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biological molecules - bio alevel > chapter 1 - biological molecules > Flashcards

chapter 1 - biological molecules Flashcards

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1
Q

What are monomers and polymers?

A
  • monomers = single units which connect to form larger molecules
  • polymers = large molecules made from lots of monomers bonded together
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2
Q

What are monosaccharides, disaccharides and polysaccharides ?

A
  • monosaccharides are simples sugars, the monomers of carbohydrates , with 3 - 7 carbons
  • disaccharides are two monosaccharides bonded together
  • polysaccharides are many monosaccharides bonded together
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3
Q

Give examples of monosaccharides

A
  • glucose, fructose, galactose and ribose
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4
Q

What is a condensation reaction ?

A
  • forming larger biological molecules from smaller biological molecules with water as a product
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5
Q

What are hydrolysis reactions ?

A
  • breaking down bigger biological molecules to smaller biological molecules using water
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6
Q

What is glucose ?

A
  • a hexose sugar with molecular formula ,C6H1206 , it is an important form of energy
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7
Q

What are isomers ?

A
  • molecules with the same molecular formula but different structure
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8
Q

What are the two isomers of glucose and what is the difference between them ?

A
  • alpha and beta glucose
  • alpha glucose = carbon -1 hydroxyl is below the ring
  • beta glucose = carbon 1 hydroxyl is above the ring
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9
Q

What is glycosidic bond ?

A
  • a bond between 2 monosaccharides , between two carbons with an oxygen between them
  • they are made during condensation reactions so produce water
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10
Q

Give examples of disaccharides

A
  • maltose , sucrose and lactose
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11
Q

What is maltose made of ?

A
  • glucose + glucose
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12
Q

What is sucrose made of ?

A
  • glucose + fructose
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13
Q

What is lactose made of ?

A
  • glucose and galactose
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14
Q

Give examples of polysaccharides ?

A
  • starch, cellulose, glycogen
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15
Q

What is starch made up of ?

A
  • amylose and amylopectin
  • alpha glucose
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16
Q

Describe amylose

A
  • a long unbranched polymer with 1 - 4 carbon glycosidic bonds
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17
Q

Describe amylopectin

A
  • a long polymer with branches
  • 1-4 bonds between the linear chain
  • 1-6 bonds between branches
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18
Q

How is starch designed for it function ?

A
  • amylose = is very long and unbranched , meaning it can fold into a helical structure and is ideal for storage
  • amylopectin = the branched structure increases surface area for rapid hydrolysis back into glucose
  • its insoluble so wont change the water potential of the cells
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19
Q

Where is starch found?

A
  • as a store of energy in plants in seeds
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20
Q

What is glycogen made of ?

A
  • alpha glucose and it is a highly branched molecule
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21
Q

Where is glycogen found ?

A
  • as an energy store in animals
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22
Q

How is glycogen designed for its function ?

A
  • its highly branched meaning it has a rage surface area for it to be broken down into glucose during glycogenolysis
  • insoluble so it does not disturb the water potential of cells
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23
Q

What is cellulose structured ?

A
  • long unbranched chains of beta glucose
  • each second beta glucose flips so that a a 1 - 4 glycosidic bond can be formed
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24
Q

Where is cellulose found ?

A
  • in the cell walls of plant cells
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25
Q

How is cellulose designed for its function ?

A
  • cellulose chains are held together by many hydrogen bonds to form microfibrils
  • hydrogen bonds are weak but because there are many of them this makes the structure strong
  • so cellulose can provide strength for the cell wall
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26
Q

What are triglycerides and how are they made ?

A
  • a glycerol with three fatty acids
  • made from a condensation reaction with a glycerol and three fatty acids
  • so three molecules of water are produced
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27
Q

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

A
  • saturated has only single carbon to carbon bonds
  • unsaturated has at least one double carbon to carbon bond
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28
Q

How does the structure of triglycerides help with energy storage ?

A
  • the large ratio of energy storing hydrogen to carbon bonds compared to the amount of carbon atoms means a lot of energy is stored in the molecule
29
Q

How does the structure of triglycerides help it be a metabolic water source ?

A
  • as there is a high ratio of hydrogen to oxygen molecules , the triglyceride can produce water if its oxidised ( broken down ) , which is good for animals that live in the desert
30
Q

How are triglycerides designed to make them not disturb the water potential of cells

A
  • the are large and hydrophobic making the insoluble
31
Q

How does the mass of triglycerides help with its function ?

A
  • as the have a relatively low mass ( compared to things like muscle ) lots of the triglyceride can be stored for energy without making the animal heavy and preventing movement
32
Q

How are lipids designed to help with insulation ?

A
  • lipids are found in adipose tissue which insulates the body and is around organs like the kidneys to protect them from injury
33
Q

How are lipids used in waterproofing ?

A
  • in waxy cuticles and when animals secrete oils
34
Q

what is a phospholipid made of ?

A
  • a glycerol, two fatty acids and a phosphate group
35
Q

Describe the head and tails of a phospholipid

A
  • head (phosphate) is polar and there is a negative charge on one of the oxygens , this makes it attracted to water so it hydrophilic
  • the tail (fatty acid ) has no charge and so repels water so its hydrophobic
  • head will repel other fatty acids
  • tails will mix with other lipids
36
Q

How is the structure of a phospholipid designed for its function

A
  • the hydrophobic tail and hydrophilic head mean chains of phospholipids can arrange themselves in a bilayer , with the tails on the inside
  • the head can stay in the intracellular fluid
37
Q

How do you test for a non - reducing sugar ?

A

-add hydrochloric acid , heat in a warm water bath then cool then neutralise ( the acid breaks down the sucrose )
- the complete the normal Benedict’s test

38
Q

Why when completing the Benedict’s test does the colour show up at the top first ?

A
  • due to convection currents , the hotter particles move to the top so the reaction happens at the top first
39
Q

How do we test for lipids ?

A
  • dissolve in ethanol ( shake it )
  • then add distilled water
  • if positive, a white milky emulsion forms
40
Q

What does a kink do to a fatty acid ?

A
  • a kink = a cis double bond prevents the lipids from packing tightly , making them liquid at room temperature
41
Q

What is the difference between cis fat and trans fat ?

A
  • cis fat = the hydrogens on carbon to carbon double bond are on same plane
  • trans fat = the hydrogens on the carbon to carbon double bonds are on different planes
42
Q

What are proteins and what are they made of ?

A
  • polymers made of amino acids
43
Q

What is the general structure of amino acids ?

A
  • and amino group, a central carbon with a hydrogen attached to it, an R group and a carboxyl group
44
Q

How do amino acids join to form dipeptides and polypeptides ?

A
  • the OH from the carboxyl group of one amino acid and the H from the amino group of another amino acid join to form water .
  • a peptide bond forms between the carbon and nitrogen.
  • this is a condensation reaction
45
Q

What are the 4 levels of structure in proteins ?

A
  • primary, secondary, tertiary and quaternary
46
Q

What is the primary structure of proteins ?

A
  • the order of amino acids in the polypeptide chain
47
Q

What is the secondary structure of proteins ?

A
  • hydrogen bonds form between the H in the amine group from one amino acid and the and th C=O from the carboxyl group of another amino acid.
  • the hydrogen bonds help hold the chains in either an alpha helix or a beta pleated sheet
  • how they bend depends on the sequence of the amino acids
48
Q

What is the tertiary structure of proteins ?

A
  • the secondary structure folds even more to form a unique 3D shape
  • these are held together by ionic, disulphide and hydrogen bonds which form between R groups of different amino acids
  • hydrophilic and hydrophobic interactions happens between polar and non polar groups, they are weak
49
Q

What is the quaternary structure of proteins ?

A
  • when a protein is made up of more than one polypeptide chain which are held by hydrogen, ionic and disulphide bonds and hydrophobic and hydrophilic interactions
  • e.g haemoglobin
50
Q

How do proteins become denatured ?

A
  • when the bonds that hold the secondary or tertiary structure break, the unique 3D shape of the protein is lost
  • this is caused by too high temperatures = to much kinetic energy
  • or to low/high pH ( too many H+ or OH- ions
51
Q
  • how can the 3D structure of proteins change ?
A
  • if one of the amino acids in the sequence changes , the hydrogen, ionic and disulphide bonds form in different places which means the 3D shape will change
52
Q

What is the test for proteins ?

A
  • add biuret regents = an alkali + plus copper sulphate solution
  • there must be at least 2 peptide bonds for the test to work
  • a positive result will go from blue to lilac
53
Q

What are proteins used for ?

A
  • enzymes
  • antibodies
  • transport across membranes
  • structural components ( creating strong fibres )
  • hormones
  • muscle contraction
54
Q

What are enzymes ?

A
  • they are biological catalysts
  • they are globular proteins with a unique tertiary structure
55
Q

How do enzymes act as catalysts ?

A

They lower the activation energy needed

56
Q

What are intracellular and extracellular enzymes ( + give examples )

A
  • intracellular enzymes = act within the cells that produce them , e.g used in DNA replication and ATP synthesis
  • extracellular enzymes = act outside the cells that produce them and are secreted, e,g used in digestion, pepsin and amylase
57
Q

How does the lock and key theory of enzymes work ?

A
  • the active site of the enzymes fits perfectly with the substrate
  • the two form an enzyme - substrate complex
  • charged R groups within the active site distort the substrate ( by forming temporary bonds )
  • this lowers the activation energy needed to break the substrate
58
Q

How does the induced fit model of enzymes work ?

A
  • the active site is a slightly different shape to the substrate
  • when the substrate enters, the active site changes shape slightly and moulds around the substrate
  • this puts a strain around the bonds in the substrate which lowers the activation energy needed to break them
  • when the products of the substrate leaves, the active site returns to its original shape
59
Q

What are the factors that affect the rates of enzyme controlled reactions ?

A
  • temperature
  • pH
  • substrate concentration
  • enzyme concentration
  • inhibitors
60
Q

How does temperature affect the rate of enzyme controlled reactions ?

A
  • at temp increases: particles have more kinetic energy = more collisions = more enzyme - substrate complexes formed
  • optimum temp: enzyme workings it’s fastest
  • too high temp: to much kinetic energy which causes bonds in tertiary structure to break = active site changes shape
61
Q

How does pH affect the rate of enzyme controlled reactions ?

A
  • at low pH: H+ ions break ionic / hydrogen bonds in tertiary structure = enzyme denatures
  • at optimum pH: pH best for enzyme and is working at its fastest
  • too high pH: OH- ions break ionic / hydrogen bonds = enzyme denatures
62
Q

How does the substrate concentration affect the rate of enzyme controlled reactions ?

A
  • as substrate concetration increases , rate of reaction increases are more enzyme substrates can be formed
  • as some point the rate of reaction will stop increasing as all the enzymes are being used so adding more substrate doesn’t do anything
63
Q

How does enzyme concentration affect the rate of reaction ?

A
  • as the enzyme concentration increases, the rate of reaction increases as more enzyme - substrate complexes can be formed
  • at some point the rate of reaction will stop chasing as all the substrates are being acted upon so adding more enzymes doesn’t do anything ( there are now empty active sites )
64
Q

What are the two types of inhibitors ?

A
  • competitive and non- competitive
65
Q

How do competitive inhibitors work ?

A
  • they have a similar shape to the substrate
  • so bind to the active site which stops the substrate from biding to it
  • which means less enzyme - substrate complexes are formed so rate of reaction decreases
66
Q

How do non - competitive inhibitors work ?

A
  • they bind away from the active site ( the allosteric site )
  • this cause the tertiary structure of the enzyme to change shape so the active site changes shape
  • so no enzyme - substrate complexes can be formed which decreases the rate of reaction
67
Q

How does increasing the concentration of the substrate affect the competitive inhibitors ?

A
  • if there is a lot of substrate, it can knock of the competitive inhibitor so the rate of reaction can increase again
68
Q

How does increasing the concentration of substrate affect non - competing inhibitors ?

A
  • it does not affect them
  • as the active site has changed shape
  • so adding more substrate will not do anything to increase the rate of reaction

biological molecules - bio alevel (2 decks)

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