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A-LEVEL BIOLOGY > Carbohydrates & Sugars > Flashcards

Carbohydrates & Sugars Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what are carbs made of?

A

carbon, hydrogen + oxygen = HC

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2
Q

uses of carbs

A
  • energy store in all organisms (starch/glycogen)
  • structural material in cell walls/membranes (cellulose+glycoproteins)
  • animal skeletons (mainly chitin)
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3
Q

general formula for carbs?

A

(CH2O)n

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4
Q

define monosaccharides

A

single sugar units -> 1 monomer unit only
building blocks for larger carbs
vary according to no. of carbon atoms + way atoms are arranged in the molecules

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5
Q

define polysaccharides

A

polymers with many monomer chains (1000s) bonded by glycosidic bonds
formed by condensation reactions

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6
Q

what’s a glycosidic bond?

A

type of covalent bond that joins a carb (sugar) molecule to another group which may or may not be another carb

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7
Q

monosaccharides examples

A 
glucose
fructose
ribose
deoxyribose
galactose
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8
Q

polysaccharaides examples

A 
starch (plants) -> energy store
cellulose (plants) -> structure
glycogen (animals) -> energy store
amylose
amylopectin
*CHECK NOTES FOR TABLE*
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9
Q

general formula of carbs?

A

(CH2O)n

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10
Q

common monosaccharides

A

CHECK MINI TABLE IN NOTES

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11
Q

what direction/order are the carbon atoms labelled?

A

clockwise

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12
Q

define qualitative estimation + give an example

A

use of non-quantifiable/quantitative methods

e.g. benedict’s test

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13
Q

benedict’s test -> stays blue

A

no simple sugar

or a simple sugar but a non-reducing sugar

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14
Q

benedict’s test -> green

A

low conc. of reducing sugar

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15
Q

benedict’s test -> yellow/orange

A

medium conc. of reducing sugar

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16
Q

benedict’s test -> red

A

high conc. of reducing sugar

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17
Q

what does a non-reducing sugar need to do to test +ve by benedict’s reagent?

A

be boiled with HCl

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18
Q

monosaccharide properties

A
  • monomers cant be broken down into simple sugars
  • suagars -> all taste sweet
  • soluble in water
  • show isomerism -> exist in more than 1 form
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19
Q

whats a carbohydrate?

A

group of substances used as both energy sources + structural materials in organisms

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20
Q

general formula for polysaccharides/many carbs?

A

(CxH2O)y

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21
Q

3 main carb groups?

A

monosaccharides -> simple sugars
disaccharides -> double sugars (2 monos…)
polysaccharides -> large molecules (many monos…)

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22
Q

describe glucose

A 
abundant + important monos...
hexose sugar -> 6 carbon atoms
major energy source for most cells
very soluble
main form in which carbs are transported in animals
*CHECK NOTES FOR DIAGRAMS*
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23
Q

describe glucose’s structure

A

forms 6 membered ring when OH group on carbon 5 adds to aldehyde group on carbon 1

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24
Q

how to tell the difference between alpha + beta hexose sugars

A

isomers on the far right
alpha -> H + OH
beta -> OH + H
has major effect on their biological roles

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25
Q

examples of hexose sugars

A

glucose

galactose

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26
Q

examples of pentose sugars

A

fructose

ribose

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27
Q

describe fructose

A

pentose
very soluble
main sugar in fruits/nectar
sweeter than glucose

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28
Q

describe galactose

A

hexose
less soluble than glucose
important role in production of glycolipids + glycoproteins

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29
Q

describe the structure of a pentose sugar

A

5 carbon atoms

long enough to form a ring

30
Q

general formula for disaccharides

A

Cn (H2O) n-2

31
Q

examples of common disaccharides?

A

sucrose
lactose
maltose
isomaltose

32
Q

how are polymers formed?

A

monomers join together by condensation to form a polymer

33
Q

describe the process of how polymers are made by condensation and hydrolysis

A

water molecule removed by condensation

hydrolysis broken down with addition of water molecule

34
Q

how is maltose formed?

A

2 glucose molecules undergo condensation + join by an alpha 1-4 glycosidic bond

35
Q

how is sucrose formed?

A

glucose + fructose join by alpha 1-4 glycosidic bond

36
Q

how is lactose formed?

A

galactose + glucose join by beta 1-4 glycosidic bond

37
Q

define reducing sugar

A

any carb that can be oxidised + cause reduction of other substances w/o being hydrolysed first

38
Q

define non-reducing sugar

A

any carb that can’t be oxidised or reduce substances w/o being hydrolysed first

39
Q

generally, why can all free monos… be oxidised?

A

they have a free aldeyde or hydroxylketonic group

after oxidation they can reduce substances -> they’re reducing sugars

40
Q

what do fehling and benedict’s solution carry out?

A

oxidation

41
Q

explain reducing sugars in terms of groups + ions

A
  • have free CHO (aldehyde) + (CO) ketonic group

- able to reduce curpic (copper 2+) ions of benedict’s sol. to cuprous (copper 1+) ions

42
Q

what’s an aldehyde group?

A

CHO

43
Q

what’s a ketonic group

A

CO

44
Q

explain non-reducing sugars in terms of groups + ions

A
  • DONT have free CHO (aldehyde) or (CO) ketonic group

- CANT reduce curpic (copper 2+) ions of benedict’s sol. to cuprous (copper 1+) ions

45
Q

main uses of polysac…?

A
  • energy store

- structural components of cells

46
Q

major polysac…?

A

starch
cellulose
glycogen

47
Q

describe starch

A 
mixture of 2 polysaccharides of a-glucose 
- amylose -> 20-30%, 1-4 g.b.
- amylopectin -> 70-80%, 1-4 + 1-6 g.b.
branched
H-bonds form interior of helix
48
Q

how is starch a better alternative to glucose?

A

compact + insoluble alternative to storing 1000’s of glucose molecules for energy storage
in plants

49
Q

where is starch found?

A

in small grains in many parts of a plant in plastids

large amounts in seeds + storage organs

50
Q

describe the structure of starch

A

a-glucose monosaccharides chains linked by glycosidic bonds from condesnation react. branched chain wounds into tight coil/spiral to make molecule compact
held together by H-bonds

51
Q

describe role of starch for energy storage

A

insoluble -> wont affect osmotic balance or diffuse out
compact -> can be stored in small places
forms a-glucose when quickly hydrolysed -> readily y=used for respiration if needed

52
Q

what type of suspensions do polysac… form unlike momosac…?

A

colloidal suspensions

53
Q

describe amylose structure

A

formed by a series of condensation react. that bond a-glucose molecules together into long chain
many glycosidic bonds formed
coils into helix

54
Q

describe amylopectin structure

A

straight chain of a-glucose units
branch points approx. at every 12th glucose unit
branch points form when carbon 6 of glucose molecule in chain forms glycosidic bond with a carbon 1 from a glucose molecule above

55
Q

what’s a plastid

A

membrane-bound organelle found in plant cells

56
Q

how is starch produced?

A

from glucose made during photosynthesis
broken down during resp.
source of carbon

57
Q

what’s glycogen?

A

carbs stored as glycogen in small granules in muscles + liver
in animals

58
Q

describe glycogen’s structure

A

1-6 glycosidic bonds -> branched structure

59
Q

how is glycogen different to starch?

A

less dense + more soluble than starch
breaks down faster -> animals need higher metabolic rate than plants
shorter chains than starch -> more readily hydrolysed to a-glucose

60
Q

describe structure of cellulose

A

beta glucose
straight unbranched chains -> parallel to eachother
OH groups protrude outwards
H-bonds form across adjacent strands between cellulose molecules
lattic struc. -> rigid -> good for cell walls + SA for photosyn.
many H-bonds make it strong

61
Q

how are b- and a- glucose diff. in terms of structure?

A

alpha -> H group on top, OH group on bottom

beta -> OH group on top, H group on bottom

62
Q

how do you link 2 b-glucose molecules together?

A

one must rotate 180 degrees

63
Q

why is cellulose strong?

A

many H-bonds

makes plant rigid

64
Q

what do cellulose molecules group together to form?

A

microfibrils

arranged in parallel groups called fibres

65
Q

why are humans considered heterotrophs?

A

we digest + absorb carbs formed from energy from sun

all energy comes from sun

66
Q

REVISE FOOD TEST STEPS

A

IN NOTES

67
Q

general formula of monosaccharides?

A

Cn H2n On

68
Q

e.g. of triose

A

pyruvate

69
Q

e.g of pentose

A

ribose

deoxyribose

70
Q

e.g. of heroes

A

glucose

71
Q

define disaccharide

A

2 monosaccharides joined together by glycosidic bonds

A-LEVEL BIOLOGY (8 decks)

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