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biological molecules Flashcards

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1
Q

how hydrogen bonds form between water molecules

A

there are intermolecular forces of attraction between a lone pair on O- of one molecule and h+ on an adjacent molecule

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2
Q

state 7 biologically important properties of water

A

~reaches max density at 4 degrees
~high surface tension
~incompressible
~ solvent for chemical reactions in the body
~high specific het capacity
~high latent heat of vaporisation
~cohesion between molecules

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3
Q

why is the incompressible nature of water important for organisms

A

provides turgidity to plant cells
provides hydrostatic skeleton for some small animals

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4
Q

explain y ice floats and y its important

A

~ice is less dense than water because h-bonds hold molecules in fixed positions further away from each other
~insulates water molecules in artic climates so aquatic organisms can survive
~prevents hole lakes freezing
~nutrient cycle continues

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5
Q

why is water an important solvent for organisms

A

polar universal solvent dissolves & transports charged particles involved in intra & extracellular reactions

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5
Q

why is the high surface tension of water important for organisms

A

~slows water loss due to transpiration in plants
~water rises unusually high in narrow tubules lowering demand on root pressure
~some insects can skim across the surface of water

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6
Q

why are the high specific heat capacity and latent of vaporisation of water important for organisms

A

~act as a temperature buffer which enables endotherms to resist fluctuations in core temperature to maintain optimum enzyme activity
~cooling effect when water evaporates from skin surfaces as sweat/ panting

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7
Q

define monomer an polymer, give examples

A

monomer: smaller units that join together to form larger molecules
-monosaccharides(glucose, fructose, galactose )
-amino acids
- nucleotides
polymer; molecules formed when many monomers join together
-polysaccharides
-proteins
-RNA/DNA

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8
Q

what happens in condensation and hydrolysis reactions

A

condensation: chemical bond forms between 2 molecules & a molecule of water is produced
hydrolysis: a water molecule is used to break a chemical bond between 2 molecules

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9
Q

describe the properties of alpha glucose

A

~small & water soluble = easily transported in bloodstream
~complementary shape to antiport for co-transport for absorption in gut
~complementary shape to enzymes for glycolysis= respiratory substrate

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10
Q

describe the structure and functions of starch

A

storage polymer of alpha glucose in plant cells
- insoluble= no osmotic effect on cells
-large= does not diffuse out of cells
made form amylose
-1,4 glycosidic bonds
-helix with intermolecular h-bonds = compact
and amylopectin
-1,4 & 1,6 glycosidic bonds
-branched = many terminal eds for hydrolysis into glucose

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11
Q

what type of bond forms when monosaccharides react

A

1,4 or 1,6 glycosidic bond
~2 monomers = 1 chemical bond= disaccharide
~multiple monomers = many chemical bonds= polysaccharide

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12
Q

name 3 disaccharides. describe how they form

A

condensation reaction forms glycosidic bond between 2 monosaccharides
- maltose: glucose + glucose
- sucrose: glucose + fructose
- lactose : glucose + galactose

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13
Q

describe the function of glycogen

A

main storage polymer of alpha glucose in animal cells (but also found in plant cells )
-1,4 & 1,6 glycosidic bonds
-branched= many terminal ends for hydrolysis
- insoluble= no osmotic effect & does not diffuse out of cells
-compact

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14
Q

describe the structure and functions of cellulose

A

polymer of beta glucose gives rigidity to plant cell walls
-1,4 glycosidic bonds
-straight chain, unbranched molecule
-alternate glucose molecules are rotated 180 degrees
-h-bonds crosslinks between parallel strands form microfibrils = high tensile sgtrength

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15
Q

how do triglycerides form

A

condensation reaction between 1 molecule of glycerol & 3 fatty acids which forms ester bonds

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16
Q

contrast saturated and unsaturated fatty acids

A

saturated
-contain only single bonds
-straight chain molecules have many contact points
-higher melting point = solid at room temperature
-found in animal fats
unsaturated
-contain C=C double bonds
-kinked molecules have fewer contact points
-lower melting point= liquid at room temperature
-found in plant oils

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17
Q

relate the structure of triglycerides to their functions

A

~high energy: mass ration = high calorific value from oxidation (energy storage)
~insoluble hydrocarbon chain = no effect on water potential of cells & used for waterproofing
~slow conductor of heat = thermal insulation
~less dense than water = buoyancy of aquatic animals

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18
Q

describe the structure and function of phospholipids

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A

amphipathic: glycerol backbone attached to 2 hydrophobic fatty acid tails & 1 hydrophilic polar phosphate head
-forms phospholipid bilayer in water = component of membranes
-tails can splay outwards = waterproofing e.g for skin

19
Q

are phospholipids and triglycerides polymers

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A

no; they are made from a small repeating unit. they are macromolecules

20
Q

describe the structure and function of cholesterol

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A

-steroid structure of 4 hydrocarbon rings. hydrocarbon tail on one side, hydroxyl group on the other side
-adds stability to cell surface phospholipid bilayer by connecting molecules & reducing fluidity

21
Q

how to prepare for food testes

Study These Flashcards
A

-grind food with a small amount of distilled water in a mortar and pestle
-once a paste add more water
-filter to remove solid food

22
Q

test for proteins

Study These Flashcards
A

-biuret regent
blue~purple

23
Q

test for lipids

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A

-cant be filtered
-add ethanol
-if present white cloudy emulsion will form

24
test for starch
add iodine orange~blue black
25
test for reducing sugars
-can donate an electron to another molecule -all monosaccharides -some disaccharides (maltose) -add benedict's solution -place in boiling bath for 5 mins blue-green-yellow-orange-brick red
26
test for non-reducing sugars
-first test for reducing sugars -can only test in low or no reducing sugars -add hydrochloric acid and place in boiling bath for 5 mins -add sodium hydroxide and benedict's solution
27
how to test for unknown solutions (colorimeter
-measure known solutions -draw colorimeter curve -test unknown solutions and compare to curve
28
colorimeter
-filter off red precipitate, leaving just blue benedict's solution -best colour to use is red light as solution absorbs it the most -light transmitted through can be detected by the photoelectrical cell -must put solution in cuvettes - 2 translucent sides, 2 transparent sides -use distilled water to set to 0
29
how do polypeptides form
-condensation reactions between amin acids
30
describe the structure and function of globular proteins
-spherical and compact -soluble in water -hydrophilic outside and hydrophobic on inside
31
describe haemoglobin
-4 subunits - 2 alpha, 2 beta -4 prosthetic groups haem, which contain fe2+ which binds to 02
32
describe insulin
-plays a role in blood glucose regulation -2 polypeptide chains linked by disulphide bridges -shape means in perfectly fits into receptor cells
33
describe enzymes - lysosome
-job is to catalyse the breakdown of a molecule in the bacteria cell wall -only react with specific substrate to molecule -single chain, which folds to form groove- active site
34
describe structure of fibrous proteins
-play a structural role -insoluble in water -form long rope like molecules
35
describe collagen
-tendons, ligaments, skin -strong molecules- polypeptides wrap tightly to form triple helix -every 3 is glycine which has a small r group so allows it to wrap tightly -many h-bonds that help to stabilise 4d structure -chains heled by crosslinks - no week points
36
describe keratin
-hair, skin, nails -extremely strong -long stranded molecule -high properties of cysteine which forms disulphide bridges makes it stronger
37
describe elastin
-stretch and recoil -long strands containing hydrophobic regions -strands are crosslinked so when stretch stay connected
38
state the role and chemical symbol of hydroxide and phosphate ions
OH- ions affect ph & can interact with bond in 3d protein structure to cause denaturation PO3-4 is a component of ATp/ADP for energy release & NADP
39
state the role and chemical symbol of nitrate and ammonium
NO-3~ is used to make DNA, amino acids, NADP for photosynthesis & NAD for respirations NH+4~ can be converted to N0-3 by saprobionts during nitrogen cycle. produced by deamination of amino acids during ornithine cycle in liver
40
state the role and symbol of sodium, potassium and chloride ions
NA+ & K+ are involved in maintenance of resting potential of neurons/ generation of action potentials NA+ is also involved in co-transport mechanisms CL- is involved in inhibitory synapses to cause hyperpolarisation
41
state the role and chemical symbol of hydrogen and hydrogen carbonate ions
H+ & HC)-3 form in organisms when CO2 dissolves in water H+ regulates ph & can interact with bonds in 3d protein structure to cause denaturation and H+ pump is involved in chemiosmosis & active loading in translocating
42
state the role and chemical symbol of calcium ions
CA2+ is used to make calcium pectate to add stability to middle lamella of plant cell walls. regulates exocytosis of neurotransmitter. binds to troponin to stimulate muscle contraction
43
how can the concentration of a solution be measured quantitatively
-use colorimetry to measure absorbance/ %transmission. interpolate a calibration curve from known solutions of conc -use biosensors a bioreceptor detects the presence of a chemical. a transducer converts the response into a detectable electrical signal
44
outline the principles and process of paper/ thin layer chromatography
1 use capillary tube to spot onto pencil start line 1cm above the bottom of paper 2 place chromatography paper in solvent 3 allow solvent to run until it almost touches other end of the paper. molecules in mixture move different distances based on relative solubility in solvent / attraction to paper
45
what are RF values, how can they be calculated
ratios that allow comparison of how far molecules have moved in chromatograms RF value = distance between origin and centre of pigment spot/ distance between origin and solvent front

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