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Biological molecules Flashcards

-add finding conc. of glucose info from savemyexams (63 cards)

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1
Q

What is an indirect evidence for evolution

A

the fact that all life on earth shares common chemistry

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2
Q

The cells of all living organisms contain only a few groups of ……. based compounds that interact in similarly

A

carbon based compounds

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3
Q

-What is the name for the monomers to all carbohydrate polymers
-give 3 common examples

A

Monosaccharides
Glucose, galactose,fructose: common monosaccharides

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4
Q

-A carbohydrate can be classified as which 3 things:
-define these 3 things

A

Carbohydrate classified as either a
Monosaccharide-single carbohydrate unit -cannot
be hydrolysed (broken down) to a simpler carb.
Disaccharide
Polysaccharide

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5
Q

examples of carbohydrates
All carbs contain only these 3 elements:

A

sugar/ starch/glucose
carbon,hydrogen,oxygen

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6
Q

monosaccharides with 6 carbon atoms eg glucose are called:
glucose is a monosaccharide. Why

A

hexose monosaccharides
it is a single sugar molecule- cannot be broken down to a simpler carb

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7
Q

what are the two isomers of glucose
draw them

A

α-glucose and β-glucose

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8
Q

*** key feature of all monosaccharides
explain why

A

soluble in water
why…

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9
Q

monosaccharides with 5 carbon atoms are called:

A

pentose monosacharides

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10
Q

what are disaccharides

A

Disaccharides are formed by the condensation of two
monosaccharides joined by a glycosidic bond.

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11
Q

how is maltose made-
what is its chemical formula-
what else is formed
draw maltose-

A

-maltose is a disaccharide formed by condensation of two
glucose molecules
-C12H22O11
-water

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12
Q

how is sucrose made-
what is its chemical formula

A
  • sucrose is a disaccharide formed by condensation of a
    glucose molecule and a fructose molecule
    C12H22O11
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13
Q

how is lactose made-
what is its chemical formula

A
  • lactose is a disaccharide formed by condensation of a
    glucose molecule and a galactose molecule.
    C12H22O11
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14
Q

what is the chemical formula for galactose

A

C6H12O6

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15
Q

what is the chemical formula for fructose

A

C6H12O6

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16
Q

how are polysacharides formed-
3 examples of polysacs-

A

Polysaccharides are formed by the condensation of many glucose
units.
starch, glycogen, cellulose

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17
Q

what is a hydrolysis reaction in terms of disaccharides

A

when water is added to a disaccharide, the glycosidic bond breaks. converted back to OG monosaccharides

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18
Q

condensation of α-glucose forms…
condensation of β-glucose….

A

Glycogen and starch
Cellulose

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19
Q

where is starch found-whats its purose

A

storage form of glucose found in plants

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20
Q

starch contains two molecules:
where is starch stored-

A

amylose , amylose pectin
in starch granules in chloroplasts

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21
Q

describe structure of amylose-3 points

A

-a polysaccharide, made of many α-glucose molecules joined by 1-4 Gbonds (basically many joined maltoses)
-unbranched
-the amylose molecule twists into a helix bcse Hbonds form btwn glucose molecules in the chain

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22
Q

why are some substances soluble in water

A

water is poler, O is slightly -ve, H is slightly +ve. This causes some substances to form hydrogen bonds (intermolecular forces) with the H2O molecules. Eg Na+ bonds to the slightly -ve oxygen.

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23
Q

-what is osmosis

-describe what low/high water potential means

A

movement of water particles from area of high water potential to area of lower water potential through partially permeable membrane.

0 = high water potential. High concentration of water, low dissolved solute. Pure water has w.p of 0
NaCl has low water potential eg -100.

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24
Q

Explain how cellulose molecules are adapted for their function in plant cells. -3 marks

A
  1. Long and straight chains;
  2. Become linked together by many hydrogen bonds to form fibrils;
  3. Provide strength (to cell wall).
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25
How are starch molecules adapted for function
Insoluble; Don’t affect water potential; OR Helical (form spirals) so Compact storage molecules OR Large molecule; Cannot leave cell.
26
Describe + explain three features of glycogen that make it well suited as an energy store.
feature: It is poorly soluble Explanation: so it won’t affect water potential in cells feature: It is compact/highly-branched Explanation: so it can fit into small storage granules; feature: It is easily synthesised and broken down Explanation: so rapidly responds to the hormones insulin/glucagon
27
what is the basic monomer unit in a carb
a saccharide (a sugar). a single monomer is therefore a MonoSaccharide
28
are monosaccharides soluble- general formula of monosaccharides
yes (CH₂O)n where n is any number 3mto 7
29
-describe structure of amylopectin- 2 points -how is its structure useful. x2
-mixture of 1,4-glycosidic bonds and 1,6-glycosidic bonds btwn alpha glucose monomers -the 1-6 Gbonds form branched structure branching: -allows folding for even more compactness - causes many terminal glucose molecules. They can be easily hydrolysed for use during cellular respiration or added to for storage.
30
where is glycogen found describe its structure- x3
animals and fungi -has1-4 and 1-6 Gbonds between alpha glucose monomers -highly branched -more than starch -straight- not coiled
31
-compare structure of glycogen to starch -where is glycogen mainly stored- why here
more highly branched shorter chains -as granules in muscles and liver - cellular respiration rate is high in these cells
32
why is the mass of carbohydrate stored in animals relatively low
bcse fat is the main storage form in animals
33
glycogens structure suits its function as stofage molecule- x3
-insoluble- not affect water potential/osmosis -compact storage molecule- coiled helical structure -has many ends that can be worked on simultaneously by enzymes-more rapidly broken down to form glucose monomers used in respiration note- this also works the other way round, more free ends where glucose molecules can be added so storage of glucose can better suit the cell
34
why is glycogen a better storage from of glucose for animals than starch- 2 points
more highly branched- more ends that can be worked on simultaneously by enzymes-more rapidly broken down to form glucose monomers used in respiration. important bcse animals hav high metabolic rate and so high respiratory rate bcse they are more active, (need more energy)
35
3 similarities + differences btwn cellulose and starch
Similarities--- Glycosidic bonds 1-4 links Made of monomers/ are polymers Insoluble Joined by condensation / broken by hydrolysis Made of glucose/ contain carbon, hydrogen and oxygen Differences--- Cellulose consists of β-glucose, starch is made of α-glucose Starch has a helical structure, cellulose has straight structure In starch all glucose molecules are the same way up, in cellulose they are alternate Starch doesn't form (micro/macro) fibrils/fibres, cellulose does Starch contains 1-6 bonds, cellulose does not
36
describe the structure of cellulose-
all 1-4 g bonds b glucose many hydrogen bonds between long straight unbranched chains form fibrils -every other b glucose molecule rotated 180 degrees
37
how are microfibrils and fibrils formed in cellulose
Cellulose chains group together to form microfibrils microfibrils group to make macrofibrils macrofibrils group to make fibrils/fibres
38
Give one similarity and one difference between the structures of glucose and fructose.
similarity Both are hexose/6-carbon sugars They have the same molecular formula C6H12O6 difference Glucose is a 6-atom ring / fructose is a 5-atom ring
39
draw structure of fructose and galactose
https://www.sparknotes.com/health/carbohydrates/section1/
40
what features does a plant cell wall /cellulose have. how is this useful
high tensile strength- cellulose stretched without breaking - cell walls withstand turgor pressure - provides rigidity . prevents cell bursting by exerting inward pressure that stops influx of water Cellulose fibrils are freely permeable -allows water/solutes to leave / reach the cell surface membrane
41
test for starch-3 steps -why is a solution used -what is this test useful for
-starchy dina- orange-brown to bluey black -add few drops of orange/brown iodine in potassium iodide solution to sample -stir/shake -if starch present, iodide ions in solution interact with the centre of starch molecules, producing distinctive blue-black colour -The iodine is in potassium iodide solution as iodine is insoluble in water -showing starch has been digested by enzymes
42
why would you test a plant for starch
to see if it has carried out photosynthesis
43
-why would you test urine for protein -for glucose
diagnose kidney problem check for diabetes
44
precaution for tests for protein/starch /glucose
-safety goggles -clear spills with water
45
how would you get a food sample ready for a protien/starch/glucose test
-grind food w/ distilled water w/ mortar and pestle -add more water once paste like and mix -filter mixture-remove solid particles-make results hard to see -carry out test on the filtrate
46
-all...... and some...... eg...... and ......are reducing sugars -what makes a sugar reducing
all monosaccharides some disaccharides- eg maltose lactose -it can donate electrons to (or reduce) a chemical. It will get oxidised
47
example of non reducing sugar
sucrose
48
what is benedicts reagent what happens in prescence of reducing sugar
-alkaline solution that has copper sulfate ions (Cu 2+) blue due to the ions -Copper (I) oxide forms - not soluble in water, so it forms precipitate. Cu+ ions in copper oxide make precipitate brick red/brown
49
-describe method for Benedicts test for reducing sugar - 3 steps -how much benedicts solution should be used -What would different positive results look like
-Add Benedict's reagent to sample solution in excess in test tube -Heat tube in water bath/ water beaker thats brought to a boil for a few minutes -If reducing sugar present, coloured precipitate forms (copper (II) sulfate reduced to copper (I) oxide) -Excess of Benedict’s solution- so there is more than enough copper (II) sulfate to react with any sugar present -A positive test result -colour change along colour scale from blue (no reducing sugar), to green, yellow ,orange (low to medium conc. of reducing sugar) to brown/brick-red (a high conc. reducing sugar)
50
is the Benedicts test qualitative/quantitative. To what degree- -How is this useful
semi-quantitative -degree of the colour change gives indication of how much (concentration of) reducing sugar present -we can estimate the approximate amount of reducing sugar
51
test for non reducing sugars -5 steps
-do benedicts test- if no colour change, test for non reducing sugar -Add dilute hydrochloric acid to sample and heat in a water bath (brought to the boil) -Neutralise solution with sodium hydrogencarbonate -Use indicator (eg red litmus paper) to identify when solutions neutralised,add little more sodium hydrogencarbonate as conditions need to be slightly alkaline for Benedict’s test to work -Do Benedict’s test- if a colour change occurs, a reducing sugar is present
52
explain how the test for non reducing sugar works
-Adding acid hydrolyses glycosidic bonds present in carbohydrate molecules- leaving its monosacs -The monosaccs have a (aldehyde or ketone) functional group that can donate electrons to copper (II) sulfate (reducing the copper), allowing a precipitate to form
53
How can we use a colorimeter to do a quantitative Benedict's test?
- Colorimeter measure the absorbance or transmission of light by a coloured solution - More concentrated solution = more light absorbed / less light transmitted - Compare to data table or calibration curve (known concentrations vs. abs/trans value)
54
what characteristics do all lipids share- x5
-contain carbon.hydrogen,oxygen -proportion of carbon to oxygen and hydrogen is smaller than in carbs -insoluble in water-hydrophobic -non-polar -soluble in organic solvents like lacohol/acetone
55
what are the two groups of lipids we need to know
phospholipids triglycerides- main component of fats and oils
56
how are triglycerides formed
Triglycerides are formed by condensation of one molecule of glycerol and three molecules of fatty acid.
57
state the functions of lipids x4
-major energy source in human -insulates- -protection- -waterproofing-
58
describe the following functions of lipids- protection- waterproofing - in plants/insects -mammals
-protection- fat stored around delicate organs (eg kidney) -waterproofing- lipids insoluble = useful as waterproofing -plants/insects have waxy lipid cuticle to conserve water -mammals produce oily secretion from skins sebaceous glands
59
describe the following functions of lipids- -energy source -insulation-2 examples
-major energy source in human diet- provide 2x more energy when oxidised than carb with same mass and release water -used to store energy in fats -insulates- fats= slow heat conductors, when stored beneath body surface- retain body heat . -act as electrical insulators- in myelin sheath around nerve cell
60
-properties of triglycerides -monomers of triglycerides -are fats/oils soli/liquid @ room temo
-hydrohobic, non polar -glycerol, fatty acids fats solid, oils liquid (at 10-20*)
61
what is glycerol is the glycerol molecule in every triglyceride the same or different
-alcohol (hydroxyl group bonded to carbon atom) -same
62
-what is the basic structure of a fatty acid- drawn- described-
RCOOH- draw then look up. -methyl group at one end of a hydrocarbon chain (R group-chains of h's bonded to c's) and carboxyl group at other end.
63
How can fatty acids vary?
-length- due to length of R group and -saturated -chain has no c=c bond. ALL carbon atoms lined to max no. of hydrogen atoms or mono unsaturated- 1 c=c double bond or polyunsaturated- more than 1 c=c double bond
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