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A-level biology (Eduquas) > Biological molecules > Flashcards

Biological molecules Flashcards

core concepts

1
Q

what is the importance of magnesium?

A

it is an important constituent of chlorophyll and essential to photosynthesis, plants lacking magnesium can not make chlorophyll so the leaves turn yellow (chlorosis) growth is stunted from lack of glucose. mammals need magnesium for their bones

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2
Q

what is the importance of iron?

A

iron is part of haemoglobin and a lack of it can lead to anaemia in humans

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3
Q

what are phosphate ions used for?

A

making nucleotides and are a constituent of phospholipids found in biological membranes

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4
Q

what is calcium used for?

A

important structural component of plant cell walls & bones

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5
Q

what are inorganic ions?

A

an ion that has no more than one carbon atom

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6
Q

how much micro/macronutrients do humans need?

A

micronutrients= needed in minute traces
macronutrients= needed in small concentrations

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7
Q

describe polypeptide primary structure

A

primary structure is determined by the base sequence on one strand of the DNA, it is a sequence of amino acids joined together by peptide bonds to create a polypeptide chain

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8
Q

describe and draw a dipeptide

A
  • NH^2,CHR^1,CO-NH,CHR^1,COOH
  • the resulting compound of a condensation reaction
    between two amino acids bonded together by a peptide
    bond
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9
Q

what is hydrophobic interaction?

A

non-polar amino acids cluster together on the inside of a protein because they are repelled by water

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10
Q

explain polypeptide quaternary structure

A

consists of more than one polypeptide chain (tertiary structure) joined together mostly by disulphide and hydrophobic bonds, sometimes containing a prosthetic group e.g: haemoglobin

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11
Q

what is this?:

          H
          |
  H  -  C  - OH
          |
  H    -C  - OH
          |
  H  -  C  -  OH
	  |
	  H
A

A GLYCEROL

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12
Q

what is this?:

     CH^2OH
     |
     C = O
     |
  HC - OH
     |
  HC - OH
     |
     CH^2OH
A

pentose sugar

a monosaccharide containing 5 carbon atoms

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13
Q

what is collagen

A

made from three identical left handed helix polypeptide chains wound around each other to form a triple helix.

held together by h-bonds. its insoluble in water. collagen molecules cross link through covalent bonds to form fibres which give strength

it is the most basic amino acid it fibrous and is found in the skin.

in each polypeptide chain every third amino acid is glycine.

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14
Q

describe haemoglobin

A

globular protein which has a metabolic function

it is a quaternary structure consisting of 4 globin molecules held together by h-bonds

has a prosthetic group made up of Fe atoms called the haem group which carry oxygen

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15
Q

what is this?:

             H        H        O
             |         |        ||
  H    -   N   -    C   -    C   -   OH
                        |
                        R
A

amino acid

Amino group, R-group, variable group

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16
Q

what bond links phospholipids and triglycerides?

A

Ester bond

an oxygen atom joining two atoms one of which is a carbon atom attached by a double bond to another oxygen atom

O2 atom joins 2 atoms 1 of which is a C-atom attached by a = bond to O2

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17
Q

what is this?:

         CHO
          |
OH  -  CH
          |
OH  -  CH
          |
       HC  - OH
          |
       HC  -  OH
          |
          CH^2OH
A

hexose

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18
Q

what is a peptide bond

A

the chemical bond formed by a condensation reaction between the amino group of one amino acid & the carboxyl group of another

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19
Q

what is represented here?:

CH^2
|
S
|
S
|
CH^2

<

A

disulphide bond

a covalent bond between the sulphur atoms of two cysteine residues in a

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20
Q

what is this?:

           O    H
           ||   |
  HO = O = C -  …
                  |
                 H
A

head of a fatty acid

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21
Q

What is the difference between a saturated fatty acid and a non-saturated fatty acid?

A

a saturated fatty acids has only carbon- carbon single bonds where as an unsaturated fatty acid has one or more c=c double bond, which puts a kink in the chain

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22
Q

what is ?:

                        H             O
                        |             ||
                H  -  C  -  O  -  C  -  R (1)
                        |              O
                        |             ||
                H  -  C  -  O  -  C  -  R (2)
                        |              O
                        |              ||
                H  -  C  -  O  -   C  -  R (3)		
                        |
                        H
A

Triglyceride

1 glycerol & 3 fatty acid tails by a condensation reaction

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23
Q

draw a condensation reaction between a glycerol and three fatty acids

A

look up answer :)

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24
Q

what is an ionic bond?

A

a type of bond that occurs between oppositly charged ions

contribute to the folding of protiens into their tertiary structure

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25
Q

describe the structure of glycogen

A

highly branched alpha glucose 1,4 & 1,6 glycosididic bonds

main storage product in animal

branching happens every 8-10 molecules

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26
Q

what is the diffrence between alpha and beta glucose?

A

ABBA
Alpha above
Beta below
(OH group)

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27
Q

draw alpha glucose

A

C6H12O6

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28
Q

Describe the structure of cellulose

A

cellulose is made up of beta glucose 1,4 glycosidic bonds each roatated 180 degrees from the one adjacent to it forming inear colums connect by hydrogen bonds between the OH groups

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29
Q

describe the structure of chitin

A

beta glucose monomers and amino acids linked by 1,4 glycosidic bonds each rotated 180 degrees to the one adjacent and each paralel chain is is linked by h-bonds forming microfibrils

the linear chains are called heteroplysacharides

30
Q

name three properties of chitin

A
  1. very strong
  2. light weight
  3. waterproof
31
Q

what is a structual difference and similarity between cellulose and chitin

A

> a diiference is that chitin has an amino group on its carbon 2 whereas cellulose has a OH group
a similarity is that they both have their OH group on the top of carbon 1 which is lost during the condenation reaction joining them together because they are both beta glucoses

32
Q

what is a glycosidic bond

A

the bond that joins to glucose monomers together

33
Q

glucose + glucose =

A

maltose

34
Q

why are hydrogen bonds formed

A

because of the diffrence in charges between the OH- and H+ atoms

35
Q

decribe the structure of galactose

A

the OH group is above on both sides of the monomer

36
Q

galactose + glucose =

A

lactose

37
Q

describe the structure of fructose

A

it has CH2OH below H on carbon one as well as oncarbon 6

38
Q

frutose + glucose =

A

sucrose

39
Q

what does LDL do

A

LDL contains and transport saturated fatty acids which are harmful, a build up of these in the arteries may lead to heart disease

40
Q

what do HDL do

A

HDL contain and transport unsaturated fatty acids which transport harmful fats to the liver for disposal, high concentrations of HDL reduce the risk of a heart attack

41
Q

describe polypeptide tertiary structure

A

further folding of the polypetide chain to forma= a 3d globular shape

42
Q

what is the structure of a phospholipid

A

glycerol, a phosphate group & two fatty acids

an important component of cell membranes

43
Q

which part of the phopholipid is hydrophobic

A

the tail is hydrophobic because it is non polar (doesn’t have a charge) so will not interact with the water

44
Q

describe polypeptide seconday structure

A

the polypetide chain folds due to hydrogen bonds forming between the amino acids along the chain into alpha helixes or beta pleted sheets

45
Q

describe the structure of amylopectine

A

a-glucose monomer are joined together by 1,4 and 1,6 glycosidic bonds this means that the chain is branched

less so than glycogen it only brances every 24-36 monomer

46
Q

describe the structure of amylose

A

tightly coiled linear chain of polysaccharides composed of 1,4 glycosidic bonds

47
Q

what are the three main functions of carbohydrates

A
  • storage of enery
  • release of energy
  • cellular structures
48
Q

what is an isomer

A

molecules with the same chemical formulea but diffrent arrangments of atoms

49
Q

what are two other hexose sugars

A

fructose and galactose

50
Q

what is a property of monosaccharides

A

soluble in water

easily dissolved in cell and transported into the blood stream

51
Q

properties of polysaccharides

A
  • compact (easily stored)
  • easily hydrolised (release glucose for respiration)
  • storage/structure
52
Q

give 4 examples of polysaccharides

A
  • starch (storage in plants)
  • glycogen (storage in animals)
  • cellulose (structure in plants)
  • chitin (structure in fungi & exosceletons)
53
Q

which polysaccharides are used for storage

A

alpha

54
Q

which polysaccharides are used for structure

A

beta

55
Q

which two molecules make up starch

A

amylose and amylopectine

56
Q

where is glycogen stored

A

liver and muscle cells

57
Q

what are four properties of lipids

A
  • insoluble in water
  • soluble in organic solvents
  • fats are solid at room tempreture
  • oils are liquid at room tempreture
58
Q

state the 6 functions of lipids

A
  • storage of energy
  • protection of vital organs
  • thermal insulation
  • boyance
  • metabolic water
  • waterproofing
59
Q

there are twenty amino acids found in natur. how do they differ from eachother

A

they have diffrent variable groups

60
Q

what bonds hold together tertiary structure of protiens

A
  • hydrogen
  • ionic (between oppositly charged R groups)
  • disulphide bridges (between S atoms)
  • hydrophobic/phylic interactions
  • peptide bonds
61
Q

what are the two classifications of protiens

A

globular and fiberose

62
Q

why are fiberous protiens effective at carrying out STRUCTUAL functions

A
  • tough
  • non-specific
  • insoluable
63
Q

what are the properties of globular protiens

A
  • they have a specific shape
  • compact
  • solubale in water
64
Q

how do you test for protiens

A
  1. add a few drops of biuret reagent to a protiens solution
  2. shake gently
  3. turn from blue to lilac
65
Q

how do you test for reducing sugars

A
  1. add a few drops of benedicts reagent to test sample
  2. heat in a water bath
  3. turn from blue to brick red

may be graduated between green yellow orange and brick red

semi-quantative

66
Q

how do you test for non reducing sugars

A

if a negative result is initally found with the benedicts test:
1. add HCl to test sample
2. heat in a waterbath ( to hydrolyse any glycosidic bonds)
3. add bicarbonate of soda to nutralise
4. add benedicts reagent and heat in a waterbath
5. if present the solution will turn from blue to brick red

67
Q

how do you test for lipids

A
  1. mix a sample with equal volumes of ethanol and water
  2. iflipids are present it will turn cloudy white
68
Q

what is cohesion

A

water molecules sticktogether as a result of the formation of hydrogen bonds

69
Q

what are the 7 properties of water

A
  • surface tensionn
  • universal solvent (excellent transport medium)
  • metabolite
  • high specific heat capacity
  • high latent heat capacity
  • density
  • transparenct
70
Q

how do you test for starch

A

add a few drops of iodine to samp,e and if its present it will turn from orange to blue black

A-level biology (Eduquas) (7 decks)

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