carbohydrates Flashcards

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1
Q

what type of carb is glucose?

A

hexose monosacchride

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2
Q

what are some useful properties of glucose?

A

soluble
allows glucose to dissolve in cytoplasm

polar
bonds with water to be transported around the body

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3
Q

what takes place in a condensation reaction?

A

2 glucose molecules

their hydroxyl groups interacts

causes bonds to break and new bonds reformed to produce a new molecule

water is produced

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4
Q

where is fructose found in

what are its properties compared to other sugars

what does it produce when combined with glucose?

A

fruit

sweetest compared to glucose , then galactose

sucrose

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5
Q

what does galactose + glucose form?

A

lactose

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6
Q

how is starch formed?

what are the uses of starch?

A

formed from amylose and amylopectin

chemical energy store (in plants)
glucose produced in photosynthesis stored as starch

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7
Q

how is amylose formed?

A

alpha-glucose molecules joined by 1-4 glycosidic bonds

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8
Q

how is a polysaccharide able to be compact?

A

angle of bonds means chain of glucose twists/coils

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9
Q

how is amylopectin formed?

A

formed from 1-4 glycosidic bonds between alpha-glucose

branches off in glycosidic bonds formed by condensation reactions between carbon 1 & carbon 6 on 2 glucose molecules

gives amylopectin a branched structure

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10
Q

what is the energy storage molecule for animals?

what are some of its properties that are useful?

A

glycogen

forms branches
lots of end points for quick release of glucose for aerobic respiration

compact

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11
Q

what are the properties important in amylopectin and amylose?

A

insoluble

branched

compact

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12
Q

C + H + O

A

carbohydrate

or lipid

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13
Q

C + H + O + N (+S)

A

protein

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14
Q

C + H + O + N + P

A

nucleic acids

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15
Q

describe the difference between an alpha and beta glucose

A

hydroxyl group on carbon 1 is in a different position

in alpha-glucose it is below the plane
in beta-glucose it is above the plane

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16
Q

describe the formation of a 1,4 glycosidic bond

A

bond formed between two glucose molecules

hydroxyl group on carbon 1 on one molecule and carbon 4 on the other molecule

interacts in a condensation reaction

removal of water molecule forms an ‘oxygen’ bridge

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17
Q

how is the structure of cellulose related to its function?

A

straight chain molecule

many hydrogen bonds between individual chains and staggered ends

grants strength to fibres

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18
Q

why does the polymerisation of beta glucose lead to cellulose instead of starch?

A

in beta glucose the hydroxyl group at carbon 1 is above the ring

alternate glucose molecules must rotate upside down

so the hydroxyl groups on carbon 1 and carbon 4 (on the alt molecule) are close enough to react

condensation reaction

forming a glycosidic bond

rotation of alternative molecules forms a straight chain molecule – cellulose

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19
Q

describe a hydrolysis reaction?

A

reverse of condensation reaction

needed for glucose, starch or glycogen to be released

requires additional water molecules and is catalysed by enzymes

20
Q

how are fibres produced from cellulose molecules?

A

cellulose molecules make hydrogen bonds with each other forming microfibrils

microfibrils form together to form macrofibrils

macrofibrils form together to form fibres

21
Q

what is the relation between cellulose and the digestive system?

A

cellulose is hard to break down into its monomers because it is a straight chain molecule

forms the roughage needed for a healthy digestive system

fibres are insoluble, strong and used to make cell walls

22
Q

what’s another name for a simple sugar?

A

monosaccharide

23
Q

what’s glucose used for?

A

production of ATP in respiration
(plants and animals)

24
Q

what’s the test procedure for the presence of reducing sugars (monosaccharides)?

A

add benedict’s reagent

heat (60-80 degrees)

turns green – red (depending on amt of sugar)

25
Q

what’s the test procedure for the benedict’s reagent on non-reducing sugars?

A

hydrolysis on molecules

add HCl (breaks glyosidic bonds) and neutralise

add benedict’s reagent

26
Q

what kind of bond is a glyosidic bond?

A

covalent

27
Q

what’s the general formula for carbohydrates?

A

(CH2O)n

28
Q

what are some uses of carbohydrates?

A

respiration to produce ATP

energy storage

structural role
(cellulose in plants)

29
Q

describe the structure of chitin

A

made of glucosamine units (glucose + amino acids) and is linked by beta 1,4 glycosidic bonds

amine groups causes more hydrogen bonding between the chains (more than cellulose)

resilient and tough

30
Q

describe the test for starch?

A

add 2-3 drops of iodine

positive result - blue/black ppt forms

31
Q

outline a biochemical test which you could use to distinguish between a solution of glucose and a solution of sucrose

A

add benedict’s reagent to each solution

heat to 60-80 degrees celsius

results:
glucose solution gives red solution
sucrose solution does not change colour

32
Q

how is starch digested

A

starch => maltose
(salivary & pancreatic) amylase
alpha amylase - breaks 1-4 links (randomly)
beta amylase - breaks alternate 1-4 links

maltose => glucose
maltase

33
Q

how is glycogen digested

A

beta cells in islets of langerhans secrete glucagon which activates enzymes for glycogenolysis

34
Q

how is cellulose digested

A

cellulase

35
Q

how does insolubility make for good storage molecules

A

osmotically inactive

doesn’t affect water potential gradient

36
Q

where is glycogen stored

A

mainly in the liver and muscles

37
Q

explain the structure of cellulose and what do these join to form

A

inverted arrangement of successive glucose molecules means thousands of hydrogen bonds form

cellulose molecules tightly cross-linked to form microfibrils

microfibrils form macro fibrils which then form fibres

fibres run across each other, interwoven and held together by a matrix of other substances

gives cellulose a mechanically strong structure

38
Q

state two ways in which the molecular structure of cholesterol is similar to the molecular structure of glucose

A

both contain carbon and hydrogen atoms

have a hydroxyl group

39
Q

explain why mammals store glycogen instead of glucose

A

insoluble
so has no effect on water potential

metabolically inactive

compact
so can store large amounts of energy

40
Q

state three structural similarities between lactose and maltose

A

two 5C rings (hexose)

1-4 glycosidic bonds

two CH2OH groups

41
Q

does lactose contain beta glucose or alpha glucose

A

beta

42
Q

how does the structure of galactose allow it to be used as a respiratory substrate

A

bonds contain energy which can be broken down

soluble so can be moved within cell

has OH groups so is water-soluble

43
Q

how is cellulose suitable for its function as a basis of plant cell walls

A

insoluble in water

unreactive

high tensile strength

flexible

forms hydrogen bonds with neighbouring chains (stability)

44
Q

state the similarities and differences between the structures of glycogen and chitin

A

similarities:
polymers
have 6 carbons
have 1-4 glycosidic bonds

differences:
chitin contains nitrogen
chitin has beta glycosidic bonds
(therefore) no branching in chitin

45
Q

Explain how the structure of glycogen differs from that of amylopectin to make it better suited as an
energy store in animals

A

glycogen (compared to amylopectin)
more branched
branching gives more free ends where glucose can be added or removed
(so) speeds up glucose release/hydrolysis

more coiled
(so is) more compact / less space needed (for storage)