B1.1 Carbs and lipids Flashcards
glucose+glucose
maltose
glucose+fructose
sucrose
glucose+galactose
lactose
glycogen(4)
alpha joined by 1, 4 and 1,6 glycosidic bonds; many side branches=energy can be released quickly as enzymes can act simultaneously on the branches; large and compact=store lots of energy; insoluble=wont affect water potential of cells and can’t diffuse out of cells
amylose
unbranched, 1,4 bonds, coiled, very compact=stores a lot of energy
amylopectin
branched, 1,4 and 1,6 bonds, many side branches can be acted on simultaneously by many enzymes and broken down to release its energy
key properties of starch(3)
insoluble so doesn’t affect cell water potential, compact so lots of energy can be stored in a small space, when hydrolysed the released alpha glucose can be transported easily
cellulose
long, unbranched, beta glucose
what are microfibrils
strong threads made of long cellulose chains running parallel to each other, joined by hydrogen bonds forming strong cross linkages
why is cellulose important?
stops cell wall from bursting under osmotic pressure, bc it exerts inward pressure that stops the influx of water so cells stay turgid and rigid maximising the SA for photosynthesis
what is Benedict’s reagant?
alkaline solution of copper(II) sulfate; when a reducing sugar is added to this and heated it forms an insoluble red precipitate copper(I) oxide
test for reducing sugars
add food sample in liquid form, add Benedicts, heat mixture in a water bath for 5 mins, if solution turns brick red then reducing sugar is present
test for non-reducing sugars
add food sample to dilute HCl; water bath for 5 mins; (dilute HCl will hydrolyse the disaccharides and polysaccharides into their constituent monosaccharides); add sodium hydrogencarbonate to neutralise the test tube bc Benedicts wont work in acidic conditions; pH paper used to check solution is neutralised; solution is retested: add benedicts and put in water bath for 5 mins if non-reducing sugar is present colour change from blue to brick-red
why are unsaturated lipids liquid at room temp?
presence of a double bond means molecule can bend, so unsaturated fats can’t pack tightly together and are liquid at room temp
triglyceride properties(2)
low mass to energy ratio=good storage bc a lot of energy being stored in a small volume=less mass for animals to move around; large and non-polar=insoluble in water so storage doesn’t affect water potential of cells
test for lipids(emulsion)
add sample and ethanol; shake tube to dissolve all the lipid; add water and shake; cloudy-white=presence of a lipid
which type of fatty acid in the diet are positively correlated with an increased risk of CHD?
saturated and trans unsaturated
what are the properties of monosaccharides?
colourless crystalline molecules, soluble in water(eg glucose)
role of glycoproteins?
receptor molecules in cell recognition, cell signaling and endocytosis
how do glycoproteins act as antigens?
they can identify cells as either ‘self’ or non-self, cells that are non-self will trigger an immune response in organism
blood types:
A have type A glycoprotein antigens, blood type B have type B glycoprotein antigens, type AB have both types, type O have neither
what happens if blood of the wrong type enters the body?
antibodies cause the incorrect antigens(from transfused blood) to clump together blocking blood vessels
which large non-polar molecules can pass through the phospholipid bilayer?
steroid hormones which contain cholesterol and the hydrocarbon region of cholesterol is non-polar allowing it to cross lipid bilayers
what are 2 examples of steroid hormones and why can they cross the lipid bilayer?
oestradiol and testosterone, produced by gonadal tissues in reproductive organs, bc of their lipid structure they can pass, inside the nucleus these hormones alter and direct the process of transcription
