food Flashcards
what are core food molecules and biomolecules
carbohydrates
proteins and enzymes
fats and oils (triglycerides)
vitamins
carbohydrates
- Cx(H2O)y
- provide a source of energy, way of storing energy, structural material
carbohydrates general structure
- dissacharides or polysaccharides are joined with a glycosidic link / ether group
lactose monomers?
galactose and glucose
sucrose monomers?
fructose and glucose
maltose monomers?
2x glucose
glucose vs fructose difference
glucose= in fischer projection there is an aldehyde group
fructose= ketone group on 2nd C
determining mass of saccharide
180 x number of glucose = ___x__
18x( no. glucose- 1) =___y___
t/f x-y
polysaccharide examples
starch - amylose and amylopectin
glycogen (alpha glucose)
cellulose (beta glucose)
starch
- energy storage components of plants
-composed of alpha glucose
-two forms - amylose and amylopectin
amylopectin
-crosslink bw glucose molecules - reaction bw OH groups on C1 and C6 sections
-less effective packing and decrease attraction bw OH groups - weaker H bond - high GI
amylose
- linear polymer that properly packs effectively - strong attraction to OH groups - low GI
amylopectin vs amylose
branching affects ability to breakdown
-amylopectin to break down faster
glycogen
-energy storage structure in humans & animals
-alpha glucose
-highly branched
- convert glucose into glycogen and stored in liver& muscle cells
cellulose
- structural material found in plants
-formed from beta glucose - tightly pack together - strength as plant fibre
- body = unable to break down & acts as dietary fibre
artificial sweeteners
- similar sized to many common sugars but are significantlly sweeter than sugars
- require lower energy/ calorie diets to obtain same amount of sweetness
aspartame
outcome of a reaction between aspartic acid, phenylalanone and methanol - is an artificial sweetener
energy carbohydrates
most common source of energy - hydrolysed to form glucoes which undergoes respiration to form energy
cellulose - indigestible carbs
- human body lacks necessary enzyme to catalyse the reaction
- considered a dietary fibre bc helps food pass through in bulk amounts and decreases risk of constipation, cancers etc.
- bodies have system to break it down but it passes through body before broken down into any nutritional value
intolerances eg. lactose
lack sufficient amount of the enzyme lactase to hydrolyse the lactose sugar
-side effects - discomfort, bloating ,cramps, diarrhoea
GMI definition
how quickly glucose is released in the bloodstream after consuming food
- low GI is slower than high GI
HIGH GI HAS WHAT
AMYLPECTIN
LOW GI HAS WHAT
AMYLOSE
diabetes
- type 1 - doesnt produce necessary insulin
-type 2 - cannot produce quickly enoigh to match the release of glucose into the blood
fats and oil (triglycerides)
- ESTERS
-contain CHO - formed in condensation reaction bw glyecrol and 3 fatty acids and forms triglyceride and water
- large relatively non polar - low solubility
unsaturated - mono or poly
C to C double bonds
saturated formuls - fatty acid
CnH2n+1COOH
monounsaturated fatty acid general form
CnH2n-1COOH
essential fatty acids
-fatty acids that the body cannot synthesise
- obtained from food / diet - omega 3 or 6 and need a good dietary balance
nonessential fatty acids
- body is capable of synthesising FA
omega 6 benefits
known to increase blood pressure, immune response and inflammation
omega 3 benefits
heart healthy effects
omega 3 or 6
depends on where the first c to c double bond is from the omega end (opposite COOH region)
trans fats
- unsaturated that are artificially produced - in hydrogenation (Ni catalyst and 15deg)
-resisted rancidity and desirable MP
rancidity - possible reactions?
-oxidative = O reacts near double bond
- microbial = bacterial action
- hydrolytic= hydrolysis to fatty acid and glycerol
rancidity
- fats and oils deterioate over time
- unsaturated fats are less stable bc more succeptible to oxidative rancidity
- deterioate food or smell
oxidative rancidity problems
lead to formation of unpleasant smelling and potential harmful short chain aldehydes and ketones - unpleasant smells & flavours
- most common = autooxidation
how are vitamins distinguished
water soluble or fat soluble
water soluble vitamins
- consumed regularly
- high proportion of OH groups that form H bonds with water and dissolve - pass through body quickly
fat soluble vitamins
long hydrocarbon chains - low OH groups so stronger dispersion forces compared to few H bonds - absorbed by the body
methods to slow rancidity
- vacuum packaging
- fill containers to the lid
- store food in dark and cold
- antioxidants
antioxidants
- eg. vitamin C
- natural or synthetic and will slow down oxidation and prevent food from spoiling
- donate an e- to free radicals in order to interupt propagation of free radicals - increase rancidity
vitamins essential or not
non essential - vitamin D
essential - other vitamins
vitamins
- perform variety of vital roles including action as a coenzyme, aiding the immune system or preventing hamrful chemical reactions (antioxidant)
difference bw carbohydrate and triglyceride in terms of structure
fatty acid has only 2 oxygen atoms whereas carbohydrates have lots of oxygen
amino acids
CHONS
zwitterions
dipolar ions
- have no overall net charge
- contains a negative and positive charge/ region
-exist at neutral pH (7)
in basic environment a zwitterion
gains H+ on the N region - net negative charge
in acidic environment a zwitterion
forms a NH3+
what links a dipeptide
amide or peptide linkages
primary protein structure
- amino acid sequence in the peptide /protein chain
- strong covalent bonds linking each aa at amide link
secondary structure protein
- forms H bonds with different sections of the protein chain -H attached to N and the O attached to C = H bonds
- primary structure folded into alpha helix or beta pleated sheets
tertiary protein structure
- unique 3d shape of the protein (globular)
-this determines its unique function - driven by the side chain/ R groups
-bonds that keep structure intact include covalent bonds, dp-dp, H bonds etc.
quaternary protein structure
- 2 or more polypeptides joined together
eg. haemoglobin
digestion of proteins
- aa are absorbed in the bloodstream and used to build up new protein
-aa not used are broken down in liver (deamination) where NH2 is converted into ammonia which is converted to urea and excreted or used to synthesise other proteins - remainder proteins composed of CHO=converted to glucose(energy), fat(storage) or aa
hydrolysis of protein
CHANGE PRIMARY STRUCTURE
covalent bonds are broken in presence of water and specific enzymes
denaturation of proteins
- change in 3D structure (tertiary) or function of molecules like proteins at extreme pH or temperature
- disrupt R groups
-can be reversible and irreversible depending on protein+ ability to reconfigure its 3D shape
enzymes - role and function
- biological catalysts
-catalyses chemical reactions in the body which is necessary to sustain life otherwise metabolic cellular processes= too slow - provides alternate reaction pathway that lowers the activation energy
- can be measured by noting ROR
enzyme action
- reactant/substrate binds to enzyme at active site - it will be S+C in terms of shape and charge
- not consumed
lock and key enzyme model
substrate perfectly fits into enzyme , like a lock
- after successful binding forms an ESC and catalyse reaction = catabolism or anabolism
enzyme induced fit
- shape of the substrate X perfectly complimentary to shape of as.
- to overcome this as adjusts to become S+C to substrate
- afterwards the as. returns to its original shape/ remains unchanged
enzyme activity definition
amount of substrate converted to product per unit time
denaturation of enzymes
-temp - increase KE makes molecules vibrate more rapidly so H bond , interaction bw R groups and arrangement of protein is disrupt
-pH -change the 3D shape of protein
enzyme - enantiomers
- only catalyses a reaction w one enantiomer bc the as is S+C - different arrangement of atoms - specificity
coenzymes
-do not catalyse a reaction
-temporarily bind to as of enzyme as they are modified to suit the shape of the substrate
- serve as a carrier of groups of atom/ e-
calibration factor electrical
CF= VxI xT
————-
delta T
calibration factor chemical
CF = E/ delta T
poorly insulated calorimeters need what
to extrapolate data back to time calorimeter was turned on
what is a condition for bomb calorimetry
high pressure to ensure reaction goes to completion
calorimetry
method where the heat released or abosrbed is measured
random errors for calorimetry
- not all food combusted
- incomplete combustion
- temperature change = inaccurate
systematic error for calorimetry
- calirometer calibrated incorrectly
- measurement to calibrate eq. = incorrect - affect energy calc.
types of calorimeter
solution and bomb
bomb calorimetry
-measures HoC of chemical reactions that involve gaseous reactants or products
-exothermic
-measures heat content of fuels and foods
solution calorimetry
- calculates energy transferred in a chemical reaction
- measure heat of solution/neutralisation
