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biology year 1 > biological molecules > Flashcards

biological molecules Flashcards

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AP® Biology flashcards
1
Q

what is a monomer?

A

a large molecule made of a single repeating unit

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2
Q

what is polymer?

A

a large molecule made of a chain of repeating units covalently bonded
formed by a condensation reaction

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3
Q

define metabolism

A

the sum total of all biochemical reactions that occur in cells of living organisms

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4
Q

what is a condensation reaction?

A

-chemical reaction where a larger molecule is formed by joining smaller molecules
- new covalent bond is formed
-a water molecule is released
- anabolic

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5
Q

what is a hydrolysis reaction?

A

-splitting larger molecules into smaller ones
-covalent bond is broken
- a water molecule is used
-catabolic

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6
Q

how is water used as a metabolite?

A

water is used as a reactant in metabolic reactions
-required in photosynthesis or splitting disaccharides by hydrolysis

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7
Q

give 2 examples of where high latent heat of vaporisation is usefull?

A

-transpiration in plants
-sweating (for reducing dogs body heat with their tongue)

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8
Q

explain waters property of high latent heat of vaporisation?

A

-evaporation of water requires a lot of energy to break hydrogen bonds
-when water evaporates, from a surface it removes heat and has a cooling effect

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9
Q

why is a high boiling point for water important?

A

so water remains liquid over a wide range of temps
this means water is a good transport medium eg plasma in blood and mineral ions in xylem

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10
Q

what is the importance of water having a low density of ice?

A

-creates habitats, solid surface as ice floats
-insulation for organisms living under ice

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11
Q

explain how water creates thermostability?

A

-through high specific heat capacity
-large amounts of energy required to increase the temp of the water as H bonds prevent movement of water molecules

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12
Q

whats the importance of thermostability for life?

A

-large bodies of water are thermostable even when there are large external fluctuations of temp

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13
Q

explain cohesion?
whats the importance?

A
  • H bonds cause molecules to stick together
  • surface tension allows some organisms to walk on water eg pond skaters
    -water can be transported up the xylem as it makes long thin colums of water dificicult to break
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14
Q

what is adhesion?

A

when water molecules stick to other surfaces eg wall of xylem

think adhesion, adhesive

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15
Q

how does water act as a solvent?

A

-due to polarity water can dissolve polar molecules like ions
-water molecules tend to cluster around charged parts of solute molecules

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16
Q

how does the transparency of water help life?

A

-aquatic organism such as algae and seaweed are able to photosynthesis as sunlight passes through the water

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17
Q

what is the role of ion in the blood?

A

the iron can attract and bind with an oxygen molecule

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18
Q

whats the structure of haemoglobin?

A

-a large protein molecule
-4 subunits
-found in eutheocytes (RBC)
-each subunit has a polypeptide chain and a non-protein haem group containing a single Fe2+ ion

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19
Q

whats the role of sodium ions in transporting glucodse/amino acids into cells?

A

used to co-transport in co-transporters linking with either glucose or amino acids
-co-transporters are specialised instrinsic proteins which span the phospholipid bilayer

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20
Q

what do phosphate groups in DNA and RNA allow?

A

phosphodiester bonds form between nucleotides forming polynucleotides

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21
Q

what are the 3 properties of monosacchardies?

A
  1. soluble in water
    2.sweet tasting
  2. form crystalls
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22
Q

whats the bonds that from between two monosaccarides?

A

glycosidic bond

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23
Q

what monosaccarides make the disacarides maltose,sucrose,and lactose?

A

maltose=glucose+glucose
sucrose=glucose+fructose
lactose=glucose+galactose

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24
Q

define monossacharide

A

simple sugars eg glucose fructose and ribose

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25
Q

define polysaccharides

A

polymers formed by combining many monoscharide molecules together by glycosidic bonds formed by condensation reaction

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26
Q

describe the stucture of starch

A

a coiled, compact polysacharide made from two polymers amylose and amylopectin and forms the main storage carbohydrate in plants

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27
Q

what are the characteristics of starch?

A

-insoluble=does not effect water potential, no osmosis
-coiled=compact,stored small spaces, can store large amount of energy in small space

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28
Q

describe amylose

A

alpha glucose monomers are joined by 1,4 gycosidic bonds

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29
Q

describe amylopectin

A

branched polymer with 1,4 glycosidic bonds between the alpha glucose and 1,6 glycosidic bonds between C1 and C6 of the adjescent alpha glucose

30
Q

describe the structure of glycogen

A

-large polysaccharide formed by condensation reaction between an alpha glucose monomers with 1,4 and 1,6 glycosidic bonds
1,4=coiled
1,6=compact

31
Q

what are the characteristics of glycogen?

A

-insoluble=water potential not affected so no osmosis
-compact=can be stored in small spaces
-coiled=large amount of energy can be stored in small space
-highly branched= many ends, meaning the glycosidic bonds can be rapidly hydrolised by enzymes to form alpha glucose monomers . easily transported, respiraton

32
Q

describe the structure of cellulose

A

made of beta glucose monomers held by 1,4 glycosidic bonds formed by condensation reaction

each beta glucose is rotated 180 degrees to next resulting alternate glycosidic bonds

many straight chains forming parallel to each other linked together through hydrogen bonds between many -OH groups to from bundles called microfibrils

33
Q

whats the role of the microfibrils?

A

very strong, support the cell wall and prevent from bursting when a plant cell becomes turgid

33
Q

whats the structure of triglycerides?

A

one molecule of glycerol joined by three covalent ester bonds formed in a condensation reaction to 3 fatty acids
three molecules of water are removed

33
Q

what are the 2 groups of lipids?

A

triglycerides and phospholipids

33
Q

define saturated triglycerides

A

fatty acid has no C to C double bonds
all carbon atoms are linked to the maximised

33
Q

in the fatty acid, what does the kinks do?

A

kink outwards
prevents closeness

33
Q

functions of triglycerides?

A

-source of energy=higher H:O proportion when oxidised releases twice the energy
-act as insulators=fat is slow conductor of heat, helps retain body heat (thermal insulator)
=electrical insulator in myelin sheath in nerve cells
-waterproofing= large non-polar molecules, insoluble in water
-protection=shock absorber around delicate organs

33
Q

whats the structure of phospholipids?

A

contain a glycerol molecule and 2 fatty acids
the third fatty acid is replaced by a phosphate group
the phosphate head is polar so attracts water (hydrophyllic)
the hydrocarbon chains are non-polar so repels water (hydrophobic)

33
Q

how are phospholipids arranged in a bilayer?

A

-phospholipids form a bilayer of 2 layers
-the hydrophobic fatty acid tails point towards the centre of the bilayer
-hydrophillic heads point outwards

33
Q

what does the phospholipid biayer do?

A

forms a barrier which controls the movement of molecules through it
hydrophobic tails prevent water soluble (e.g. ions) molecules directing directly through the bilayer
lipid soluble, non-polar, small molecules can diffuse through directly

33
Q

what are the functions of proteins?

A

structural
enzymes
hormones
antibodies
protein receptors
transport proteins
antigens

34
Q

what are proteins used for?

A

as structural components used in making new cells for growth and repair
also important as enzymes that controll metabolic reactions

35
Q

what are amino acids?

A

monomer units of protein

36
Q

what do amino acids consist of?

A

a central carbon atom linked with:
a hydrogen atom
amine group
variable region
carboxylic acid group

37
Q

how many diff types of amino acids are there?

A

20

38
Q

how is a dipeptide formed?

A

-condensation reaction between carboxylic acid of one amino acid and the amine group of another
-strong covalent bond called a peptide bond is formed
-water molecule is released

39
Q

describe the primary structure of protein

A

the sequence of amino acids held by peptide bonds

40
Q

describe the secondary structure of a protein

A

further folding of primary structure
polypeptide chain coils=alpha helix
or folds=beta pleated sheet
both held by many hydrogen bonds

41
Q

describe the tertiary structure of a protein

A

further folding of the polypeptide chain to give a more complex shape
stabilised by:
-hydrogen bonds = between R groups
-ionic bonds =between R groups
-Disulphide bonds= covalent between sulfurs in R group of amino acid cyteine
-hydrophobic interations= between non-polar R groups - centre

42
Q

describe the quaternary structure of a protein

A

more than one polypeptide chain

43
Q

give an example of a protein with a quaternary structure, what does it consist of?

A

haemoglobin

-4 polypeptide chains
-2 alpha chains
-2 beta chains
-each chain has a haem group with an Fe2+ ion

44
Q

what are the 2 main groups of 3D shaped molecules?

A

globular and fibrous proteins

45
Q

what are fibrous proteins?

A

-they form long fibres
-have a regular, repetitive sequences of amino acids
-insoluble in water usually
-tend to have structural roles

46
Q

give 3 examples of fibrous proteins

A

myosin in muscles
collagen in skin
keratin in hair

47
Q

describe the structure of collagen

A

-3 left handed helixes - triple helix so more strength
-3 polypeptide chains held by hydrogen bonds
-every 1/3rd amino acid is glycine

48
Q

what gives collagen its strength?

A

collagen molecules cross-link through covalent bonds to form fibres

49
Q

describe the structure of globular proteins

A

-these fold up into a compact ball like shape
-hydrophobic R groups turned inwards to centre and hydrophilic R groups on outside means more water soluble
so metabolic role

50
Q

role of globular proteins

A

metabolic role in living organisms

51
Q

define precipitate

A

solid forming in a solution (benedicts)

52
Q

define emulsion

A

fine droplets of one liquid dispensed in another liquid
(lipids test)

53
Q

what are reducing sugars capable of giving away?

A

electrons

54
Q

examples of reducing sugars?

A

fructose
glucose
galactose

55
Q

describe the test for reducing sugars

A

add benedicts to sample of equal volumes in test tube
heat at 80 degrees in a waterbath

blue to brickred

56
Q

describe the test for non-reducing sugars

A

-need to test for reducing first, if negative then can carry out non-reducing test
-place 1cm3 of sample in test tube
-add 5 drops of HCL (beaks glycosidic bonds releasing sugars)
-boil for 3 mins in water bath
-neutralise with 5 drops of NaOH
-add 1cm3 benedicts solution
-heat at 80 degrees for 5 mins in waterbath (hydrolyses the glycosidic bond releasing monosaccharides)

57
Q

describe the test for starch

A

add 3 drops of iodine to 1cm3 sample
shake gently

orange to black

58
Q

describe the test for protein

A

add equal volume of 1cm3 of biuret solution to sample in test tube

blue to lilac

59
Q

describe the test for lipids

A

place 1cm3 of sample in a test tube
add 1cm3 of ethanol
shake
add water
shake

clear to white emulsion

60
Q

after adding ethanol why should u shake?

A

to quicken the dissolving of fats

61
Q

what chemicals are biological molecules made of?

A

carbon
hydrogen
oxygen

biology year 1 (7 decks)

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