active sites will be occupied so increasing substrate concentration won't further increase the rate of reaction as active sites are a limiting factor
79
what do inhibitors do and what are the two types?
inhibitors can prevent enzyme activity by binding to the enzymes competitive inhibitors non-competitive inhibitors
80
what are competitive inhibitors and how do they effect rate of reaction?
competitive inhibitors have a similar 3D shape to the substrate/ a complimentary 3D shape to the active site. when the competitive inhibitor binds to the active set it prevents enzyme-substrate complexes from forming so fewer products formed per second so there is a lower rate of reaction
81
what are non-competitive inhibitors and how do they effect rate of reaction?
non-competitive inhibitors binds to a binding site (binding site is away form active site) causing the active site to have a 3D shape change by bending the bonds, so active site is no longer complementary to substrate preventing successful enzyme-substrate complexes from forming once non-competitive inhibitors are removed the active site will return to its original shape

Biology A level (13 decks)

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