Sources of EnergySources of Energy

Unit 5Unit 5

CarbohydratesCarbohydrates All contain Carbon, Hydrogen & OxygenAll contain Carbon, Hydrogen & Oxygen Monosaccharide (‘single’ sugar):Monosaccharide (‘single’ sugar): E.g. glucose, fructoseE.g. glucose, fructose Water solubleWater soluble Many are Many are reducing sugarsreducing sugars - donate electrons to other substances- donate electrons to other substances Disaccharides (‘double’ sugars)Disaccharides (‘double’ sugars) E.g maltose, sucrose E.g maltose, sucrose Water solubleWater soluble Maltose is reducing, sucrose is non-reducingMaltose is reducing, sucrose is non-reducing Acid hydrolysis can make sucrose reducingAcid hydrolysis can make sucrose reducing

CarbohydratesCarbohydrates Polysaccharides:Polysaccharides: Long chains of monosaccharidesLong chains of monosaccharides Water insolubleWater insoluble E.g. starch – long chain of glucose E.g. starch – long chain of glucose

(stored in plants)(stored in plants) E.g. glycogen – branched chain of E.g. glycogen – branched chain of

glucose (stored in animals)glucose (stored in animals)

All carbohydrates are energy richAll carbohydrates are energy rich Many need to be broken down into Many need to be broken down into

monosaccharides to release energymonosaccharides to release energy

Carbohydrate testsCarbohydrate tests

Water solubilityWater solubility: Polysaccharides wont dissolve: Polysaccharides wont dissolve BenedictsBenedicts: brick-red colour indicates presence of : brick-red colour indicates presence of

reducing sugar reducing sugar - (glucose, lactose, fructose, maltose)- (glucose, lactose, fructose, maltose) Acid HydrolysisAcid Hydrolysis: If soluble, but –ve for Benedicts : If soluble, but –ve for Benedicts – – after acid hydrolysis should be +ve for Benedictsafter acid hydrolysis should be +ve for Benedicts ClinistixClinistix: specifically for glucose: specifically for glucose Barfoed’sBarfoed’s: rapid change = monosaccharide, slow : rapid change = monosaccharide, slow

change = disaccharidechange = disaccharide IodineIodine: black = starch, purple-red = glycogen: black = starch, purple-red = glycogen

LipidsLipids Contain Carbon, Hydrogen Contain Carbon, Hydrogen

& Oxygen, but much less & Oxygen, but much less oxygen overalloxygen overall

All are water insolubleAll are water insoluble Simple LipidsSimple Lipids e.g. fats (solid) and oils e.g. fats (solid) and oils

(liquid at room temp)(liquid at room temp) Known as triglyceridesKnown as triglycerides Made of glycerol and 3 fatty Made of glycerol and 3 fatty

acidsacids

LipidsLipids Phospholipid:Phospholipid: Glycerol, 2 fatty acids, 1 Glycerol, 2 fatty acids, 1

phosphatephosphate Phosphate ‘head’ is Phosphate ‘head’ is hydrophilic hydrophilic

(water soluble)(water soluble) Fatty acids ‘tail’ is Fatty acids ‘tail’ is hydrophobic hydrophobic

(water insoluble)(water insoluble) Steroids:Steroids: 3 6-carbon rings attached to a 5-3 6-carbon rings attached to a 5-

carbon ringcarbon ring E.g cholesterol – basic molecular E.g cholesterol – basic molecular

structurestructure

Role of lipidsRole of lipids 1) Energy Store:1) Energy Store: Fat is stored in fatty (adipose) tissueFat is stored in fatty (adipose) tissue Triglyceride is broken down by enzymes into glycerol and Triglyceride is broken down by enzymes into glycerol and

fatty acidsfatty acids Glycerol Glycerol 3 C sugar3 C sugar Pyruvic Acid Pyruvic Acid Fatty AcidsFatty Acids Acetyl CoAAcetyl CoA Fat produce x2 more energy than carbohydrateFat produce x2 more energy than carbohydrate All above reactions are reversibleAll above reactions are reversible Therefore excess glucose can be stored as fatTherefore excess glucose can be stored as fat

Role of lipidsRole of lipids 2) Insulation:2) Insulation: Adipose tissue under the skin Adipose tissue under the skin

insulates heatinsulates heat Nerve fibres are sheathed in Nerve fibres are sheathed in

myelin myelin (insulates nerve impulses)(insulates nerve impulses) 3) Vitamins:3) Vitamins: Vitamins A,D,E & K are fat-soluble Vitamins A,D,E & K are fat-soluble – – can be transported from digestive can be transported from digestive

to lymphatic systemto lymphatic system Hormones & Fat Pads:Hormones & Fat Pads: Sex Hormones – e.g. testosterone, Sex Hormones – e.g. testosterone,

oestrogenoestrogen Pads – cushion palms of hands, Pads – cushion palms of hands,

soles of feet, kidneyssoles of feet, kidneys

ProteinsProteins

Broken down into amino acidsBroken down into amino acids Excess dietary amino acids cannot be Excess dietary amino acids cannot be

storedstored Dietary proteins undergo Dietary proteins undergo deaminationdeamination Urea & organic acids (e.g pyruvic) producedUrea & organic acids (e.g pyruvic) produced Organic acids & intermediates go into Organic acids & intermediates go into

aerobic respiration - ATP productionaerobic respiration - ATP production Tissue protein is an energy source only after Tissue protein is an energy source only after

prolonged starvationprolonged starvation

Marathon RunningMarathon Running

First few mins – glucose from muscle First few mins – glucose from muscle glycogen usedglycogen used

As race continues – blood-borne fuels used As race continues – blood-borne fuels used up (blood glucose & slow-acting fatty acids)up (blood glucose & slow-acting fatty acids)

Latter stages – fatty acids are the main Latter stages – fatty acids are the main sourcesource

If athlete loads up on carbs, fat reserves If athlete loads up on carbs, fat reserves may not be affected as muchmay not be affected as much