food and digestion Flashcards
Fatty acids and glycerol are used
-For energy
-To build cell membranes
-To make hormones
amino acids
used for building cell components
Glucose
used to supply energy
breakdown of fat
Firstly, bile (released by the gall bladder) allows the fat to ‘mix’ with water by breaking the fat into smaller droplets and increases the surface area of fat droplets. This is called emulsification
Secondly, the digestive enzyme lipase breaks each fat molecule into the smaller glycerol and fatty acid molecules.
enzymes
Enzymes are biological catalysts and they catalyse most chemical reactions in cells such as respiration, photosynthesis and protein synthesis.
Enzymes are large protein molecules made from a unique sequence of coiled amino acids this gives the active site - the area that is attached to the substrate a very specific shape that fits the substrate exactly
COMPLIMENTARY
enzymes function
enzymes help to:
* break down large molecules into smaller ones
* build large molecules from smaller ones.
* Change one molecule into another molecule.
temperature effect on enzyme activity
glucose food test
Reagent - Benedict’s
Method - add Benedict’s with food into test tube, heat
initial colour – blue
positive result - brick red
starch food test
Reagent - iodine
Method - add iodine to food.
initial colour – yellow
positive result – blue/black
lipids food test
Reagent - ethanol
Method - mash food in distilled water and pour liquid into test tube, add ethanol, shake and add cold water
initial colour – colourless
positive result – white milky emulsiom
Carbohydrase
released in - Salivary glands, Pancreas, small intestine
function - breaks down carbohydrates into sugars e.g. starch into glucose
lipase
lipase
released in – pancreas, small intestine
function - breaks down liquids into fatty acids and glycerol
protease
released in – stomach, pancreas, small intestine
function - breaks down proteins into amino acids
Carbohydrates
for energy
fats (lipids)
for energy & making cell membranes
protein
for growth and repair
minerals
in small amounts to make body chemicals
vitamins
in small amounts for cells to work properly
fibre
to keep your bowels working
water
for chemical reactions to occur + transportation
mouth
Your teeth help chop up food here and masticates it. it gives the food a larger surface area for enzymes to work on. this mixes food with saliva making it easier to swallow.
saliva
saliva contains Carbohydrase and mucus for lubrication.
oesophagus
a muscular tube carrying food from the throat to the stomach. when food enters this tube, the muscles in the oesophagus start to contract & force the food towards the stomach by peristalsis.
gastric juice
a mixture of hydrochloric acid mucus and enzymes
stomach
muscular bag filled with gastric juice helping chemically digest food down further. There’s also mechanical digestion with the stomach churning the food and turning it into a pulp called chyme.
pancreas
This makes a lot of enzymes. E.g. lipase carbohydrase protease.
liver
stores some nutrients, vitamins and minerals from digestion, changes them from one form to another and releases them into the blood according to the needs of the body. The liver also makes bile which is stored in the gall bladder but released by the bile duct.
small intestine
site of maximum absorption
three liquids are added here:
bile - helps to neutralise acid added to food in the stomach and is the best PH for enzymes to work. it also helps breakdown fats.
Pancreatic and intestinal juices - have enzymes to break food down so nutrients can dissolve into the blood stream
Large intestine
Water & Body minerals are absorbed here back into the blood. the remaining non nutritional matter is formed into semisolid brown faeces.
Rectum
end of large intestine where faeces are stored
anus
the place where the faeces come out
protein food test
Reagent - biuret
Method - mash food in distilled water and add to test tube with biuret.
initial colour – blue
positive result – purple / lilac
