carbohydrates Flashcards by ; ;

what type of carb is glucose?

hexose monosacchride

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what are some useful properties of glucose?

soluble
allows glucose to dissolve in cytoplasm

polar
bonds with water to be transported around the body

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what takes place in a condensation reaction?

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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where is fructose found in

what are its properties compared to other sugars

what does it produce when combined with glucose?

fruit

sweetest compared to glucose , then galactose

sucrose

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what does galactose + glucose form?

lactose

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how is starch formed?

what are the uses of starch?

formed from amylose and amylopectin

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

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how is amylose formed?

alpha-glucose molecules joined by 1-4 glycosidic bonds

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how is a polysaccharide able to be compact?

angle of bonds means chain of glucose twists/coils

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how is amylopectin formed?

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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what is the energy storage molecule for animals?

what are some of its properties that are useful?

glycogen

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

compact

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what are the properties important in amylopectin and amylose?

insoluble

branched

compact

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C + H + O

carbohydrate

or lipid

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C + H + O + N (+S)

protein

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C + H + O + N + P

nucleic acids

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describe the difference between an alpha and beta glucose

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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describe the formation of a 1,4 glycosidic bond

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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how is the structure of cellulose related to its function?

straight chain molecule

many hydrogen bonds between individual chains and staggered ends

grants strength to fibres

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

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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describe a hydrolysis reaction?

reverse of condensation reaction

needed for glucose, starch or glycogen to be released

requires additional water molecules and is catalysed by enzymes

how are fibres produced from cellulose molecules?

cellulose molecules make hydrogen bonds with each other forming microfibrils

microfibrils form together to form macrofibrils

macrofibrils form together to form fibres

what is the relation between cellulose and the digestive system?

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

what’s another name for a simple sugar?

monosaccharide

what’s glucose used for?

production of ATP in respiration
(plants and animals)

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

add benedict’s reagent

heat (60-80 degrees)

turns green – red (depending on amt of sugar)

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

hydrolysis on molecules add HCl (breaks glyosidic bonds) and neutralise add benedict's reagent

what kind of bond is a glyosidic bond?

covalent

what's the general formula for carbohydrates?

(CH2O)n

what are some uses of carbohydrates?

respiration to produce ATP energy storage structural role (cellulose in plants)

describe the structure of chitin

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

describe the test for starch?

add 2-3 drops of iodine positive result - blue/black ppt forms

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

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

how is starch digested

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

how is glycogen digested

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

how is cellulose digested

cellulase

how does insolubility make for good storage molecules

osmotically inactive doesn't affect water potential gradient

where is glycogen stored

mainly in the liver and muscles

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

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

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

both contain carbon and hydrogen atoms have a hydroxyl group

explain why mammals store glycogen instead of glucose

insoluble so has no effect on water potential metabolically inactive compact so can store large amounts of energy

state three structural similarities between lactose and maltose

two 5C rings (hexose) 1-4 glycosidic bonds two CH2OH groups

does lactose contain beta glucose or alpha glucose

beta

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

bonds contain energy which can be broken down soluble so can be moved within cell has OH groups so is water-soluble

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

insoluble in water unreactive high tensile strength flexible forms hydrogen bonds with neighbouring chains (stability)

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

similarities: polymers have 6 carbons have 1-4 glycosidic bonds differences: chitin contains nitrogen chitin has beta glycosidic bonds (therefore) no branching in chitin

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

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)