(1) biological molecules Flashcards

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1
Q

what is a monosaccharide and what are some examples?

A

the monomers from which lather carbohydrates are made
glucose(C6H12O6) ( alpha, beta), fructose, galactose

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2
Q

what is the test for reducing sugars?

A

only reacts with sugars with an aldehyde group, makes it a reducing sugar

add Benedict’s reagent (alkaline solution of copper II sulfate to food, heat mixture for 5 mins

will turn red if reducing sugar is present (forms an insoluble precipitate of copper I oxide)

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3
Q

how is a disaccharide formed?
how does the hydrolysis of a disaccharide work?

A

when monosaccharides join together in a condensation reaction forming a glycosidic bond

water is added to a disaccharide and it breaks the glycosidic bond releasing the monosaccharides

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4
Q

What is the test for non-reducing sugars?

A

test w Benedict’s reagent in a water bath for 5 minutes, still blue = no reducing sugar present
add food sample with a dilute acid (HCL)in a test tube and in the water bath to hydrolyse the disaccharide into its monosaccharides
then add NAOH to neutralise the HCL and test with pH paper
then add BR and heat again and if turns orange brown reducing sugar is present (hydrolysis of non reducing sugar proved reducing sugars)

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5
Q

how is
a) lactose
b) maltose
c) sucrose
made

A

a) galactose n glucose
b) glucose and glucose
c) fructose and glucose

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6
Q

what is a polysaccharide?

A

polymers formed by combining many monosaccharide molecules
large molecules that are insoluble and useful for storage and when hydrolysed they break down into mono and disaccharides

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7
Q

what are some examples of polysaccharides?

A

starch, glycogen and cellulose

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8
Q

what are the properties of a starch molecule?

A

forms an important component of food and is the main energy source in most diets
found in many parts of a plant in the form of small grains

made up of chain of alpha glucose monosaccharides linked by glycosidic bonds formed by condensation reactions

can be un/branched: unbranded chains are wound into a tight coil that makes the molecule compact

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9
Q

what is the role of starch and how is its structure suited for its role?

A

main role: energy storage

  • insoluble and therefore doesn’t affect water potential so water is not drawn into the cell by osmosis
  • large and insoluble: does not diffuse out of cells
  • compact: it can be stored in a small space
  • when hydrolysed it forms alpha glucose which is easily transported and can be used for respiration
  • the branched form has many ends which can be acted on by enzymes to release glucose monomers rapidly
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10
Q

what glycosidic bonds do amylose and amylopectin have?

A

amylose: 1-4 g bond
amylopectin: 1-6 1-4g bond

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11
Q

what are the properties of glycogen?

A

found in animals and bacteria but not plants
made of alpha glucose and has shorter and more highly branched chains that starch

main carbohydrates storage in animals
stored as small molecules in the liver and muscles

mass is small because fat is the main storage molecule in animals g

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12
Q

how does glycogen’s structure suit for storage?

A

insoluble: does not draw water into cell by osmosis
insoluble: does not diffuse out of cell
compact: can be stored in a small space

more Highly branched with more ends than starch which can be acted on by enzymes. More rapidly broken down to form glucose monomers used in respiration
important to animals as they have a higher metabolic rate and respiratory rate as they are more active

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13
Q

how does the structure of cellulose suit its function?

A

made of monomers of beta glucose
has straight unbranched chain, run parallel to one another allowing hydrogen bonds to form cross-linkages between adjacent chain which add collective strength

cellulose molecules group together to form microfibrils which make up fibres to provide more strength

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14
Q

what are the characteristics of lipids?
what are the main groups?

A

contain carbon hydrogen and oxygen (proportion of oxygen to carbon and hydrogen is smaller than carbohydrates)
Insoluble in water
soluble in organic solvents such as alcohols and acetone

triglycerides and phospholipids

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15
Q

what are the roles of lipids?

A

source of energy: when oxidised lipids provide more than twice the energy as the same mass of carbohydrate and release valuable water

waterproofing: lipids are insoluble in water and are useful as waterproofing
(plants and insects have waxy lipid cuticles that conserve water, while mammals produce an oily secretion from sebaceous glands in the skin)

insulation: fats are slow conductors of heat and when stored beneath the body surface heal to retain body heat

protection: fat is stored around delicate organs

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16
Q

what is the formation of triglyceride?

A

glycerol + 3 fatty acids -> triglyceride and 3 water molecules

In the condensation reaction each fatty acid forms an ester bond with glycerol

17
Q

what is the characteristic of an
a) saturated glycerol molecule
b) mono unsaturated
c) polyunsaturated

A

a) single bonds between carbon atoms only
b) one double bond between carbon atoms
c) more than one double bond between carbon atoms

18
Q

how are triglycerides a good source of energy, good storage molecules, an important source of water?

A

good source of energy: high ratio of energy-storing carbon hydrogen bonds to carbon

good storage molecules: much energy can be stored in a small volume

source of water: when oxidised they release water as they have a high ratio of hydrogen to oxygen atoms

19
Q

what is the formation of a phospholipid?
what 2 parts is a phospholipid made of ?

A

glycerol + 2 fatty acids and a phosphate ion

hydrophilic head and hydrophobic tail

20
Q

what is the emulsion test?

A

add sample of food to a test tube and add ethanol and add water (Ethanol extracts the liquid from the crushed solid sample and the lipid comes out of the solution when water is added)

cloudy white colour indicates the presence of a lipid (A layer is formed at the top as lipids are less dense than water, droplets diffract water turning cloud white)

21
Q

what is the general structure of an amino acid?

A

central carbon atom surrounded by:

amino group (NH2) (L)
carboxyl group (COOH) (R)
H atom (T)
R group (B) each amino acid has a different R group

22
Q

what are the biological roles of proteins?

A

structural: main component of body tissues
catalytic: all enzymes are proteins catalysing biochemical reactions
signalling: many hormones and receptors are proteins
immunological: all antibodies are proteins

23
Q

how is a dipeptide formed?

A

when 2 amino acids join together in a condensation reaction to produce a dipeptide and water
the 2 amino acid monomers are linked together by a peptide bond
can be broken in hydrolysis

24
Q

what is the primary structure of proteins?

A

many amino acids monomers can be joined in polymerisation
the sequence of amino acids in a polypeptide chain that form the protein

25
Q

what is the secondary structure of proteins?

A

form when the polypeptide chains coil (because of the hydrogen bonds) and form an alpha helix or beta pleated sheet

26
Q

what is the tertiary structure of proteins?

A

the 3D shape is held together by different bonds (disulphide, hydrogen, ionic and hydrophobic and hydrophilic interactions

27
Q

what is the quaternary structure of proteins?
examples?

A

some proteins formed by more than one polypeptide chain, (produced when different polypeptides interact)
haemoglobin, collagen

28
Q

what is an enzyme?

A

large globular proteins that catalyse the biochemical reactions that cells need to survive and carry out its function

29
Q

how does the formation of an enzyme sub rate comp,ex increase the rate of reaction?

A

when the active site and substrate bind to create the enzyme substrate complex, bonds are created and bent which allows the activation energy to be lowered and speed up the reaction

30
Q

what does the lock and key model state?

A

the substrate fits into the active of an enzyme like a lock and key, the shapes are complementary and the same remain the same throughout

31
Q

what does the induced fit model state:

A

the enzyme changes shape slightly to allow the substrate to enter the active site
this can happen because the hydrogen bonding holding much of the protein together is quite weak, so bonds can be reformed and broken easily

32
Q

what are the 4 factors that affect enzyme activity?

A

temperature
pH
enzyme concentration
substrate concentration

33
Q

how does temp affect enzyme activity?

A

high temp: molecules gain kinetic energy and collide with eachother more often and more e-s complexes are formed
too high temp affects the hydrogen binding, causes bonds to break and alters shape of active site
substrate will not fit into the active site, causes denaturation of enzyme
low temp, molecules will move slowly and meet less often therefore fewer reaction will happen and less product is made

34
Q

how does pH affect enzyme activity?

A

in highly acidic or alkaline environments, H+ or OH- ions interact with amino acids in the enzyme, breaking bonds and altering the shape of the active site causing the enzyme to denature

35
Q

how does enzyme and substrate concentration affect enzyme activity?

A

high concentration, higher rate of reaction as more molecules meet and more ES complexes are formed and more product is made

36
Q

what are inhibitors?

A

substances that interfere with enzyme activity

37
Q

what is a competitive inhibitor?

A

the inhibitor molecule binds to the active site and prevents the substrate from enetering

38
Q

what is non competitive inhibitor?

A

inhibitor molecule bonds to the enzyme away from the active site and alters the shape of the active site, preventing an ES complex from forming

39
Q
A